Range of motion of body segments is larger during the maximal instep kick than during the submaximal kick in experienced football players.

BACKGROUND Football players with groin injury refrain from maximal kicking. Previous groin injury is related to decreased hip range of motion (ROM). Information on ROM differences between maximal and submaximal kicking within players is lacking. The first aim of this study is to quantify ROM of body segments during the maximal (MaxK) and submaximal (SubK) instep kick at four key points. The second aim is to study ROM differences of tension arc and movement trajectories between MaxK and SubK. METHODS Maximal (100% ball speed) and submaximal (70% ball speed) instep kicks from 15 experienced football players were registered with motion capture. ROM of hip, spine, pelvis and knee segments were determined at four key points. Differences in segmental ROM for the tension arc and movement trajectories between MaxK and SubK were studied. Effect sizes (ES) were calculated. RESULTS Ball speed was 98.8±9.0 km/h for MaxK and 69.5±7.1 km/h for SubK. Three key points timed similarly (P<0.05) for MaxK and SubK. MaxK shows increased ROM for all segments (P<0.05) but not for hip flexion. MaxK results in enlargement of tension arc and movement trajectories. Spine flexion (ES=3.2) and pelvis posterior tilt (ES=2.2) show the greatest relative increase. CONCLUSIONS Maximal kicking shows larger segmental ROM than submaximal kicking. Enlargement of tension arc and movement trajectories relate to increased segmental velocity, according to biomechanical concepts. Central body actions play an important role in kicking. This information can be used to further identify kicking strategies in athletes with injury.