Acute and sub-acute effects of repetitive kicking on hip adduction torque in injury-free elite youth soccer players

Hip adduction strength is important for kicking and acceleration in soccer players. Changes in hip adduction strength may therefore have an effect on soccer players' athletic performance. The purpose of this study was to investigate the acute and sub-acute effects of a kicking drill session on hip strength, concerning isometric hip adduction, abduction and flexion torque of the kicking leg and the supporting leg. Ten injury-free male elite soccer players, mean +/- s age of 15.8 +/- 0.4 years participated. All players underwent a specific 20 min kicking drill session, comprising 45 kicks. The players were tested the day before, 15 min after and 24 h after the kicking drill session by a blinded tester using a reliable test procedure. The isometric hip-action and leg-order were randomized. For the kicking leg, hip adduction torque increased from 2.45 (2.19-2.65) Nm . kg(-1), median (25th-75th percentiles), at pre-kicking to 2.65 (2.55-2.81) Nm . kg(-1) (P = 0.024) 24 h postkicking. This may have implications for the soccer player's ability to maximally activate the hip adductors during kicking and acceleration, and thereby improve performance the day after a kicking drill session.