Bilateral Leg Differences in Soccer Kick Kinematics Following Exhaustive Running Fatigue

Abstract

Background: Understanding fatigue effects on kicking technique with both legs would allow coaches to design soccer-specific training programs. Objectives: The purpose of the present study was to examine whether fatigue effects on soccer kick kinematics would differ between the preferred and the non-preferred leg. Methods: Ten adult amateur male players (age: 24.5 ± 5.8 yrs; height: 179.2 ± 4.3 cm; mass: 79.3 ± 5.4 kg; training age: 11.5 ± 2.9 yrs) performed two instep kicks with their preferred and non-preferred leg prior to and after running on a treadmill till exhaustion. Three-dimensional kinematics were collected pre and post-fatigue. Results: Analysis of variance indicated a statistically significant decline in ball speed after fatigue for both legs (P < 0.05). Maximum linear and angular velocity for all joints was significantly lower post fatigue for both preferred and non-preferred leg (P < 0.05). Similarly, alterations on joint kinematics were evident for both legs. Conclusions: Soccer kick performance declined after fatigue and this reduction was higher for the non-preferred leg compared to preferred leg performance. These findings indicate the need for specific exercises during the training process in order to reduce the effects of fatigue, especially for the non-preferred leg.