Regression Equations for Estimating the Quality of Maximal Instep Kick by Males and Females in Soccer

Biomechanics research of soccer skills has greatly lagged behind the sport’s popularity compared to many other sports. Even for basic skills, such as the maximal instep kick, relatively few quantitative studies exist. Further, most of these fail to provide practical means to judge kick quality. The current study proposes to address this deficiency by establishing user-friendly regression equations that apply to both novice and advanced players. These allow an easy way for coaches/teachers to evaluate kick quality. The method consisted of 3D data collection (VICON system with nine high-speed cameras, 120 Hz), full-body biomechanical modeling and correlation and regression analyses of ball release speed with flexion/extension of shoulder, trunk, hip, knee and rotation of trunk as well as last stride length and body height. Twenty-four male and twenty-six female college students, equally divided into novice and advanced cohorts, participated. Results showed many of the correlations to be reliable predictors of a kick’s effectiveness. However, they are not practical since extensive use of technology and time-consuming data processing is needed. Further analyses showed multi-regressions using last stride length and body height as independent parameters to have equally reliable evaluation potential. The study concludes that, since the last two independent parameters are easy to measure, these regression equations provide an eminently practical means to evaluate the maximal instep soccer kick.