ECSS Paris 2023: CP-BM13
INTRODUCTION: Proximal to distal sequencing of body segments, typically characterized by shoulder–hip separation, is a fundamental biomechanical determinant of baseball pitching performance. While previous studies have primarily emphasized the magnitude of segmental separation, the temporal coordination between segments remains underexplored. Therefore, this study aimed to investigate the relationships among timing differences of body segments and pitching performance, specifically ball velocity and strike outcome, by using a wearable inertial measurement unit (IMU) system. METHODS: Twelve male collegiate baseball pitchers (age: 19.3±1.3 years, height: 181.0±7.1cm, weight: 85.5±13.3kg) participated in this study. Five IMUs were attached on the throwing arm, sternum, sacrum, axial-leg thigh, and lead leg. Each pitcher performed ten fastball pitches from an indoor turf mound. Pitch outcome (strike or ball) was determined by a catcher, resulting in 60 strikes and 32 balls. Ball velocity was measured using a radar gun positioned behind the pitcher. Only pitches reaching at least 80% of each pitcher’s maximal velocity were included. Timing differences between body segments—including throwing arm–thorax, throwing arm–pelvis, and thorax–pelvis—were calculated using the IMU system (Movella DOT) and exported for offline analysis. Spearman’s rank correlations and Wilcoxon signed-rank tests were employed for statistical analysis. RESULTS: Timing differences between the throwing arm–pelvis (p = .008) and between the thorax–pelvis (p = .041) were significantly greater in strikes than in balls, whereas no difference was found for the throwing arm–thorax timing (p = .666). Spearman’s rank correlations revealed a moderate negative association between throwing arm–pelvis timing difference and ball velocity (ρ = −0.516, p < .001), indicating that greater temporal separation was associated with reduced ball velocity. No significant correlations were found between ball velocity and either throwing arm–thorax or thorax–pelvis timing difference (p > .05). CONCLUSION: These findings suggest that temporal coordination of the throwing arm and pelvis plays a critical role in regulating the speed-accuracy trade-off during baseball pitching. Although increased temporal separation may facilitate improved segmental control and strike accuracy, it may simultaneously reduce the efficiency of the kinetic chain required for maximal ball velocity. Coaches and practitioners should consider that optimizing shoulder-hip separation timing may require distinct strategies depending on whether the tactical emphasis is velocity or precision.
Read CV Szu-Ching ChenECSS Paris 2023: CP-BM13
INTRODUCTION: Climbing performance is influenced by multiple factors including grip strength, technical proficiency, and muscular endurance. However, the combined effects of climbing experience and grip-specific demands on neuromuscular and biomechanical have received limited attention. This study examined how different climbing skill levels (sedentary, intermediate, advanced) and grip types (sloper, crimp, pinch) influence muscle activation, postural stability, and joint kinematics in male and female participants during the armlifting exercise; an exercise commonly used by climbers for strength and endurance training. METHODS: Forty-two adults (21 males, 21 females) were assigned to sedentary, intermediate, or advanced climbing groups. Participants performed one-repetition maximum (1RM) tests and submaximal endurance trials with three grip types. Surface EMG was recorded from eight upper limb muscles. Motion capture, and dual force plates captured kinematics and postural stability. Linear mixed-effects models assessed Ranking, Grip, and their interaction (α = 0.05) by sex. RESULTS: Significant Rank × Grip interactions were found for 1RM force, with advanced climbers outperforming others across grips (p < .0001). EMG data revealed higher flexor muscle activation (FDP, FDS, BRD) in advanced males, especially with the crimp grip (p < .01), while sedentary females showed consistently higher FDP and BRD activation across grips (p < .01), suggesting compensatory recruitment. Median EMG frequency, an indicator of fatigue, was lower in sedentary participants, with significant differences in FDS and FDP for both sexes (p < .05). ROM analysis showed that advanced males had greater knee ROM in the sloper grip (p = .01), while sedentary females demonstrated greater shoulder, pelvis, and thorax ROM than climbers in the sloper and crimp grips (p < .01). Intermediate females exhibited superior ankle ROM compared to sedentary peers (p < .0001). CoP-based stability metrics differed by sex and grip: advanced males had larger CoPy displacements in crimp (p < .0001), while advanced females showed greater fatigue index in GRFz with the sloper grip (p = .03). CONCLUSION: Findings indicate distinct biomechanical and neuromuscular adaptations across skill levels and sexes during climbing-specific tasks. Advanced climbers exhibit efficient force production with reduced co-activation and fatigue, while sedentary participants compensate with increased muscle activation and joint ROM. These results support the development of targeted training interventions based on grip type, sex, and experience, and highlight the relevance of EMG, force, and kinematic measures in assessing climbing-specific performance.
Read CV Gabriela GarciaECSS Paris 2023: CP-BM13
INTRODUCTION: Batting is a primary means of scoring in fast-pitch softball and a complex, time-constrained motor skill. Because the ball’s flight time to home plate is extremely short, batters must accurately perceive the ball’s trajectory, arrival location, and timing to hit it. A successful swing requires coordinated whole-body movement and effective force transmission from the body through the bat to the ball to enhance post-impact ball velocity and flight distance. This study examined the role of lead-foot movement adjustments in regulating batting timing and their influence on hitting performance. METHODS: Eight collegiate female softball players were recruited. Two collegiate pitchers delivered 10 fastballs and 10 change-ups in a randomized order. High-speed cameras recorded both pitchers’ and batters’ movements. The videos were analyzed using Simi Motion to identify key temporal events, including pitcher movement onset, ball release, and five batting events from lead-foot lift to ball contact. The trajectories of the bat tip and the ball were digitized to derive their velocities. Linear mixed models and Pearson product–moment correlations were used for statistical analyses, with the significance level set at α = .05. RESULTS: Fastball speeds ranged from 85–80 km/h, and change-ups from 76–65 km/h. Linear mixed model analysis showed significant differences between fastball and change-up in Release–Swing and Swing–Impact duration (ps < .001). By examining the timing of batting movement events for each batter, it was found that only one batter’s landing occurred after ball release, and only this batter showed a significant negative correlation between Release–Weighting and Weighting–Swing, r(15) = −.651, p < .005. Trials were categorized as pre- or post-release landing. The maximum post-impact ball velocity was significantly higher in the post-release landing condition than in the pre-release landing condition (p < .001). CONCLUSION: The findings indicated that batters adjusted their swing onset in response to ball speed. However, only one participant demonstrated a functional adjustment by landing the lead foot after ball release, a movement coordinated with swing timing and associated with higher batted-ball velocity. These findings indicate that the lead-foot action is not merely preparatory for force production but also plays a functional role in regulating movement timing. Accordingly, training design should emphasize the adaptability of lead-foot movements and preserve perception–action coupling, rather than repeatedly practicing fixed movement patterns, to enhance batting adaptability and performance.
Read CV Yun-Ting ChenECSS Paris 2023: CP-BM13