Differences in lower leg kinetics of soccer instep kicking between female and male players.

We aimed to clarify the difference in lower leg segment kinetics of soccer instep kicking between female and male players. Instep kicking motions of seven female and seven male university soccer players were captured at 500 Hz. Lower leg angular velocity, knee joint moment and the interaction moment acting on the lower leg were calculated. Discrete variables were compared using two sample-t-test, and statistical parametric mapping were used to compare the time-series changes between the two groups. Although female players maintained a comparable magnitude of lower leg angular velocity, they exhibited significantly lower knee extension moment in the latter part of kicking and significantly smaller forward angular impulse due to that moment. In contrast, female players were found to have a comparable magnitude of angular impulse due to forward component of interaction moment to that of male players. Eventually, female players come to have significantly larger ratio of angular impulses (forward interaction moment/knee extension moment) than male players. It can be considered that the forward component of interaction moment acting on the lower leg of female players may compensate their reduced exertion of knee extension moment, thereby achieving a comparable lower leg angular velocity to that of male players.

Sex difference in soccer instep kicking.

We aimed to clarify the differences in soccer instep kicking dynamics between sex groups. The instep kicking of seven female (height: 160.3 ± 6.1 cm; mass: 54.3 ± 5.2 kg) and seven male (height: 173.0 ± 5.9 cm; mass: 70.0 ± 9.0 kg) players were recorded by a motion capture system (500 Hz). Joint moments of the kicking leg were computed and normalized by the body mass and height. Statistical parametric mapping was used to compare the entire kicking motion between the two groups. Significantly slower resultant ball velocity seen in female players was most likely explained by their significantly slower run-up velocity, shorter leg length and lower foot-ball velocity ratio. Female players exhibited significantly smaller knee joint moment in the latter part (80-86%) of kicking. Also, significantly smaller positive work done by knee extension moment and the ratio of work (knee extension/hip flexion) were found in female players. These results suggested that the suppressed knee extension moment action was identified as a key kinetic characteristic in the instep kicking of female players, and to compensate for this action, they more rely on the work due to hip flexion moment to execute the instep kicking.