Biomechanical study of mechanism of speed-accuracy trade-off in a side-foot soccer kick

Abstract

The objective of the present study was to investigate kinematically as well as kinetically the mechanism of the speed-accuracy trade-off in a side-foot soccer kick. Eight experienced male soccer players and eight inexperienced players participated in the experiment. They were instructed to perform five grounder side-foot kicks under two conditions. In one condition, they were emphasized on accuracy rather than speed. In an other condition, they were emphasized on speed rather than accuracy. The resultant performance (i.e. ball speed and absolute error against the target line) was recorded. The joint torques and joint angles of the kicking leg were also determined based on the three-dimensional kinematic data acquired using a motion capture system. The present results suggested that the degree of the speed-accuracy trade-off effect was different depending on the skill level. The inexperienced players significantly lost their accuracy by emphasizing on ball speed. In contrast, the experienced players could keep their good accuracy even by emphasizing on ball speed because of their good impact skill. The mean ball speed of the experienced players was significantly faster than that of the inexperienced players regardless of speed-or-accuracy emphasis. This seems to be because skilled soccer players can use the hip-flexion torque more efficiently than unskilled players. In conclusion, skilled soccer players may emphasize ball speed when they kick a placed ball with the medial aspect of the foot under certain situations such as a penalty kick.