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Proceedings, 2020, ISEA 2020

The 13th Conference of the International Sports Engineering Association

Online | 22–26 June 2020

Editors: Motomu Nakashima, Takeo Maruyama and Yusuke Miyazaki


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Open AccessEditorial
The 13th Conference of the International Sports Engineering Association (ISEA 2020)
Proceedings 2020, 49(1), 111; https://doi.org/10.3390/proceedings2020049111 - 15 Jun 2020
Viewed by 322
Abstract
Every second year, the International Sports Engineering Association (ISEA) conducts a conference somewhere around the world. [...] Full article
Open AccessProceedings
Comparison between Indoor Sled Tests on the SkillrunTM Treadmill and Outdoor Field Tests at Increasing Sled Loads
Proceedings 2020, 49(1), 18; https://doi.org/10.3390/proceedings2020049018 - 15 Jun 2020
Viewed by 485
Abstract
The aim of the study was to compare the power output during indoor sprints on a SKILLRUNTM treadmill with the power output expressed in outdoor sprints pushing an instrumented sled. The SKILLRUNTM has been chosen because it is able to simulate [...] Read more.
The aim of the study was to compare the power output during indoor sprints on a SKILLRUNTM treadmill with the power output expressed in outdoor sprints pushing an instrumented sled. The SKILLRUNTM has been chosen because it is able to simulate the outdoor sprint pushing a sled setting different loads and providing performance output data like speed and power. Two athletes were involved in this pilot study and were asked to perform indoor and outdoor sprints with the same overloads. Two dynamometric handles were designed and applied both on the treadmill for the indoor sprints and on the sled for the outdoor sprints. Power data were calculated throughout the force measured at the handles and the speed collected during the sprints. Kinematics data of trunk and lower limbs were also calculated by means of a set of inertial sensors (Xsens, Enschede, The Netherlands). The power–speed and the load–speed curves together with the kinematics results derived from the indoor and outdoor tests were compared, showing, in general, a good agreement between the indoor and outdoor conditions. These results highlighted the validity of the SKILLRUNTM treadmill in simulating a sprint with overloads. Full article
Open AccessProceedings
Plantar Pressure Distribution under Uniform and Gradient Foam during Running and Jumping
Proceedings 2020, 49(1), 116; https://doi.org/10.3390/proceedings2020049116 - 15 Jun 2020
Viewed by 503
Abstract
Auxetic materials have a negative Poisson’s ratio, meaning they contract laterally during axial compression. Auxetics can also absorb more energy during impacts than conventional materials. Auxetic foam was fabricated by volumetrically compressing open cell foam to buckle cell ribs and impart a re-entrant [...] Read more.
Auxetic materials have a negative Poisson’s ratio, meaning they contract laterally during axial compression. Auxetics can also absorb more energy during impacts than conventional materials. Auxetic foam was fabricated by volumetrically compressing open cell foam to buckle cell ribs and impart a re-entrant cell structure, then the imposed structure was fixed by heating and cooling. Passing pins through the foam allowed localised control over compression during fabrication, producing gradient foam with regions with differing Poisson’s ratios and stress vs. strain relationships. Uniform sheets had volumetric compression ratios of three, gradient sheets had volumetric compression ratios of one (unchanged) or three in different regions. One participant jumped barefoot on all foams, cut out to fit pressure sensors; another ran wearing shoes containing uniform converted and unconverted foam insoles. Pressure distribution was measured underneath the foams and foam insoles. Peak pressure was lowest underneath converted foams, warranting further investigation with more participants. Full article
Open AccessProceedings
Force Pattern and Acceleration Waveform Repeatability of Amateur Runners
Proceedings 2020, 49(1), 136; https://doi.org/10.3390/proceedings2020049136 - 15 Jun 2020
Viewed by 402
Abstract
Although accelerometers’ responses during running are not perfectly understood, they are widely used to study performance and the risk of injury. To outline the typical tibial acceleration pattern during running, this study aims to investigate the repeatability of acceleration signals with respect to [...] Read more.
Although accelerometers’ responses during running are not perfectly understood, they are widely used to study performance and the risk of injury. To outline the typical tibial acceleration pattern during running, this study aims to investigate the repeatability of acceleration signals with respect to the ground reaction force waveforms. Ten amateur runners were asked to perform ten trials along a straight line. One participant was asked to perform this protocol over ten sessions. Tibial accelerations and ground reaction forces were measured during the stance phase. The coefficient of multiple correlation R was computed to study the intra- and inter-test and subject repeatability of accelerometric and force waveforms. A good (R>0.8) intra- and inter-test repeatability was observed for all measured signals. Similar results were observed for intra-subject repeatability. A good inter-subject repeatability was observed only for the longitudinal acceleration and vertical and antero-posterior forces. Typical accelerometric signatures were outlined for each case studied. Full article
Open AccessProceedings
Features Observed Using Multiple Inertial Sensors for Running Track and Hard-Soft Sand Running: A Comparison Study
Proceedings 2020, 49(1), 12; https://doi.org/10.3390/proceedings2020049012 - 15 Jun 2020
Viewed by 476
Abstract
Variability in the running surface can cause an athlete to alter their gait. Most literature report running on grass, a treadmill or athletics running tracks using inertial sensors. This study compares the signals obtained by 9 degrees of freedom (DOF) inertial-magnetic sensors incorporating [...] Read more.
Variability in the running surface can cause an athlete to alter their gait. Most literature report running on grass, a treadmill or athletics running tracks using inertial sensors. This study compares the signals obtained by 9 degrees of freedom (DOF) inertial-magnetic sensors incorporating an accelerometer (±16 g), gyroscope (±2000°/s) and magnetometer (±8 gauss). The sensors were placed on the participant’s shank, knee, lower spine and upper spine, and the participants were asked to run on three different surfaces (running track, hard sand and soft sand). The calculated player loads for a 400 m run on each surface type was very similar. The mean and standard deviation values were 577 ± 130, 581 ± 128, 568 ± 124 for soft sand, hard sand and the running track, respectively. This did not correlate with the participant’s self-assessment RPE (Rate of perceived exertion), which demonstrated running on soft sand to be significantly more challenging, yielding a mean and standard deviation of 5.3 ± 2.5 (Hard to Very Hard). Soft sand running had a decreased swing time duration but increased variability (0.44 ± 0.02 s—Swing Time, 6.5 ± 1.1%—CV), hard sand running had the longest swing and intermediate variability duration (0.46 ± 0.02 s—Swing Time, 3.30 ± 2.58 %—CV) and running track running had the medium swing time but lowest variability (0.45 ± 0.02 s, 2.7 ± 0.9%—CV). Gait dominance was not consistent across the surfaces for each participant and remained below a ratio of 0.4. These results provide an insight into how athletes modify their gait mechanics to accommodate different running surfaces. Full article
Open AccessProceedings
Mechanical Advantages and Disadvantages of a Lower Limb Using Forefoot to Heel Strike Landing
Proceedings 2020, 49(1), 15; https://doi.org/10.3390/proceedings2020049015 - 15 Jun 2020
Viewed by 504
Abstract
A previous study reported that habitually barefoot Kenyan distance runners tend to use a mid-foot strike or a forefoot-heel strike (FHS). Current findings indicate FHS helps enhance Kenyans’ running performance. However, no study has investigated how FHS modulates leg stiffness (kleg) [...] Read more.
A previous study reported that habitually barefoot Kenyan distance runners tend to use a mid-foot strike or a forefoot-heel strike (FHS). Current findings indicate FHS helps enhance Kenyans’ running performance. However, no study has investigated how FHS modulates leg stiffness (kleg) and altered running velocity with changes in kleg. Because vertical displacement of the centre of mass and kleg during hopping are applicable to the running process, this study investigated how FHS affects kleg and hopping frequency (fhopping) during hopping. Subjects hopped at 2.2 Hz with normal hopping (NH-2.2Hz) and at a comfortable frequency with FHS (FHS-CF). According to each subject’s comfortable frequency at FHS-CF, they were divided into higher (HG, 2.49 ± 0.11 Hz) and lower (LG, 2.16 ± 0.19 Hz) groups. With FHS-CF, the flight duration in HG was significantly shorter than that in LG. kleg in HG was greater than that in LG. Negative work in the first half of the stance phase and positive work in the second half of the stance phase at all three joints were smaller in HG than in LG. The touchdown angle was larger and angular displacements at the joints were smaller in HG than in LG. The findings indicate that when hoppers used FHS, they increased their preferred fhopping by stiffening their leg joints during the stance phase and jumping with a lower height than in normal hopping; additionally, it is important to increase the touchdown joint angle for a stiffened joint. Full article
Open AccessProceedings
Measurement of Pelvic Orientation Angles during Sprinting Using a Single Inertial Sensor
Proceedings 2020, 49(1), 10; https://doi.org/10.3390/proceedings2020049010 - 15 Jun 2020
Viewed by 234
Abstract
The purpose of this study was to elucidate pelvic orientation angles using a single lower back-mounted inertial sensor during sprinting. A single inertial sensor was attached to each sprinter’s lower back, used to measure continuous pelvic movements including pelvic obliquity (roll), anterior-posterior tilt [...] Read more.
The purpose of this study was to elucidate pelvic orientation angles using a single lower back-mounted inertial sensor during sprinting. A single inertial sensor was attached to each sprinter’s lower back, used to measure continuous pelvic movements including pelvic obliquity (roll), anterior-posterior tilt (pitch) and rotation (yaw) during sprinting from a straight to bend section. The pelvic orientation angles were estimated with the three-dimensional sensor orientation using a sensor fusion algorithm. Absolute angles derived from the sensor were compared with angles obtained from an optical motion capture system over a 15 m length. The root mean squared error between the sensor and motion capture data were 4.1° for roll, 2.8° for pitch and 3.6° for yaw. Therefore, the sensor was comparable to the motion capture system for tracking pelvic angle changes. The inertial sensor is now supported as a valid tool to measure movements of the pelvis during sprinting. Full article
Open AccessProceedings
A Study of Skin-Close Heat and Moisture with Different Types of Backpacks in Cycling
Proceedings 2020, 49(1), 86; https://doi.org/10.3390/proceedings2020049086 - 15 Jun 2020
Viewed by 347
Abstract
The aim of this project was to evaluate effects of backpacks with different design intended for use during cycling on skin-close temperature and relative humidity, oxygen uptake, heart rate and aerodynamic drag. Seven subjects took part in the study cycling on a mountain [...] Read more.
The aim of this project was to evaluate effects of backpacks with different design intended for use during cycling on skin-close temperature and relative humidity, oxygen uptake, heart rate and aerodynamic drag. Seven subjects took part in the study cycling on a mountain bike mounted on a “smart trainer” placed on a force plate in a wind tunnel. Three series of experiments were carried out: without backpack, with conventional backpack and with a backpack having innovative rear panel design. As hypothesized, the results showed that an innovatively designed backpack with the ducts deflecting part of the airflow towards some areas of the user’s back provided lower temperature and relative humidity for the microclimate compared to a conventional backpack without airflow channels. Further, reference tests without any backpack resulted in the lowest temperature and humidity. However, no differences were found between the three tests for oxygen uptake, heart rate and aerodynamic drag. Full article
Open AccessProceedings
Exposure of Children in a Bicycle Trailer to Whole-Body Vibration
Proceedings 2020, 49(1), 114; https://doi.org/10.3390/proceedings2020049114 - 15 Jun 2020
Viewed by 380
Abstract
This study investigated the effects of road surface (tarmac, gravel, cobblestones), load case (single passenger, two passengers), tire pressure (3.0, 4.0, 5.0 bar), and cycling velocity (10.0, 17.5, 25.0 km/h) on the whole-body vibration of children being transported in a bicycle trailer. Two [...] Read more.
This study investigated the effects of road surface (tarmac, gravel, cobblestones), load case (single passenger, two passengers), tire pressure (3.0, 4.0, 5.0 bar), and cycling velocity (10.0, 17.5, 25.0 km/h) on the whole-body vibration of children being transported in a bicycle trailer. Two types of passive dummies were utilized to mimic a baby and a toddler passenger in terms of weight and height. Road type and cycling velocity caused statistically significant change on the magnitude of whole-body vibrations. Overall, vibration total values were on the “uncomfortable” level of the vibration discomfort scale or even above. The major limitation of the study is the application of passive dummies, which might not represent the biodynamics of the target population. Full article
Open AccessProceedings
Understanding the Effect of Gloves on Hand-Arm Vibrations in Road Cycling
Proceedings 2020, 49(1), 70; https://doi.org/10.3390/proceedings2020049070 - 15 Jun 2020
Viewed by 384
Abstract
The aim of this research was to study the effects of cycling gloves on hand-arm vibrations in realistic load scenarios. A test has been performed in the laboratory, a road bicycle handlebar was mounted to the hydraulic cylinder of a universal testing machine, [...] Read more.
The aim of this research was to study the effects of cycling gloves on hand-arm vibrations in realistic load scenarios. A test has been performed in the laboratory, a road bicycle handlebar was mounted to the hydraulic cylinder of a universal testing machine, and the bicycle was fixed on an indoor trainer. Tests were executed for three different hand sizes (small, medium, large), three different frequency ranges (15–25, 35–45, 85–95 Hz), with two different types of gloves (gel-padded; non-padded) and without gloves. The amplitudes and each frequency bands were obtained from a previous field test. Hand-arm vibrations were quantified by means of root mean square values of the frequency-weighted accelerations measured at the subject’s wrist joint. Analysis of variance (ANOVA) showed no significant effect of gloves in reducing vibration transmissibility. Full article
Open AccessProceedings
Bicycle Disc Brake Thermal Performance: Combining Dynamometer Tests, Bicycle Experiments, and Modeling
Proceedings 2020, 49(1), 100; https://doi.org/10.3390/proceedings2020049100 - 15 Jun 2020
Viewed by 324
Abstract
High-power bicycle disc braking can create excessive temperatures and boiling brake fluid, resulting in performance degradation and damage. The goal of this work is to understand brake friction performance and thermal behavior for bicycle disc brakes. A previously described disc braking dynamometer is [...] Read more.
High-power bicycle disc braking can create excessive temperatures and boiling brake fluid, resulting in performance degradation and damage. The goal of this work is to understand brake friction performance and thermal behavior for bicycle disc brakes. A previously described disc braking dynamometer is used to assess brake pad performance of sintered metallic brake pads, organic brake pads, and ‘power’ organic pads in up to 400 W of braking power. The friction coefficient is found to be dependent on both temperature and normal force. Friction curve fits are provided for temperatures between 300 K and 550 K. Organic and ‘power’ organic pads are found to have similar behavior, and have higher friction coefficients compared to metallic pads. Further, brakes on an instrumented bicycle are tested in outdoor field trials during downhill descent. A MATLAB thermal model successfully predicts the downhill field brake disc temperatures when using the friction data curve fits. Full article
Open AccessProceedings
On the Effectiveness of Suspension Stems in Reducing the Vibration Transmitted to a Cyclist’s Hands in Road Cycling
Proceedings 2020, 49(1), 20; https://doi.org/10.3390/proceedings2020049020 - 15 Jun 2020
Viewed by 342
Abstract
The practice of road cycling is often associated with low levels of comfort for the cyclist and can be a physically painful experience on bad roads. Apart from cushioning in the saddle, applying handlebar tape, or reducing tyre pressure, a road bicycle offers [...] Read more.
The practice of road cycling is often associated with low levels of comfort for the cyclist and can be a physically painful experience on bad roads. Apart from cushioning in the saddle, applying handlebar tape, or reducing tyre pressure, a road bicycle offers in itself few options for comfort improvement, as it is primarily designed for performance, with emphasis on low mass and high stiffness. However, a range of components exist (e.g., suspension stems and seatposts) that can be fitted to a road bicycle, which can potentially improve comfort. In this context, the aim of this study was to assess the effectiveness of suspension stems in reducing the vibration transmitted to a cyclist’s hands in the case of impact loading. The results showed an important reduction in the vibrational energy transmitted to a cyclist’s hands with two commercially available suspension stems compared to a regular stem. Full article
Open AccessProceedings
Development of a Feedback System to Control Power in Cycling
Proceedings 2020, 49(1), 22; https://doi.org/10.3390/proceedings2020049022 - 15 Jun 2020
Viewed by 432
Abstract
Here we seek to control mechanical power output in outdoor cycling by adjusting commanded cadence of a cyclist. To understand cyclist’s dynamic behavior, we had one participant match their cadence to a range of commanded cadences. We then developed a mathematical model that [...] Read more.
Here we seek to control mechanical power output in outdoor cycling by adjusting commanded cadence of a cyclist. To understand cyclist’s dynamic behavior, we had one participant match their cadence to a range of commanded cadences. We then developed a mathematical model that predicts the actual mechanical power as a function of commanded cadence. The average absolute error between the predicted power of our model and the actual power was 15.9 ± 11.7%. We used this model to simulate our closed-loop controller and optimize for proportional and integral controller gains. With these gains in outdoor cycling experiments, the average absolute error between the target and the actual power was 3.2 ± 1.2% and the average variability in power was 2.9 ± 1.3%. The average responsiveness, defined as the required time for the actual power to reach 95% of the target power following changes in target power, was 7.4 ± 2.0 s. Full article
Open AccessProceedings
The Steel Bicycle Project: Bringing Together Tube Manufacturers, Frame Builders, and Engineers through Sports Engineering
Proceedings 2020, 49(1), 166; https://doi.org/10.3390/proceedings2020049166 - 15 Jun 2020
Viewed by 265
Abstract
Steel, being the most commonly used bicycle frame material, has a major role to play in future developments within the bicycle industry, and there is scope to enhance the role of engineering in the development of steel bicycles. This paper introduces The Steel [...] Read more.
Steel, being the most commonly used bicycle frame material, has a major role to play in future developments within the bicycle industry, and there is scope to enhance the role of engineering in the development of steel bicycles. This paper introduces The Steel Bicycle Project (TSBP), an open-ended project which aims to raise awareness of engineering principles that relate to steel bicycle frames and aims to support frame builders in designing and fabricating better and safer products. In this paper, we give details of the main project themes (Design and simulation, Materials and fabrication, Testing and measurements, Knowledge and education) and outcomes. We also present some initial activities from the early stages of the project and will discuss general models to bring together key partners under the umbrella of the sports engineering community. Full article
Open AccessProceedings
Enhancing the Performance of Elite Speed Skaters Using SkateView: A New Device to Measure Performance in Speed Skating
Proceedings 2020, 49(1), 133; https://doi.org/10.3390/proceedings2020049133 - 15 Jun 2020
Viewed by 220
Abstract
In speed skating, environmental circumstances and the near-frictionless movement of the skate in a fore–aft direction over the ice make it difficult to measure technical performance parameters on a regular basis while training in an indoor speed skating rink. SkateView has been developed [...] Read more.
In speed skating, environmental circumstances and the near-frictionless movement of the skate in a fore–aft direction over the ice make it difficult to measure technical performance parameters on a regular basis while training in an indoor speed skating rink. SkateView has been developed to overcome these challenges, comprising of two IMU’s (Inertial Measurement Unit), ultra-light force sensors, a mobile phone and an app providing feedback to coach and skater. The feedback, directly on the ice or shortly after a training session, consists of basic parameters like ice contact time, stroke frequency and lap times, and more parameters can be added. Stroke frequency is an important performance parameter, which is presented on a stroke–by–stroke basis and provides a direct insight into the activity. Full article
Open AccessProceedings
2D Video Analysis System to Analyze the Performance Model of Figure Roller Skating: A Pilot Study
Proceedings 2020, 49(1), 155; https://doi.org/10.3390/proceedings2020049155 - 15 Jun 2020
Viewed by 317
Abstract
Figure roller skating is a discipline composed of various movements which involve jumps, artistic figures and spins in a seamless program which has both technical and shapely difficult. A biomechanical analysis of a double salchow was performed using a 2D video analysis of [...] Read more.
Figure roller skating is a discipline composed of various movements which involve jumps, artistic figures and spins in a seamless program which has both technical and shapely difficult. A biomechanical analysis of a double salchow was performed using a 2D video analysis of one European and in two Italian roller skaters. On average, the high level (HL) roller skater showed a horizontal velocity of the center of mass higher than the average, especially in the prop stage, whereas the medium level (ML) and low level (LL) athletes reduced their velocity significantly. The spin angular velocity of the ML and LL skaters was always higher than of the HL. This phenomenon would seem to be a compensatory strategy for a lower jump height, with a reduced trunk-thigh angle and less thigh lever arm (coxo-femur/knee joints) during the take-off and landing phases of the double salchow jump. Full article
Open AccessProceedings
Comparing Broom Conditions in Curling: Measurements Using Ice Topography
Proceedings 2020, 49(1), 82; https://doi.org/10.3390/proceedings2020049082 - 15 Jun 2020
Viewed by 629
Abstract
The sport of curling is played on an ice surface with raised ice pebbles and uses curling rocks made of granite. The effect of sweeping is thought to straighten the rock’s projected curved path and increase the distance travelled. Recent anecdotes suggest that [...] Read more.
The sport of curling is played on an ice surface with raised ice pebbles and uses curling rocks made of granite. The effect of sweeping is thought to straighten the rock’s projected curved path and increase the distance travelled. Recent anecdotes suggest that sweeping from the center of the running surface with the direction of rotation and curl is thought to increase the amount of curl, whereas sweeping against and opposite the curl is thought to decrease the amount of curl. The purpose of this study is to observe the topography of the ice surface while comparing scratch measurements from different broom materials. Nine conditions were replicated: nipped pebble, rock traversing the ice, and seven broom conditions. Replicas of the ice were created with vinyl polysiloxane and observed with an optical microscope. Roughness profiles of the replicas were measured, and broom materials were compared using data from an optical profiler. Full article
Open AccessProceedings
Multi-Technology Correction Based 3D Human Pose Estimation for Jump Analysis in Figure Skating
Proceedings 2020, 49(1), 95; https://doi.org/10.3390/proceedings2020049095 - 15 Jun 2020
Viewed by 242
Abstract
Jump analysis in figure skating is important. Recovering the 3D pose of a figure skater has become increasingly important. However, issues such as restrictions from an athlete’s clothing, self-occlusion, abnormal pose and so on will result in poor results. This paper proposes a [...] Read more.
Jump analysis in figure skating is important. Recovering the 3D pose of a figure skater has become increasingly important. However, issues such as restrictions from an athlete’s clothing, self-occlusion, abnormal pose and so on will result in poor results. This paper proposes a multi-technology correction framework to obtain a 3D human pose. The framework consists of three key components: temporal information-based mutational point correction, multi-perspective-based reconstructed point selection and trajectory smoothness-based inaccurate point correction. Firstly, temporal information is used to correct the mutational points at the 2D level. Secondly, a multi-perspective is used to select the correct spatial points at the 3D level. Thirdly, trajectory smoothness is used to correct inaccuracies at the 3D level. This work will serve the purpose of displaying the 3D animated pose of a figure skater. The quality grade of the result rate on the test sequences is 87.25%. Full article
Open AccessProceedings
Kinematic Analysis of Figure Skating Jump by Using Wearable Inertial Measurement Units
Proceedings 2020, 49(1), 124; https://doi.org/10.3390/proceedings2020049124 - 15 Jun 2020
Viewed by 229
Abstract
The purpose of this study was to demonstrate the feasibility of measuring and analyzing characteristics of figure skating jumps using wearable sensors. One elite figure skater, outfitted with five inertial measurement units (IMUs), performed flip jumps with single, double, and triple revolutions. Take-off [...] Read more.
The purpose of this study was to demonstrate the feasibility of measuring and analyzing characteristics of figure skating jumps using wearable sensors. One elite figure skater, outfitted with five inertial measurement units (IMUs), performed flip jumps with single, double, and triple revolutions. Take-off event and flight phase of each trial were under analysis. Kinematic differences among jumps with variant revolutions as well as key factors for performing successfully landed triple jumps were determined by IMU signals. Compared with a video-based method, this study revealed the following characteristics that coincide with previous studies: at take-off event, the skater performed pre-rotation and took off with preferred postural positions as revolutions increased (p < 0.01); during flight, the skater struggled more to maintain the smallest inertial of moment as revolutions increased (p < 0.01); in order to perform successfully landed jumps, it was crucial that the skater improved the control of preparation for flight at take-off (p < 0.05). Full article
Open AccessProceedings
Optimal Shooting Cadence in the Laser-Run Trial of Modern Pentathlon
Proceedings 2020, 49(1), 46; https://doi.org/10.3390/proceedings2020049046 - 15 Jun 2020
Viewed by 260
Abstract
In the laser-run trial in modern pentathlon, athletes must perform series of five successful shots with a laser pistol. A miss does not lead to a penalty but costs the time needed to lower the arm, charge the weapon and raise the arm. [...] Read more.
In the laser-run trial in modern pentathlon, athletes must perform series of five successful shots with a laser pistol. A miss does not lead to a penalty but costs the time needed to lower the arm, charge the weapon and raise the arm. Pentathletes face the following dilemma: is it better to shoot fast or accurately? We investigate experimentally the effect of the shooting cadence on the accuracy. We then predict the consequence of this unavoidable speed-accuracy tradeoff in terms of total time needed to succeed the specific trial of laser-run. We find an optimal shooting cadence for each athlete, which minimizes this time. Full article
Open AccessProceedings
Use of Acceleration Sensors in Archery
Proceedings 2020, 49(1), 98; https://doi.org/10.3390/proceedings2020049098 - 15 Jun 2020
Viewed by 381
Abstract
Archery is a quasi-static sport. Nevertheless, it requires maximum concentration, as well as precision from the archer. Previous research used combinations of several sensors, video analysis and electromyography to analyse the motion sequence and to identify parameters leading to a worse score. Therefore, [...] Read more.
Archery is a quasi-static sport. Nevertheless, it requires maximum concentration, as well as precision from the archer. Previous research used combinations of several sensors, video analysis and electromyography to analyse the motion sequence and to identify parameters leading to a worse score. Therefore, the aim of this study is to verify if solely an acceleration sensor on the archer’s hand, without complex data processing, could be used to set up a feedback system. For testing, six participants with a three dimensional acceleration sensor on each hand shot indoors at a vertical triple target. The parameters analysed were the duration of the movement, the range of motion and the coefficient of variation. The results indicate that the analysis of the coefficient of variation shows no correlation with the score reached, whereas the analysis of the duration and the range of motion does. Full article
Open AccessProceedings
Experimental and Computational Study of Archery Arrows Fletched with Straight Vanes
Proceedings 2020, 49(1), 56; https://doi.org/10.3390/proceedings2020049056 - 15 Jun 2020
Viewed by 223
Abstract
The aerodynamic characteristics of archery arrows fletched with two types of straight vanes, for which the area is different, were studied. The arrows’ pitching moment (CM), lift (CL) and drag (CD) coefficients were measured [...] Read more.
The aerodynamic characteristics of archery arrows fletched with two types of straight vanes, for which the area is different, were studied. The arrows’ pitching moment (CM), lift (CL) and drag (CD) coefficients were measured in the 60 × 60 cm Magnetic Suspension and Balance System (MSBS) from JAXA. At a Reynolds number of Re = 1.2 × 104, the values of CD were 1.56 and 2.05 for the short and large vanes, respectively. In a second experimental procedure, the arrows’ deceleration in free flight was measured by inserting an acceleration sensor inside their shafts. For shots with an initial velocity of around 56.4 ms−1, a velocity decay of around 8% was measured. A turbulent–laminar boundary layer transition during free flight was found for shots with an average Re = 1.8 × 104. Lastly, through numerical computations, the area difference of the two vanes was analyzed to verify the importance of CM and CL during the arrows’ flights. Full article
Open AccessProceedings
Development of an Archery Robot for the Selection of Arrows
Proceedings 2020, 49(1), 115; https://doi.org/10.3390/proceedings2020049115 - 15 Jun 2020
Viewed by 227
Abstract
The appropriate selection of arrows in the sport of archery is important to the achievement of high-quality results. In this regard, a shooting machine that is compatible with the wide variety of available bows and arrows is necessary. However, bow strength and arrow [...] Read more.
The appropriate selection of arrows in the sport of archery is important to the achievement of high-quality results. In this regard, a shooting machine that is compatible with the wide variety of available bows and arrows is necessary. However, bow strength and arrow length vary among different athletes. It is also important to develop a shooting machine that reproduces the movement of the right fingers that releases an arrow, and the forward jump of a bow after shooting an arrow. In this study, a shooting machine was developed that considered these factors. Its efficacy was examined in terms of its ability to determine the characteristics of each arrow, and to distinguish between normal and flawed arrows. Based on the experimental results, we identified the factors that affected the shooting accuracy of arrows. In addition, the developed shooting machine was able to distinguish between normal and flawed arrows. Full article
Open AccessProceedings
Motion and Muscle Activity of Synchronized Rolling-Type Double-Leg Circles on a Pommel Horse
Proceedings 2020, 49(1), 31; https://doi.org/10.3390/proceedings2020049031 - 15 Jun 2020
Viewed by 231
Abstract
Experimental analyses of motions of a double-leg circle were conducted for a smooth and dynamic movement. A motion capture system provided the data for two different gymnasts; one is well trained and the other has an average skill level. Lissajous analysis was done [...] Read more.
Experimental analyses of motions of a double-leg circle were conducted for a smooth and dynamic movement. A motion capture system provided the data for two different gymnasts; one is well trained and the other has an average skill level. Lissajous analysis was done for a tip-toe circling motion and a rolling motion around a longitudinal axis of a body. The results show that synchronization between the tip-toe circling and the body-rolling around the body’s longitudinal axis is crucial. Muscle activity was also analyzed from electromyogram data when the gymnasts performed double-leg circles, and the muscle activity characteristics of synchronized rolling-type circles were uncovered. Full article
Open AccessProceedings
Investigation of the Athlete’s Motion Using the Gymnastics Apparatus’s Motion
Proceedings 2020, 49(1), 120; https://doi.org/10.3390/proceedings2020049120 - 15 Jun 2020
Viewed by 278
Abstract
In gymnastics, the skeleton of the athletes can be estimated from many points with three-dimensional coordinate data by measurement control using Laser Imaging Detection and Ranging (LIDAR), and the motion can be derived. However, the system cannot know what kind of load is [...] Read more.
In gymnastics, the skeleton of the athletes can be estimated from many points with three-dimensional coordinate data by measurement control using Laser Imaging Detection and Ranging (LIDAR), and the motion can be derived. However, the system cannot know what kind of load is being put on the athletes’ bodies. Additionally, it is not possible to know in detail how top-level athletes handle apparatus. Therefore, it is important to understand the dynamic response of the apparatus to the athlete’s motion. This study shows that the apparatus’s motion can be identified by performing a static load test using a multi-sensing system that can sense how the bar deforms during a game and determine the apparatus’s motions as an inverse analysis. Full article
Open AccessProceedings
Fully Coupled Modeling of Athlete Force Application and Power Transfer in Rowing Ergometry
Proceedings 2020, 49(1), 108; https://doi.org/10.3390/proceedings2020049108 - 15 Jun 2020
Viewed by 290
Abstract
A fully coupled model of an athlete’s muscular force output combined with a load resistance is developed and investigated in context of ergometer rowing. The athlete force is based on a simple Hill equation hyperbolic-in-speed, and parabolic-in-length model. Coupling this force function with [...] Read more.
A fully coupled model of an athlete’s muscular force output combined with a load resistance is developed and investigated in context of ergometer rowing. The athlete force is based on a simple Hill equation hyperbolic-in-speed, and parabolic-in-length model. Coupling this force function with the dynamics of the ergometer load and inertia and athlete’s own body mass inertia produces a trajectory of the resultant motion in force-speed-length space. The coupled equations were solved using a first order time-marching procedure, and iteratively calculated starting conditions based on ergometer spin-down during the recovery period between strokes. The results agree well with experimental measurements available from Kleshnev particularly given the relatively simple, and untuned, athlete force model used. Changing the load resistance changed the trajectory of the stroke, with qualitative agreement with the expected outcomes. Full article
Open AccessProceedings
Association between Changes in Swimming Velocity, Vertical Center of Mass Position, and Projected Frontal Area during Maximal 200-m Front Crawl
Proceedings 2020, 49(1), 60; https://doi.org/10.3390/proceedings2020049060 - 15 Jun 2020
Viewed by 242
Abstract
We examined the association between changes in swimming velocity, vertical center of mass (CoM) position, and projected frontal area (PFA) during maximal 200-m front crawl. Three well-trained male swimmers performed a single maximal 200-m front crawl in an indoor 25-m pool. Three-dimensional (3D) [...] Read more.
We examined the association between changes in swimming velocity, vertical center of mass (CoM) position, and projected frontal area (PFA) during maximal 200-m front crawl. Three well-trained male swimmers performed a single maximal 200-m front crawl in an indoor 25-m pool. Three-dimensional (3D) shape data of the whole body were fitted to 3D motion data during swimming by using inverse kinematics computation to estimate PFA accurately. Swimming velocity decreased, the vertical CoM position was lowered, and PFA increased with swimming distance. There were significant correlations between swimming velocity and vertical CoM position (|r| = 0.797–0.982) and between swimming velocity and PFA (|r| = 0.716–0.884) for each swimmer. These results suggest that descent of the swimmer’s body and increasing PFA with swimming distance are associated with decreasing swimming velocity, although the causal factor remains unclear. Full article
Open AccessProceedings
Simulation Model of Flip Turn in Swimming
Proceedings 2020, 49(1), 165; https://doi.org/10.3390/proceedings2020049165 - 15 Jun 2020
Viewed by 286
Abstract
The swimming turn is one of the important factors in producing results in a race. Knowing the mechanical quantities in turns is useful to quantify the turning technique. However, experimental measurements often require considerable time and costs. The aim of this study was [...] Read more.
The swimming turn is one of the important factors in producing results in a race. Knowing the mechanical quantities in turns is useful to quantify the turning technique. However, experimental measurements often require considerable time and costs. The aim of this study was to construct a simulation model of a flip turn in the crawl stroke by extending the swimming human simulation model SWUM. The joint motion was created based on the standard crawl motion and a turn commentary video on the Internet. Furthermore, the contact with the wall was represented as forces by virtual springs and dampers and the frictional forces. As a result of simulation, a successful turning motion was confirmed. It was also found that the simulated contact time, the maximum force, and the impulse were within the ranges of the previous research. Full article
Open AccessProceedings
The Difference of Propulsive Force between Water Surface and Underwater Conditions in Flutter Kick Swimming
Proceedings 2020, 49(1), 167; https://doi.org/10.3390/proceedings2020049167 - 15 Jun 2020
Viewed by 290
Abstract
This study investigates differences in propulsive force between the water surface and underwater conditions in the flutter kick swimming technique. The subjects were well-trained university male swimmers. A towing device was set up in a 25 m swimming pool to measure the towing [...] Read more.
This study investigates differences in propulsive force between the water surface and underwater conditions in the flutter kick swimming technique. The subjects were well-trained university male swimmers. A towing device was set up in a 25 m swimming pool to measure the towing force and velocity of the swimmer under two conditions: the swimmer was near the water surface and at a depth of 0.60 m. The swimmers performed the gliding trials and the kicking trials with maximum effort with five towing velocities from 1.2 to 2.4 m/s. The passive drag and the resultant force of the propulsive and drag forces in kick swimming were formulated, respectively. The propulsive force was calculated from the difference between the two formulas. A difference of the propulsive force under conditions in high swimming velocity was observed. This suggests that the water surface condition has advantages of raising the foot above water. Full article
Open AccessProceedings
Comparing the Aerodynamic Behaviour of Real Footballs to a Smooth Sphere Using Tomographic PIV
Proceedings 2020, 49(1), 150; https://doi.org/10.3390/proceedings2020049150 - 15 Jun 2020
Viewed by 282
Abstract
Many studies have investigated the forces acting on a football in flight and how these change with the introduction or modification of surface features; however, these rarely give insight into the underlying fluid mechanics causing these changes. In this paper, force balance and [...] Read more.
Many studies have investigated the forces acting on a football in flight and how these change with the introduction or modification of surface features; however, these rarely give insight into the underlying fluid mechanics causing these changes. In this paper, force balance and tomographic particle image velocimetry (PIV) measurements were taken on a smooth sphere and a real Telstar18 football at a range of airspeeds. This was done under both static and spinning conditions utilizing a lower support through the vertical axis of the ball. It was found that the presence of the seams and texturing on the real ball were enough to cause a change from a reverse Magnus effect on the smooth ball to a conventional Magnus on the real ball in some conditions. The tomographic PIV data showed the traditional horseshoe-shaped wake structure behind the sphere and how this changed with the type of Magnus effect. It was found that the positioning of these vortices compared well with the measured side forces. Full article
Open AccessProceedings
Numerical Investigation of the Flow around a Feather Shuttlecock with Rotation
Proceedings 2020, 49(1), 28; https://doi.org/10.3390/proceedings2020049028 - 15 Jun 2020
Viewed by 381
Abstract
This paper presents the first scale resolving computational fluid dynamic (CFD) investigation of a geometrically realistic feather shuttlecock with rotation at a high Reynolds number. Rotation was found to reduce the drag coefficient of the shuttlecock. However, the drag coefficient is shown to [...] Read more.
This paper presents the first scale resolving computational fluid dynamic (CFD) investigation of a geometrically realistic feather shuttlecock with rotation at a high Reynolds number. Rotation was found to reduce the drag coefficient of the shuttlecock. However, the drag coefficient is shown to be independent of the Reynolds number for both rotating and statically fixed shuttlecocks. Particular attention is given to the influence of rotation on the development of flow structures. Rotation is shown to have a clear influence on the formation of flow structures particularly from the feather vanes, and aft of the shuttlecock base. This further raises concerns regarding wind tunnel studies that use traditional experimental sting mounts; typically inserted into this aft region, they have potential to compromise both flow structure and resultant drag forces. As CFD does not necessitate use of a sting with proper application, it has great potential for a detailed study and analysis of shuttlecocks. Full article
Open AccessProceedings
Investigation of the Aerodynamic Drag of Baseballs with Gyro Spin
Proceedings 2020, 49(1), 162; https://doi.org/10.3390/proceedings2020049162 - 15 Jun 2020
Viewed by 271
Abstract
The following considers drag measurements of baseballs with backspin (spin axis horizontal and normal to trajectory) and gyro spin (spin axis parallel to trajectory) orientations. Balls were propelled through still air in a laboratory setting at 36 m/s and spin ranging from 1250 [...] Read more.
The following considers drag measurements of baseballs with backspin (spin axis horizontal and normal to trajectory) and gyro spin (spin axis parallel to trajectory) orientations. Balls were propelled through still air in a laboratory setting at 36 m/s and spin ranging from 1250 rpm to 1750 rpm. Balls were projected with backspin and gyro spin in the two- and four-seam orientations. Speed and position sensors measured the speed and location of the balls at three locations from which the coefficient of drag and lift were found. Drag was observed to depend on spin rate, spin axis and seam orientation. The largest and smallest coefficient of drag was found with the gyro four-seam and two-seam spin orientation, respectively. Drag was observed to correlate with seam height with back spin, but not with gyro spin. Lift was observed for baseballs with back spin, but not with gyro spin. Full article
Open AccessProceedings
Influence of Surface Properties on Soccer Ball Trajectories
Proceedings 2020, 49(1), 143; https://doi.org/10.3390/proceedings2020049143 - 15 Jun 2020
Viewed by 350
Abstract
In this paper, we summarize our recent research work on soccer balls. Employing wind tunnels and analyses of simulated trajectories, we have gained an understanding of how various surface features influence soccer ball aerodynamics. Wind tunnels provide aerodynamic coefficients for non-spinning soccer balls. [...] Read more.
In this paper, we summarize our recent research work on soccer balls. Employing wind tunnels and analyses of simulated trajectories, we have gained an understanding of how various surface features influence soccer ball aerodynamics. Wind tunnels provide aerodynamic coefficients for non-spinning soccer balls. The coefficients then help determine the trajectories of various simulated kicked balls. Surface features include panel texturing, seam width, and seam depth. We have determined that small changes in surface texturing can lead to hard-kicked soccer balls experiencing lateral deflections as large as 10%–20% of their horizontal ranges. We have also found that the critical Reynolds number for soccer balls is more strongly correlated with seam width than with seam depth. Full article
Open AccessProceedings
Comparison of Aerodynamic Properties of Badminton Feather and Synthetic Shuttlecocks
Proceedings 2020, 49(1), 104; https://doi.org/10.3390/proceedings2020049104 - 15 Jun 2020
Viewed by 277
Abstract
The purpose of this study is to investigate the difference in aerodynamic properties between the feather shuttlecock and the synthetic shuttlecock. In particular, we focus on the aerodynamic stability of the two types of shuttlecock during impulsive change of an angle of attack [...] Read more.
The purpose of this study is to investigate the difference in aerodynamic properties between the feather shuttlecock and the synthetic shuttlecock. In particular, we focus on the aerodynamic stability of the two types of shuttlecock during impulsive change of an angle of attack (flip movement). Wind tunnel experiments are performed by using two types of the badminton shuttlecock (feather and synthetic shuttlecocks) to measure the fluid forces, and to visualize the flow fields around the shuttlecock. It is confirmed that the pitching moment coefficient at a near-zero angle-of-attack for feather shuttlecock is larger than that for synthetic shuttlecock. The results indicate that the feather shuttlecock demonstrates high stability in response to the flip phenomenon. Full article
Open AccessProceedings
Serve Ball Trajectory Characteristics of Different Volleyballs and Their Causes
Proceedings 2020, 49(1), 146; https://doi.org/10.3390/proceedings2020049146 - 15 Jun 2020
Viewed by 304
Abstract
Volleyball is a sport that starts with a serve, so effective service is essential to win the game. The trajectory of the ball is complicatedly affected by the fluid force, which depends on the speed, spin speed, and panel shape. To understand the [...] Read more.
Volleyball is a sport that starts with a serve, so effective service is essential to win the game. The trajectory of the ball is complicatedly affected by the fluid force, which depends on the speed, spin speed, and panel shape. To understand the aerodynamic characteristics of the ball and to propose an ideal serve method, we measured the fluid force and flight trajectory. The fluid force applied to the ball was measured at a wind speed of 4–30 m/s in the wind tunnel. The fluid force on the ball was strongly dependent on the ball type and orientation of the panel. In the flight trajectory measurement, the trajectory of the ball was measured using a high-speed camera under controlled speed and spin speed using a shotting machine. The effect of the panel orientation shown by the fluid force measurement was consistent with the results of the trajectory analysis, clarifying the importance of the panel orientation in serving. Full article
Open AccessProceedings
Difference of Reynolds Crisis Aspects on Soccer Balls and Their Panels
Proceedings 2020, 49(1), 117; https://doi.org/10.3390/proceedings2020049117 - 15 Jun 2020
Viewed by 335
Abstract
The soccer ball panel pattern, which changes every World Cup, greatly affects the ball’s aerodynamics and flight characteristics. In this study, the fluid force of 11 soccer balls with different panel patterns was measured by wind tunnel tests. The drag crises with different [...] Read more.
The soccer ball panel pattern, which changes every World Cup, greatly affects the ball’s aerodynamics and flight characteristics. In this study, the fluid force of 11 soccer balls with different panel patterns was measured by wind tunnel tests. The drag crises with different Reynolds numbers were confirmed depending on the panel shape. To understand this, the shapes of panel grooves were measured and the relationship between them was investigated. The flow separation point was also visualized by the oil film method and the particle image velocimetry (PIV) analysis. The separation points were confirmed to be different depending on the panel groove by the oil film method in a supercritical Reynolds region. The flow separation points were found to be almost the same position in the subcritical and supercritical state and to be partly different around the Reynolds number of drag crisis. Full article
Open AccessProceedings
Measurement of the Aerodynamic Forces Acting on a Non-Spinning Javelin Using an MSBS
Proceedings 2020, 49(1), 144; https://doi.org/10.3390/proceedings2020049144 - 15 Jun 2020
Viewed by 286
Abstract
Using the world’s largest magnetic suspension and balance system (MSBS) and a low-turbulence wind tunnel, we successfully measured the aerodynamic forces acting on a non-spinning women’s javelin. It was found that the drag and the lift increased as the angle of attack was [...] Read more.
Using the world’s largest magnetic suspension and balance system (MSBS) and a low-turbulence wind tunnel, we successfully measured the aerodynamic forces acting on a non-spinning women’s javelin. It was found that the drag and the lift increased as the angle of attack was increased up to 18°. The pitching moment increased for angles of attack up to about 9°, and then decreased, becoming negative above 12°, indicating nose-down rotation. We used a pseudo supporting rod to simulate a javelin attached to a support, as used in a conventional setup, and confirmed that this interferes with the javelin by creating differences between the aerodynamics forces acting on the javelin with and without the pseudo supporting rod. Full article
Open AccessProceedings
Measurements of the Flight Trajectory of a Spinning Soccer Ball and the Magnus Force Acting on It
Proceedings 2020, 49(1), 88; https://doi.org/10.3390/proceedings2020049088 - 15 Jun 2020
Viewed by 197
Abstract
The trajectory of a soccer ball, kicked with a spin to curve it into the goal, is strongly influenced by aerodynamic factors such as the Magnus force. Several studies using a wind-tunnel and high-speed cameras have investigated the Magnus force acting on a [...] Read more.
The trajectory of a soccer ball, kicked with a spin to curve it into the goal, is strongly influenced by aerodynamic factors such as the Magnus force. Several studies using a wind-tunnel and high-speed cameras have investigated the Magnus force acting on a spinning soccer ball. However, the exact effect of the Magnus force on the trajectory of a spinning soccer ball in free flight remains unclear. This study set out to use an optical three-dimensional motion-capture system to record the details of the flight of such a spinning soccer ball. The maximum curvature of the ball’s trajectory occurred in the middle of its flight. The sideways-directed Magnus force acting on the ball decreased as the ball’s speed decreased during the entire flight. Thus, it was concluded that the deflection of the trajectory of the ball decreases as the sideways-acting force decreases throughout the flight. Full article
Open AccessProceedings
Effect of Horizontal Ground Reaction Forces during the Golf Swing: Implications for the Development of Technical Solutions of Golf Swing Analysis
Proceedings 2020, 49(1), 45; https://doi.org/10.3390/proceedings2020049045 - 15 Jun 2020
Viewed by 356
Abstract
The swing is a key movement for golf. Its in-field performance could be estimated by embedded technologies, but often only vertical ground reaction forces (VGRF) are estimated. However, as the swing plane is inclined, horizontal ground reaction forces (HGRF) are expected to contribute [...] Read more.
The swing is a key movement for golf. Its in-field performance could be estimated by embedded technologies, but often only vertical ground reaction forces (VGRF) are estimated. However, as the swing plane is inclined, horizontal ground reaction forces (HGRF) are expected to contribute to the increase of the club angular velocity. Thus, this study aimed at investigating the role of the HGRF during the golf swing. Twenty-eight golf players were recruited and performed 10 swings with their own driver club, in a motion analysis laboratory, equipped with a full body marker set. Ground reaction forces (GRF) were measured with force-plates. A multibody kinematic optimization was performed with a full body model to estimate the instantaneous location of the golfer’s center of mass (CoM). Moments created by the GRF at the CoM were investigated. Results showed that horizontal forces should not be neglected regarding to VGRF because of their lever arm. Analyzing golf swing with only VGRF appeared not enough and further technological developments are still needed to ecologically measure other components. Full article
Open AccessProceedings
Just Noticeable Differences in the Length of Golf Irons
Proceedings 2020, 49(1), 147; https://doi.org/10.3390/proceedings2020049147 - 15 Jun 2020
Viewed by 351
Abstract
Current custom fitting guidelines for golf clubs suggest the smallest change in club length from a standard length iron should be 6 mm (1/4”). However, no previous research suggests why this length change is used. This study aims to identify the minimum noticeable [...] Read more.
Current custom fitting guidelines for golf clubs suggest the smallest change in club length from a standard length iron should be 6 mm (1/4”). However, no previous research suggests why this length change is used. This study aims to identify the minimum noticeable difference in the length of 7-iron clubs using just noticeable difference analysis techniques. Fifty golfers of varying ability were asked to compare a standard length 7-iron to test 7-irons of varying lengths, regarding changes in the perception of club length and body position at address. Irrespective of golfing ability, golfers could perceive a just noticeable difference of 13 mm (1/2”) from the standard length club. However, when asked if changes in body position were present, category 1 golfers noticed differences with a 6 mm change in club length and category 2 golfers noticed differences with a 13 mm change. No changes in body position were perceived by highly handicapped golfers. Full article
Open AccessProceedings
Investigating the Influence of Shaft Balance Point on Clubhead Speed: A Simulation Study
Proceedings 2020, 49(1), 156; https://doi.org/10.3390/proceedings2020049156 - 15 Jun 2020
Viewed by 299
Abstract
In this study, a dynamic golfer model was used to investigate the influence of the golf shaft’s balance point (i.e., center of mass) on the generation of clubhead speed. Three hypothetical shaft designs having different mass distributions, but the same total mass and [...] Read more.
In this study, a dynamic golfer model was used to investigate the influence of the golf shaft’s balance point (i.e., center of mass) on the generation of clubhead speed. Three hypothetical shaft designs having different mass distributions, but the same total mass and stiffness, were proposed. The golfer model was then stochastically optimized 100 times using each shaft. A statistically significant difference was found between the mean clubhead speeds at impact (p < 0.001), where the clubhead speed increased as the balance point moved closer to the grip. When comparing the two shafts with the largest difference in balance point, a 1.6% increase in mean clubhead speed was observed for a change in balance point of 18.8 cm. The simulation results have implications for shaft design and demonstrate the usefulness of biomechanical models for capturing the complex physical interaction between the golfer and golf club. Full article
Open AccessProceedings
Influence of Grip Mass on Driving Performance
Proceedings 2020, 49(1), 81; https://doi.org/10.3390/proceedings2020049081 - 15 Jun 2020
Viewed by 265
Abstract
The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40 experienced [...] Read more.
The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40 experienced golfers (handicap = 7.5 ± 5.3) representing a range of clubhead speeds (36 to 54 m/s). Each participant executed 12 drives per condition using matched grips and shafts and a single clubhead. Club mass was modified by inserting 50 g and 100 g into the grips of the two heavier conditions. The heaviest condition was associated with the slowest clubhead speed (p = 0.018) and highest vertical launch (p = 0.002), which resulted in no net influence on driving distance (p = 0.91). Lateral dispersion was greatest with the 325 g condition (p = 0.017), as was horizontal impact spot variability on the driver face (p = 0.031). Findings at the individual golfer level were not reliable enough to suggest that grip mass could be effectively used in a fitting environment to either shift ball flight tendencies or improve consistency. Full article
Open AccessProceedings
Clustering Golfers through Force Plate Analysis
Proceedings 2020, 49(1), 63; https://doi.org/10.3390/proceedings2020049063 - 15 Jun 2020
Viewed by 246
Abstract
Golf is a sport which requires players to use ground interaction to generate clubhead speed in order to propel the ball towards the target. Force platforms are a technology which can be used to measure these ground reaction forces. Golfers generate force through [...] Read more.
Golf is a sport which requires players to use ground interaction to generate clubhead speed in order to propel the ball towards the target. Force platforms are a technology which can be used to measure these ground reaction forces. Golfers generate force through a combination of jumping, sliding or twisting actions during the swing. Understanding how golfers generate these forces and if there are any groups which golfers could be clustered into could be used to enhance golf instruction as well as clubhead design or fitting practices for golf equipment. A total of 105 right-handed experienced golfers (handicap mean = 8.32 ± 8.31) consented to participate in the study of different swing speeds (31 below 95 mph, 41 over 105 mph and 33 between 95 and 105 mph). A calibrated single force plate was used for the test which sampled at 1000 Hz and recorded force and moment data in three axes. After a self-guided warm up, the players were instructed to hit five 7-iron shots and five drives to the best of their ability in an indoor hitting bay which used a launch monitor to record the club delivery and ball flight information. It was found that handicap or swing speed did not dictate the primary force production mechanism (sliding, jumping or twisting/spinning). This knowledge could aid engineers to design equipment better suited to the individual and help coaches build individualized programs to create power and clubhead speed in all players. Full article
Open AccessProceedings
Proposal of Golf Swing Analysis Method Using Singular Value Decomposition
Proceedings 2020, 49(1), 91; https://doi.org/10.3390/proceedings2020049091 - 15 Jun 2020
Viewed by 267
Abstract
We analyzed the relationship between the cooperative actions of golf swings and the differences in swing trajectory. To extract cooperative actions from different swings, we acquired swing data in an experiment on an experienced golfer who swung with two different trajectories. We measured [...] Read more.
We analyzed the relationship between the cooperative actions of golf swings and the differences in swing trajectory. To extract cooperative actions from different swings, we acquired swing data in an experiment on an experienced golfer who swung with two different trajectories. We measured the swings with motion capture system (VICON). We built an observance matrix from the collected positional data and conducted singular value decomposition (SVD) on it. The SVD yielded the cooperative actions as independent modes. Next, we compared the cooperative actions of different swing trajectories in the main mode. The results indicate that the analysis of the golf swing could be divided into a dominant behavior and an accompanying behavior. Full article
Open AccessProceedings
The Effect of Golf Club Moment of Inertia on Clubhead Delivery and Golfer Kinematics
Proceedings 2020, 49(1), 96; https://doi.org/10.3390/proceedings2020049096 - 15 Jun 2020
Viewed by 191
Abstract
The purpose of this study was to determine the effect of modifying whole club moment of inertia (MOI) on clubhead delivery, thorax and wrist kinematics. Seven skilled golfers hit ~10 shots with two driver conditions (MOI difference ~400 kg∙cm2). A GOM [...] Read more.
The purpose of this study was to determine the effect of modifying whole club moment of inertia (MOI) on clubhead delivery, thorax and wrist kinematics. Seven skilled golfers hit ~10 shots with two driver conditions (MOI difference ~400 kg∙cm2). A GOM system tracked the clubhead at impact and a 12-camera Vicon system was used to determine golfer biomechanics. Paired sample t-tests were conducted to quantify the effect of MOI on clubhead delivery, whilst biomechanical differences during the downswing were determined using statistical parametric mapping. Increasing MOI significantly reduced clubhead velocity (p = 0.001) but had a small and non-significant effect (p ≥ 0.294) on clubhead direction and orientation. The increase in MOI significantly decreased lead wrist flexion, thorax lateral bend and thorax axial rotation velocities during the downswing. The timing and magnitude of the decreases in both thorax velocities, suggests that these were contributing factors of the observed decrease in clubhead velocity. Full article
Open AccessProceedings
Introducing a New Activity-Based Balance Index Using Accelerometer Data and Evaluating It as a Predictor of Skill Level among Elite Junior Soccer Players
Proceedings 2020, 49(1), 78; https://doi.org/10.3390/proceedings2020049078 - 15 Jun 2020
Viewed by 283
Abstract
The aim of this study was to introduce a new activity-based balance index by using accelerometer data. Twenty-seven junior soccer players from the Iranian premier league were selected. Four functional tests, consisting of one leg stance, dynamic Y balance, running and dribbling tests, [...] Read more.
The aim of this study was to introduce a new activity-based balance index by using accelerometer data. Twenty-seven junior soccer players from the Iranian premier league were selected. Four functional tests, consisting of one leg stance, dynamic Y balance, running and dribbling tests, were conducted to assess the players’ balance, activity and skill. During these four tests, besides their relative scores, the acceleration of their body center was also recorded. Activity-based balance index (ABI) was calculated using these acceleration data. The results showed positive correlations between ABI and both static and dynamic balance scores. Additionally, negative correlations were found between ABI and dribbling scores, which demonstrate the agility required for this skill. It seems that this new index achieves the evaluation of both the balance and the skill level of soccer players. Perhaps this is a new way of talent identification and also a re-development of balance tests from traditional to modern. Full article
Open AccessProceedings
Development and Verification of a Highly Accurate and Precise Passing Machine for American Football
Proceedings 2020, 49(1), 94; https://doi.org/10.3390/proceedings2020049094 - 15 Jun 2020
Viewed by 215
Abstract
Passing a ball is a central aspect in the game of American Football. However, current passing machines do not fulfill the high quality standards for adequate catch training. The goal was to realize a passing machine that could do precise and accurate passes [...] Read more.
Passing a ball is a central aspect in the game of American Football. However, current passing machines do not fulfill the high quality standards for adequate catch training. The goal was to realize a passing machine that could do precise and accurate passes in a fully automated way in order to create high quality automated catch training. Automation was carried out to a degree that the release angle in terms of azimuth and elevation, release velocity and the release spin of the ball could be controlled via a wireless device within a reasonable range. Additionally, a pass prediction model was developed to determine where the pass went to and which height to catch it by least squares fit of 225 sample points with a second order function (R2>0.99). Normalized precision and accuracy of the machine were verified in an experiment with precision being less than 1% and accuracy less than 3% for more than 90% of all relevant passes. Full article
Open AccessProceedings
Peak Compression Force Physics in Rugby Union Scrum
Proceedings 2020, 49(1), 151; https://doi.org/10.3390/proceedings2020049151 - 15 Jun 2020
Viewed by 305
Abstract
Scrums play a major role in Rugby Union games, and are historically known as a showdown between the two packs of opposing teams, composed of their eight forwards players organized in a 3-4-1 configuration, respectively. We investigate scrum mechanics by working with professional [...] Read more.
Scrums play a major role in Rugby Union games, and are historically known as a showdown between the two packs of opposing teams, composed of their eight forwards players organized in a 3-4-1 configuration, respectively. We investigate scrum mechanics by working with professional male forward players from Racing 92, a high-level French Rugby club, and measuring the forces they apply on the French Rugby Federation instrumented scrum machine. Signal analysis reveals two major phases in the force production during a scrummaging effort: an impulsive engagement force, and then a force sustained for a few seconds. We experimentally compare individual performances of the engagement phase. We discuss the influence of the mass and the engagement speed of the players, and we introduce the model we are investigating to describe the individual impact on a scrum machine. We expect this model to be the elementary component of a collective model of a pack. Full article
Open AccessProceedings
Non-Parametric Shape Optimization of a Football Boot Bottom Plate
Proceedings 2020, 49(1), 152; https://doi.org/10.3390/proceedings2020049152 - 15 Jun 2020
Viewed by 271
Abstract
This paper describes the non-parametric shape optimization process for a football boot bottom plate. The non-parametric shape optimization process changes the nodes’ location of a model and outputs an optimum shape, which satisfies an optimization objective. The methodology presented in this study was [...] Read more.
This paper describes the non-parametric shape optimization process for a football boot bottom plate. The non-parametric shape optimization process changes the nodes’ location of a model and outputs an optimum shape, which satisfies an optimization objective. The methodology presented in this study was able to change the shape of the football boot bottom plate, especially the dimensions of key features, to achieve four different target bending stiffnesses. Tosca Structure sensitivity-based shape optimization was used to perform the optimization process and output optimum bottom plates. Future research is needed to investigate the accuracy of the process in comparison with that of the previously developed parametric optimization process. Full article
Open AccessProceedings
Simulation-Driven Design of a Portable Basketball Hoop System
Proceedings 2020, 49(1), 131; https://doi.org/10.3390/proceedings2020049131 - 15 Jun 2020
Viewed by 263
Abstract
A simulation-driven design process is proven to generate improved, more robust, and cost-effective designs within a shorter design cycle. Incorporating simulation and optimization early in the design cycle helps shape the concept designs so fewer iterations and rework are necessary as the design [...] Read more.
A simulation-driven design process is proven to generate improved, more robust, and cost-effective designs within a shorter design cycle. Incorporating simulation and optimization early in the design cycle helps shape the concept designs so fewer iterations and rework are necessary as the design matures. For this case study, a portable basketball hoop system is chosen for several reasons. This is a product that is common in everyday life, easily understood, and has several design challenges. To achieve the various design goals for this product, several optimization tools and simulation disciplines are coupled: multibody simulation to determine the kinematics and dynamics; finite element analysis to find displacements and stresses caused by external loads; topology optimization to define the essential structure to efficiently support the loads the product endures throughout its life cycle; and finally, multimodel optimization to consider all the loads when the structure is in several configurations during the optimization process. Full article
Open AccessProceedings
Analysis of Arm Joint Torques at Ball-Release for Set and Jump Shots in Basketball
Proceedings 2020, 49(1), 4; https://doi.org/10.3390/proceedings2020049004 - 15 Jun 2020
Viewed by 248
Abstract
A kinetic model of the shooting arms has estimated arm joint torques for one-hand set- and jump-shots in basketball. The dynamic model has three rigid planar links with rotational joints imitating an upper arm, forearm and hand with shoulder, elbow and wrist joints. [...] Read more.
A kinetic model of the shooting arms has estimated arm joint torques for one-hand set- and jump-shots in basketball. The dynamic model has three rigid planar links with rotational joints imitating an upper arm, forearm and hand with shoulder, elbow and wrist joints. In general shots controlled by hand, forearm and upper arm motions, there are many torque combinations of shoulder, elbow and wrist joints to produce shooters’ desired ball-release speed, angle and backspin angular velocity. The minimum of the sum of squares of the torque combinations exists at ball-release, when the release angular velocities of the hand and forearm are equal, and the release angular accelerations of the hand and forearm are also equal. Each torque of the shooting arm joints for the set-shot with upward shoulder speed is smaller than that for the jump-shot. Shoulder, elbow and wrist torques increase in proportion to horizontal shot distances. As release backspin angular speed increases, each of the shoulder, elbow and wrist torques also increases. The torques of the shoulder, elbow and hand affect the horizontal shot distance and the ball-release backspin. Full article
Open AccessProceedings
Differences in Simulated EMG Activities between a Non-Rotational Shot and an Ordinary Instep Kick Identified by Principal Component Analysis
Proceedings 2020, 49(1), 154; https://doi.org/10.3390/proceedings2020049154 - 15 Jun 2020
Viewed by 197
Abstract
The aim of this study was to clarify the major differences in the electromyographic (EMG) activities in the hip joint required to achieve a non-rotational (NR) shot as compared with an instep kick from the spatiotemporal data. For this purpose, simulated EMG activities [...] Read more.
The aim of this study was to clarify the major differences in the electromyographic (EMG) activities in the hip joint required to achieve a non-rotational (NR) shot as compared with an instep kick from the spatiotemporal data. For this purpose, simulated EMG activities obtained from NR shots and instep kicks were analyzed using principal component analysis (PCA). The PCA was conducted using an input matrix constructed from the time-normalized average and the standard deviation of the EMG activities (101 data x (15 muscles; iliacus, gluteus maximus, rectus femoris, biceos femoris, vastus lateralis, vastus medialis, vastus intermedius, semimembranosus, semitendinosus, sartorius, tensor fasciae latae muscle, adductor magnus muscle, adductor longus muscle, gasctrocnemius, and tibialis anterior)). The PCA revealed that the 3rd, 4th and 8th principal component vectors (PCVs) of the 10 generated PCVs were related to achieving the NR shot (p < 0.05). Full article
Open AccessProceedings
The Coefficient of Friction of Soccer Balls
Proceedings 2020, 49(1), 92; https://doi.org/10.3390/proceedings2020049092 - 15 Jun 2020
Viewed by 235
Abstract
Nine soccer balls were tested for their friction against a leather sheet, using a force plate. An average normal force of 63.6 N was applied and the movement of the ball had an average velocity of 15 mm/s. Each test was repeated 15 [...] Read more.
Nine soccer balls were tested for their friction against a leather sheet, using a force plate. An average normal force of 63.6 N was applied and the movement of the ball had an average velocity of 15 mm/s. Each test was repeated 15 times and the average Coefficient of Friction (COF) was reported. The following results were obtained: Jabulani (COF: 0.62 ± 0.05); Fracas (COF: 0.41 ± 0.01); Ordem 3 (COF: 0.63 ± 0.02); Teamgeist (COF: 0.38 ± 0.01); Brazuca (COF: 0.45 ± 0.01); Kopanya (COF: 0.39 ± 0.01); React (COF: 0.37 ± 0.01); Finale 15 (COF: 0.39 ± 0.06); Vintage T-panel leather ball (COF: 0.41 ± 0.02). Overall, the COF of all balls tested ranged between 0.37 and 0.62. The Finale 15 ball showed a decreasing COF trend with repeated trials and the React ball produced pronounced slip-stick phenomenon. Full article
Open AccessProceedings
Comparison of Biomechanical Factors among Straight, Curve and Knuckle Kicking Motions in Soccer
Proceedings 2020, 49(1), 119; https://doi.org/10.3390/proceedings2020049119 - 15 Jun 2020
Viewed by 220
Abstract
The rotation of a soccer ball is affected by several factors, such as impact point and foot posture, which are generated by joint torque in the lower limb. This study aimed to investigate joint torque in the lower limb that generates foot posture [...] Read more.
The rotation of a soccer ball is affected by several factors, such as impact point and foot posture, which are generated by joint torque in the lower limb. This study aimed to investigate joint torque in the lower limb that generates foot posture and swing trajectory, and compare three types of kicks before and after a practice period for participants to learn to control the ball rotation. An optical three-dimensional motion capture system was used to record the kicking motion of the participants. The results indicate that the adduction torque of the hip joint at the moment of impact decreased for curve kicks (from 0.56 to 0.25 Nm/kg) and increased for knuckle kicks (from −0.09 to 0.37 Nm/kg). We considered that the curve and knuckle kicks swing towards the inside (because of their positive values in the post experiment) with hip joint adduction before impact to control ball rotation. Full article
Open AccessProceedings
Development of Silicone Elastomer for Use in the Assessment of Padded Clothing in Rugby Union
Proceedings 2020, 49(1), 77; https://doi.org/10.3390/proceedings2020049077 - 15 Jun 2020
Viewed by 238
Abstract
Rugby Union is a collision sport, with both player to player and player to pitch impacts being frequent. Current test standards for padded clothing in rugby use impact surrogates, which may not accurately replicate the human response. Modern technologies use silicone elastomers to [...] Read more.
Rugby Union is a collision sport, with both player to player and player to pitch impacts being frequent. Current test standards for padded clothing in rugby use impact surrogates, which may not accurately replicate the human response. Modern technologies use silicone elastomers to represent human soft tissue when testing padding, however many commercially available silicones do not match the load response seen by human tissue. This paper describes the fabrication and validation of a bespoke formulation of commercially available silicone elastomer and deadener concentrations that portray a similar load response to relaxed organic muscle tissue. The mechanical responses, both at quasi-static and dynamic strain rates, have been compared, with improved, more representative behaviour being presented. The validation of this silicone elastomer formulation is important in developing a more biofidelic impact surrogate for the assessment of padded clothing in rugby. Full article
Open AccessProceedings
Perception of Running Shoe Cushioning: Objective and Subjective Measurements in Short-Distance Running
Proceedings 2020, 49(1), 121; https://doi.org/10.3390/proceedings2020049121 - 15 Jun 2020
Viewed by 347
Abstract
The aim of this study is to investigate the link between the cushioning feature of running shoes in objective and subjective measurements (OM and SM). In OM, four insoles materials were chosen after impact tests (S1 = 12.6 g, S2 = 7.2 g, [...] Read more.
The aim of this study is to investigate the link between the cushioning feature of running shoes in objective and subjective measurements (OM and SM). In OM, four insoles materials were chosen after impact tests (S1 = 12.6 g, S2 = 7.2 g, G = 11.54 g, and E = 32.41 g). In SM (n = 19), perceived cushioning comfort of insoles was measured using pairwise comparison tests and a Visual analogue scale (VAS) during running. Lower impact peak (IP) leads to greater perceived comfort of cushioning only between S1, S2 and G. But insole E with the highest IP was rated as the most comfortable in cushioning. Its relationship can be explained by associating acceleration magnitudes from the beginning contact to the IP in two possible ways: i) participants did not reach the critical impact peak in SM or ii) participants perceived the critical impact peak, but other factors such as energy rebound and perceived stability influenced their rating in the pairwise comparison tests. Full article
Open AccessProceedings
Influence of Running Shoes and Running Velocity on “Ride” during Running
Proceedings 2020, 49(1), 54; https://doi.org/10.3390/proceedings2020049054 - 15 Jun 2020
Viewed by 305
Abstract
“Ride” has been established to subjectively describe the heel-to-toe transition during walking and running. Recently, a study was published aiming to quantify “ride” by linking it to the maximum velocity of the anterior-posterior (AP) progression of the center of pressure (COP) during the [...] Read more.
“Ride” has been established to subjectively describe the heel-to-toe transition during walking and running. Recently, a study was published aiming to quantify “ride” by linking it to the maximum velocity of the anterior-posterior (AP) progression of the center of pressure (COP) during the first 30% of the stance phase. While that study investigated the parameter when running at a constant velocity of approximately 3.5 m/s (i.e., 12.6 km/h), this study was carried out to evaluate the influence of running velocity on “ride” when running. Five healthy participants performed runs on a treadmill at 8, 10 and 12 km/h with three different running shoes, and their plantar pressure was measured at 300 Hz using pressure-sensing insoles. “Ride” was calculated as suggested by the previously mentioned study. In two of the three shoes, “ride” decreased with increasing running speed. Between the shoes, however, there is no clear image of how the shoes influence this parameter. Full article
Open AccessProceedings
In-Shoe Plantar Pressure Measurement—Influence of Insole Placement on Selected Parameters during Running
Proceedings 2020, 49(1), 50; https://doi.org/10.3390/proceedings2020049050 - 15 Jun 2020
Viewed by 279
Abstract
While it is assumed that pressure-sensing insoles are usually placed directly below the foot and on top of the shoes’ standard insoles, nearly no previously published study actually describes the procedure, which leaves a slight uncertainty. Therefore, the aim of this study was [...] Read more.
While it is assumed that pressure-sensing insoles are usually placed directly below the foot and on top of the shoes’ standard insoles, nearly no previously published study actually describes the procedure, which leaves a slight uncertainty. Therefore, the aim of this study was to evaluate whether the placement has an influence on selected parameters or not. Five healthy participants took part in the measurements and ran on a treadmill at a running velocity of 10 km/h with three different running shoes. Plantar pressure was measured using pressure-sensing insoles, which were once placed on top and once below the shoes’ standard insoles. Selected parameters were the maximum and mean pressure and the range of the center of pressure (COP) in anterior–posterior and medial–lateral directions. The results indicate that maximum and mean pressure decrease when the pressure-sensing insole lies below the shoe’s insole and the medial–lateral COP is the least effected parameter. Full article
Open AccessProceedings
Running Shoes—Possible Correlations of Biomechanical and Material Tests
Proceedings 2020, 49(1), 25; https://doi.org/10.3390/proceedings2020049025 - 15 Jun 2020
Viewed by 334
Abstract
Today’s development of running shoes is often supported by the assessment of biomechanical tests (BIOs) as well as material tests (MATs). In order to possibly reduce the number of relevant tests, the aim of this study was to find out whether there are [...] Read more.
Today’s development of running shoes is often supported by the assessment of biomechanical tests (BIOs) as well as material tests (MATs). In order to possibly reduce the number of relevant tests, the aim of this study was to find out whether there are correlations between the selected BIO and MATs. Therefore, four different running shoes were tested. For the BIO, the ground reaction force and tibial acceleration of 19 experienced runners were measured. The evaluated parameters were first peak, time to first peak, impulse during the first 75 ms of stance, maximum vertical ground reaction force, loading rate, mean peak acceleration and median power frequency. The MATs included compression tests and an impact test with and without insoles at the forefoot as well as the heel area. The results show that carrying out MATs (especially impact tests) without insoles give the most insight into the parameters analysed with the BIO. Full article
Open AccessProceedings
Effect of Rest Periods on Mechanical Ageing of Running Shoes
Proceedings 2020, 49(1), 138; https://doi.org/10.3390/proceedings2020049138 - 15 Jun 2020
Viewed by 443
Abstract
Running is a popular form of exercise, although runners are prone to injury from repeated impact. Running shoes can limit impact forces, but they deteriorate with use. Mechanical ageing typically involves repeatedly compressing the midsole while measuring the energy absorbed within compression cycles [...] Read more.
Running is a popular form of exercise, although runners are prone to injury from repeated impact. Running shoes can limit impact forces, but they deteriorate with use. Mechanical ageing typically involves repeatedly compressing the midsole while measuring the energy absorbed within compression cycles to assess degradation. Literature suggests mechanical aging often causes a higher rate of degradation than natural ageing. This work investigated the effect of introducing rest periods into mechanical ageing. Five shoes were mechanically aged using a sine plus dwell waveform (1.25 Hz, max. load 1.5 kN) for seven hours, equating to a simulated distance of 60 km. Three of the shoes were rested for 22 hours every 20 km. The shoes aged with rest periods absorbed more energy than their unrested counterparts for the first 10 km when testing recommenced. This finding has implications for the mechanical ageing, design and recommended lifespan of running shoes. Full article
Open AccessProceedings
Classification of the Runner’s Preferences in Running Shoes Based on Equilibrium-Point-Based Muscle Synergies
Proceedings 2020, 49(1), 85; https://doi.org/10.3390/proceedings2020049085 - 15 Jun 2020
Viewed by 252
Abstract
For many runners, mechanical characteristics of running shoes, such as cushioning ability, are important in finding their suitable shoes. In addition to that, subjective comfort has come to be regarded as a non-negligible factor these days. According to previous studies, it has been [...] Read more.
For many runners, mechanical characteristics of running shoes, such as cushioning ability, are important in finding their suitable shoes. In addition to that, subjective comfort has come to be regarded as a non-negligible factor these days. According to previous studies, it has been found that more comfortable shoe conditions are associated with less oxygen consumption and fewer injury frequencies as compared to the less comfortable shoe conditions. However, there is also the fact that the shoes that they feel comfortable with are different from runner to runner, and it still remains unclear why the runners consider their shoes comfortable. Therefore, in this study, we tried to find the differences between several groups with different shoe preferences, applying an equilibrium-point (EP)-based muscle synergy analysis to know the reason why runners consider the shoes comfortable. As a result of the study, it was found that ankle EP velocity could distinguish between the groups classified by shoe preference. This fact indicates that some force-related parameters calculated from posture and stiffness affect the feeling of comfort. Full article
Open AccessProceedings
Impact of Alternative Synthetic Turf Infills on Athlete Performance and Safety
Proceedings 2020, 49(1), 35; https://doi.org/10.3390/proceedings2020049035 - 15 Jun 2020
Viewed by 249
Abstract
The objective of this study is to determine the impact of three alternative infills of various particle size on athlete performance and safety in a third generation (3G) synthetic fields. A complete randomized design composed of three different infill materials (thermoplastic elastomer, coconut [...] Read more.
The objective of this study is to determine the impact of three alternative infills of various particle size on athlete performance and safety in a third generation (3G) synthetic fields. A complete randomized design composed of three different infill materials (thermoplastic elastomer, coconut and cork mixture, and recycled Nike shoes (Nano)) with all infills having the same infill depth, fiber length, fiber density, and shock pad. The study took place at the Center for Athletic Field Safety (CAFS) during the summer of 2017 in Knoxville, TN. Each plot received 120 traffic events with the CAFS traffic simulator. This study found that alternative infills do impact the safety and performance of the field, while showing a variation of performance properties among the alternative infills. The results of this study indicate that particle size and distribution of the infill plays a key role in the superior field performance in 3G turf. Full article
Open AccessProceedings
Impact of Brushing and Infill Maintenance on Field Safety of Third Generation Synthetic Turf
Proceedings 2020, 49(1), 34; https://doi.org/10.3390/proceedings2020049034 - 15 Jun 2020
Viewed by 222
Abstract
The objective of this study was to investigate the impact of brushing and infill maintenance of third generation (3G) synthetic turf on field safety. A split-plot randomized complete block design was used with six different fiber pile heights, infill depths, and shock pad [...] Read more.
The objective of this study was to investigate the impact of brushing and infill maintenance of third generation (3G) synthetic turf on field safety. A split-plot randomized complete block design was used with six different fiber pile heights, infill depths, and shock pad combinations subjected to 120 games in the summer of 2017 at the Center for Athletic Field Safety (CAFS) in Knoxville, TN, USA. Traffic was applied with a CAFS traffic simulator. Half of the plots received maintenance every 20 games with a rotating power broom and infill applied to those below manufacturer’s recommendations. All 3G synthetic turf systems required maintenance to the same degree, and maintenance was necessary to keep surface hardness of 3G synthetic turf systems consistent and acceptable. Overall, field safety and consistency increased in this study due to maintenance, thus suggesting brushing and infill maintenance plays a vital role in maintaining high performance on 3G synthetic fields. Full article
Open AccessProceedings
A Penetrometer for Quantifying the Surface Stiffness of Sport Sand Surfaces
Proceedings 2020, 49(1), 64; https://doi.org/10.3390/proceedings2020049064 - 15 Jun 2020
Viewed by 303
Abstract
Sand sports include running, volleyball, soccer, beach flags, ironman, and fitness training. An increased amount of soft tissue injuries have been widely reported. A novel technique of determining the surface stiffness of beach sand in-situ used a simple drop-test penetrometer. The relationship between [...] Read more.
Sand sports include running, volleyball, soccer, beach flags, ironman, and fitness training. An increased amount of soft tissue injuries have been widely reported. A novel technique of determining the surface stiffness of beach sand in-situ used a simple drop-test penetrometer. The relationship between drop height and the depth of penetration squared was linear (Pearson’s correlation coefficient r2 > 0.92). The stiffness ratio between the soft dry sand and ocean-saturated wet sand compacted by eight hours of coastal water exposure was approximately seven, which was similar to previously reported stiffness measurements in a sand box. However, the absolute stiffness values were much smaller. While this technique was manually operated, an automatic system is postulated for future studies. Full article
Open AccessProceedings
Influence of Ambient Temperature on TVOC Released from Polyurethane Athletics Track
Proceedings 2020, 49(1), 1; https://doi.org/10.3390/proceedings2020049001 - 15 Jun 2020
Viewed by 253
Abstract
The athletics track consists of multiple organic hydrocarbons and their derivatives, which are easy to release TVOC under specific conditions such as high temperature. Taking polyurethane athletics track as the research object, the TVOC release of an athletics track is carried out in [...] Read more.
The athletics track consists of multiple organic hydrocarbons and their derivatives, which are easy to release TVOC under specific conditions such as high temperature. Taking polyurethane athletics track as the research object, the TVOC release of an athletics track is carried out in a 0.1 m3 environmental chamber, and TVOC mass concentration detection is performed using a TVOC gas detector. The results show that the increase in ambient temperature will promote the release of VOCs from a PU athletics track, and the increase rate and decline rate of TVOC mass concentration will increase with the increase in ambient temperature. The increase in ambient temperature will result in a significant shortening of the rapid release of VOCs released from a PU athletics track and a prolonged slow-release period. The ambient temperature rises, the maximum and 24 h value of TVOC mass concentration of the PU athletics track are steadily increasing, and this trend is more significant in the high-temperature section. The research conclusions can provide a basis for the improvement of athletics tracks. Full article
Open AccessProceedings
Shoe–Surface Tribology in Hardcourt Tennis
Proceedings 2020, 49(1), 90; https://doi.org/10.3390/proceedings2020049090 - 15 Jun 2020
Viewed by 268
Abstract
Sports shoes used for hardcourt tennis vary greatly in outsole tread design. In this study, a series of experiments were conducted on individual shoe tread elements, replicating the tribological conditions they will experience during hardcourt step and slide movements. It was found that [...] Read more.
Sports shoes used for hardcourt tennis vary greatly in outsole tread design. In this study, a series of experiments were conducted on individual shoe tread elements, replicating the tribological conditions they will experience during hardcourt step and slide movements. It was found that tread element orientation does not influence the friction during step movements, but has a moderate effect on the friction during hardcourt slides. This is considered to be due to differing amounts of wear and frictional heat experienced. Full article
Open AccessProceedings
Spatial Measurements for Artificial Turf Systems Using Hall Effect Sensors
Proceedings 2020, 49(1), 160; https://doi.org/10.3390/proceedings2020049160 - 15 Jun 2020
Viewed by 238
Abstract
The purpose of this study was to evaluate a bespoke spatial measurement methodology using Hall Effect Sensors (HES), i.e., utilizing inductance between a permanent magnet and sensor to indirectly measure the magnet position. The aim is to embed the magnet in a boot’s [...] Read more.
The purpose of this study was to evaluate a bespoke spatial measurement methodology using Hall Effect Sensors (HES), i.e., utilizing inductance between a permanent magnet and sensor to indirectly measure the magnet position. The aim is to embed the magnet in a boot’s stud and use an array of sensors in the artificial turf. To evaluate the accuracy and applicability of a HES system in sports turf, two studies were carried out. To measure the spatial position vertically, a standard mechanical dynamic impact testing with the magnet embedded, and the sensors below the turf carpet, was compared to the gold standard optical reference measurement system (GOM UK Ltd.: Coventry, UK) . A second study evaluated the horizontal spatial accuracy for sensors in a variable array with a controlled incremental step movement of the magnet on a precise engineering workshop table. Full article
Open AccessProceedings
Hardness Safety Testing of Artificial Turf
Proceedings 2020, 49(1), 130; https://doi.org/10.3390/proceedings2020049130 - 15 Jun 2020
Viewed by 180
Abstract
This paper compares four sport surface hardness impact test devices, for use on artificial turf (AT) surfaces to control safety. Sports governing bodies require sport surfaces to be assessed with the “Advanced Artificial Athlete” (AAA) mechanical test. The AAA data presented here demonstrate [...] Read more.
This paper compares four sport surface hardness impact test devices, for use on artificial turf (AT) surfaces to control safety. Sports governing bodies require sport surfaces to be assessed with the “Advanced Artificial Athlete” (AAA) mechanical test. The AAA data presented here demonstrate that this high energy test causes compaction of the particulate rubber infill during testing, such that the derived “field test value” is less relevant to the initial state of the surface and arguably also to player comfort. This paper reports on alternative impact test methods and their correlation to the AAA, including a novel comparison to the more portable Fieldtester. The potential use of a lightweight 0.5 kg Clegg Hammer for assessing the change in state of the infill and monitoring the effectiveness of field maintenance is also reported. These results expand our understanding of factors influencing surface hardness and safety, with useful implications for practitioners. Full article
Open AccessProceedings
High Load Stress-Strain Property of Natural Turf for Professional Use, Various Types of Natural, Hybrid and Artificial Turfs in Football
Proceedings 2020, 49(1), 142; https://doi.org/10.3390/proceedings2020049142 - 15 Jun 2020
Viewed by 226
Abstract
High load quasi stress-strain (qSS) properties of professionally maintained natural turf (N-pro) was compared with eight natural, hybrid or artificial turfs: one professionally maintained natural turf in a sub field and one grown in a test field without maintenance, two hybrid turfs (one [...] Read more.
High load quasi stress-strain (qSS) properties of professionally maintained natural turf (N-pro) was compared with eight natural, hybrid or artificial turfs: one professionally maintained natural turf in a sub field and one grown in a test field without maintenance, two hybrid turfs (one in the sub field and one grown in the test field without maintenance), three new artificial turfs (sand, rubber and sand/rubber infill) and one aged artificial turf (eight years old with sand/rubber infill). N-pro was characterized with a distinctive magnitude of plastic deformation and hysteresis profile, indicating its more energy absorbable properties compared to the artificial turfs. Apparent differences exist between N-pro and other natural turfs, suggesting factors such as daily maintenance work and sod compositions are very influential. Clear differences were also observed when the hybrid turf was professionally maintained. The aged artificial turf becomes substantially stiffer indicating usage over years affects the stiffness. Full article
Open AccessProceedings
Sprint and Change of Direction Performances on Three Different Futsal Playing Surfaces
Proceedings 2020, 49(1), 17; https://doi.org/10.3390/proceedings2020049017 - 15 Jun 2020
Viewed by 222
Abstract
This study was conducted to clarify the differences in sprint and change of direction performances on different futsal flooring systems (area-elastic (AE) vs. combined-elastic (CE)). Eight recreational athletes were recruited to perform the 505-agility test on three different EN 14904-certified futsal playing surfaces [...] Read more.
This study was conducted to clarify the differences in sprint and change of direction performances on different futsal flooring systems (area-elastic (AE) vs. combined-elastic (CE)). Eight recreational athletes were recruited to perform the 505-agility test on three different EN 14904-certified futsal playing surfaces (AE, CE1 and CE2). All participants wore an identical footwear during the test. Timing-gate systems were utilized to record the time of 5-m sprint run-up and the change of direction components from the agility test. Participants were also requested to evaluate the perceived shoe-surface overall traction performance after each trial. The differences of performance across all surfaces were analyzed by one-way ANOVA repeated measures (p < 0.05). Results revealed that there was significant difference in change of direction performance between CE1 and CE2 surfaces (p = 0.04). It was also found that the mean score of the perceived traction performance evaluated by the participants were significantly different across all surfaces (p < 0.05). Full article
Open AccessProceedings
The Role of Friction and Tangential Compliance on the Resultant Launch Angle of a Golf Ball
Proceedings 2020, 49(1), 27; https://doi.org/10.3390/proceedings2020049027 - 15 Jun 2020
Viewed by 330
Abstract
A thorough understanding of how the delivered face angle and club path of a golf club influences the initial launch direction of a golf ball can play a significant role in the design of various club types as well as help players and [...] Read more.
A thorough understanding of how the delivered face angle and club path of a golf club influences the initial launch direction of a golf ball can play a significant role in the design of various club types as well as help players and coaches better understand performance in the field. A theoretical model based on a Hertzian impact formulation with the inclusion of tangential compliance via Coulomb friction is compared to empirical results. This comparison demonstrates that the initial launch direction of a golf ball for a given club path and face angle can be sufficiently predicted by the theoretical model, providing insights into the mechanisms leading to different launch direction percentages relative to face angle for various club types. Additionally, the relationship between launch direction and the coefficient of friction is explored for various angles of incidence. Full article
Open AccessProceedings
Adjusting a Momentum-Based Golf Clubhead-Ball Impact Model to Improve Accuracy
Proceedings 2020, 49(1), 47; https://doi.org/10.3390/proceedings2020049047 - 15 Jun 2020
Viewed by 242
Abstract
In this paper, two simple and physically meaningful adjustments were made to a momentum-based clubhead-ball impact model to predict golf ball launch conditions with better accuracy. These adjustments were motivated by two shortcomings of the momentum-based impact model, namely the absence of shaft [...] Read more.
In this paper, two simple and physically meaningful adjustments were made to a momentum-based clubhead-ball impact model to predict golf ball launch conditions with better accuracy. These adjustments were motivated by two shortcomings of the momentum-based impact model, namely the absence of shaft effects and golf ball deformation. Kinematic data from a golf impact motion capture experiment was used to empirically determine the parameter adjustments that minimized the ball speed and spin errors. It was found that the original model’s ball speed deficiency could be corrected by adding less than 3 g to the clubhead mass, and the amount of added mass correlated with the mass of the shaft. Additionally, the original model’s backspin and sidespin errors were significantly reduced by making a slight adjustment to the golf ball’s center of mass position relative to the impact location. Specifically, moving the golf ball center of mass approximately 0.5 mm downward and 0.07 mm towards the heel reduced the mean backspin and sidespin errors by approximately 85% each. Full article
Open AccessProceedings
Exploration of Center of Gravity, Moment of Inertia, and Launch Direction for Putters with Ball Speed Normalizing Face Properties
Proceedings 2020, 49(1), 2; https://doi.org/10.3390/proceedings2020049002 - 15 Jun 2020
Viewed by 279
Abstract
The forgiveness of golf putters is traditionally achieved through weight distribution. Putters are often designed with large footprints, which help to increase the moment of inertia (MOI), but consequently move the center of gravity (CG) farther behind the face. The use of higher [...] Read more.
The forgiveness of golf putters is traditionally achieved through weight distribution. Putters are often designed with large footprints, which help to increase the moment of inertia (MOI), but consequently move the center of gravity (CG) farther behind the face. The use of higher MOI putters will result in less ball speed loss on impacts away from the sweet spot (i.e., more forgiveness). It has been shown that certain face properties, such as milling patterns, grooves, or soft inserts, can be leveraged to have a similar effect. This paper explores the relationships between impact location, MOI, CG depth, discretionary mass placement, and launch direction for these putters. A novel design strategy is proposed. Minimizing CG depth for putters with ball speed normalizing face properties, even at the expense of MOI, can result in more consistent launch direction and distance control for the average player. Full article
Open AccessProceedings
A Review of Equestrian Polo and a Methodology for Testing the Mechanical Properties of the Mallet
Proceedings 2020, 49(1), 99; https://doi.org/10.3390/proceedings2020049099 - 15 Jun 2020
Viewed by 242
Abstract
: Equestrian polo is struggling to grow and attract young players due to the perception it is a game played by royals and the rich only, and is not a real sport. This study highlights the high level of skill and athletic challenge [...] Read more.
: Equestrian polo is struggling to grow and attract young players due to the perception it is a game played by royals and the rich only, and is not a real sport. This study highlights the high level of skill and athletic challenge faced by the players. Literature is scarce for polo despite its global appeal and the high value of the game in terms of historical reach and investment by the polo community. The game is also unique in sports due to the multiplicity of interactions such as player–pony, pony–ground, player–mallet, and mallet–ball. This work introduces the basics of the game with a graphical interpretation of the motion of the mallet during play. The mallet is constructed of natural materials, the shaft from a rattan cane whilst the handle and head are crafted from hardwood. Using a materials analysis approach, a testing methodology is proposed that will enable quantifiable data to be produced based on the properties and performance of the mallet. The purpose of this is to enable benchmarking of the mallet based on the material properties and their assembled response to the testing. Quasi-static load tests using a universal testing instrument are followed by dynamic testing using inertial sensors. All testing is done in planes chosen to replicate the common lines of action of match play. The quasi-static tests enabled a value for stiffness (k), and the dynamic testing enabled a damping coefficient (c) to be calculated. These quantities will enable a quantitative measure for the properties and performance of any mallet and thereby remove the subjective nature of assessment. Subsequent study will then determine how these data correlate with the performance in play, as well as impact, trajectory, and fatigue responses. Full article
Open AccessProceedings
Effects of Pimple Height of a Table Tennis Rubber on Ball Rebound Behavior
Proceedings 2020, 49(1), 55; https://doi.org/10.3390/proceedings2020049055 - 15 Jun 2020
Viewed by 256
Abstract
The objective of this study was to construct a finite element (FE) model of table tennis rubber (Sandwich rubber) with pimples structure, which can accurately estimate the rebound behavior of the ball at impact, and to investigate effects of its structure on ball [...] Read more.
The objective of this study was to construct a finite element (FE) model of table tennis rubber (Sandwich rubber) with pimples structure, which can accurately estimate the rebound behavior of the ball at impact, and to investigate effects of its structure on ball rebound behavior. The sandwich rubber is composed of a combination of a rubber and foam layers. The FE model of the sandwich rubber was constructed with non-linearity, strain rate dependency, and energy absorption which were expressed based on the results of material tests. Impact analyses were conducted using the developed model of sandwich rubber and ball with different pimple heights. The simulation results of rebound behavior do not tend to be proportional to the pimple height. The trend of the rebound behavior was mainly affected by the amount of impulse during impact calculated using the horizontal component of the contact force which was varied with changes in pimple height. Full article
Open AccessProceedings
A Study on the Mechanical Characteristics of String Planes of Badminton Racquets by Nonlinear Finite Element Analysis
Proceedings 2020, 49(1), 42; https://doi.org/10.3390/proceedings2020049042 - 15 Jun 2020
Viewed by 256
Abstract
In this study, the finite element analysis of the string planes of badminton racquets was investigated to evaluate the effect of the mechanical characteristics of polymer strings. The nonlinear mechanical characteristics of commercially available polymer strings were obtained by the uniaxial loading tests [...] Read more.
In this study, the finite element analysis of the string planes of badminton racquets was investigated to evaluate the effect of the mechanical characteristics of polymer strings. The nonlinear mechanical characteristics of commercially available polymer strings were obtained by the uniaxial loading tests experimentally. The effects of the strain rate on the mechanical characteristics of the polymer strings were also investigated to consider the dynamic effect on the numerical simulation. The numerical simulation code used to analyze the string planes of the badminton racquets was developed originally. A nonlinear elastic model (Yeoh model) was applied to the mechanical characteristics of the polymer string. Simulated results were compared with the experimental results. The effect of the mechanical characteristics of the polymer strings and the geometrical shape of the badminton racquets on the out-of-plane stiffnesses were investigated. Full article
Open AccessProceedings
Impact Characteristics of a Badminton Racket with Realistic Finite Element Modeling
Proceedings 2020, 49(1), 106; https://doi.org/10.3390/proceedings2020049106 - 15 Jun 2020
Viewed by 247
Abstract
The tension of strings on a badminton racket can be adjusted by players according to their personal experiences. The best way to execute such an adjustment remains unclear. A finite element model was employed in this study to investigate the effect of having [...] Read more.
The tension of strings on a badminton racket can be adjusted by players according to their personal experiences. The best way to execute such an adjustment remains unclear. A finite element model was employed in this study to investigate the effect of having nonuniform string tension on string-bed deformation, and the direction of force applied to shuttlecock head upon impact. The racket model was based on a commercially available racket with a simplified string-bed of 16 strings established using SolidWorks. A displacement was applied to the ball to simulate impacting on the string-bed. The simulations revealed that slightly lowering the tension of off-centered strings had a minimal effect on the von Mises stress distribution of the ball and string-bed. The off-centered impact caused comparable contact force magnitude but altered force direction. Further investigation is needed for understanding the effect of varying string tension on badminton racket performance. Full article
Open AccessProceedings
Influence of Ball Impact Location on Racquet Kinematics, Forearm Muscle Activation and Shot Accuracy during the Forehand Groundstrokes in Tennis
Proceedings 2020, 49(1), 89; https://doi.org/10.3390/proceedings2020049089 - 15 Jun 2020
Viewed by 205
Abstract
We aimed to clarify the effect of ball–racquet impact locations on the dynamic behavior of tennis racquet, the accuracy of shots and muscle activation of the forearm. Eight male intermediate tennis players performed ten forehand groundstrokes. A motion capture system was used to [...] Read more.
We aimed to clarify the effect of ball–racquet impact locations on the dynamic behavior of tennis racquet, the accuracy of shots and muscle activation of the forearm. Eight male intermediate tennis players performed ten forehand groundstrokes. A motion capture system was used to measure the motions of racquet, ball and human body at 2000 Hz, and electromyography (EMG) activities of wrist extensor and flexor muscles were measured simultaneously. The flight parameters of the ball were measured by ballistic measurement equipment. All shots were divided into tertiles based on ball impact location along the lateral axis of tennis racquet. We found that the off-center, upper-side impact induces a larger muscular activity in extensor carpi radialis. Passive radial deviation of the wrist occurring immediately after ball impact may account for this. Furthermore, the off-center, upper-side impact could be associated with a missed shot having a lower, outward ball launch angle. Full article
Open AccessProceedings
A Customised Finn Dinghy Rudder for Optimal Olympic Performance
Proceedings 2020, 49(1), 105; https://doi.org/10.3390/proceedings2020049105 - 15 Jun 2020
Viewed by 277
Abstract
Because of the long history of the Finn Dinghy sailing class, the difference between a gold medal and a mediocre result often comes down to personal mistakes of the sailor, or to who has the most optimised equipment. Regarding the latter, the Finn [...] Read more.
Because of the long history of the Finn Dinghy sailing class, the difference between a gold medal and a mediocre result often comes down to personal mistakes of the sailor, or to who has the most optimised equipment. Regarding the latter, the Finn class rules permit certain design variations of the hull, mast, sail and rudder. In the current contribution, we describe a method for developing a customised rudder system aimed at optimal performance during the Tokyo 2020 Olympics. Based on hydrodynamic analysis of existing rudder designs, an improved rudder geometry was developed. Based on the concept geometry, the rudder and tiller were structurally designed and manufactured to achieve high stiffness and sufficient strength, while respecting the minimum mass requirements as specified by the rules. Full article
Open AccessProceedings
Hydrodynamic Characterization of Planing Surfboards Using CFD
Proceedings 2020, 49(1), 68; https://doi.org/10.3390/proceedings2020049068 - 15 Jun 2020
Viewed by 246
Abstract
Computational fluid dynamics is recently being considered as an interesting tool to predict and analyze surfboards’ hydrodynamic characteristics for the purpose of optimizing the design. In this paper we define a systematic methodology that could be used to measure forces and moments exerted [...] Read more.
Computational fluid dynamics is recently being considered as an interesting tool to predict and analyze surfboards’ hydrodynamic characteristics for the purpose of optimizing the design. In this paper we define a systematic methodology that could be used to measure forces and moments exerted by the fluid on the surfboard. We define a “surfboard attitude” matrix, for instance varying the angle of attack and the tip surfacing height, and we fill it with values of drag, lift and moment. With these data, we can calculate the position of the center of pressure and analyze static equilibrium conditions in the presence of external forces that represent the weight of a surfer. Full article
Open AccessProceedings
The Hydrodynamics of High Diving
Proceedings 2020, 49(1), 73; https://doi.org/10.3390/proceedings2020049073 - 15 Jun 2020
Viewed by 235
Abstract
Diving consists of jumping into water from a platform, usually while performing acrobatics. During high diving competitions, the initial height reaches 27 m. From this height, the crossing of the water surface occurs at 85 km/h, and as such it is very technical [...] Read more.
Diving consists of jumping into water from a platform, usually while performing acrobatics. During high diving competitions, the initial height reaches 27 m. From this height, the crossing of the water surface occurs at 85 km/h, and as such it is very technical to avoid injuries. Major risks occur due to the violent impact at the water entry and the formation and collapse of the air cavity around the diver. In this study, we investigate experimentally the dynamics of the jumper underwater and the hydrodynamic causes of injuries in high dives by monitoring dives from different heights with high-speed cameras and accelerometers in order to understand the physics underlying diving. Full article
Open AccessProceedings
Numerical CFD Investigation of Shortboard Surfing: Fin Design vs. Cutback Turn Performance
Proceedings 2020, 49(1), 132; https://doi.org/10.3390/proceedings2020049132 - 15 Jun 2020
Viewed by 255
Abstract
The surfing performance of two shortboard fin types with surface features were compared to a standard (control) fin with a smooth surface using dynamic computational fluid dynamics (CFD) simulations. The fins with surface features included designs with a partially grooved and serrated surface [...] Read more.
The surfing performance of two shortboard fin types with surface features were compared to a standard (control) fin with a smooth surface using dynamic computational fluid dynamics (CFD) simulations. The fins with surface features included designs with a partially grooved and serrated surface (CR), and humpback whale-inspired fins with tubercles and other features (RW). Surfboard roll, pitch and yaw during cutback maneuvers were simulated based on field data from surfers of intermediate, expert and professional (WCT) skill level surfing on ocean waves. Sustained resultant forces relative to the rider direction were significantly different between fin types, and lowest for RW at WCT-level rotations. CFD results also revealed RW’s ability to dampen effects of turbulent flow. RW fins were always the last to stall during a turn, and always exhibited the most gradual stall. CR fins had significantly lower pre-turn drag, and the highest mean resultant forces during the turn. Overall, CR fins appear best for forward acceleration and hold on the wave, while RW fins appear best for maneuverability and stability. Full article
Open AccessProceedings
Field Research and Numerical CFD Analysis of Humpback Whale-Inspired Shortboard Fins
Proceedings 2020, 49(1), 158; https://doi.org/10.3390/proceedings2020049158 - 15 Jun 2020
Viewed by 266
Abstract
Compared to other Olympic sports, little research exists on competitive shortboard surfing—especially research comparing field and numerical data. In this paper, GPS sensors with 9-axis motion sensors were used to collect data on nearly 2000 surfed waves. Data were collected from four surfers [...] Read more.
Compared to other Olympic sports, little research exists on competitive shortboard surfing—especially research comparing field and numerical data. In this paper, GPS sensors with 9-axis motion sensors were used to collect data on nearly 2000 surfed waves. Data were collected from four surfers of differing skill levels, ranging from intermediate/advanced (Level 6) to top-ranked professional (Level 9). The results revealed a positive correlation between surfer skill level and roll/pitch/yaw rates during a cutback. Some surfers used two different fin types: a standard commercial fin (C), and a 3D-printed, humpback whale-inspired fin (RW). Statistically significant cutback performance improvements were seen when surfers used the RW fin. Because of the skill level differences suggested by the field data, dynamic computational fluid dynamics (CFD) analysis was performed to simulate cutback maneuvers at three different rotation rates (roll/pitch/yaw). Sustained resultant forces relative to the rider direction were lower for RW fins during the turn, suggesting a less-skilled surfer could generate faster and more powerful turns using RW fins. Field results also confirmed that a skill Level 8 surfer performed closer to skill Level 9 when using RW fins, but not control fins. Surfers experienced more stability using RW fins, and CFD results confirmed RW’s ability to dampen the effects of turbulent flow. Full article
Open AccessProceedings
Flow Behavior Caused by Air Permeability of Ski Jumping Suit Fabric
Proceedings 2020, 49(1), 109; https://doi.org/10.3390/proceedings2020049109 - 15 Jun 2020
Viewed by 303
Abstract
The purpose of this study was to investigate the effect of the air permeability of ski jumping suit fabric on aerodynamic characteristics. In the study, four types of fabric with different air permeabilities were installed onto a fabric-clothed elliptic cylinder, and the flow [...] Read more.
The purpose of this study was to investigate the effect of the air permeability of ski jumping suit fabric on aerodynamic characteristics. In the study, four types of fabric with different air permeabilities were installed onto a fabric-clothed elliptic cylinder, and the flow behavior around its surface was investigated through wind tunnel experiments. The stall was delayed by using the fabric with higher air permeability. The air flow permeated the surface of the elliptic cylinder through the fabric for the fabric with high air permeability. This air flowed out into the separation region through the fabric again, which suppress stall. The stall characteristics for the fabric-clothed elliptic cylinder were influenced by the air permeability of the fabric. The boundary layer thickness on the outer surface and the turbulence levels of the boundary layer affected the air permeability of the fabric. The higher air permeability fabrics improved the stall characteristics. Full article
Open AccessProceedings
Blockage Correction and Reynolds Number Dependency of an Alpine Skier: A Comparison Between Two Closed-Section Wind Tunnels
Proceedings 2020, 49(1), 19; https://doi.org/10.3390/proceedings2020049019 - 15 Jun 2020
Viewed by 201
Abstract
The purpose of this study was to investigate the impact of blockage effect and Reynolds Number dependency by comparing measurements of an alpine skier in standardized positions between two wind tunnels with varying blockage ratios and speed ranges. The results indicated significant blockage [...] Read more.
The purpose of this study was to investigate the impact of blockage effect and Reynolds Number dependency by comparing measurements of an alpine skier in standardized positions between two wind tunnels with varying blockage ratios and speed ranges. The results indicated significant blockage effects which need to be corrected for accurate comparison between tunnels, or for generalization to performance in the field. Using an optimized blockage constant, Maskell’s blockage correction method improved the mean absolute error between the two wind tunnels from 7.7% to 2.2%. At lower Reynolds Numbers (<8 × 105, or approximately 25 m/s in this case), skier drag changed significantly with Reynolds Number, indicating the importance of testing at competition specific wind speeds. However, at Reynolds Numbers above 8 × 105, skier drag remained relatively constant for the tested positions. This may be advantageous when testing athletes from high speed sports since testing at slightly lower speeds may not only be safer, but may also allow the athlete to reliably maintain difficult positions during measurements. Full article
Open AccessProceedings
One-Way Fluid Structure Interaction of a Go-Kart Spoiler Using CFD Analysis
Proceedings 2020, 49(1), 51; https://doi.org/10.3390/proceedings2020049051 - 15 Jun 2020
Viewed by 258
Abstract
The spoiler on a go-kart is required to prevent the vehicle becoming airborne at speeds of 80 km/h or more. An optimal spoiler design balances this safety aspect with speed and fuel economy. This paper reports the results of a project to improve [...] Read more.
The spoiler on a go-kart is required to prevent the vehicle becoming airborne at speeds of 80 km/h or more. An optimal spoiler design balances this safety aspect with speed and fuel economy. This paper reports the results of a project to improve the aerodynamic aspects of a go-kart spoiler design using CFD Analysis. We investigated the design of a rear spoiler with three proposed angles (θ1 = 9.5°, θ2 = 19.5°, θ3 = 29.5°). The drag force produced by each of the three designs is compared. Different computational results are discussed such as the air flow velocity, pressure and the applied forces in terms of CFD analysis using one-way fluid structure interaction (one-way FSI) to determine the spoiler stress, strain and drag coefficient. The findings of this paper have implications for the leisure and tourism industries, and may be applicable to other recreational vehicles’ spoilers. Full article
Open AccessProceedings
Measurement and Visualization of Airflow through Sports Textiles
Proceedings 2020, 49(1), 21; https://doi.org/10.3390/proceedings2020049021 - 15 Jun 2020
Viewed by 246
Abstract
In marathon running, maintenance of body temperature is critical for peak performance. Race apparel should maximize ventilation yet current fabric permeability standards are based on airflow rates that are not generated during running. A novel flow measurement device was used to measure airflow [...] Read more.
In marathon running, maintenance of body temperature is critical for peak performance. Race apparel should maximize ventilation yet current fabric permeability standards are based on airflow rates that are not generated during running. A novel flow measurement device was used to measure airflow through textiles and the effects of fabric hole size, coverage area and standoff distance between a simulated torso and fabric at velocities of 3.3, 5.3 and 10 m.s−1. Fluorescent dye injection in a tow tank or flume permitted visualization of flow through fabrics. Ventilation is constrained by the low flow velocity in the stagnation area over the chest of an athlete, with freestream airflows of 3.3 and 10 m.s−1 reduced to 1.31 +/− 0.10 m/s (39.6%) and 3.51 +/− 0.27 m.s−1 (35.0%), respectively at a yaw angle of 20°. The initial low flow velocity precludes improvements in airflow despite changes in the standoff distance, fabric hole size or coverage area. Full article
Open AccessProceedings
How to Assess Repeatability and Reproducibility of a Mechanical Test? An Example for Sports Engineers
Proceedings 2020, 49(1), 122; https://doi.org/10.3390/proceedings2020049122 - 15 Jun 2020
Viewed by 427
Abstract
Several sources of variation can affect the performance of a mechanical test. Hence, the measurement system performance should be assessed. The gage repeatability and reproducibility study is a method used to assess and quantify the variation of a mechanical test. Since it seems [...] Read more.
Several sources of variation can affect the performance of a mechanical test. Hence, the measurement system performance should be assessed. The gage repeatability and reproducibility study is a method used to assess and quantify the variation of a mechanical test. Since it seems that this method has not yet found its way into the field of sports engineering, this paper promotes its application by demonstrating a practical example based on a current problem in sports shoe development. In detail, a novel mechanical simulation to determine the forefoot bending stiffness of athletic footwear during plantar flexion movement was developed and its quality assessed. The ANOVA Gage R&R study was performed based on 64 randomized trials of eight footwear samples assessed by two appraisers. The mechanical test was evaluated as acceptable for the desired application and the resolution was quantified to be 0.04 Nm/°. Full article
Open AccessProceedings
Assessment of Measurement Uncertainty in Optical Marker Tracking of High-Speed Motion
Proceedings 2020, 49(1), 72; https://doi.org/10.3390/proceedings2020049072 - 15 Jun 2020
Viewed by 320
Abstract
Optical marker tracking is used in research environments to understand the dynamics of moving objects of interest. Due to the complexity of the systems and the wide field of applications, there is no simple method to assess system accuracy. In this approach, a [...] Read more.
Optical marker tracking is used in research environments to understand the dynamics of moving objects of interest. Due to the complexity of the systems and the wide field of applications, there is no simple method to assess system accuracy. In this approach, a driver clubhead functioned as a rigid body and was tracked during the delivery phase of the golf swing. Marker tracking uncertainty was assessed by measures of inter-marker distance errors. The effect of swing speed on marker tracking uncertainty was tested in the range 0 m/s (static) to 50 m/s. Results demonstrated that the rigid body position in the capture volume has a large effect on marker tracking uncertainty. Positive correlations were found between marker tracking uncertainty and swing speed. Marker size and number of cameras used for marker reconstruction were optimised to provide mean marker tracking uncertainties around the tee position of below 0.13 mm. Full article
Open AccessProceedings
Can We Trust Inertial and Heart Rate Sensor Data from an APPLE Watch Device?
Proceedings 2020, 49(1), 128; https://doi.org/10.3390/proceedings2020049128 - 15 Jun 2020
Viewed by 415
Abstract
The use of wearable technologies for the monitoring of human movement has increased considerably in the past few years, with applications to sports and other physical activities. Energy expenditure, walking and running distance, step count, and heart rate are some of the metrics [...] Read more.
The use of wearable technologies for the monitoring of human movement has increased considerably in the past few years, with applications to sports and other physical activities. Energy expenditure, walking and running distance, step count, and heart rate are some of the metrics provided by such devices via smart phone applications. Most of the research studies have involved validating the accuracy and reliability of the activity monitors by using the post-processed data from the device. The aim of this preliminary study was to determine if we can trust sensor data obtained from an Apple watch. This study evaluated the pre-processed data from the watch through step counting and heart rate measurements, and compared it with known validated devices (in-house 9DOF inertial sensor and Polar H10TM). Repeated activities (walking, jogging, and stair climbing) of varying duration and intensity were conducted by participants of varying age and body mass index (BMI). Pearson correlation (r > 0.95) and Bland–Altman statistical analyses were applied to the data to determine the level of agreement between the validated devices and the watch. The sensors from the Apple watch counted steps and measured heart rate with a minimum error and performed as expected. Full article
Open AccessProceedings
Quantifying Topographical Changes in Muscle Activation: A Statistical Parametric Mapping Approach
Proceedings 2020, 49(1), 71; https://doi.org/10.3390/proceedings2020049071 - 15 Jun 2020
Viewed by 279
Abstract
Regional changes in muscle activation occur at different contraction intensities. These changes can be observed with activity maps created with high-density electromyography (HDEMG). When quantifying these changes, statistical parametric mapping (SPM) is a neuroimaging technique that may be used to perform statistical analyses [...] Read more.
Regional changes in muscle activation occur at different contraction intensities. These changes can be observed with activity maps created with high-density electromyography (HDEMG). When quantifying these changes, statistical parametric mapping (SPM) is a neuroimaging technique that may be used to perform statistical analyses with high sensitivity and spatial resolution. The aim of this study was to identify regional changes in muscle activation at different contraction intensities, comparing SPM and the HDEMG barycenter (centroid). Twelve participants performed plantar flexion isometric contractions at 20%, 40%, and 60% of the maximal voluntary contraction (MVC), while HDEMG was recorded from the medial gastrocnemius. An SPM repeated measures ANOVA design revealed specific mediolateral and cephalocaudal changes in muscle activation with increasing contraction intensities, which were not clearly detected by the variation in the barycenter coordinates. Only SPM revealed statistically significant nonuniform changes in EMG amplitude between all increasing levels of muscle activation. Full article
Open AccessProceedings
Evaluation of a Framework for Visual-Feedback Training Based on a Modified Self-Organizing Map Using Sensing Information Including Muscle Activity
Proceedings 2020, 49(1), 40; https://doi.org/10.3390/proceedings2020049040 - 15 Jun 2020
Viewed by 259
Abstract
In this research, we propose a visual-feedback system and evaluate it based on motion-sensing and computational technologies. This system will help amateur athletes imitate the motor skills of professionals. Using a self-organizing map (SOM) to visualize high-dimensional time-series motion data, we recorded the [...] Read more.
In this research, we propose a visual-feedback system and evaluate it based on motion-sensing and computational technologies. This system will help amateur athletes imitate the motor skills of professionals. Using a self-organizing map (SOM) to visualize high-dimensional time-series motion data, we recorded the cyclic motion information, including the muscle activities, of a male subject as he pedaled a bicycle ergometer. To clarify the difference between the subject’s motor skill and the target motor skill in a cyclic movement, we used the modified SOM algorithm; a visual-feedback system was developed, which displayed the target motion as a circular trajectory on a two-dimensional motor skills map. The subject trained by observing only the displayed static target trajectory; the subject’s real-time trajectory was constructed from the subject’s real-time motion. We validated our proposed framework for the visual-feedback system by evaluating the motion performance of a subject using feedback training. Full article
Open AccessProceedings
Dynamic Motion Analysis Using a Wearable Sensor System in a Stabilometer Installed with Generation Function of Disturbance from a Floor
Proceedings 2020, 49(1), 164; https://doi.org/10.3390/proceedings2020049164 - 15 Jun 2020
Viewed by 315
Abstract
In this study, we developed an evaluation method using posture and joint torque for the evaluation of balance ability. The evaluation and analysis of standing with a disturbance is conducted for effective balance evaluations. Center of pressure information is mainly used for the [...] Read more.
In this study, we developed an evaluation method using posture and joint torque for the evaluation of balance ability. The evaluation and analysis of standing with a disturbance is conducted for effective balance evaluations. Center of pressure information is mainly used for the evaluation of balance ability using a stabilometer. It is necessary for a more detailed analysis to combine the measurements of body motion. The analysis of posture and joint angle is conducted by body-motion measurement, and joint torque is calculated using ground reaction force and posture information. In this study, we estimated posture and joint torque using a wearable sensor system in the balance evaluation of standing using a stabilometer that generates a disturbance. The analytical results indicated the posture information and joint torque. Analysis and feedback in a short time can be conducted using the wearable sensor system. Full article
Open AccessProceedings
Measuring the Boxing Punch: Development and Calibration of a Non-Embedded In-Glove Piezo-Resistive Sensor
Proceedings 2020, 49(1), 13; https://doi.org/10.3390/proceedings2020049013 - 15 Jun 2020
Viewed by 179
Abstract
Biomechanics measurement in boxing is becoming increasingly important for the analysis of boxing technique in order to promote exciting and safer boxing at both amateur and professional levels. Despite this interest, there have been few experiments within this field of research that have [...] Read more.
Biomechanics measurement in boxing is becoming increasingly important for the analysis of boxing technique in order to promote exciting and safer boxing at both amateur and professional levels. Despite this interest, there have been few experiments within this field of research that have utilised a non-embedded in-glove sensor to measure the resultant power generated by a boxing punch. The aim of this study was to develop a dynamic measurement system, utilising a non-embedded in-glove sensor system. Two sensors were utilised; a tri-axial accelerometer to measure acceleration and a piezo-resistive force sensor hand wrap to measure the impact force of a boxer’s punch. The piezo-resistive system was calibrated using a static measurement system utilising simple load cells for force and laser displacement sensors for glove speed measurements. The system was tested on 31 novice boxing athletes participating in the study. A mean impact force of 2.31 kN ± 3.28 kN, an instantaneous velocity prior to impact of 4.73 m/s ± 0.35 m/s, an impact acceleration of 91 g ± 11 g, deceleration immediately following impact of 223 g ± 21 g and a maximum power dissipation of 11.2 kW ± 2.05 kW were measured. These values correspond well with prior studies using alternate measurement approaches. The calibration of the non-embedded in-glove piezo-resistive force sensor on the static measurement system yielded a correlation coefficient of 0.85. Full article
Open AccessProceedings
An Examination of the Biomechanics of the Cross, Hook and Uppercut between Two Elite Boxing Groups
Proceedings 2020, 49(1), 61; https://doi.org/10.3390/proceedings2020049061 - 15 Jun 2020
Viewed by 254
Abstract
In boxing, an efficient punch requires a combination of force, velocity and stability of the athlete. Being able to monitor these parameters has the potential to better inform training practices required to reach high performance. Hence, the aim of this study was to [...] Read more.
In boxing, an efficient punch requires a combination of force, velocity and stability of the athlete. Being able to monitor these parameters has the potential to better inform training practices required to reach high performance. Hence, the aim of this study was to investigate the differences in punching execution between two groups of elite boxers (senior vs. junior) using three biomechanical indicators of performance in boxing. Each athlete was equipped with an instrumented suit composed of 17 inertial measurement units (IMU) and were asked to perform several series of punches with 3 standardized punching techniques (cross, hook and uppercut) on a punching bag with maximal force. Linear velocity, stability and punch forces were computed from the different sensors. Our findings show that senior boxers systematically produced more force and at a higher velocity for the three punching techniques compared to juniors. The IMU analysis also reveals differences of joint contributions between seniors and juniors, juniors presenting a higher contribution of the shoulder for the three punching techniques. Full article
Open AccessProceedings
Measurement of Flight Dynamics of a Frisbee Using a Triaxial MEMS Gyroscope
Proceedings 2020, 49(1), 66; https://doi.org/10.3390/proceedings2020049066 - 15 Jun 2020
Viewed by 204
Abstract
A Frisbee with a mass of 0.21 kg, diameter of 0.27 m and moment of inertia (MOI) of 0.002 kg·m2 was instrumented with a triaxial gyroscope. The Frisbee was thrown at low angular velocities as the measurement limit of a single gyroscope [...] Read more.
A Frisbee with a mass of 0.21 kg, diameter of 0.27 m and moment of inertia (MOI) of 0.002 kg·m2 was instrumented with a triaxial gyroscope. The Frisbee was thrown at low angular velocities as the measurement limit of a single gyroscope was at 6.065 rps. The angular velocities of the triaxial gyroscope were analysed to study the attitude of a Frisbee before and after release. The angular velocities measured were post-processed and the following data were obtained: spin rate at release—3.9–6.14 rps; user-induced peak torque—0.483–0.9 Nm, and peak angular acceleration—204–358 rad/s2; and power input 7.53–19.56 W. The Frisbee wobbled at release which decreased during the flight due to a damping effect. This affected the spin decay, the reduction of wobble lead to a reduced drag force and thus to a smaller spin decay, which was initially 1.12–0.31 rev/s2 and then asymptoted to 0.11–0.01 rev/s2. Full article
Open AccessProceedings
The Effect of Instrumentation on Sports Balls During Flight, Exemplified by A Smart AFL Ball: Model and Experiment
Proceedings 2020, 49(1), 102; https://doi.org/10.3390/proceedings2020049102 - 15 Jun 2020
Viewed by 177
Abstract
Sensors incorporated in a sports ball for data collection can affect the properties of a ball, specifically the spin rate of a ball if the mass distribution (moments of inertia, MOI) is altered. This paper provides a method for assessing the MOIs of [...] Read more.
Sensors incorporated in a sports ball for data collection can affect the properties of a ball, specifically the spin rate of a ball if the mass distribution (moments of inertia, MOI) is altered. This paper provides a method for assessing the MOIs of a smart ball by means of spin rate data, collected from a gyroscopic sensor. The critical elevation angle of the angular velocity vector defines the separatrix condition, which decides whether the angular velocity vector precesses about the axis with the greatest MOI or with the smallest MOI. The critical elevation angle can be directly determined from the experimental of the angular velocity data, and, together with the ratio of precession speed to angular velocity, applied to calculating the three MOIs. In the smart AFL ball used for the experiments, the critical angle was 13.5°, and the ratio of the two small MOIs was 1.014. Full article
Open AccessProceedings
Smart Headgear for Assessment of Auditory Response Reaction Time of Professional and Amateur Kendokas
Proceedings 2020, 49(1), 93; https://doi.org/10.3390/proceedings2020049093 - 15 Jun 2020
Viewed by 313
Abstract
In Kendo, the ability to execute a technique within the shortest time is essential for winning. The purpose of this study was to utilise an in-house developed automatic headgear-scoring sensor with a buzzer to determine the auditory response reaction time (ARRT) of professional [...] Read more.
In Kendo, the ability to execute a technique within the shortest time is essential for winning. The purpose of this study was to utilise an in-house developed automatic headgear-scoring sensor with a buzzer to determine the auditory response reaction time (ARRT) of professional (PK) and amateur (AK) Kendo practitioners. ARRT is defined as the time required for a participant to hit a target after a buzzer is sounded. A total of 14 participants took part in this study. The participants were requested to hit the opponent’s headgear target, which consisted of a pressure sensor, upon hearing the buzzer. The average reaction time of PK is 0.44 s, and for AK 0.58 s, with a significant difference between the two groups (p < 0.0001). The in-house developed automatic headgear-scoring sensor with buzzer can be utilised to assist a Kendo practitioner in training to shorten the response reaction time to improve competition performance. Full article
Open AccessProceedings
Gait Analysis Using Load-Controlled Single- and Split-Belt Treadmills
Proceedings 2020, 49(1), 48; https://doi.org/10.3390/proceedings2020049048 - 15 Jun 2020
Viewed by 221
Abstract
We developed a self-paced load-controlled treadmill with two built-in force plates to enhance lower limb muscles. Since the load can be changed freely with a load-controlled treadmill, it can be widely utilized in fields such as rehabilitation and training. In this paper, we [...] Read more.
We developed a self-paced load-controlled treadmill with two built-in force plates to enhance lower limb muscles. Since the load can be changed freely with a load-controlled treadmill, it can be widely utilized in fields such as rehabilitation and training. In this paper, we experimentally investigated the difference between single-belt and split-belt load-controlled treadmills with two subjects, who walked 30 s with a constant load r = 0, 5, 10, 15% based on the maximum driving force on both treadmills. Our result showed that the angular range of the motion of the ankle joints when walking on a single-belt treadmill was up to 2.68 times larger than walking on a split-belt treadmill. The ground reaction force reading showed that the ankle joint moment on a single-belt was larger during the terminal stance, suggesting that single-belt treadmills more effectively enhance lower limb muscles. Full article
Open AccessProceedings
Development of Force Plates Installed with Five-Axis Load Cells and Analysis Using a Wearable Sensor System
Proceedings 2020, 49(1), 16; https://doi.org/10.3390/proceedings2020049016 - 15 Jun 2020
Viewed by 190
Abstract
In this study, we developed a new force plate system. Conventional force plates output force and moment by using the signals of three-axis load cells. The developed force plate installs four 5-axis load cells, and each load cell can output 3-axis force and [...] Read more.
In this study, we developed a new force plate system. Conventional force plates output force and moment by using the signals of three-axis load cells. The developed force plate installs four 5-axis load cells, and each load cell can output 3-axis force and 2-axis moment relating to deflection. The moment components of load cells are used for the compensation of cross talk and the calculation of moment in the force plate. The force plate can measure force and moment on the outside of load cells installed in the force plate. Gait measurement and analysis were conducted by using the developed force plate, a conventional force plate, and a wearable sensor system (wearable force plate). The results of the comparison of the developed force plates and the conventional force plate outputs indicated a difference in performance on the outside of load cells. Full article
Open AccessProceedings
Motion and Force Analysis in Load Control Type Treadmill Using Wearable Sensor System
Proceedings 2020, 49(1), 14; https://doi.org/10.3390/proceedings2020049014 - 15 Jun 2020
Viewed by 202
Abstract
In this study, we developed a load control type treadmill installed with a force plate and an automatic controller. A conventional treadmill does not measure ground reaction force, and the belt is rotated at a constant speed. The developed system can measure ground [...] Read more.
In this study, we developed a load control type treadmill installed with a force plate and an automatic controller. A conventional treadmill does not measure ground reaction force, and the belt is rotated at a constant speed. The developed system can measure ground reaction force and control the belt speed by feeding back measured propulsion force. A participant can obtain the load by controlling the belt speed corresponding to the target load value. The system provides an environment close to actual motion on a road. We conducted measurement experiments on the treadmill using a wearable motion sensor system in gait and running conditions, and we estimated joint angles in gait condition. The result of the vertical and propulsion force and the joint angles indicated the difference of performance in the levels of the target load value, and the characteristics of load control type treadmill are indicated. Full article
Open AccessProceedings
A Novel Approach for a Faster Prototyping of Winter Sport Equipment Using Digital Image Correlation and 3D Printing
Proceedings 2020, 49(1), 125; https://doi.org/10.3390/proceedings2020049125 - 15 Jun 2020
Viewed by 306
Abstract
The optimization of sport equipment parts requires considerable time and high costs due to the high complexity of the development process. For this reason, we have developed a novel approach to decrease the cost and time for the optimization of the design, which [...] Read more.
The optimization of sport equipment parts requires considerable time and high costs due to the high complexity of the development process. For this reason, we have developed a novel approach to decrease the cost and time for the optimization of the design, which consists of producing a first prototype by 3D printing, applying the forces that normally acts during the sport activity using a test bench, and then measuring the local deformations using 3D digital image correlation (DIC). The design parameters are then modified by topological optimization and then DIC is performed again on the new 3D-printed modified part. The DIC analysis of 3D-printed parts has shown a good agreement with that of the injection-molded ones. The deformation measured with DIC are also well correlated with those provided by finite element method (FEM) analysis, and therefore DIC analysis proves to be a powerful tool to validate FEM models. Full article
Open AccessProceedings
Comparing the Performance of the Biathlon Rifles with Wooden and Titanium Frames
Proceedings 2020, 49(1), 62; https://doi.org/10.3390/proceedings2020049062 - 15 Jun 2020
Viewed by 222
Abstract
The present paper describes preliminary results of studies carried out using a new measurement setup and a biathlon rifle with two different interchangeable stocks: a commercial, mainly wooden one and one additively manufactured from titanium alloy and a polymer PA 2200, employing lightweight, [...] Read more.
The present paper describes preliminary results of studies carried out using a new measurement setup and a biathlon rifle with two different interchangeable stocks: a commercial, mainly wooden one and one additively manufactured from titanium alloy and a polymer PA 2200, employing lightweight, 3D lattice architecture. A finite element analysis of the predicted mechanical properties of new design elements was carried out prior to the manufacturing. Experiments were carried out using a novel setup for the assessment of athlete and rifle performance in biathlon shooting. Data acquisition was carried out at the rates of few kilosamples per second, using a combination of an airbag-based rifle butt pressure sensor, a trigger loading sensor, strap load cell, and two tri-axis MEMS sensors—an accelerometer and a gyroscope. All tests indicate that a rifle stock additively manufactured from titanium alloy could provide better recoil damping compared to the commercial, mainly wooden one. Together with the high capacity of additive manufacturing technologies in equipment individualization, this may provide additional possibilities for the improvement of sports rifle construction and help athletes achieve better results in competitions. Full article
Open AccessProceedings
Modelling Bending Stiffness and Vibration Characteristics to Enable Simulation-Driven Ski Design
Proceedings 2020, 49(1), 157; https://doi.org/10.3390/proceedings2020049157 - 15 Jun 2020
Viewed by 247
Abstract
When developing alpine skis, new design is often built upon experience from what has been done in the past. This allows for stable but incremental improvements that limit the possibilities of ground-breaking design changes. To allow such major changes, without risking spending a [...] Read more.
When developing alpine skis, new design is often built upon experience from what has been done in the past. This allows for stable but incremental improvements that limit the possibilities of ground-breaking design changes. To allow such major changes, without risking spending a fortune on trial and error studies, simulation-based design is a must. This paper presents a method for such a simulation-based design approach, focusing on the effect of the internal ski structure and its effect on bending and vibration characteristics. As a prototype ski, we have studied Faction Skis’ Candide 3.0, for which a finite element model was developed and validated. In the next step, the effect of a design ski variation was analysed to demonstrate how simulation-based screening of design options can be easily implemented. Full article
Open AccessProceedings
Effect of Surrogate Surface Compliance on the Measured Stiffness of Snowboarding Wrist Protectors
Proceedings 2020, 49(1), 84; https://doi.org/10.3390/proceedings2020049084 - 15 Jun 2020
Viewed by 276
Abstract
Wrist injuries have been reported to account for 35%–45% of snowboarding injuries. Snowboarding wrist protectors are designed to limit impact forces and prevent wrist hyperextension. The absence of a standard for snowboarding wrist protectors makes it hard to identify models offering an adequate [...] Read more.
Wrist injuries have been reported to account for 35%–45% of snowboarding injuries. Snowboarding wrist protectors are designed to limit impact forces and prevent wrist hyperextension. The absence of a standard for snowboarding wrist protectors makes it hard to identify models offering an adequate level of protection. Wrist surrogates are well suited for testing and benchmarking wrist protectors. This study investigated the effect of introducing a soft tissue simulant onto an otherwise stiff wrist surrogate on the bending stiffness of snowboarding wrist protectors. A compliant surrogate (stiff core and 3 mm thick silicone layer) and a comparable stiff surrogate were fabricated. Two snowboarding wrist protectors were tested on each surrogate, under three strapping conditions, following a bend test to ~80° wrist extension. The introduction of a compliant layer to the wrist surrogate gave higher torque values for a given wrist extension angle, increasing protector effective stiffness, relative to a rigid surrogate. Full article
Open AccessProceedings
Comparative Study of Ski Damping Technologies by Accelerance Maps
Proceedings 2020, 49(1), 49; https://doi.org/10.3390/proceedings2020049049 - 15 Jun 2020
Viewed by 307
Abstract
The vibratory response of alpine skis plays a significant role in the overall skier’s experience. This response is more important than ever as skiers now demand light and approachable (i.e., soft) skis. To improve the vibratory response, many companies now offer technologies to [...] Read more.
The vibratory response of alpine skis plays a significant role in the overall skier’s experience. This response is more important than ever as skiers now demand light and approachable (i.e., soft) skis. To improve the vibratory response, many companies now offer technologies to damp the ski’s motion. Even if widely used, these technologies are still widely misunderstood. This paper presents a method based on accelerance maps to evaluate the vibratory response (i.e., bending and torsional modes up to 250 Hz) and the damping at all points on the ski forebody. A variety of commercial technologies are evaluated (i.e., tuned-mass damper, particle damper, constrained-layer and rod activated viscoelastic bushing) and compared to the more traditional effects brought by adjusting mass, bending/torsional stiffnesses and construction. Full article
Open AccessProceedings
Historical Trends in Alpine Ski Design: How Skis Have Evolved Over the Past Century
Proceedings 2020, 49(1), 135; https://doi.org/10.3390/proceedings2020049135 - 15 Jun 2020
Viewed by 373
Abstract
Alpine skis have changed dramatically in the last century. Long and straight wood skis have evolved into shorter lengths and now contain a plethora of modern materials. Shaped skis have become the norm. Today’s skis also offer a variety of waist widths and [...] Read more.
Alpine skis have changed dramatically in the last century. Long and straight wood skis have evolved into shorter lengths and now contain a plethora of modern materials. Shaped skis have become the norm. Today’s skis also offer a variety of waist widths and shapes to cater to specific uses. By studying how skis have evolved, it is possible to gain insight into how the design of alpine skis has progressed. To do so, the mechanical properties of 1016 skis, from the 1920s to 2019, were measured with a machine developed at the University of Sherbrooke. The resulting data are used to calculate various geometric, stiffness and performance parameters. The evolution of these parameters over the years is analyzed. This analysis provides a better understanding of the evolution of ski design and shows when the introduction of new materials and shaping concepts has changed the way skis are designed. Full article
Open AccessProceedings
Convenient Method for Detecting Ski-Turn Features with Inertial and Plantar Pressure Sensors
Proceedings 2020, 49(1), 24; https://doi.org/10.3390/proceedings2020049024 - 15 Jun 2020
Viewed by 266
Abstract
Skiers need a convenient method that uses actual ski-turn data to determine their skill level quantitatively without impeding their movement. In this study, we propose a feature detection method designed to quantitatively assess the skill level involved in ski turns. Actual data were [...] Read more.
Skiers need a convenient method that uses actual ski-turn data to determine their skill level quantitatively without impeding their movement. In this study, we propose a feature detection method designed to quantitatively assess the skill level involved in ski turns. Actual data were acquired from both expert and intermediate skiers while skiing by using a comfortable measurement system that uses compact inertial sensors attached to the user’s skis and waist, and plantar pressure sensors. The changes in body posture and the behavior of the skis were examined using acceleration and angular velocity (each on three axes) data output by the inertial sensors. The plantar pressure distributions generated during skiing were also examined. The results show that it is possible to detect the relationship between the behavior of the skis and the changes in body posture or the plantar pressure distribution, which allows the skier’s skill level to be quantitatively assessed. Full article
Open AccessProceedings
Effectiveness of a Snowboarding Simulation Using the Distinct Element Method
Proceedings 2020, 49(1), 101; https://doi.org/10.3390/proceedings2020049101 - 15 Jun 2020
Viewed by 187
Abstract
Some snowboarding simulation methods have been developed. Although snow has unique properties such as granular material and continuum, few snowboard simulation methods can reproduce the discrete behavior of snow. Conventional simulations are unsuitable for reproducing the characteristics of snow when ski and snowboard [...] Read more.
Some snowboarding simulation methods have been developed. Although snow has unique properties such as granular material and continuum, few snowboard simulation methods can reproduce the discrete behavior of snow. Conventional simulations are unsuitable for reproducing the characteristics of snow when ski and snowboard turns carve through snow and create grooves in it with their edges. We developed a snowboarding simulation based on the distinct element method (DEM) to reproduce the characteristics of snow and compare the results of the developed method with those of a conventional simulation method. The developed simulation was validated by comparing with the results of an experiment involving a few miniature snowboards of different shapes and a pseudo-snow slope. The turn trajectory and board posture predicted by the DEM simulation were closer to the test results than those predicted by the conventional simulation. Full article
Open AccessProceedings
Effects of a Disturbed Kinetic Chain in the Fastball Pitch on Elbow Kinetics and Ball Speed
Proceedings 2020, 49(1), 67; https://doi.org/10.3390/proceedings2020049067 - 15 Jun 2020
Viewed by 381
Abstract
The purpose of the present study was to investigate the effect of an experimentally imposed kinetic chain disturbance in baseball pitching on ball speed and elbow kinetics. The experimental design consisted of two (within-subject) conditions. In one condition there was no manipulation (control [...] Read more.
The purpose of the present study was to investigate the effect of an experimentally imposed kinetic chain disturbance in baseball pitching on ball speed and elbow kinetics. The experimental design consisted of two (within-subject) conditions. In one condition there was no manipulation (control condition). The other condition involved a manipulation of the kinetic chain by taping the pelvis and trunk. In both conditions, pitchers were instructed to throw fastballs until a minimum of 15 pitches were captured. Inverse dynamic solutions were used calculate the internal elbow moments of six elite youth baseball pitchers. The pitchers that were hampered in throwing fastballs, by the taped pelvis and trunk, showed significant lower ball speeds and peak internal varus moments compared to the pitchers that were allowed to throw without any hindrance. Full article
Open AccessProceedings
Novel Experimental Protocol to Capture Movement Data and Predict Shot Execution in Cricket Batting
Proceedings 2020, 49(1), 41; https://doi.org/10.3390/proceedings2020049041 - 15 Jun 2020
Viewed by 325
Abstract
Shot execution in cricket batting is reliant on intricate movement patterns of crucial body segments. When there is a substantial amount of batting movement data available, supervised machine learning can be used to classify when a batting shot execution takes place in a [...] Read more.
Shot execution in cricket batting is reliant on intricate movement patterns of crucial body segments. When there is a substantial amount of batting movement data available, supervised machine learning can be used to classify when a batting shot execution takes place in a cricket batting cycle. An automated approach to identify and assess cricket batting could be useful for the applications including performance evaluation, talent identification and injury prevention. Current evaluation of movements and shot execution are generally undertaken in an artificial environment with camera-based, motion tracking systems to collect batting movement data, which require careful preparation, data collection and post-processing, and risk changing the natural gameplay of a batsman. By training a model based on data obtained from a close representation of a cricket batting innings, supervised machine learning was found to be capable of reliably predicting cricket batting shot execution. Full article
Open AccessProceedings
Wood Bat Durability as a Function of Bat Profile and Slope of Grain
Proceedings 2020, 49(1), 97; https://doi.org/10.3390/proceedings2020049097 - 15 Jun 2020
Viewed by 221
Abstract
During the 2008 Major League Baseball (MLB) season, there was a perception that the rate at which wood bats were breaking was on the rise. MLB responded by implementing changes to the wood bat regulations that were essentially transparent to the players, e.g., [...] Read more.
During the 2008 Major League Baseball (MLB) season, there was a perception that the rate at which wood bats were breaking was on the rise. MLB responded by implementing changes to the wood bat regulations that were essentially transparent to the players, e.g., changing the orientation for the hitting surface on maple bats, setting a lower bound on wood density, and reducing the allowable range for the slope of grain (SoG) of the wood used to make bats. These new regulations resulted in a 65% reduction in the wood-bat breakage rate. It is proposed that a further reduction to the multi-piece failure (MPF) rate can be realized by accounting for the role that bat profile plays with respect to bat durability. Durability is defined here as the relative bat/ball speed that results in crack initiation, i.e., the higher the breaking speed, the better the durability. The aim of the current work is to complete a parametric study to investigate if bat profile influences bat durability with respect to SoG. Three bat profiles with very different geometries and volumes are analyzed using the finite element software, LSDYNA®. The mechanical behavior of the wood is modeled using the *MAT_WOOD material model in combination with the *MAT_ADD_EROSION option. The effective wood material properties are varied as a function of wood density and SoG. Results include how varying bat profile and SoG influences bat durability. The study is limited to maple wood bats. Full article
Open AccessProceedings
Comparison of Two Methods to Estimate the Maximal Velocity of a Ball during an Overhand Throw
Proceedings 2020, 49(1), 43; https://doi.org/10.3390/proceedings2020049043 - 15 Jun 2020
Viewed by 258
Abstract
Maximal ball velocity is a significant performance indicator in many sports, such as baseball. Doppler radar guns are widely assumed to underestimate velocity. Accuracy increases as the cosine angle between the radar gun and the object decreases. The purpose of this study was [...] Read more.
Maximal ball velocity is a significant performance indicator in many sports, such as baseball. Doppler radar guns are widely assumed to underestimate velocity. Accuracy increases as the cosine angle between the radar gun and the object decreases. The purpose of this study was to investigate the impact of player handedness and the location of the radar gun on the accuracy of ball velocity. Throws were analyzed in four conditions: the radar gun on the right side, throwing with the right arm, then with the left arm; and the radar gun on the left side, throwing with the right arm, then with the left arm. The Cronbach’s alpha for all four conditions showed α-values above 0.97; however, a paired t-test indicated significant differences between the 3D motion analysis and the radar gun. Bland–Altman plots show a high degree of scatter in all conditions. Results suggest that the radar gun measurements can be highly inconsistent when compared to 3D motion analysis. Full article
Open AccessProceedings
Spin Rate Measurements in Cricket Bowling Using Magnetometers
Proceedings 2020, 49(1), 11; https://doi.org/10.3390/proceedings2020049011 - 15 Jun 2020
Viewed by 629
Abstract
The ability to measure and classify spin has been of great interest to cricket organizations, coaches, and athletes. While video is common, an alternative approach is to use 3D motion capture analysis with reflective spheres, which changes the aerodynamics of the ball. An [...] Read more.
The ability to measure and classify spin has been of great interest to cricket organizations, coaches, and athletes. While video is common, an alternative approach is to use 3D motion capture analysis with reflective spheres, which changes the aerodynamics of the ball. An instrumented cricket ball has proved to be effective in measuring high-speed spin rates using gyroscopes. In this study, an instrumented ball with a 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer located at the center mass of the ball was constructed. The spin rate was calculated using the magnetometer, and two spin types (off-spin and leg-spin) were classified. The sensor data was validated using motion capture. In addition, inertial measurement units (IMUs) mounted on the wrist and elbow of a wrist-spin and off-spin bowler were used to verify and validate the spin classification. The magnetometer can be effectively used in conjunction with conventional IMU sensors on the bowler’s arm to tailor training sessions by addressing deficiencies identified in a bowler’s spinning technique and to monitor their performance. Full article
Open AccessProceedings
Standard of the Initial Ball Velocity for a Fly Ball in Baseball Hitting
Proceedings 2020, 49(1), 137; https://doi.org/10.3390/proceedings2020049137 - 15 Jun 2020
Viewed by 274
Abstract
This study aimed to determine the minimum required initial velocity to hit a fly ball toward the same field (left-field for right-handed batters), center field, and opposite field (right field for right-handed batters). Six baseball players hit fastballs launched by a pitching machine. [...] Read more.
This study aimed to determine the minimum required initial velocity to hit a fly ball toward the same field (left-field for right-handed batters), center field, and opposite field (right field for right-handed batters). Six baseball players hit fastballs launched by a pitching machine. The movements of the balls before and after bat-to-ball impact were recorded using two high-speed video cameras. The flight distance was determined using a measuring tape. Seventy-nine trials were analyzed, and the minimum required initial velocities of batted balls were quantified to hit balls 60, 70, 80, 90, 100, 110, and 120 m in each direction through regression analysis. As a result, to hit a ball 120 m, initial velocities of 43.0, 43.9, and 46.0 m/s were required for the same field, center field, and opposite field, respectively. The result provides a useful index for batters to hit a fly ball in each of the directions. Full article
Open AccessProceedings
Quantification of a Ball-Speed Generating Mechanism of Baseball Pitching Using IMUs
Proceedings 2020, 49(1), 57; https://doi.org/10.3390/proceedings2020049057 - 15 Jun 2020
Viewed by 256
Abstract
The purpose of this study was to propose a methodology which quantifies the ball-speed generating mechanism of baseball pitching with the use of inertial measurement units (IMUs). IMUs were attached to the upper trunk, upper arm, forearm, and hand segments. The initial orientation [...] Read more.
The purpose of this study was to propose a methodology which quantifies the ball-speed generating mechanism of baseball pitching with the use of inertial measurement units (IMUs). IMUs were attached to the upper trunk, upper arm, forearm, and hand segments. The initial orientation parameters of each segment were identified using the differential iteration method from the acceleration and angular velocity of the sensor coordinate system output by IMUs attached to each segment. The motion of each segment was calculated and the dynamic contributions were then calculated. The motion of a baseball pitcher, who was instructed to throw at the target, was measured with a motion capture (mocap) system and IMUs. The results show that quantitative analysis of the ball-speed generation mechanism by the proposed method is almost similar to that conducted by the mocap system. In the future, this method will be employed to evaluate the ball-speed generation mechanism outside controlled laboratory conditions in an effort to help understand and improve the player’s motion. Full article
Open AccessProceedings
Development of New Baseball Pitching Machine with Four-Roller Throwing Mechanism
Proceedings 2020, 49(1), 8; https://doi.org/10.3390/proceedings2020049008 - 15 Jun 2020
Viewed by 162
Abstract
At present, there are only a few developed pitching machines that can throw a ball with gyro spin. In this study, we aimed to develop a new baseball pitching machine using four rollers, where the rotational speed of each of the four rollers [...] Read more.
At present, there are only a few developed pitching machines that can throw a ball with gyro spin. In this study, we aimed to develop a new baseball pitching machine using four rollers, where the rotational speed of each of the four rollers and the crossing angle of the opposite gyro rollers can be controlled optionally to generate an objective gyro spin more efficiently. We also elucidate the throwing mechanism of the developed baseball pitching machine and confirm its performance by finite element analysis. The newly developed pitching machine can throw a baseball with a wide range of speeds from 22.2 m/s (80 km/h) to 44.4 m/s (160 km/h) with all pitch types (fastball, curveball, gyroball, etc.), and the spin axis can be controlled in any designated direction. Moreover, this machine is capable of throwing a baseball with higher accuracy compared to commercially available pitching machines. Full article
Open AccessProceedings
Bowling Performance Assessed with a Smart Cricket Ball: A Novel Way of Profiling Bowlers
Proceedings 2020, 49(1), 141; https://doi.org/10.3390/proceedings2020049141 - 15 Jun 2020
Viewed by 214
Abstract
Profiling of spin bowlers is currently based on the assessment of translational velocity and spin rate (angular velocity). If two spin bowlers impart the same spin rate on the ball, but bowler A generates more spin rate than bowler B, then bowler A [...] Read more.
Profiling of spin bowlers is currently based on the assessment of translational velocity and spin rate (angular velocity). If two spin bowlers impart the same spin rate on the ball, but bowler A generates more spin rate than bowler B, then bowler A has a higher chance to be drafted, although bowler B has the potential to achieve the same spin rate, if the losses are minimized (e.g., by optimizing the bowler’s kinematics through training). We used a smart cricket ball for determining the spin rate and torque imparted on the ball at a high sampling frequency. The ratio of peak torque to maximum spin rate times 100 was used for determining the ‘spin bowling potential’. A ratio of greater than 1 has more potential to improve the spin rate. The spin bowling potential ranged from 0.77 to 1.42. Comparatively, the bowling potential in fast bowlers ranged from 1.46 to 1.95. Full article
Open AccessProceedings
Profiling of a Pitcher’s Performance with a Smart Baseball: A Case Report
Proceedings 2020, 49(1), 103; https://doi.org/10.3390/proceedings2020049103 - 15 Jun 2020
Viewed by 219
Abstract
A pitcher’s action, when delivering a fastball, was analyzed from the data provided by a smart baseball. The spin rate at the release of the ball was merely 15.7 rps, however, the peak torque was excessively high, namely 0.396 Nm. The reason why [...] Read more.
A pitcher’s action, when delivering a fastball, was analyzed from the data provided by a smart baseball. The spin rate at the release of the ball was merely 15.7 rps, however, the peak torque was excessively high, namely 0.396 Nm. The reason why the pitcher was not able to translate the torque entirely to angular kinetic energy and this to the spin rate was that the spin axis changed its direction suddenly three times when moving across the ball’s surface. This resulted in angles between torque and angular velocity vectors of greater than 90°, high precession and precession torque, and negative spin torques, causing a very low efficiency (5.4%) and a slow spin rate at the release of the ball. Full article
Open AccessProceedings
Effect of Throwing Kinematics and Kinetics on Different Ranges of Long Toss in Youth Baseball Players
Proceedings 2020, 49(1), 118; https://doi.org/10.3390/proceedings2020049118 - 15 Jun 2020
Viewed by 209
Abstract
Long-toss throwing is a baseball exercise that enhances the throwing performance of youth players. However, throwing kinematics and kinetics have not been fully investigated. This study aimed to analyze the effect of throwing kinematics and kinetics on different ranges of long toss in [...] Read more.
Long-toss throwing is a baseball exercise that enhances the throwing performance of youth players. However, throwing kinematics and kinetics have not been fully investigated. This study aimed to analyze the effect of throwing kinematics and kinetics on different ranges of long toss in 22 youth players of the same age. The throwing motion was analyzed as the range of long toss was increased by 10 m each time until the ball did not directly reach the target. The twelve subjects who could throw long distances had a significantly larger physique and larger throwing kinematics and kinetics compared to the other 10 subjects who could not. No differences in the proximal force of the shoulder and elbow joints were observed between the two groups. These findings suggest that baseball coaches should set a suitable range of long toss for youth players according to the individual’s physical growth and strength. Full article
Open AccessProceedings
Rapid Sensory Profiling of Tennis Rackets
Proceedings 2020, 49(1), 123; https://doi.org/10.3390/proceedings2020049123 - 15 Jun 2020
Viewed by 316
Abstract
Tennis racket manufacturers rely on subjective assessments from testers during the development process. However, these assessments often lack validity and include multiple sources of inconsistency in the way testers make subjective ratings. The purpose of this research was to investigate the suitability of [...] Read more.
Tennis racket manufacturers rely on subjective assessments from testers during the development process. However, these assessments often lack validity and include multiple sources of inconsistency in the way testers make subjective ratings. The purpose of this research was to investigate the suitability of the free-choice profiling (FCP) method in combination with principle component analysis (PCA) and multiple factor analysis (MFA) to determine the sensory profile of rackets. FCP was found to be a suitable technique to quickly evaluate the sensory profile of rackets; however, consumer testers tended to use ill-defined, industry-generated terms, which negatively impacted discrimination and inter-rater agreement. Discrimination and inter-rater agreement improved for attributes referring to measurable parameters of the rackets, such as vibration. This study furthers our understanding of tennis racket feel and supports racket engineers in designing new subjective testing methods, which provide more meaningful data regarding racket feel. Full article
Open AccessProceedings
2K-Reality and the Compliant Sports Augmentation Framework for Grassroots Sports
Proceedings 2020, 49(1), 83; https://doi.org/10.3390/proceedings2020049083 - 15 Jun 2020
Viewed by 232
Abstract
In this paper, we introduce the Compliant Sports Augmentation Framework (CSAF), which aims to promote a sociocultural approach to the design of sports technology for grassroots sports. The CSAF design criteria advocate enhancing the experiential qualities of grassroots sports by respecting, protecting and [...] Read more.
In this paper, we introduce the Compliant Sports Augmentation Framework (CSAF), which aims to promote a sociocultural approach to the design of sports technology for grassroots sports. The CSAF design criteria advocate enhancing the experiential qualities of grassroots sports by respecting, protecting and cultivating existing practices, meanings and values. We developed the CSAF by synthesising the theory, practice and evaluation components of our 2K-Reality design research project that sought to enhance the enjoyment of playing and watching pickup basketball with digital technology. The disciplines that contributed to our development of the CSAF include sports philosophy, sports psychology, games studies, public health and sports management. Full article
Open AccessProceedings
Are You for Real? Engineering a Virtual Lab for the Sports Sciences Using Wearables and IoT
Proceedings 2020, 49(1), 110; https://doi.org/10.3390/proceedings2020049110 - 15 Jun 2020
Viewed by 300
Abstract
In tertiary education, disciplines such as sports science that require experimental components in their courses represent a significant challenge for online and distance education. This paper demonstrates the design and construction of an enriched experiment, together with the prototype software solution which can [...] Read more.
In tertiary education, disciplines such as sports science that require experimental components in their courses represent a significant challenge for online and distance education. This paper demonstrates the design and construction of an enriched experiment, together with the prototype software solution which can all be operated remotely using a web-based client. It presents research that investigated how to visualise data from internet of things (IoT) sensor devices (inertial sensor) used for tracking football sideline throw-ins. In this simple experiment, data was collected from one footballer, fitted with a single inertial sensor. A two-dimensional (2D) video, three-dimensional (3D) motion capture system and inertial sensor were all used to detect the release point of a sideline ball throw-in. In this project, inertial sensor data was used to create a 3D model using web graphical language and three.js. Full article
Open AccessProceedings
Toward Augmented Reality Displays for Sports Spectators: A Preliminary Study
Proceedings 2020, 49(1), 129; https://doi.org/10.3390/proceedings2020049129 - 15 Jun 2020
Viewed by 281
Abstract
The sports industry and researchers work on improving spectators’ enjoyment to influence their consumption behavior. Many studies evaluated the variables impacting on enjoyment, but they did not consider the recent new technologies popularization. This study aims to update these considerations and reevaluate enjoyment [...] Read more.
The sports industry and researchers work on improving spectators’ enjoyment to influence their consumption behavior. Many studies evaluated the variables impacting on enjoyment, but they did not consider the recent new technologies popularization. This study aims to update these considerations and reevaluate enjoyment parameters’ impact, considering display technologies use. Most of the previous research works identified identification to the players and teams as the most powerful enjoyment variable, but considering our survey results, participants cared more about the game understanding parameter, and manifested the wish to improve it via a display. Full article
Open AccessProceedings
Comparison and Evaluation of Sizing Systems Used in Commercial Women’s Compression Sportswear
Proceedings 2020, 49(1), 140; https://doi.org/10.3390/proceedings2020049140 - 15 Jun 2020
Viewed by 219
Abstract
Currently, there is no published research evaluating sizing methodologies for commercial sports compression garments (SCGs), so this study addresses the research gap by analysing sizing systems used for women-specific SCGs. Firstly, fit trials with whole-body SCGs were conducted with 33 active females. Secondly, [...] Read more.
Currently, there is no published research evaluating sizing methodologies for commercial sports compression garments (SCGs), so this study addresses the research gap by analysing sizing systems used for women-specific SCGs. Firstly, fit trials with whole-body SCGs were conducted with 33 active females. Secondly, the upper and lower body size charts of 12 SCG brands were analysed. Thirdly, the fitness of the size charts for the sample was assessed. Findings of the fit trials indicated that the fit of the SCGs varied from the intended fit in most participants at certain body locations, which is problematic for consistent pressure delivery. New sizing approaches are needed for SCGs, as fit requirements differ from conventional clothing, and current approaches appear to be inappropriate. The inclusion of a limb circumference measurement as a key dimension could be beneficial due to the interrelation of fabric tension and limb girth in pressure delivery (Laplace’s Law). Full article
Open AccessProceedings
Investigation on Indoor Air Quality in the Badminton Hall of Wuhan Sports University in winter Based on Subjective Questionnaire Survey and Field Test
Proceedings 2020, 49(1), 148; https://doi.org/10.3390/proceedings2020049148 - 15 Jun 2020
Viewed by 221
Abstract
More and more people play badminton and pay close attention to indoor air quality (IAQ) in the badminton hall. In order to get the perception of the reception for IAQ from the badminton players, a subjective questionnaire was done separately in the badminton [...] Read more.
More and more people play badminton and pay close attention to indoor air quality (IAQ) in the badminton hall. In order to get the perception of the reception for IAQ from the badminton players, a subjective questionnaire was done separately in the badminton hall of Wuhan Sports University. A Field Test was done in the badminton hall and testing parameters included carbon monoxide (CO2), PM2.5, Volatile Organic Compounds (TVOC), etc. The results show that the testing result was consistent with the questionnaire and the environmental parameters were within the scope of national standards. The results indicated that, although IAQ in the badminton halls can be accepted currently, there are still many unsatisfactory elements. The air freshness in most indoor badminton halls is relatively low, the ventilation is insufficient and the mugginess is strong. Full article
Open AccessProceedings
Exploring the Effect of Pacing Plan Feedback for Professional Road Cycling
Proceedings 2020, 49(1), 58; https://doi.org/10.3390/proceedings2020049058 - 15 Jun 2020
Viewed by 521
Abstract
In road cycling, cyclists strategically use their energetic resources in unique race-specific circumstances. For time-trial events, professional cycling teams design pacing plans aimed at the effective management of anaerobic work capacities of individual cyclists, allowing for more consistent speeds and therefore, faster times. [...] Read more.
In road cycling, cyclists strategically use their energetic resources in unique race-specific circumstances. For time-trial events, professional cycling teams design pacing plans aimed at the effective management of anaerobic work capacities of individual cyclists, allowing for more consistent speeds and therefore, faster times. Patently, adherence to such plans is essential. This paper reports on a field user-study on the effectiveness of providing a pacing plan to cyclists with the following information: (1) printed table alongside a display device with non-processed information (power, distance); and (2) aggregated, processed, just-in-time information on the same device (past, present, prospective; power, distance, W’). In both conditions, 15 road cyclists completed an 8 km open route mimicking race conditions, while adhering to pre-set pacing plans designed relative to their individual critical-power capabilities. Results indicated a linear load-to-adherence relationship and better adherence in condition (2). These findings will help guide future designs of adaptive feedback mechanisms for professional road cycling. Full article
Open AccessProceedings
Drafting Effect in Cycling: On-Site Aerodynamic Investigation by the ‘Ring of Fire’
Proceedings 2020, 49(1), 113; https://doi.org/10.3390/proceedings2020049113 - 15 Jun 2020
Viewed by 384
Abstract
An on-site Ring of Fire (RoF) experiment is performed at the Tom Dumoulin bike park in Sittard-Geleen, the Netherlands. The current work investigates the aerodynamic drag of a cyclist following a lead cyclist at different lateral and longitudinal separations; additionally, the athletes’ skills [...] Read more.
An on-site Ring of Fire (RoF) experiment is performed at the Tom Dumoulin bike park in Sittard-Geleen, the Netherlands. The current work investigates the aerodynamic drag of a cyclist following a lead cyclist at different lateral and longitudinal separations; additionally, the athletes’ skills to maintain their position and distance with respect to the preceding riders are evaluated. The effect of the relative size of the lead cyclist on the drag area of the drafting cyclist is also investigated. The results show drag reductions of the trailing cyclist in the range from 27% to 66% depending on the longitudinal and lateral separation from the leading rider. The aerodynamic advantage of the drafting rider decreases with increasing lateral and longitudinal separation between riders, with the lateral separation found to be more relevant. Besides this, the drag reduction of the drafting cyclist benefits from an increase in drag area of the leading cyclist. Full article
Open AccessProceedings
Investigation of Influence of Adjustments in Cyclist Arm Position on Aerodynamic Drag Using Computational Fluid Dynamics
Proceedings 2020, 49(1), 159; https://doi.org/10.3390/proceedings2020049159 - 15 Jun 2020
Viewed by 370
Abstract
In professional cycling, even small adjustments in position could mean that valuable seconds are gained over the course of a time-trial race. This study investigates the influence of arm position on the aerodynamic drag of a cyclist. Based on a 3D scanned model [...] Read more.
In professional cycling, even small adjustments in position could mean that valuable seconds are gained over the course of a time-trial race. This study investigates the influence of arm position on the aerodynamic drag of a cyclist. Based on a 3D scanned model of a professional cyclist, 64 alternate positions are generated. The parameters that are investigated are the distance between elbows, elbow extension, and distance between hands. Computational fluid dynamics (CFD) simulations of all positions are performed, and a regression model is built from the results. The results indicate that the optimal posture is achieved for a minimum in all investigated parameters, which means that the hands and elbows should be kept together with hands up towards the face. Furthermore, elbow extension seems to be the most crucial parameter, followed by the distance between elbows, and then by the distance between the hands. The presented methodology can be applied to study other parameters relevant to cycling aerodynamics or be applied to other sport activities as well. Full article
Open AccessProceedings
Improving Numerical Estimation of Cyclist Drag Area in Static Conditions Using Unsteady RANS
Proceedings 2020, 49(1), 139; https://doi.org/10.3390/proceedings2020049139 - 15 Jun 2020
Viewed by 301
Abstract
Herein, we compare the drag area estimated using unsteady Reynolds-averaged Navier-Stokes (URANS), using the γ−ReΘ transitional shear stress transport (SST) k−ω (SSTLM) turbulence model with published experimental measurements of a static full-scale cyclist mannequin in an open test section wind tunnel, with [...] Read more.
Herein, we compare the drag area estimated using unsteady Reynolds-averaged Navier-Stokes (URANS), using the γ−ReΘ transitional shear stress transport (SST) k−ω (SSTLM) turbulence model with published experimental measurements of a static full-scale cyclist mannequin in an open test section wind tunnel, with the left leg fully extended. The turbulence model employs a local empirical correlation based upon a classical Blasius boundary layer behavior to predict flow transition. For a given mesh density, we aim to improve drag area estimation by modifying the empirical correlation coefficient to better capture actual boundary layer transition location around the arms and legs, to facilitate computationally economical cyclist simulations. Large Eddy Simulation (LES), in conjunction with experimental wake data in the vicinity of the arms and legs, is used to assess boundary layer shape factors, which are related to the empirical coefficient. Overall, the drag area predicted by LES is within 3.7% of the measured results, while the original SSTLM is within 7.8%. By tuning the correlation coefficient, the drag area error is improved to 6.0% at no additional computational cost. The tuning was relatively coarse, and was only considered for the appendages. In other regions, the original SSTLM coefficient seems to perform better, suggesting that local coefficient selection may lead to further improvements in results over the currently employed global value. Full article
Open AccessProceedings
Understanding the Aerodynamic Benefits of Drafting in the Wake of Cyclists
Proceedings 2020, 49(1), 32; https://doi.org/10.3390/proceedings2020049032 - 15 Jun 2020
Viewed by 331
Abstract
A new approach is presented to characterize the aerodynamic benefit from riding in the wake of another cyclist at different downstream locations. The method presented uses the dynamic pressure deficit in the wake of a cycling mannequin to estimate percentage drag savings. In [...] Read more.
A new approach is presented to characterize the aerodynamic benefit from riding in the wake of another cyclist at different downstream locations. The method presented uses the dynamic pressure deficit in the wake of a cycling mannequin to estimate percentage drag savings. In the experiments, the time-averaged velocity behind a cycling mannequin was recorded in 1 × 0.95 m cross-planes by two four-hole pressure (Cobra) probes for four static leg positions (0°, 90°, 180°, and 270°). It was found that the wake of the cycling mannequin propagated to one side or the other as it developed downstream, depending on the strength of the two large-scale counter-rotating streamwise vortical structures shed off the hips of the mannequin. In the near wake, the complex wake dynamics resulted in an inaccurate prediction of the relative drag reduction based upon a dynamic pressure deficit. However, as the wake developed and stabilised further downstream, the dynamic pressure deficit was found to provide a reasonable estimate of the aerodynamic drag reduction of riding in the wake of the lead rider. Full article
Open AccessProceedings
Improving Road Bike Leaning Skills on Downhill Corners (Developing a System for Detecting Curvature Change Points and the Angle of a Road Bike while Riding)
Proceedings 2020, 49(1), 153; https://doi.org/10.3390/proceedings2020049153 - 15 Jun 2020
Viewed by 277
Abstract
In road bicycle races, advanced skills are needed to traverse downhill corners quickly and safely. A previous study revealed that in specific experimental corners, some beginners tend to lean their bikes more compared to experts. Therefore, in seeking to develop a support method [...] Read more.
In road bicycle races, advanced skills are needed to traverse downhill corners quickly and safely. A previous study revealed that in specific experimental corners, some beginners tend to lean their bikes more compared to experts. Therefore, in seeking to develop a support method for improving rider skill in controlling bike position, the authors aimed to design a system that indicates to users the positions of their bikes to lean it at the appropriate inclination when making turns. First, we determined the corner starting points using the RTK (Real Time Kinematic) positioning system. Then, we calculated the theoretical inclination and compared this to the inclination practiced by an expert. The experiment with this system showed that the expert started leaning the bike approximately 5 m short of a corner’s starting point with the speed maintained at approximately 25 km/h, with some correlation found between the theoretically ideal degree of inclination and the expert’s actual inclination. Full article
Open AccessProceedings
Optimization of the Internal Structure and Shape of a 470 Dinghy Centerboard
Proceedings 2020, 49(1), 36; https://doi.org/10.3390/proceedings2020049036 - 15 Jun 2020
Viewed by 244
Abstract
The purpose of this paper is to design an improved centerboard for the Olympic 470 sailing dinghy sailing upwind. The design is improved by introducing a composite design that makes the centerboard twist to windward when sailing upwind, thereby reducing the angle of [...] Read more.
The purpose of this paper is to design an improved centerboard for the Olympic 470 sailing dinghy sailing upwind. The design is improved by introducing a composite design that makes the centerboard twist to windward when sailing upwind, thereby reducing the angle of attack of the hull. The results show that a beneficial twist up to 1.5° is possible to achieve without compromising the centerboard strength. According to our estimates, by utilizing the improved design it is possible to obtain a gain of up to 9 s per race in a world cup race. Full article
Open AccessProceedings
Modern Surfboards and Their Structural Characterization: Towards an Engineering Approach
Proceedings 2020, 49(1), 65; https://doi.org/10.3390/proceedings2020049065 - 15 Jun 2020
Viewed by 268
Abstract
Recently, manufactures who produce surfboards using computer aided design and robotic (CNC) shaping tools have gained a larger share of the surfing market, allowing board producers and shapers to produce lighter and more durable boards. The improvement in design and production process of [...] Read more.
Recently, manufactures who produce surfboards using computer aided design and robotic (CNC) shaping tools have gained a larger share of the surfing market, allowing board producers and shapers to produce lighter and more durable boards. The improvement in design and production process of surfboards has been directly linked with the adaption of technologies tested and validated in other industries. However, the surfing industry still lacks methodologies, standards and testing facilities to scientifically investigate and quantify the structural and hydrodynamic properties of surfboards. It is widely accepted that distributed rigidity, damping and stiffness in the three directions play a huge role in defining surfboard performance. These properties are rarely stated by producers and never measured. The present paper compares two boards with equal outline and geometric shape but built with two different technologies: one board built with a traditional high density polyurethane (PU) blank, polyester resin and a stringer to improve longitudinal stiffness and one board built with bio epoxy resin, expanded polystyrene (EPS) and two side inserts made of cork to improve longitudinal stiffness and damping. Different tests were carried out to compare the two boards and a testing methodology with the aim to evaluate board structural properties and identify key parameters that will influence the board performances. Accelerometers were used to characterize stiffness and damping while a custom-made flex machine was used to evaluate the torsional stiffness. Differences between the two boards are highlighted, leading to the fact that the two boards, even being identical in size, will behave differently in different wave conditions and for different surfers. Full article
Open AccessProceedings
Parametric Shape and Manufacturing Optimization of Customized Kitesurf Hydrofoils
Proceedings 2020, 49(1), 126; https://doi.org/10.3390/proceedings2020049126 - 15 Jun 2020
Viewed by 261
Abstract
To minimize the costs of the current manufacturing of kitesurf hydrofoil wings, a workflow using a finite elements model was developed. By coupling a computational fluid dynamic (CFD) analysis with a structural finite element analysis (FEA), an optimization based on a genetic algorithm [...] Read more.
To minimize the costs of the current manufacturing of kitesurf hydrofoil wings, a workflow using a finite elements model was developed. By coupling a computational fluid dynamic (CFD) analysis with a structural finite element analysis (FEA), an optimization based on a genetic algorithm is implemented. The design space of the optimization is defined by the manufacturing processes. This enables the algorithm to find wing shapes which are not only suitable for the rider’s weight and preferred take-off speed but can also be produced directly on a universal mold surface. To reduce the amount of cut-off material and sustain the mechanical stresses, the output of the optimization contains the required number and orientation of all fiber layers within the reinforcement structure. This research shows that a single mold can produce different wing shapes to satisfy the needs of a wide range of customers. Full article
Open AccessProceedings
A New Measurement System for Performance Analysis in Flatwater Sprint Kayaking
Proceedings 2020, 49(1), 39; https://doi.org/10.3390/proceedings2020049039 - 15 Jun 2020
Viewed by 303
Abstract
The full comprehension of the impact with which each force is involved in kayak propulsion is very difficult. The measure of the force on the paddle or the stroke rate only is often not enough for the coach to identify the best actions [...] Read more.
The full comprehension of the impact with which each force is involved in kayak propulsion is very difficult. The measure of the force on the paddle or the stroke rate only is often not enough for the coach to identify the best actions useful to improve the performances of a kayaker. To this purpose, the synchronous measurement of all parameters involved in the kayak propulsion, both dynamic (force acting on paddle and foot brace) and kinematic (stroke frequency, displacement, velocity, acceleration, roll, yaw, and pitch of the boat) could suggest to the coach more appropriate strategies for better understanding of the paddler’s motion and the relevant effects on the kayak behavior. Some simulation models, as well as measurement systems of increasing complexity, have been proposed in the recent years. In this paper, we present the e-Kayak system: A multichannel Digital Acquisition (DAQ) system specifically customized for flatwater kayaking. The system will be described in depth and its capability investigated through specific measurement results. Full article
Open AccessProceedings
Numerical Simulation of Mutual Influence in 470 Sailing Hull and Rudder at Different Hull Speeds
Proceedings 2020, 49(1), 134; https://doi.org/10.3390/proceedings2020049134 - 15 Jun 2020
Viewed by 242
Abstract
A 470 sailing race requires effective cooperation between athletes to optimize the hull position and the correct heading. To understand the effect of the hull on the maneuverability of the rudder and the influence of the rudder on the stability and rapidity of [...] Read more.
A 470 sailing race requires effective cooperation between athletes to optimize the hull position and the correct heading. To understand the effect of the hull on the maneuverability of the rudder and the influence of the rudder on the stability and rapidity of the hull at different ship speeds, requires numerical 3D simulation and research on the viscous flow field of 470 sailing based on Reynolds-averaged Navier-Stokes equations. The results show that the rudder can reduce the wave making characteristics of the hull, reducing energy loss and thus improving the hull’s rapidity when the speed is greater than 6 m/s, as the effective area of rudder decrease and increases the stall angle, which reduces the manipulatable performance of the rudder to some extent. This study could quantify the performance of the hull and rudder at different speeds. Moreover, this study might provide strategies for the athletes to effectively control the rudder and hull at different speeds. Full article
Open AccessProceedings
Water Ski Binding Release Characteristics in Forward Lean
Proceedings 2020, 49(1), 76; https://doi.org/10.3390/proceedings2020049076 - 15 Jun 2020
Viewed by 199
Abstract
To reduce the risk of injury, waterski bindings should secure the foot to the ski when the likelihood of lower leg injury is low (retention) and free the foot when the likelihood of injury is high (release). Unlike snow skiing, there are no [...] Read more.
To reduce the risk of injury, waterski bindings should secure the foot to the ski when the likelihood of lower leg injury is low (retention) and free the foot when the likelihood of injury is high (release). Unlike snow skiing, there are no standards dictating the release of waterski bindings. Testing was completed to determine release torques in forward lean of three commercially available waterski boot-binding systems. Each binding was mounted to a 66-inch waterski and the boot was fitted on a lower leg surrogate with a torque transducer. A forward-lean bending moment was applied quasi-statically about the transverse axis of the ski until the binding released the boot. For the three boot-binding systems, the range of release torques were 126 to 219, 50 Nm to 141, and 63 to 127 Nm. Full article
Open AccessProceedings
Conceptual Design of a New Multi-Component Test Bench for the Dynamic Characterization of Running Specific Prostheses
Proceedings 2020, 49(1), 75; https://doi.org/10.3390/proceedings2020049075 - 15 Jun 2020
Viewed by 264
Abstract
Stiffness properties of running specific prostheses (RSP) for Paralympic runners are fundamental in the selection of the optimal running prosthetic foot (RPF) for sprint and jump events, depending on the athlete’s anthropometry and characteristics. RPFs are J-shaped or C-shaped, clamped to the socket [...] Read more.
Stiffness properties of running specific prostheses (RSP) for Paralympic runners are fundamental in the selection of the optimal running prosthetic foot (RPF) for sprint and jump events, depending on the athlete’s anthropometry and characteristics. RPFs are J-shaped or C-shaped, clamped to the socket or the pylon of the prosthetic leg. The aim of this work was to develop a test bench suitable for the static and dynamic characterization of a running prosthetic feet (RPF). Based on the evidence that the ground reaction force components change their relative orientation to the pylon or socket during the stance, loads were resolved in the socket reference frame and a multi-component test bench was designed and constructed. Two perpendicular actuators can apply static and dynamic loads to the foot while contacting a surrogate ground inclined at different angles. The preliminary tests show how the alignment, load combination, and ground angle can affect RPF stiffness curves. Full article
Open AccessProceedings
Collection of Structural Loads Acting on Instrumented Running Specific Prostheses during Field Tests on Elite Atletes
Proceedings 2020, 49(1), 74; https://doi.org/10.3390/proceedings2020049074 - 15 Jun 2020
Viewed by 243
Abstract
The knowledge of loads acting on Running Specific Prostheses (RSP), and in particular, on Running Prosthetic Feet (RPF) is crucial for evaluating the athlete’s running technique, designing RPF, and developing models of the runners. The aim of this work was to develop a [...] Read more.
The knowledge of loads acting on Running Specific Prostheses (RSP), and in particular, on Running Prosthetic Feet (RPF) is crucial for evaluating the athlete’s running technique, designing RPF, and developing models of the runners. The aim of this work was to develop a set of instrumented RPF (iRPF) suitable for track data collection of start, sprinting, and whole run-in and take-off of long jump. The system allows measuring with a portable data logger forces acting on the foot clamp on multiple steps of the athlete without modifying the RSP behavior: The method involves strain gauge bridges applied to each RPF in a configuration that allows decoupling the loads parallel and normal to the foot clamp during the stance phase. Comparison with literature data and validation against force platform data gave confirmation of the validity of the method in the estimation of determinants of sprint performance. Full article
Open AccessProceedings
Shape Optimization of Running Specific Prosthesis Based on Force-Displacement Characteristics
Proceedings 2020, 49(1), 7; https://doi.org/10.3390/proceedings2020049007 - 15 Jun 2020
Viewed by 257
Abstract
Usage of carbon fiber reinforced plastics (CFRPs) in running-specific prostheses increases day by day. The tailorable properties of CFRP blades bring many discussions about design and performance. In this study, the effect of shape on performance is investigated through force-displacement characteristics of the [...] Read more.
Usage of carbon fiber reinforced plastics (CFRPs) in running-specific prostheses increases day by day. The tailorable properties of CFRP blades bring many discussions about design and performance. In this study, the effect of shape on performance is investigated through force-displacement characteristics of the prosthesis. For this purpose, the geometry of prosthesis is defined by using B-splines with an initially given thickness. The prosthesis is exposed to vertical tip load at the mounting point, and contact is defined between the prosthesis and ground without friction. The aim of the simulation is to observe the contact behavior of athletes at different positions during the contact phase of a prosthesis. While the prosthesis is in contact with the ground, two different behaviors are observed: compression occurs at a larger contact zone, whereas release occurs at a smaller contact region (almost only the tip of the prosthesis). Different force-displacement characteristics, such as linear and second order, are obtained and the geometry of the prosthesis is optimized to adjust the behavior in the first region. The releasing phase of a prosthesis is related to the contact angle (angle of attack) and stiffness of the prosthesis. The two phases of contact are combined into a non-linear spring-mass system. Ground reaction forces are estimated through the non-linear mass-spring system. Finally, the importance of contacting area, length of moment arm during contact, and effect of each type of force-displacement characteristics on performance is discussed. Full article
Open AccessProceedings
Measurement of Dynamic Behavior of Running- Specific Prostheses by an Impact Test
Proceedings 2020, 49(1), 145; https://doi.org/10.3390/proceedings2020049145 - 15 Jun 2020
Viewed by 239
Abstract
The objective of this study was to evaluate rebound characteristics for running-specific prostheses by quantifying their dynamic behavior by an impact experiment. The impact experiment was conducted to produce a typical ground foot strike contact, and to obtain the dynamic behavior of blades [...] Read more.
The objective of this study was to evaluate rebound characteristics for running-specific prostheses by quantifying their dynamic behavior by an impact experiment. The impact experiment was conducted to produce a typical ground foot strike contact, and to obtain the dynamic behavior of blades during and after impact. The motion of the impactor and displacement of the blade was quantified by tracking markers attached to the surface of the impactor and blade using the digital image correlation method. Impact load was also calculated using the history of acceleration. An average spring stiffness, which was obtained by dividing the maximum impact load by its displacement, was proposed to evaluate the rebound characteristics for prostheses. As a result, the difference between the types of blades can be observed using the proposed stiffness and velocity ratio. This relationship indicates that the stiffness and the ratio may have the potential to be applicable to evaluate the performance of blades. Full article
Open AccessProceedings
Evaluation of Operability for a Competition Wheelchair Using Manipulability
Proceedings 2020, 49(1), 53; https://doi.org/10.3390/proceedings2020049053 - 15 Jun 2020
Viewed by 267
Abstract
The objective of this study was to evaluate the operability for a competition wheelchair by estimating biomechanical parameters during the forward linear operation of a wheelchair using an inverse dynamics analysis. During operation of the wheelchair, the vector of ideal hand force in [...] Read more.
The objective of this study was to evaluate the operability for a competition wheelchair by estimating biomechanical parameters during the forward linear operation of a wheelchair using an inverse dynamics analysis. During operation of the wheelchair, the vector of ideal hand force in the posture of the arm was calculated using the reaction force between the hand and the wheel. Hand manipulability was defined as the angles between its vector and the vector of hand force estimated from the simulation. The effects of the design parameters for the wheelchair on manipulability were investigated by conducting simulations with changes in axle positions. As a result, it may be effective to set the axle to higher positions to increase the energy efficiency of the upper limbs during operation of the wheelchair. This indicates that adjustment of the axle position leads to improvement of operability of the wheelchair. Full article
Open AccessProceedings
Analysis of Swimming Motion for a Swimmer with Unilateral Transradial Deficiency to Develop Better Training Paddles
Proceedings 2020, 49(1), 9; https://doi.org/10.3390/proceedings2020049009 - 15 Jun 2020
Viewed by 232
Abstract
Devices for swimmers with arm amputation/deficiency have not been developed a lot and therefore many improvements can be realized. Although swimmers often use paddles during training, paddles on the market are basically for swimmers without amputation/deficiency. The objective of this study was to [...] Read more.
Devices for swimmers with arm amputation/deficiency have not been developed a lot and therefore many improvements can be realized. Although swimmers often use paddles during training, paddles on the market are basically for swimmers without amputation/deficiency. The objective of this study was to analyze the swimming motion of a swimmer with unilateral transradial deficiency and to obtain the findings for development of better training paddles. The crawl stroke was filmed for a swimmer with unilateral transradial deficiency. The body geometry as well as the joint motion based on the filmed images were put into the swimming human simulation model SWUM, and a simulation was conducted. From the simulation, the coordination and thrusts of both limbs were obtained and fully discussed. Overall, significant asymmetry between the intact and deficient limbs was found. It was also found that the deficient limb contributed to the propulsion only for 7% of the intact limb. Full article
Open AccessProceedings
Development of Customised Wheelchair Racing Gloves Using Digital Fabrication Techniques
Proceedings 2020, 49(1), 44; https://doi.org/10.3390/proceedings2020049044 - 15 Jun 2020
Viewed by 217
Abstract
Wheelchair racing gloves are typically solid 3D structures held in a clenched fist which help to propel the chair by pushing the glove against a rotating rail which is attached to the wheel to drive the wheelchair forward. There has been a recent [...] Read more.
Wheelchair racing gloves are typically solid 3D structures held in a clenched fist which help to propel the chair by pushing the glove against a rotating rail which is attached to the wheel to drive the wheelchair forward. There has been a recent movement towards developing customisable gloves using 3D scanning technique, however, currently there are no commercial offerings which allow for product customisation without being prohibitively expensive. The aim of this project, therefore, was to develop a scalable method for producing customised wheelchair racing gloves in a cost-effective way. The generated 3D forms were 3D printed in a variety of infill densities and finished with a grip liner. These 3D printed gloves were compared in terms of fit and perception of performance, and for their mass, cost and energy/power cost. The 3D printed gloves provided a substantially reduced mass with only a minimal reduction in overall strength at a comparable cost to the solid equivalent. Full article
Open AccessProceedings
Evaluation of Driving Performance of Two Types of Competitive Wheelchairs for Badminton Made of Two Different Metallic Materials
Proceedings 2020, 49(1), 161; https://doi.org/10.3390/proceedings2020049161 - 15 Jun 2020
Viewed by 214
Abstract
Currently, various types of wheelchairs for badminton have been developed for weight saving and functional improvement. The purpose of this study was to evaluate each performance of two types of competitive wheelchairs for badminton made of two different metallic materials. One of the [...] Read more.
Currently, various types of wheelchairs for badminton have been developed for weight saving and functional improvement. The purpose of this study was to evaluate each performance of two types of competitive wheelchairs for badminton made of two different metallic materials. One of the wheelchairs used in this study was made of magnesium composite material, which was 45 GPs of Young’s modulus, 1.738 g/cm3 of the specific weight, and 9.57 kg of weight. Another was made of scandium-aluminum composite material, which was 70 GPa of Young’s modulus, 2.70 g/cm3 of the specific weight, and 10.81 kg of weight. The frames and weights of the wheelchairs were similar. In this experiment, the subject’s electromyograms from six muscles in driving each wheelchair were measured and analyzed. Furthermore, the motion in driving was captured and analyzed using a three-dimensional motion capture system. This experiment led to the following result: no significant difference was found in wheelchair performance due to the different materials. Full article
Open AccessProceedings
Model for Heart Rate Estimation in Driving Wheelchair Using Wearable Device
Proceedings 2020, 49(1), 52; https://doi.org/10.3390/proceedings2020049052 - 15 Jun 2020
Viewed by 188
Abstract
Recently, in the field of sports, studies have been actively conducted to collect and analyze human behavior data from various sensors for assisting exercise. However, there are very few studies targeting disabled subjects. The purpose of this study was to suggest a model [...] Read more.
Recently, in the field of sports, studies have been actively conducted to collect and analyze human behavior data from various sensors for assisting exercise. However, there are very few studies targeting disabled subjects. The purpose of this study was to suggest a model for heart rate estimation in driving a wheel-chair using a wearable device and to assist the exercise of wheel-chair users. The suggested model estimated the heart rate transformed from the data of 6-axis sensors (accelerations and angular velocities) using machine learning. The sensors were attached to the undercarriage of the wheel-chair. Input to the suggested model were acceleration toward a driving direction, angle of slope and oxygen intake. The suggested model estimated the heart rate every 12 s. When the suggested model was applied to heart rate estimation during normal driving of the wheel-chair, it was confirmed that estimation was possible within 9.34 bpm mean absolute error. Full article
Open AccessProceedings
Influence of Material on Wheelchair Vibrations
Proceedings 2020, 49(1), 127; https://doi.org/10.3390/proceedings2020049127 - 15 Jun 2020
Viewed by 209
Abstract
Wheelchair sports have a tendency to depend on the performance of wheelchairs, and the weight reduction of wheelchairs made of various alloys has helped improve the performance of players. Some players have mentioned, however, that the operability and riding comfort of competition wheelchair [...] Read more.
Wheelchair sports have a tendency to depend on the performance of wheelchairs, and the weight reduction of wheelchairs made of various alloys has helped improve the performance of players. Some players have mentioned, however, that the operability and riding comfort of competition wheelchair have been affected by changing the wheelchair materials; stiffness and weight are considered to be related to operability and riding comfort. In this experiment, we installed some weights on the center of the mass of a competitive wheelchair made of magnesium alloy to be the same mass of a wheelchair made of aluminum alloy; vibrations that occurred on both wheelchairs while driving were measured and compared. The experiment was performed using 3-axis sensors. This experiment showed that the vibration frequency of the wheelchair made of magnesium alloy was different from that made of aluminum alloy. This result was thought to be influenced by the difference in Young’s modulus or the specific weight. Full article
Open AccessProceedings
Are UCL Injuries a Matter of Bad Luck? The Role of Variability and Fatigue Quantified
Proceedings 2020, 49(1), 107; https://doi.org/10.3390/proceedings2020049107 - 15 Jun 2020
Viewed by 357
Abstract
Upper extremity injuries are common in baseball. One of these is the ulnar collateral ligament (UCL) injury. In the field of sports injuries, most research focuses on average kinematics and kinetics between subjects, whereas focusing on within-subject variability appears to be more relevant [...] Read more.
Upper extremity injuries are common in baseball. One of these is the ulnar collateral ligament (UCL) injury. In the field of sports injuries, most research focuses on average kinematics and kinetics between subjects, whereas focusing on within-subject variability appears to be more relevant for determining injury risk. We constructed a simple explanatory simulation model to illustrate the relationship between within-subject load variability and risk, illustrating how pitchers with a higher load variability are more likely to sustain an injury compared to pitchers with less load variability. Furthermore, the model comprises the (theoretical) effect of fatigue on load variability and injury threshold over time. Full article
Open AccessProceedings
Defining the Individual Injury Profile of Recreational Runners: Integrating Off-Training and Subjective Factors into the Assessment of Non-Professional Athletes
Proceedings 2020, 49(1), 87; https://doi.org/10.3390/proceedings2020049087 - 15 Jun 2020
Viewed by 319
Abstract
Non-professional runners make extensive use of consumer-available wearable devices and smartphone apps to monitor training sessions, health, and physical performance. Despite the popularity of these products, they usually neglect subjective factors, such as psychosocial stress, unexpected daily physical (in)activity, sleep quality perception, and/or [...] Read more.
Non-professional runners make extensive use of consumer-available wearable devices and smartphone apps to monitor training sessions, health, and physical performance. Despite the popularity of these products, they usually neglect subjective factors, such as psychosocial stress, unexpected daily physical (in)activity, sleep quality perception, and/or previous injuries. Consequently, the implementation of these products may lead to underperformance, reduced motivation, and running-related injuries. This paper investigates how the integration of subjective training, off-training, and contextual factors from a 24/7 perspective might lead to better individual screening and health protection methods for recreational runners. Using an online-based Ecological Momentary Assessment survey, a seven-day cohort study was conducted. Twenty participants answered daily surveys three times a day regarding subjective off-training and contextual data; e.g., health, sleep, stress, training, environment, physiology, and lifestyle factors. The results show that daily habits of people are unstructured, unlikely predictable, and influenced by factors, such as the demands of work, social life, leisure time, or sleep. By merging these factors with sensor-based data, running-related systems would be able to better assess the individual workload of recreational runners and support them to reduce their risk of suffering from running-related injuries. Full article
Open AccessProceedings
Efficacy of Density in Predicting the Protective Properties of Padded Clothing in Rugby
Proceedings 2020, 49(1), 38; https://doi.org/10.3390/proceedings2020049038 - 15 Jun 2020
Viewed by 308
Abstract
World Rugby™ permits players to wear padded clothing meeting the requirements of Regulation-12, which limits density, thickness and impact performance. Due to non-uniform geometry, measuring the density of padding can be challenging and provides limited information on mechanical properties. This study investigated how [...] Read more.
World Rugby™ permits players to wear padded clothing meeting the requirements of Regulation-12, which limits density, thickness and impact performance. Due to non-uniform geometry, measuring the density of padding can be challenging and provides limited information on mechanical properties. This study investigated how well density could predict the impact performance of rugby padding, whilst reviewing compliance parameters as alternatives. Eleven samples of rugby padding, plus one control material, were tested for compliance, then impacted at energies of 4.9, 9.8 and 14.7 J using the setup as defined in Regulation-12, and finally cut to calculate density. The density and compliance parameters were correlated against peak impact accelerations using a Spearman’s rank test. Density was not significantly correlated with peak acceleration at any energy level, with compliance tests significantly correlated with impact acceleration at only 4.9 J. Full article
Open AccessProceedings
Effect of Football Size and Mass in Youth Football Head Impacts
Proceedings 2020, 49(1), 29; https://doi.org/10.3390/proceedings2020049029 - 15 Jun 2020
Viewed by 406
Abstract
In youth association football, the use of different size and/or mass footballs might represent a feasible intervention for addressing heading impact severity and player safety concerns. This study assessed the effects of football size and mass on head impacts based on defensive heading [...] Read more.
In youth association football, the use of different size and/or mass footballs might represent a feasible intervention for addressing heading impact severity and player safety concerns. This study assessed the effects of football size and mass on head impacts based on defensive heading in youth football. Three-dimensional trajectories of U16 youth academy free kicks were modelled to derive three impact trajectories, representing defensive heading in youth football. Three football models (standard: S5, standard-light: S5L, and small: S4) impacted an instrumented headform; Head Injury Criterion (HIC15) and Rotational Injury Criterion (RIC15) were calculated. For headform impacts, S4 and S5L footballs yielded lower HIC15 magnitudes than S5 footballs. Further, S4 footballs yielded lower HIC15 and lower RIC15 magnitudes than S5 and S5L footballs. Initial findings indicated that smaller, S4 footballs reduced linear and rotational head injury criteria for impacts representative of defensive heading in youth football. Full article
Open AccessProceedings
Brain Pressure Wave Propagation during Baseball Impact
Proceedings 2020, 49(1), 149; https://doi.org/10.3390/proceedings2020049149 - 15 Jun 2020
Viewed by 298
Abstract
Keywords: baseball; brain injury; novel surrogate head; finite element method; pressure wave propagation Full article
Open AccessProceedings
Applicability of Thermoplastic Elastomers to Impact Load Reduction in Sports Equipment
Proceedings 2020, 49(1), 163; https://doi.org/10.3390/proceedings2020049163 - 15 Jun 2020
Viewed by 293
Abstract
In this paper, mechanical properties of thermoplastic elastomers were investigated to expand the applicability of thermoplastic elastomers to the impact load reduction for the sports equipment. The thermoplastic elastomers show both thermoplastic and elastomeric properties. These are expected to apply to the impact [...] Read more.
In this paper, mechanical properties of thermoplastic elastomers were investigated to expand the applicability of thermoplastic elastomers to the impact load reduction for the sports equipment. The thermoplastic elastomers show both thermoplastic and elastomeric properties. These are expected to apply to the impact load reduction in sports equipment due to good processability and less-smell. In this study, thermoplastic elastomers were applied for monotonic and cyclic tensile loading tests. The thermoplastic elastomer (TPE) materials in this study were newly developed for the specific purpose of impact load reduction. The nonlinear hyperelastic model considering the viscosity and damage model was applied to the tensile loading test results. finite element analysis (FEA) results of TPE specimens with periodic geometric shapes to reduce impact load were investigated. Full article
Open AccessProceedings
Semi-Automating Low Back Compression Force Estimations with an Inertial Sensor
Proceedings 2020, 49(1), 37; https://doi.org/10.3390/proceedings2020049037 - 15 Jun 2020
Viewed by 223
Abstract
There are currently no evidence-based practical automated injury risk factor estimation tools to monitor low back compressive force in ambulatory or sporting environments. For this purpose, inertial sensors may potentially replace laboratory-based systems with comparable results. The objective was to investigate inertial sensor [...] Read more.
There are currently no evidence-based practical automated injury risk factor estimation tools to monitor low back compressive force in ambulatory or sporting environments. For this purpose, inertial sensors may potentially replace laboratory-based systems with comparable results. The objective was to investigate inertial sensor validity to monitor low back compression force. Thirty participants completed a series of lifting tasks from the floor. Back compression force was estimated using a hand calculated method, an inertial sensor method and a three-dimensional motion capture method. Results demonstrated that semi-automation with a sensor had a higher agreement with motion capture compared to the hand calculated method, with angle errors of less than six degrees and back compression force errors of less than 200 Newtons. It was concluded that inertial sensors are valid to implement for static low back compression force estimations. Full article
Open AccessProceedings
Analysis on the Effect of Ball Pressure on Head Acceleration to Ensure Safety in Soccer
Proceedings 2020, 49(1), 3; https://doi.org/10.3390/proceedings2020049003 - 15 Jun 2020
Viewed by 204
Abstract
Soccer/football is one of the most popular sports in the world. Any sport requires continuous adjustments to rules to keep the game safe and engaging. Increased awareness of concussions in the American National Football League (NFL) has consequently raised attention to concussion-related injuries [...] Read more.
Soccer/football is one of the most popular sports in the world. Any sport requires continuous adjustments to rules to keep the game safe and engaging. Increased awareness of concussions in the American National Football League (NFL) has consequently raised attention to concussion-related injuries in other sports. One of the first steps the United States Soccer Federation (USSF) has taken to reduce head injuries is to implement age restrictions on heading. This encourages safer play but discourages an important skill until players are a certain age which is not good for player development. An alternative is to ensure mean head acceleration from a header is reduced with minimal rule changes. This paper presents a dynamic model of a player heading a soccer ball to examine the general relationship between ball pressure and mean head acceleration toward the purpose of motivating a more complex and comprehensive analysis of heading in soccer. Full article
Open AccessProceedings
Chronic Ankle Instability Does Not Influence Tibiofemoral Contact Forces during Drop Landings
Proceedings 2020, 49(1), 5; https://doi.org/10.3390/proceedings2020049005 - 15 Jun 2020
Viewed by 186
Abstract
Chronic ankle instability (CAI) is a very common sequela after ankle sprains. Previous studies observed some knee biomechanical and neuromuscular alterations of CAI that could potentially relate to the knee injury mechanism during landings. However, to our knowledge, no studies have assessed the [...] Read more.
Chronic ankle instability (CAI) is a very common sequela after ankle sprains. Previous studies observed some knee biomechanical and neuromuscular alterations of CAI that could potentially relate to the knee injury mechanism during landings. However, to our knowledge, no studies have assessed the tibiofemoral contact forces for individuals with CAI. The purpose of the study was to compare the tibiofemoral contact forces of participants with CAI versus controls during landings using a computer-simulated musculoskeletal model. Twenty-one female participants with CAI and 21 pair-matched controls performed a drop landing task on a tilted force plate. A seven-camera motion capture system and two force plates were used to test participants’ lower extremity biomechanics. A musculoskeletal model was used to calculate the tibiofemoral contact forces (femur on tibia). No significant between-group differences were observed for the peak tibiofemoral contact forces (p = 0.25–0.48) during the landing phase based on paired t-tests. The group differences ranged from 0.05 to 0.58 body weight (BW). Most participants demonstrated a posterior force (peak = ~1.1 BW) for most of the landing phase and a medial force (peak = ~0.9 BW) and a large compressive force (peak = ~10 BW) in the landing phase. We conclude that CAI may not be related to the increased tibiofemoral contract forces or knee injury mechanisms during landings on tilted surfaces. Full article
Open AccessProceedings
Measuring Running Workload and Key Points during Treadmill Running Using a Custom Build ‘Nodes’ System
Proceedings 2020, 49(1), 30; https://doi.org/10.3390/proceedings2020049030 - 15 Jun 2020
Viewed by 251
Abstract
Within this study the aim is to measure running workload and relevant running technique key points on varying cadence in recreational runners using a custom build sensor system ‘Nodes’. Seven participants ran on a treadmill at a self-chosen comfortable speed. Cadence was randomly [...] Read more.
Within this study the aim is to measure running workload and relevant running technique key points on varying cadence in recreational runners using a custom build sensor system ‘Nodes’. Seven participants ran on a treadmill at a self-chosen comfortable speed. Cadence was randomly guided by a metronome using 92%, 96%, 100%, 104%, and 108% of the preferred cadence in 2-min trials. Workload was measured by collecting the heart rate and the rating of perceived exertion (RPE 1 to 10) scores. Heart rate data shows that the 100% cadence trial was most economical with a relative heart rate of 99.2%. The 108% cadence trial had the lowest relative RPE score with 96.2%. The sample rate of the Nodes system during this experiment was too low to analyze the key points. Three requirements are proposed for the further engineering of a wearable running system, (i) sampling frequency of minimal 50 Hz, (ii) step-by-step analysis, and (iii) collecting workload in the heart rate and RPE. Full article
Open AccessProceedings
The Influence of Backpack-Design on Thermophysiological Parameters during Simulated Hiking Activities
Proceedings 2020, 49(1), 59; https://doi.org/10.3390/proceedings2020049059 - 15 Jun 2020
Viewed by 279
Abstract
To assess the thermoregulatory capacities of backpack-designs, five male participants were equipped with a temperature and moisture measuring system. Relative humidity (rH) and temperature (T) were measured underneath the participants’ t-shirt—microclimate (MC)—and between shirt and backpack—interlayer climate (ILC). Participants completed a test protocol [...] Read more.
To assess the thermoregulatory capacities of backpack-designs, five male participants were equipped with a temperature and moisture measuring system. Relative humidity (rH) and temperature (T) were measured underneath the participants’ t-shirt—microclimate (MC)—and between shirt and backpack—interlayer climate (ILC). Participants completed a test protocol simulating a hiking exercise in three conditions in a randomized order: (W) without backpack and (B1-B2) with each of the backpacks (total weight: 5.4 kg). The test-protocol consisted of a 5-min rest, 10-min walk at 4 km/h without gradient, 15-min walk at 4 km/h with 8% incline, and a final 10-min rest. Results showed that the temperature and absolute humidity (aH) values generally decreased from the microclimate to the interlayer climate. Differences of up to ΔT = 1.27 °C and ΔaH = 2.55 g/m3 in the microclimate of the upper back area were observed for different backpack designs, indicating the influence of backpack design on thermoregulation. Full article
Open AccessProceedings
Collection of Kinematic and Kinetic Data of Young and Adult, Male and Female Subjects Performing Periodic and Transient Gait Tasks for Gait Pattern Recognition
Proceedings 2020, 49(1), 6; https://doi.org/10.3390/proceedings2020049006 - 15 Jun 2020
Viewed by 273
Abstract
The aim of the study was to develop a database of biomechanical data for multiple gait tasks. This database will be used to create a real-time gait pattern classifier that will be implemented in a new-generation active knee prosthesis. With this intent, we [...] Read more.
The aim of the study was to develop a database of biomechanical data for multiple gait tasks. This database will be used to create a real-time gait pattern classifier that will be implemented in a new-generation active knee prosthesis. With this intent, we collected kinematic and kinetic data of 40 subjects performing 16 gait tasks, categorized as periodic and transient motions. We analyzed four distinct sub-populations, differentiated by age and gender. As the classifier will be based also on inertial data, we chose to synthesize these signals within the motion capture environment. To assess the effects of gender and age we performed a correlation analysis on the signals used as input of the classifier. The results obtained indicate that there is no need to differentiate into four distinct classes for the development of the classifier. Sample data of the dataset are made publicly available. Full article
Open AccessProceedings
The IART System for Race Walking: Experience with World-Class Olympic Race Walkers
Proceedings 2020, 49(1), 79; https://doi.org/10.3390/proceedings2020049079 - 15 Jun 2020
Viewed by 230
Abstract
Race walking is a discipline in which the best chronometric performance is constrained by infringements. Currently, the judgment and training of race walkers is entrusted to subjective observations made by judges. In this paper, with the objective of supporting coaching and judging, we [...] Read more.
Race walking is a discipline in which the best chronometric performance is constrained by infringements. Currently, the judgment and training of race walkers is entrusted to subjective observations made by judges. In this paper, with the objective of supporting coaching and judging, we present a wearable inertial sensor system (IART) for the evaluation of performances and infringements in race walking. The system is composed of an inertial sensor positioned close to the center of mass of the subject and a management unit designed for coaches and judges. IART allows: (i) a step sequence classification according to the competition rules; (ii) a customized assessment of elite race walkers based on key performance and infringement indices. The system is experimentally validated in field conditions by nine world-class Olympic race walkers. The results show that IART improves the current evaluation of step sequences and offers a meaningful support for the overall evaluation of the technical gesture. Full article
Open AccessProceedings
Use of an Inertial Measurement System to Calculate Maximal Power during Running Sprint Acceleration: Comparison with the Radar System
Proceedings 2020, 49(1), 23; https://doi.org/10.3390/proceedings2020049023 - 15 Jun 2020
Viewed by 253
Abstract
The maximal total power (Pmax) is one of the major determinants of sprint performance. It can be calculated using a simple model based on the runner’s velocity. This velocity has already been measured with force plates, video cameras or a [...] Read more.
The maximal total power (Pmax) is one of the major determinants of sprint performance. It can be calculated using a simple model based on the runner’s velocity. This velocity has already been measured with force plates, video cameras or a radar system, but not with an inertial system. The purpose of this study was to compare Pmax measured with a radar system and with a multiple inertial sensors system. Seven participants (174.0 ± 6.9 cm; 67.7 ± 10.1 kg; 22.3 ± 1.7 years) realized two maximal 40-m sprints. Each athlete was equipped with an instrumented suit composed of 17 inertial measurement units (IMU) (Xsens), and a radar (Stalker ATS) was placed behind them. Both systems measured the athletes’ instantaneous horizontal velocity during the acceleration phase. Using an exponential model, Pmax, maximal velocity (Vmax), the slope of the exponential model (τ), maximal force (F0) and the slope of the force, the velocity relationship (SFV) was calculated. The results showed that Pmax, Vmax, τ, F0 and SFV were not significantly different between the radar and the Xsens system (p > 0.13). Pmax, Vmax and F0 measured with the radar were correlated with the same parameters measured with Xsens (r > 0.81 and p ≤ 0.03). The IMU system can be accurately used to measure the main parameters that determine the sprint running performance: Pmax, Vmax and F0. Moreover, contrary to the radar system, multiple inertial sensors will allow for an understanding of the role of the segments in maximal sprint running. Full article
Open AccessProceedings
Evaluation of 3-Axial Knee Joint Torques Produced by Compression Sports Tights in Running Motion
Proceedings 2020, 49(1), 69; https://doi.org/10.3390/proceedings2020049069 - 15 Jun 2020
Viewed by 245
Abstract
In this paper, 3-axial knee joint torques given by compression sports tights were performed by numerical simulations using 3-dimensional computer graphics of a human model. Running motions of the human model were represented as the 3-dimensional computer graphics, and the running motions were [...] Read more.
In this paper, 3-axial knee joint torques given by compression sports tights were performed by numerical simulations using 3-dimensional computer graphics of a human model. Running motions of the human model were represented as the 3-dimensional computer graphics, and the running motions were determined by the motion capturing system of human subjects. Strain distribution on the surface of the 3-dimentional computer graphics of the human model was applied to the boundary conditions of the numerical simulations. An anisotropic hyperelastic model considering stress softening of fabric materials was implemented to reproduce the mechanical characteristics of the compression sports tights. Based on the strain-time relationships, knee joint torques in 3-dimentional coordinates given by the compression sports tights were calculated. As a result, the three types of knee joint torque generated by the compression sports tights in running motions were calculated. From the calculated results, the maximum value of flexion/extension, varus/valgus, and internal/external knee joint torques were given as 2.52, 0.59, and 0.31 Nm, respectively. The effect of compression sports tights on the knee joint was investigated. Full article
Open AccessProceedings
Technologies to Aid Public Understanding in Running Performance
Proceedings 2020, 49(1), 26; https://doi.org/10.3390/proceedings2020049026 - 15 Jun 2020
Viewed by 286
Abstract
Measurement technologies and visualisation techniques are changing the way public audiences engage with televised coverage of sport. However, the adoption of measurement technologies for broadcast coverage of running—to engage audiences and improve public understanding of performance—has been limited. This might reflect measurement challenges [...] Read more.
Measurement technologies and visualisation techniques are changing the way public audiences engage with televised coverage of sport. However, the adoption of measurement technologies for broadcast coverage of running—to engage audiences and improve public understanding of performance—has been limited. This might reflect measurement challenges of athletic competition environments; athlete-worn measurement devices can be impractical, and video-based analyses typically require well-defined input videos for analysis (e.g., calibration, etc.). Recently, single-camera and calibration-independent video processing has advanced practical analyses of running performance in sports environments. This paper presents (1) the application of a method to quantify temporal running parameters using broadcast footage of 100 m sprint and 1-mile endurance running, (2) the application of human posture detection to quantify spatial running parameters using hand-held action camera footage and (3) examples of co-developed data visualisations, aimed at improving public engagement and understanding of running performance. Full article
Open AccessProceedings
The Role of Technology in Promoting Physical Activity: A Case-Study of parkrun
Proceedings 2020, 49(1), 80; https://doi.org/10.3390/proceedings2020049080 - 15 Jun 2020
Viewed by 274
Abstract
Around a third of people worldwide are physically inactive, causing 3.2 million deaths each year. People often use wearables and smartphone trackers to motivate them to be active, but there is evidence to show that use of these trackers declines quickly, often within [...] Read more.
Around a third of people worldwide are physically inactive, causing 3.2 million deaths each year. People often use wearables and smartphone trackers to motivate them to be active, but there is evidence to show that use of these trackers declines quickly, often within weeks. One intervention that appears to successfully motivate people to be active is parkrun, a free, weekly timed 5 km run or walk every Saturday morning. The system used by parkrun is surprisingly low-tech: it uses printable barcodes, stopwatches and scanners, and the internet. A survey of 60,694 parkrun participants showed that levels of self-reported physical activity increased following participation in parkrun, especially for those with previously low levels of activity. Nine out of ten reported feeling a sense of personal achievement and improvements to fitness and physical health since starting parkrun. Based on a taxonomy of behaviour change interventions, the technology used by parkrun was shown to incorporate at least seven techniques that inform and encourage parkrunners. It is concluded that physical activity technologies should not be central to an intervention, rather, they should enhance interventions where behaviour change takes precedence. Full article
Open AccessProceedings
Use of Video for Teaching Sports Mechanics
Proceedings 2020, 49(1), 112; https://doi.org/10.3390/proceedings2020049112 - 15 Jun 2020
Viewed by 410
Abstract
There is a shortage of young people studying physics and engineering and these professions could benefit from greater diversity. Sports engineering is often used as a tool to change the public perceptions of engineering and sporting examples can be used in physics and [...] Read more.
There is a shortage of young people studying physics and engineering and these professions could benefit from greater diversity. Sports engineering is often used as a tool to change the public perceptions of engineering and sporting examples can be used in physics and engineering classes to engage people. Video analysis is widely used by sports engineers, and this publication showcases how the video analysis of sporting scenarios can be used to teach mechanics. Examples illustrate how the movement of an athlete and equipment can be analysed and linked to basic physics, for sports ranging from sumo to soccer. The examples presented can be used for teaching and outreach, with a view to enthuse students about physics and engineering. Full article
Open AccessProceedings
STEMfit: Student Centric Innovation to Improve STEM Educational Engagement Using Physical Activity, Wearable Technologies and Lean Methodologies
Proceedings 2020, 49(1), 33; https://doi.org/10.3390/proceedings2020049033 - 15 Jun 2020
Viewed by 317
Abstract
School-based education programmes are increasingly focused on the teaching of skills thought to be more suitable for an increasingly technological society. These STEM (Science, Technology, Engineering and Mathematics) skills are often seen as enablers for the workforce of tomorrow. This paper utilises wearable [...] Read more.
School-based education programmes are increasingly focused on the teaching of skills thought to be more suitable for an increasingly technological society. These STEM (Science, Technology, Engineering and Mathematics) skills are often seen as enablers for the workforce of tomorrow. This paper utilises wearable sensors during prescribed physical activity as a vehicle for student engagement through their direct involvement in the creation of personalised data sets, direct questioning about their physical activity and the development of a nexus between what they do and fundamental physical properties such as the laws of motion. Results demonstrate the technical challenges, including the selection of appropriate monitoring technologies and development of appropriate technology tools suitable for school cohorts, together with sample results obtained through field trials in metropolitan and remote schools to demonstrate the utility of such technologies. Full article
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