Kinematic Analysis of a Side Volley in Soccer
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V. Mrdaković, S. Kostić, N. Janković, M. Matić, F. Kukić, M. Ubović, D. Ilić.
Univ. of Belgrade, FSPE; Technical School Ub, Serbia; PROFEX – Academy of Healthy Life, Belgrade, Serbia.
indent Abstract
The purpose of this study was to analyze kinematic variables of side volley in elite soccer players, as well as examining kinematic variables adjustment in relation to the change of velocity and height of incoming ball. Thirty professional soccer players participated in this study. The experimental protocol implied kicking the ball towards the subject at three different velocities and three different heights. Th e analysis included a total of the following seven dependent variables: Maximum linear velocity of the foot, the knee and the hip (V_FOOT_max, V_KNEE_max, V_HIP_max), Maximum knee and hip joint angular velocities (W_KNEE_max, W_HIP_max), Distance between the foot and the hip at impact with the ball (D_hip.foot_tk), and Angle between the shoulder and hip axis and the hip and foot axis at impact with the ball (α_SHF_tk). Also, for the purpose of descriptive kinematic analysis, the variables of changed angles and hip and knee joint angular velocities were used in different phases of side volley performance, as well as the variables of changed linear velocity of the foot, the knee and the hip. The variables of side volley kinematics were measured with the 3D kinematic analysis system (Qualisys). Th e eff ects of the ball height and velocity, and their interaction, on dependent kinematic variables were tested by using the statistical method of two-way analysis of variance with repeated measures (two-way ANOVA). The velocity and height of the incoming ball had a signifi cant eff ect on V_ FOOT_max in the sense that, as ball velocity grew, V_FOOT_max increased as well, while as ball height increased, V_FOOT_max dropped. A similar effects of the ball velocity and ball height was observed for V_ HIP_max, but is observed only a tendency towards statistical significance. Also, it was observed that increased speed of the incoming ball aff ected increase of D_hip.foot_tk, as well as α_SHF_tk, while values of W_HIP_max were decreased. The statistical analysis revealed that changes in the mechanical conditions in which side volleys were performed such as a different velocity/height of the incoming ball affected the modulation of the velocity of the farthermost proximal and distal ends of the kinetic chain/hip and foot joints, while the knee joint function was primarily to fine-tune the distance between the subjects' position and the ball.
keywords SOCCER TECHNIQUE / COORDINATION / VELOCITY / ANGULAR VELOCITY / JOINT ANGLE