抄録
This study aimed to clarify sex differences in the effects of arm swing on sprint performance and trunk motion in adolescent middle school track and field athletes. The participants included 8 male and 8 female middle school students belonging to a track and field club. A comparative experiment was conducted under 2 conditions: normal sprinting and sprinting with restriction of arm swing. Sprint velocity, step frequency, and stride length were calculated from high-speed camera recordings, and 3-dimensional motion analysis was performed to measure shoulder and pelvic rotation angles and angular velocities.
The results revealed that restriction of arm swing led to a significant decrease of sprint velocity and stride length in both males and females, while step frequency also decreased significantly in females. Furthermore, the percentage changes in sprint velocity and step frequency were significantly greater in females than in males. In terms of trunk motion, males exhibited a significant increase in shoulder rotation angle and angular velocity under arm restriction, whereas no significant changes were observed in females. Additionally, females subjected to arm swing restriction showed a significant negative correlation between the percentage change in shoulder rotation angle and the percentage changes in sprint velocity and step frequency, relative to the normal condition. Overall, the results revealed clear sex differences in how arm swing influences sprint performance and trunk mechanics. In females relative to males, arm swing appears to play a smaller role in directly constraining trunk rotation; however, it may play a greater role in mitigating trunk rotation-related declines in step frequency and sprint velocity. By contrast, in males relative to females, arm swing seems to contribute more to suppression of trunk rotation and may be more closely associated with maintaining or increasing step length.
