Lower limbs muscle activation during instep kick in soccer: effects of dominance and ball condition

Muscle activation during soccer kicking has been studied exclusively with players kicking stationary balls with the dominant foot. This study evaluated swinging and support limb muscle activation during the same kind of kick (instep) using different feet and ball approach conditions. Vastus medialis (VM), biceps femoris (BF), gastrocnemius medialis (GM) and tibialis anterior (TA) activations were evaluated during maximal instep kicks performed with both feet and with the ball in five conditions (n=18): stationary (STAT), approaching anteriorly (ANT), posteriorly (POST), laterally (LAT) and medially (MED). A repeated-measures two-way ANOVA compared muscle activations between feet and ball conditions throughout the kicking (0-100%) and follow-through phases (101-200%). Close to ball contact (81-124%), non-dominant support GM had greater activation compared to the dominant one. The LAT and MED conditions differed at certain points of the cycle in the swinging VM (0-21%; 191-200%), BF (13-70%; 121-161%), GM (22-82%; 121-143%) and TA (0-32%; 55-97%; 186-200%) and in support VM (0-81%), BF (6-24%; 121-161%) and GM (24-87%). Players require greater support GM activation to stabilize the ankle joint during non-dominant kicks. Furthermore, lower limb muscle activation differences between LAT and MED indicate that the kicking strategies are altered when kicking balls approaching from different conditions.