Learning process of knuckle kicking skill in soccer from introspection and coaching

Abstract

    In soccer, straight kick, curve kick and knuckle kick are used. Knuckle kick is performed in free kicks frequently, because it is easier to gain ball velocity than curve kick. So it became important kick skill. This study investigated effective training methods for knuckle kicks by considering the training processes used in a motor training experiment. In this study, 15 male collegiate soccer players participated in organized training with a coach approximately once every two weeks over a two-month period. During training, participant setbacks were recorded alongside commentary from the participants about their own kicks. An optical three-dimensional motion capture system was used to conduct motion analysis before and after the training period, analysing where the point of impact occurred on both the foot and ball. According to the motion analysis, the horizontal rotation of the ball was significantly decreased after the training period (p<0.05), showing improvement in the skills. Regard to learning of increasing ball velocity and decreasing ball rotation in knuckle kick skill, participants are divided into stepwise and simultaneous types. The setback that ball rotation get increase accompany with raising ball velocity was observed in the stepwise type. With respect to verbalization, participants were divided into two separate groups: voluntary verbalizing and onomatopoeic types. In the learning process, it was considered that participant of simultaneous and verbalizing type learned more effectively than others. It is therefore suggested that, amongst the training methods investigated in this study, training for simultaneous learning with verbalization is the most effective approach.