Search Results (104)

Background: Pes planus is a condition where the arch of the foot collapses, resulting in the entire sole contacting the ground. The biomechanical implications of pes planus on gait have been widely studied; however, research specific to Black African populations, particularly recreational runners, is scarce. Aim: This study aimed to describe the forefoot centre of pressure (CoP) trajectory during the barefoot gait cycle among Black African recreational runners with pes planus. Methods: A prospective explorative and quantitative study design was employed. Participants included Black African male recreational runners aged 18 to 45 years diagnosed with pes planus. A Freemed™ 6050 force plate was used to collect gait data. Statistical analysis included cross-tabulations to identify patterns. Results: This study included 104 male participants across seven weight categories, with the majority in the 70-to-79 kg range (34.6%, n = 36). Most participants with pes planus showed a neutral foot posture (74.0%, n = 77) on the foot posture index 6 (FPI-6) scale. Flexible pes planus (94.2%, n = 98) was much more common than rigid pes planus (5.8%, n = 6). Lateral displacement of the CoP was observed in the right forefoot (90.4%, n = 94) and left forefoot (57.7%, n = 60). Load distribution patterns differed between feet, with the right foot favouring the medial heel, arch, and metatarsal heads, while the left foot favoured the lateral heel, medial heel, and lateral arch. No statistical significance was found in the cross-tabulations, but notable lateral CoP displacement in the forefoot was observed. Conclusions: The findings challenge the traditional view of pes planus causing overpronation and highlight the need for clinicians to reconsider standard diagnostic and management approaches. Further research is needed to explore the implications of these findings for injury prevention and management in this population. Full article

Background: Reaction time is analyzed in various situations in sporting events and is reported to be so important that it can make the difference between victory and defeat. This study focused on teeth clenching resulting in remote muscle activation, and examined whether it improves performance of reaction time. This study examined the effects of clenching and clenching strength on the systemic simple reaction time. Methods: This study included 20 healthy adults with normal clenching and a right dominant foot. The task movement for the systemic simple reaction time measurement was a 30 cm forward step. The following three clenching conditions were used: no clenching without dental contact (no-bite condition), a condition in which the participants were instructed to clench with moderate strength (moderate condition), and a condition in which the participants clenching with maximum effort (max condition). The analysis items were release time, grounding time, soleus muscle (Sol) reaction time, and masseter muscle activity. Results: The max condition significantly reduced the reaction time compared with the no-bite condition. Sol reaction and grounding times showed a negative correlation between clenching strength under moderate conditions and the rate of change in reaction time under no-bite and moderate conditions. Release time exhibited no significant correlation between clenching strength under the moderate condition and the rate of change in reaction time under the no-bite and moderate conditions. The remote facilitation effect of clenching improved the systemic reaction time by producing immediate muscle activity. Conclusions: Clenching shortens the systemic simple reaction time. This finding highlights the potential importance of clenching in enhancing performance during sporting events. Full article

Foot plantar pressure refers to the pressure or force that the foot generates in contact with the ground, varying across different regions of the foot. This parameter is essential in static and dynamic analyses to access accurate diagnoses, study the human body biomechanics, create functional footwear designs, aid in rehabilitation and physiotherapy, and prevent injuries in athletes during sports practice. This study presents an experimental comparison between two different plantar pressure measurement devices, Pedar^® (sensorized insoles) and Physiosensing^® (pressure platform). The devices were selected based on their capacity to measure contact area and peak pressure points. Results showed that Physiosensing^® provided a more uniform measurement of the contact area, proving its efficiency for weight distribution and stability analysis applications, particularly in posture assessment and balance studies. The Pedar^® system showed higher capacity in peak pressure point detection. Therefore, the insole system is more suitable for applications requiring precise high-pressure zone localization. Comparative analysis highlights the strengths and limitations of each device and offers insights regarding its optimal usage in clinical, sports, and research settings. Full article

Balance control in pirouettes has previously been characterized by constraint of the topple angle. However, there is a paucity of research using the margin of stability (MoS) as a dynamic measure of balance related to pirouettes. Therefore, this study aimed primarily to examine the MoS as a metric of balance during a single-turn en dehors pirouette in healthy female amateur ballet dancers. Four participants performed pirouettes until five successful pirouettes were achieved without hopping or loss of balance. Three-dimensional motion capture was used to record the motion trajectories of anatomical markers based on the Plug-in-Gait and Oxford Foot models. Motion synchronized with ground reaction forces was used to calculate the center of pressure (CoP), base of support (BoS), center of the pivot foot, center of mass (CoM), and extrapolated center of mass (XCoM) throughout the turn phase, using laboratory (LCS) and virtual left foot (LFT) coordinate systems. In the LCS and LFT coordinate system, the excursions and patterns of motion of both the CoM and XCoM relative to the CoP were similar, suggesting a neurological relationship. Two different measures of the margin of stability (MoS) in the LFT coordinate system were tabulated: the distance between the (1) XCoM and CoP and (2) XCoM and BoS center. The magnitude of both versions of the MoS was greatest at turn initiation and toe-touch, which was associated with two foot contacts. The MoS values were at a minimum approximately 50% of the stance during the turn phase: close to zero along the anteroposterior (A/P) axis and approximately 50 mm along the mediolateral (M/L) axis. On average, MoS magnitudes were reduced (mean across participants: approximately 20 mm) along the A/P axis, and larger MoS magnitudes (mean across participants: approximately 50 mm) along the M/L axis throughout the turn phase. Although all turns analyzed were completed successfully, the larger MoS values along the M/L axis suggest a fall potential. The variability between trials within a dancer and across participants and trials was documented and showed moderate inter-trial (16% to 51%) and across-participant CV% (range: 10% to 28%), with generally larger variations along the A/P axis. Although our results are preliminary, they suggest that the MoS may be useful for detecting faults in the control of dynamic balance in dehors pirouette performance, as a part of training and rehabilitation following injury. Full article

Body asymmetry is often analysed in the context of low back pain (LBP). To date, research has mainly focused on the general relationships between asymmetry and pain, with less attention paid to issues related to pressure distribution and its potential impact on the occurrence of LBP. The aim of this study was to compare biomechanical parameters in people with anatomical leg length discrepancy with and without LBP to identify overloads that may lead to pain. Early detection of common abnormalities in these parameters in both groups may influence the early prevention of 0LBP in the course of LLD. Materials and methods: This study included 60 patients with diagnosed LLD, of whom 30 had LBP (group 1, NP) and 30 were pain-free (group 2, NwP). Body weight distribution during standing and walking was analysed using pedobarography. The analysis was carried out in two stages, the first being the analysis of the biomechanical parameters for the whole study population, for group 1 with LBP and group 2 without LBP, while the second stage focused on the main issue, i.e., the comparison of the group with LBP with the group without LBP. The study included standing and walking tests. Left–right pressure distribution and ground contact time were analysed. In addition, the angle of foot abduction was analysed to indirectly assess compensatory mechanisms resulting from the asymmetry. Results: The standing test showed significantly greater pressure on the longer limb (p = 0.022) in the whole study population (N = 60). When divided into groups, it was found that in those with LBP (NP = 30), the difference was not statistically significant (p = 0.359), whereas in those without pain (NwP = 30), the pressure on the longer limb was significantly greater (p = 0.002). No differences were found between the groups in the comparative analysis. The angle of foot abduction was greater than normal across the study population (N = 60), with greater values in the shorter limb (12.83° vs. 11.04°), which was close to significance (p = 0.065). The group with LBP (NP = 30) showed a similar trend, also close to statistical significance (p = 0.054), with significantly higher values of abduction angle in both legs compared to the group without LBP (NwP = 30). In the walking test, the left–right load distributions were significantly dispersed. The mean pressure on the longer limb was significantly higher in group 1 (NP = 30) (p = 0.031), whereas this difference was not statistically significant in group 2 (NwP = 30). For mean peak pressure, there were no significant differences in any of the groups tested. In addition, the mean ground contact time during gait was longer for the longer limb in the whole study population (N = 60) (938.8 ms vs. 915 ms), but again, this difference did not reach statistical significance (p = 0.305). Comparative analysis showed no differences between the groups. Conclusions: This study showed that in people with anatomical LLD, both with and without LBP, most parameters reflected marked asymmetries in peak and mean pressures and abduction angles. A prolongation of ground contact time has also been shown, and even though some parameters were not statistically significant, it is important to note the high dispersion of left–right loading, which provides information on body load asymmetries in patients with anatomical LLD. Given that there were no differences between the groups for most of the parameters, it is important for both clinical practice and further research that the abnormalities observed in both groups (NP = 30, NwP = 30) may have been a significant predictor of the development of LBP, as the abnormalities preceded the onset of pain. This should be taken into account in diagnostic and preventive measures. Full article

Wheel-legged robots combine the advantages of both wheeled robots and traditional quadruped robots, enhancing terrain adaptability but posing higher demands on the perception of foot–ground contact forces. However, existing approaches still suffer from limited accuracy in estimating contact positions and three-dimensional contact forces when dealing with flexible tire–ground interactions. To address this challenge, this study proposes a foot–ground contact state detection technique and optimization method based on multi-sensor fusion and intelligent modeling for wheel-legged robots. First, finite element analysis (FEA) is used to simulate strain distribution under various contact conditions. Combined with global sensitivity analysis (GSA), the optimal placement of PVDF sensors is determined and experimentally validated. Subsequently, under dynamic gait conditions, data collected from the PVDF sensor array are used to predict three-dimensional contact forces through Gaussian process regression (GPR) and artificial neural network (ANN) models. A custom experimental platform is developed to replicate variable gait frequencies and collect dynamic contact data for validation. The results demonstrate that both GPR and ANN models achieve high accuracy in predicting dynamic 3D contact forces, with normalized root mean square error (NRMSE) as low as 8.04%. The models exhibit reliable repeatability and generalization to novel inputs, providing robust technical support for stable contact perception and motion decision-making in complex environments. Full article

Running socks play an important role in alleviating foot impact and preventing foot injuries. Despite the variety of commercial options, their cushioning effectiveness is not well understood. This study examines three different types of running socks made of bio-based and synthetic textiles. Material testing includes compression, tensile, and shock absorption, while wear tests assess plantar loading in 10 adult recreational runners on a treadmill. Results show that specialized running socks offer superior shock absorption compared to regular running socks, largely due to fabric thickness and weight. Socks made of high-performance bio-composite fibers significantly reduced maximum peak pressure and impulse in the great toe (p < 0.05) and first metatarsal head (p < 0.05) during running. Additionally, ground contact time in the forefoot (p < 0.05) area was significantly lower with specialized running socks. Compared to regular running socks, five-toed running socks can reduce the pressure load on the forefoot area. These findings can guide the design of specialized sockwear for better foot protection and improved sports performance. Full article

To improve the traction performance of mobile mechanisms on soft ground, such as paddy fields, tidal flats, and swamps, a mallard (Anas platyrhynchos) foot was adopted as a bionic prototype to explore the influence and contribution of the plantar morphology of the toes and webbing on the anti-subsidence function during its locomotion on wet and soft substrates and to apply this to the bionic design of high-traction wheel grousers. A handheld three-dimensional laser scanner was used to scan the main locomotion postures of a mallard foot during ground contact, and the Geomagic Studio software was utilized to repair the scanned model. As a result, the main three-dimensional geometric models of a mallard foot during the process of touching the ground were obtained. The plantar morphology of a mallard foot was divided into three typical parts: the plantar irregular edge curve, the lateral webbing surface, and the medial webbing surface. The main morphological feature curves/surfaces were extracted through computer-aided design software for the fitting and construction of a mathematical model to obtain the fitting equations of the three typical parts, and the mathematical model construction of the plantar irregular morphology of the mallard foot was completed. In order to verify the sand-fixing and flow-limiting characteristics of this morphological feature, based on the discrete element method (DEM), the numerical simulation of the interaction between the plantar surface of the mallard foot and sand particles was carried out. The simulation results show that during the process of the mallard foot penetration into the loose medium, the lateral and medial webbing surfaces cause the particles under the foot to mainly move downward, effectively preventing the particles from spreading around and significantly enhancing the solidification effect of the particles under the sole. Based on the principle and technology of engineering bionics, the plantar morphology and movement attitude characteristics of the mallard were extracted, and the characteristics of concave middle and edge bulge were applied to the wheel grouser design of paddy field wheels. Two types of bionic wheel grousers with different curved surfaces were designed and compared with the traditional wheel grousers of the paddy field wheel. Through pressure-bearing simulation and experiments, the resistance of different wheel grousers during the process of penetrating into sand particles was compared, and the macro–micro behaviors of particle disturbance during the pressure-bearing process were analyzed. The results show that a bionic wheel grouser with unique curved surfaces can well encapsulate sand particles at the bottom of the wheel grouser, and it also has a greater penetration resistance, which plays a crucial role in improving the traction performance of the paddy field wheel and reducing the disturbance to the surrounding sand particles. This paper realizes the transformation from the biological model to the mathematical model of the plantar morphology of the mallard foot and applies it to the bionic design of the wheel grousers of the paddy field wheels, providing a new solution for improving the traction performance of mobile mechanisms on soft ground. Full article

Background/Objectives: Thrombocytopenia–absent radius (TAR) syndrome is a rare genetic disorder characterized by the bilateral absence of the radius and thrombocytopenia, often leading to functional limitations and gait asymmetries. Prosthetic devices are sometimes employed to improve mobility and posture, but their impact on gait mechanics in pediatric patients remains poorly understood. Methods: The methodology used is based on a study that evaluated the gait parameters of a 10-year-old child with TAR syndrome under static and dynamic conditions, both with and without the use of a custom-designed upper limb prosthesis. The analysis focused on assessing the prosthesis’s impact on gait symmetry and biomechanics. A key aspect of the methodology involved studying the distribution of pressure forces on the ground during walking using the FreeMed EXTREME Maxi baropodometric platform. Results: Gait analysis demonstrated asymmetries between the left and right feet. In the absence of the prosthesis, the patient exhibited excessive forward loading and uneven pressure distributions. The use of a custom prosthesis, particularly with counterbalancing features, improved gait symmetry but led to increased reliance on the left foot. This foot experienced higher pressures (738–852 g/cm²) and longer ground contact times (690–865 ms) compared to the right foot (619–748 g/cm² and 673–771 ms). The left foot displayed elevated forefoot pressures (61–65%), while the right foot bore weight laterally (66–74%). Conclusions: The custom prosthesis influenced gait mechanics by redistributing plantar pressures and modifying ground contact times, partially improving gait symmetry. However, compensatory strategies, such as increased loading on the left foot, could contribute to musculoskeletal strain over time. Individualized rehabilitation programs and prosthetic designs are essential for optimizing gait mechanics, improving mobility, and minimizing long-term complications in TAR syndrome patients. Full article

Objective: Botulinum neurotoxin type A (BoNT/A) injections and the new vibration ergometry training (VET) are studied for their combined effect on improving functional mobility in patients with asymmetric lower limb spasticity. Method: Gait was analyzed using the Infotronic^® system, which measures ground reaction forces and foot contact patterns by means of special force-sensitive shoes strapped over feet or street shoes. Gait was measured several times, depending on the protocol patients underwent. Seven patients with asymmetric lower limb spasticity were analyzed according to the control protocol (CG-group): after a baseline walk of 20 m (NV-W1) patients received their routine BoNT/A injection and had to walk the same distance a second time (NV-W2). Approximately 3–5 weeks later, they had to walk a third time (NV-W3). A further seven patients (VG-group) were analyzed according to the vibration protocol: after a baseline walk (V-W1), patients underwent a first vibration training (VET1), walked a second time (V-W2), received their routine BoNT/A injection, and walked a third time (V-W3). About four weeks later, they had to walk again (V-W4), received another vibration training (VET3), and walked a fifth time (V-W5). At least six months after the analysis according to the vibration protocol, these patients were also analyzed according to the control protocol. Eleven gait parameters were compared between the CG- and VG-group, and within the VG-group. Result: Patients in the VG-group experienced a significant improvement in gait four weeks after BoNT/A injection, unlike the patients in the CG-group. VG-patients also showed improved gait after two VET sessions. However, there was no further functional improvement of gait when BoNT/A injections and VET sessions were combined. Conclusions: BoNT/A injections enhance functional mobility in patients with mild asymmetric leg spasticity. VET also induces an immediate gait improvement and offers a further treatment approach for leg spasticity. Whether combining BoNT treatment and vibration training offers superior outcomes compared to either treatment alone requires further investigation. Full article

This paper addresses the fundamental challenge of achieving stable and efficient walking in a lightweight, underactuated humanoid robot that lacks an ankle roll degree of freedom. To tackle this relevant critical problem, we present a hierarchical optimization framework that combines model predictive control (MPC) with a tailored whole body planner and controller (WBPC). At the high level, we employ a matrix exponential (ME)-based discretization of the MPC, ensuring numerical stability across a wide range of step sizes (5 to 100 ms), thereby reducing computational complexity without sacrificing control quality. At the low level, the WBPC is specifically designed to handle the unique kinematic constraints imposed by the missing ankle roll DOF, generating feasible joint trajectories for the swing foot phase. Meanwhile, a whole body control (WBC) strategy refines ground reaction forces and joint trajectories under full-body dynamics and contact wrench cone (CWC) constraints, guaranteeing physically realizable interactions with the environment. Finally, a position–velocity–torque (PVT) controller integrates feedforward torque commands with the desired trajectories for robust execution. Validated through walking experiments on the MuJoCo simulation platform using our custom-designed lightweight robot X02, this approach not only improves the numerical stability of MPC solutions, but also provides a scientifically sound and effective method for underactuated humanoid locomotion control. Full article

The analysis of running gait has conventionally taken place within an expensive and restricted laboratory space, with wearable technology offering a practical, cost-effective, and unobtrusive way to examine running gait in more natural environments. This pilot study presents a wearable inertial measurement unit (IMU) setup for the continuous analysis of running gait during an outdoor parkrun (i.e., 5 km). The study aimed to (1) provide analytical validation of running gait measures compared to time- and age-graded performance and (2) explore performance validation. Ten healthy adults (7 females, 3 males, mean age 37.2 ± 11.7 years) participated. The participants wore Axivity AX6 IMUs on the talus joint of each foot, recording tri-axial accelerometer and gyroscope data at 200 Hz. Temporal gait characteristics—gait cycle, ground contact time, swing time, and duty factor—were extracted using zero-crossing algorithms. The data were analyzed for correlations between the running performance, foot strike type, and fatigue-induced changes in temporal gait characteristics. Strong correlations were found between the performance time and both the gait cycle and ground contact time, with weak correlations for foot strike types. The analysis of asymmetry and fatigue highlighted modest changes in gait as fatigue increased, but no significant gender differences were found. This setup demonstrates potential for in-field gait analysis for running, providing insights for performance and injury prevention strategies. Full article

Ground reaction forces (GRFs) are known to be high during front foot contact of fast bowling deliveries in cricket. There is a lack of published data on the GRFs during follow through foot contacts. The aim of this study was to quantify and compare peak GRFs and impulse of the delivery stride and the follow through of fast bowling deliveries. Ten trained male fast bowlers (ball release speed mean ± SD; 32.6 ± 2.3 m/s) competing in the Men’s Victorian Premier League participated in the study. Peak GRF and impulse data were collected using in-ground force plates in a laboratory setting. Linear mixed modelling of GRFs and impulse showed a significant effect of foot strike (p < 0.001). Front foot contact had the greatest magnitude of peak vertical GRF (5.569 ± 0.334 BW) but was not significantly greater than back foot recontact (4.471 ± 0.285 BW) (p = 0.07). Front foot impact had the greatest vertical impulse (0.408 ± 0.018 BW·s) but was similar to back foot (0.377 ± 0.012 BW·s) and front foot (0.368 ± 0.006 BW·s) recontacts (p = 0.070 to 0.928). The high GRF and impulse during the follow through highlights the need for further kinetic and kinematic research on this phase of the fast bowling delivery. Full article

This paper shows the optimal cost design for T-shaped combined footings of reinforced concrete (RC), which are subjected to biaxial bending in each column to determine the steel areas and the thickness of the footings assuming a linear distribution of soil pressure. The methodology used in this paper is as follows: First, the minimum contact surface between the footing and the ground is investigated. The design equations for the combined footing are then used to determine the objective function and its constraints to obtain the lowest cost, taking into account the ACI code requirements. Flowcharts are shown for the lowest cost and the use of Maple 15 software. The current model for design is developed as follows: A footing thickness is proposed, and then it is verified that the thickness complies with the effects produced by moments, bending shears, and punching shears. Furthermore, four numerical examples are presented under the same loads and moments applied to each column, with different conditions applied to obtain the optimal contact surface and then the minimum cost design. The results show that the optimal cost design (lowest cost) is more economical and more accurate than any other model, and there is no direct proportion between the minimum contact surface and lowest cost for the design of T-shaped combined footings. In this way, the minimum cost model shown in this work can be applied to the design of rectangular and T-shaped combined footings using optimization techniques. Full article

This study presents the design and a thorough analysis of a six-bar crank-driven leg mechanism integrated with a skew pantograph, developed for walking robots. The mechanism’s dimensions were optimized using a rigorous dimensional synthesis process in GIM software (version 2024). Subsequently, a detailed kinematic analysis was performed in GIM to simulate the leg’s motion trajectory, velocity, and acceleration. In parallel, kinematic equations were formulated using the vector loop method, implemented in MATLAB (version R2013-b), and compared with the GIM results for validation, demonstrating the strong agreement between both tools. These results confirm the mechanism’s ability to generate a compact, high-lift foot trajectory while maintaining system stability and energy efficiency. An inverse dynamic analysis was carried out to determine the actuator’s driving torque, ensuring efficient operation under expected load conditions. Furthermore, topology optimization conducted in SOLIDWORKS (version 2021) significantly reduced the weight of the ground-contacting link while preserving its structural integrity. A subsequent stress analysis validated the mechanical viability of the optimized design, supporting its feasibility for real-world implementation. This research provides a robust foundation for the development of a functional prototype. Its potential applications include mobile robots for sectors such as agriculture and all-terrain vehicles, where efficient, reliable, and adaptive locomotion is crucial. The proposed mechanism strikes an optimal balance between mechanical simplicity, cost-effectiveness, and high performance, making it well-suited for challenging operational environments. Full article