Search Results (834)

Background: Strength and the strength–power continuum may increase athletic performance, although data are scarce regarding the effects of long-term periodized training on the athletic performance of adolescent track and field athletes. The purpose of this study was to investigate performance modifications following 8 weeks of strength and strength–power resistance training, focusing on the athletic performance of adolescent track and field athletes. Methods: Following an equivalent single-arm pre–post intervention design, 16 adolescent athletes (age: 16.3 ± 0.5 years; mass: 56.5 ± 10.4 kg; height: 1.67 ± 0.07 m) participated in the study. Athletes followed an 8-week periodized resistance training program aiming to increase strength and strength–power. Measurements were performed before (T1), at the middle (T2) and at the end of the training period (T3) and included the standing long jump, single-leg standing long jump, five-step long jump, seated medicine ball throw, 0–80 m sprint and 1RM in the bench press and parallel squat. Results: The standing long jump (F_(2,14) = 109.564; η² = 0.940; p = 0.001), single-leg long jump (F_(2,14) > 41.801; η² = 0.857; p = 0.001) and five-step long jump (F_(2,14) = 148.564; η² = 0.955; p = 0.001) improved significantly from T1 to T2 (p < 0.001) and from T2 to T3 (p < 0.001). The seated medicine ball throw (F_(2,14) = 124.305; η² = 0.947; p = 0.001) and sprinting performance (F_(2,14) = 51.581; η² = 0.828; p = 0.001) were significantly enhanced from T1 to T2 (p < 0.001) and from T2 to T3 (p < 0.001). The 1RM in the bench press (F_(2,14) = 36.280; η² = 0.838, p = 0.001) and in the parallel squat (F_(2,14) = 48.165; η² = 0.873, p = 0.001) increased significantly from T1 to T2 (p < 0.001) and from T2 to T3 (p < 0.01). Conclusions: Strength and the strength–power continuum appear to have a positive effect on the physical fitness of adolescent track and field athletes, which highlights the importance of strength-based resistance training programs in adolescent athletes. Full article

This study introduced Softball Pitching Plane (SPP), a best-fit geometric plane designed to characterize the throwing arm spatial trajectory during the windmill softball pitch. The purpose was to evaluate the reliability of this planar representation and determine whether deviations from the SPP were associated with ball velocity. Forty-nine adolescent softball pitchers each performed 15 drop-ball pitches (735 total pitches). Kinematics were recorded using a 15-sensor electromagnetic tracking system. A weighted orthogonal least-squares algorithm was applied to compute the best-fit plane across three intervals (WU–BR, TOP–BR, and DS–BR). Reliability was assessed using within-subject variability, leave-one-trial-out error, and ICCs. Linear mixed-effects models were used to examine associations between SPP parameters and ball velocity. The downswing–ball release interval of the wrist trajectory showed the most stable planar pattern (RMS = 0.053 m). SPP parameters demonstrated high reliability (CV ≤ 4.2%; ICC = 0.81–0.90). RMS deviation negatively predicted ball velocity at both within-pitcher (−0.11 km·h⁻¹ per cm, p = 0.003) and between-pitcher levels (−0.40 km·h⁻¹ per cm, p = 0.03). These findings indicate that, in adolescent softball pitchers, the SPP provides a reliable geometric description of throwing-arm motion during the downswing–ball release phase, with reduced deviation associated with higher pitch velocity. Full article

Pitching requires effective transfer of ground reaction force (GRF), and structural breakdown of the medial longitudinal arch (MLA) may influence glenohumeral internal rotation (IR) deficits. This study investigated whether changes in foot morphology of the stride leg and soft tissue characteristics are associated with loss of IR during repeated pitching. Fifteen male college pitchers completed 60 pitches in a simulated game. IR range of motion (IRROM) was assessed before and after pitching. The navicular height, mechanical properties of the abductor hallucis (AbH) and plantar fascia, and GRF were measured at multiple time points. Correlation analysis and a linear mixed model were used to identify predictors of IRROM change. The mean change in shoulder IRROM during pitching was −21.9° ± 8.4°. IRROM and navicular height decreased significantly over time. The AbH elasticity increased throughout the pitching sequence. Greater reductions in IRROM appeared related to a higher vertical GRF (p = 0.021) and increased AbH elasticity (p = 0.046). Vertical GRF was unrelated to fastball velocity (p = 0.260), whereas anteroposterior GRF correlated with fastball velocity (p = 0.038). Morphological and mechanical changes in the stride leg, particularly within the support of the MLA, can influence IRROM. Reducing vertical GRF and stress on the AbH may help preserve the IRROM without compromising performance. Full article

This study aims to explore the development characteristics and evolutionary patterns of strike–slip fault zones in carbonate rocks, through quantitative characterization of fault elements and their interrelationships. Taking three strike–slip fault zones in the Daniudi Block of the northeastern Ordos Basin, China, as examples, we analyzed the distribution of fault damage zone width and throw along the strike of the fault zones at equal intervals, based on data derived from 3D seismic interpretation. The relationship between damage zone width and throw was also explored. The results indicate the following: (1) The throw–distance curve of strike–slip fault zones exhibits bimodal or multimodal patterns. As the peak of the curve is located near the overlap zone of the fault, this signifies that the fault is in the independent stage, whereas a peak situated in the middle of a fault segment suggests that the strike–slip fault has achieved integrity through “hard linkage”. (2) The width of the fault damage zone is controlled by the scale of the fault zone and its associated structures. (3) A strong power–law relationship exists between the damage zone width and throw, with a more pronounced positive correlation observed in the Taigemiao Fault Zone. (4) The strike–slip fault zone is primarily composed of a “ternary” structure, including fault core, damage zone, and fracture zone, and has undergone three evolutionary stages. Analyzing the relationships among fault elements contributes to understanding the interaction and evolutionary history of subsurface strike–slip faults in the study area. Full article

Background: Marker-based motion capture systems are commonly used for three-dimensional movement analysis in sports. Novel, markerless motion capture systems enable the collection of comparable data under more time-efficient conditions with higher flexibility and fewer restrictions for the athletes during movement execution. Studies show comparable results between markerless and marker-based systems for kinematics of the lower extremities, especially for walking gait. For more complex movements, such as throwing, limited data on the agreement of markerless and marker-based systems is available. The aim of this study is to compare the outcome of a video-based markerless motion capture system with a marker-based approach during an artificial basketball-throwing task. Methods: Thirteen subjects performed five simulated basketball throws under laboratory conditions, and were recorded simultaneously with the marker-based measurement system, as well as two versions of a markerless measurement system (differing in their release date). Knee, hip, shoulder, elbow and wrist joint angles were acquired and root mean square distance (RMSD) was calculated for all subjects, parameters and attempts. Results: The RMSD of all joint angles of the marker-based and markerless systems ranged from 7.17° ± 3.88° to 26.66° ± 14.77° depended on the joint. The newest version of the markerless system showed lower RMSD values compared to the older version, with an RMSD of 16.68 ± 5.03° for elbow flexion, capturing 93.84% of the data’s RMSD of 22.22 ± 5.52, accounting for 87.69% of the data. While both versions showed similar results for right knee flexion, lower differences were observed in the new version for right hip flexion, with an RMSD of 8.17 ± 3.75 compared to the older version’s 13.24 ± 5.78. Additionally, the new version demonstrated lower RMSD values for right hand flexion. Conclusions: Overall, the new version of the markerless system showed lower RMSD values across various joint angles during throwing movement analysis compared to the older version. However, the differences between markerless and marker-based systems are especially large for the upper extremities. In conclusion, it is not clearly explainable if the detected inter-system differences are due to inaccuracies of one system or the other, or a combination of both, as both methodologies possess special limitations (soft tissue vibration or joint center position accuracy). Further investigations are needed to clarify the accordance between markerless and marker-based motion capture systems during complex movements. Full article

Background: Seated shot put is a core Paralympic event in which lower-limb-impaired athletes generate throwing power primarily through the trunk and upper limbs. The configuration of the throwing frame may influence performance stability and biomechanics. This study aimed to evaluate the effect of two seated orientations on throwing performance, kinematics, and within-subject reliability in a Paralympic F55 athlete using markerless motion capture. Methods: A para-athlete F55-class (age: 37 years; body mass: 93 kg; height: 180 cm; training experience: 20 years) performed 20 throws (10 per seat position: perpendicular and 54.5° rotated). Kinematic data were recorded with an eight-camera, 250 Hz markerless motion capture system. Variables included throw distance, trial time, release angle, wrist acceleration and velocity, and torso angular velocities. Reliability was assessed using intraclass correlation coefficients (ICC), standard error of measurement (SEM), coefficient of variation (CV%), Bland–Altman analysis, and ROC curve discrimination. Results: Throw distance did not differ significantly between positions (p = 0.1086), but trial duration was significantly shorter in the rotated position (p = 0.0114). Most kinematic variables showed poor-to-moderate reliability (ICC = −0.51 to 0.40). Bland–Altman and ROC analyses indicated stable performance measures but higher variability in torso motion, with torso rotation (AUC = 0.72) showing the strongest discriminative ability. Conclusions: Seated orientation minimally affected performance but influenced trunk kinematics and reliability, emphasizing the need for individualized biomechanical assessment in Paralympic shot put training. Full article

Between December 1773 and May 1775, several port cities and towns across the American seaboard participated in a “tea party” as an act of political defiance toward the recent onslaught of taxation laws implemented by the British government on American colonists. Indeed, on 19 October 1774, in Annapolis, Maryland, taxpayer Anthony Stewart was coerced by the Sons of Liberty to burn his ship to the water line to prove his patriotism to the American cause, despite his Loyalist leanings. The circumstances that led to the Patriots targeting tea as their symbol for destruction, the Bostonian group to attire themselves as Mohawks and throw boxes overboard, the multiple threats made to Customs officials and Loyalists alike, speak to the American Revolution borne of a relationship between the mechanisms of hydrocolonialism (concentrated at the Custom House and at major trade docks) and countersurveillance systems implemented by the Sons and Liberty (represented by a number of different groups) and enforced by emerging poetic forms rising with the times of revolution. This is most demonstrated in the “poet of the American Revolution,” Philip Morin Freneau, and his poetic responses to the events leading up to and during the American Revolution. Taking the example of the Annapolis Tea Party and Freneau’s poetry under the consideration of hydrocolonialism among other critical interventions, this essay will consider the push and pull of imperial surveillance and patriotic countersurveillance at the breaking point of the American Revolution, when riots between colonists over goods and taxes spoke to larger socioeconomic systems of control that remain ever present in American cultural values. Full article

Food leftovers are a key component of household food waste. A nationwide survey of 1115 Polish adults conducted in 2019 examined how such leftovers are managed, considering socio-demographic and economic factors. It also explored the impact of selected food management practices on the throwing away of unconsumed meal leftovers. The data obtained indicated that one-quarter of the respondents always and usually use unconsumed meals to prepare other dishes. The following positions were taken by: giving to animals (23.68%), disposal in a waste container (15.97%), freezing (15.78%) and ex aequo giving to family or friends and composting (8.07%). Place of residence strongly influenced behaviours. Rural residents were much more likely than city dwellers to feed animals unused ready meals and compost them. On the other hand, city dwellers and young consumers more often stated that they would dispose of such products in a waste container. The constructed regression model indicated that only the frequency of purchasing ready-made chilled and frozen meals and the importance of storage conditions, in the respondents’ opinion, significantly impacted throwing away leftovers in a waste container. In summary, Polish respondents do not follow the food waste hierarchy. For this reason, it is important to develop and implement various educational programmes and campaigns. Full article

High-precision analyses of baseball pitching have traditionally relied on optical motion capture systems, which, despite their accuracy, are complex and impractical for widespread use. Classifying sequential pitching phases, essential for biomechanical evaluation, conventionally requires manual expert labeling, a time-consuming and labor-intensive process. Accurate identification of phase boundaries is critical because they correspond to key temporal events related to pitching injuries. This study developed and validated a smartphone-based system for automatically classifying the five key pitching phases—wind-up, stride, arm-cocking, arm acceleration, and follow-through—using pose estimation artificial intelligence and machine learning. Slow-motion videos (240 frames per second, 1080p) of 500 healthy right-handed high school pitchers were recorded from the front using a single smartphone. Skeletal landmarks were extracted using MediaPipe, and 33 kinematic features, including joint angles and limb distances, were computed. Expert-annotated phase labels were used to train classification models. Among the models evaluated, Light Gradient Boosting Machine (LightGBM) achieved a classification accuracy of 99.7% and processed each video in a few seconds demonstrating feasibility for on-site analysis. This system enables high-accuracy phase classification directly from video without motion capture, supporting future tools to detect abnormal pitching mechanics, prevent throwing-related injuries, and broaden access to pitching analysis. Full article

Although the hamstring muscles play an important role in running, very little is known about the individual contributions of each hamstring muscle (biceps femoris_{long head}, biceps femoris_{short head}, semitendinosus, and semimembranosus) toward running economy. As such, our study examined all the muscles in the hamstring to provide insight into which muscles contribute the most to running economy. Such information can provide insight in designing precise exercise training programs for enhancing running performance. Secondary analysis from our cross-sectional study conducted on 23 male recreational runners examined the relationships between stretch shortening cycle potentiation (via leg press throw), running net VO₂ (inverse of running economy) (at 11.3 km/h), and maximum cross-sectional area of biceps femoris_{long head}, biceps femoris_{short head}, semitendinosus, and semimembranosus was assessed via magnetic resonance imaging. We obtained significant correlations between the maximum cross-sectional area of the biceps femoris_{long head} and log₁₀running net VO₂ (r = −0.52; p < 0.05). Our multiple regression model showed that the maximum cross-sectional area of biceps femoris_{long head} but not stretch shortening cycle potentiation predicted log₁₀running net VO₂ (r = −0.52; p < 0.01). We found no other relationship between any other hamstring muscles and log₁₀running net VO₂. Our findings provide preliminary evidence of the importance of the biceps femoris_{long head} toward running economy. This may be due to the preferential activation of efficient slow twitch muscle fibers of the biceps femoris_{long head}. Additionally, we noted that the biceps femoris_{short head}, semitendinosus, and semimembranosus muscles were not related to running economy in recreational male runners. Full article

Background/Objectives: Age-related declines in motor and functional abilities can compromise independence and quality of life in later life. Motor competence (MC) plays an important role in maintaining quality of life and independence. However, few reliable instruments exist to assess MC in this population. The study adapts the Motor Competence Assessment (MCA) battery to meet the MC assessment and safety requirements of community-dwelling older adults. Methods: Seventy-six community-dwelling, physically active older adults (age = 73.4 ± 7.0 years) enrolled in a multi-phase adaptation process involving expert review, pilot and field testing, and validation of six motor tasks across three MC domains. Adaptations emphasized in the following four stages: accomplishing participant safety, autonomy, and the reliability of MC measurement principles. Results: The adapted version demonstrated very high completion rates, being safe and reliable for accessing MC, showing strong reliability in the manipulative domain. The use of the Challenge by Choice principle improved participant autonomy, confidence, and perceived motor competence. The main alterations to stability and locomotor tasks allow feasibility while maintaining test validity. Adjustments in instructions and practice trials reduced cognitive load and improved performance, addressing age-related perceptual and comprehension challenges. Ball Kicking and Throwing Velocity tests showed high reliability (ICC between 0.828 and 0.925), with minor gender-related differences. Conclusions: The adapted MCA is a safe, feasible, and reliable instrument for assessing MC in community-dwelling older adults. It preserves the conceptual foundations of MC while accommodating age-related MC alterations, offering a valuable resource for research and clinical applications. Full article

This paper introduces innovative approaches to the design of railway point machines, with particular emphasis on the implementation of multi-component AlNiCoFe alloys, classified as semi-hard magnetic materials. A comprehensive review of existing mechanisms for mechanical force transmission—from the electric motor to the throwing bar—was conducted. The inherent limitations of conventional dry friction clutches, commonly used in current point machine designs, are critically analyzed. Furthermore, the feasibility of employing multi-component AlNiCoFe alloys as functional materials in hysteresis magnetic clutches is examined, with a view toward enhancing the reliability and performance of railway point actuation systems. A review of diagnostic methods for railway point machines was conducted to evaluate the potential application of a novel magnetic torque limiter as a means to eliminate maintenance activities typically required for systems utilizing dry friction clutches. Experimental research was performed on AlNiCoFe alloys employed as the hysteresis layer in the proposed torque limiter. Microstructural and compositional analyses were carried out using scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD) to determine the crystallographic structure, chemical composition, and selected physical properties of the tested materials. The hysteresis loops of the tested materials were measured using a Vibrating Sample Magnetometer (VSM) over a wide temperature range. A prototype magnetic clutch, functioning as a torque limiter in a railway point machine, was developed and presented. The operational characteristics—specifically the throwing force as a function of time—were recorded for a railway point machine equipped with an electromechanical module incorporating the new magnetic torque limiter. The advantages of the proposed solution in terms of force transmission and overall system performance in railway point machine design were analyzed and discussed. Full article

Background: The study evaluated the acute effect of dryland maximum strength (MS) training on water polo performance. Methods: Twelve female players (20.3 ± 1.4 years) underwent initial assessments, including a head-out 20 m swim and a one-repetition maximum (1RM) strength test in three exercises: bench press, seated pull row, and half squat. These exercises were used as the experimental (EXP) condition. During the main testing sessions, participants completed the EXP and a control (CON) condition. In the EXP, players completed MS training (three sets of six repetitions at 80% 1RM), followed 15 min later by in-water testing. In the CON, only the in-water tests were performed. These included a 10 s tethered swim to measure force, a 20 m head-out swim at maximum intensity to measure performance time, ten goal-targeted throws to reach the highest accuracy and throwing velocity, and three in-water vertical jumps as high as possible. Results: The performance time in the head-out 20 m swim (EXP: 14.21 ± 0.4, CON: 14.18 ± 0.5 s), tethered swimming force (EXP: 86.85 ± 14.82, CON: 89.58 ± 15.92 N), shooting velocity (EXP: 14.67 ± 1.19, CON: 14.91 ± 0.32 m·s⁻¹), shooting accuracy (EXP: 16.5 ± 5.4, CON: 19.0 ± 5.1 points), and in-water vertical jump height (EXP: 51.7 ± 5.6, CON: 52.9 ± 4.2 cm) were no different between conditions (p > 0.05). Conclusions: Dryland maximum strength training performed with high loads (80% 1RM) does not impair subsequent performance during sport-specific testing in female water polo players. These findings suggest that such MS training can be safely implemented 15 min prior to in-water training sessions. Full article

The vortex throw, similar to the javelin throw, requires exceptional mastery of technique and specific motor abilities to ensure success. This study examines the anthropometric and motoric status of young female track-and-field athletes and investigates their relationship with vortex throwing performance. This research included 63 young female athletes; the results of 14 motor tests, three anthropometric measures, and training experience were compared with vortex throwing distance and vortex release velocity. Pearson’s correlation analysis revealed that the most valuable strong correlation was between the release velocity and the throwing distance (r > 0.75), indicating that they almost equally contributed to throwing performance. The most valuable moderate correlations were those between the leg tapping test, the overhead medicine ball throw, and the chest medicine ball launch and the performance of both forms of throwing. Accounting for shared variance among predictors, multivariable models explained 43% of the variance in vortex release velocity and 58% in vortex throwing distance, with the standing long jump uniquely predicting release velocity and the overhead 1-kg medicine ball throw uniquely predicting throwing distance. Finally, the motor abilities recognized in athletes in this research are valuable indicators of quality throwing performance and could play a crucial role in throwing success, which supports previous evidence on similar topics. Collectively, these results support using release velocity alongside distance to evaluate youth vortex throwers and highlight simple field tests (leg tapping, medicine ball throws, and long jumps) as practical markers for training prescription and early talent identification. Full article

STEM (Science, Technology, Engineering, and Mathematics) education faces the challenge of incorporating advanced technologies that foster motivation, collaboration, and hands-on learning. This study proposes a portable system capable of transforming ordinary surfaces into interactive learning spaces through gamification and spatial perception. A prototype based on multi-agent architecture was developed on the PANGEA (Platform for automatic coNstruction of orGanizations of intElligent agents) platform, integrating LIDAR (Light Detection and Ranging) sensors for gesture detection, an ultra-short-throw projector for visual interaction and a web platform to manage educational content, organize activities and evaluate student performance. The data from the sensors is processed in real time using ROS (Robot Operating System), generating precise virtual interactions on the projected surface, while the web allows you to configure physical and pedagogical parameters. Preliminary tests show that the system accurately detects gestures, translates them into digital interactions, and maintains low latency in different classroom environments, demonstrating robustness, modularity, and portability. The results suggest that the combination of multi-agent architectures, LIDAR sensors, and gamified platforms offers an effective approach to promote active learning in STEM, facilitate the adoption of advanced technologies in diverse educational settings, and improve student engagement and experience. Full article