The biomechanical characteristics of the instep soccer kick have been extensively studied (1,2). However, there are several types of kicks which are commonly used during a soccer game and have not received the appropriate attention. PURPOSE To examine the kinematic differences between instep soccer kick and kick with the outside portion of the foot (outstep kick). METHODS Ten pubertal soccer players (age: 13.6 ± 0.7 yrs, mass: 47.5 ± 13.1 kg, height: 153.5 ± 8.8 cm) performed 10 consecutive kicking trials in a random order after a two step angled approach with the instep and the outside portion of the dominant foot. The kick with the highest ball velocity was further analyzed. Bilateral three-dimensional kinematics in sagittal, coronal and transverse axis (six camera Vicon motion analysis system, 200Hz) were collected. The maximum ball speed, ball speed / foot speed ratio, segmental angular velocities and joint displacements were also estimated. A dependent Student t-test was used for comparisons between the two types of kick. RESULTS Significant (P < 0.05) differences in ball speed were observed between the instep (19.62 ± 1.89 m•sec-1) and the outstep soccer kick (18.55 ± 1.60 m•sec-1). Similarly, the ball/foot speed ratio was significantly (P < 0.05) lower for the outstep kick (1.52 ± 0.32) compared with the instep kick (1.63 ± 0.41). Non-significant differences in angular and linear sagittal kinematic parameters between the two types of kick were observed (P > 0.05) except the foot angular velocity which displayed significantly higher values during the instep kick (P < 0.05). In contrast, the outstep kick displayed higher hip abduction and internal rotation, internal knee rotation and ankle inversion (P < 0.05). DISCUSSION The present study indicated significant differences in the main biomechanical indicators of kicking success between the instep and the outstep kick. Similar results were reported for other types of kick (3) ranking the instep kick as the most powerful kick. During the outstep kick, the player needs to change the motion in the trunk-thigh, thigh-tibia and tibia-foot plane orientation in order to take the appropriate position for the kick. These changes seems to alter the proximal-to-distal transfer of energy between segments (4), thus leading to lower foot angular velocities and therefore lower ball speed values.
© Copyright 2009 14th annual Congress of the European College of Sport Science, Oslo/Norway, June 24-27, 2009, Book of Abstracts. Published by The Norwegian School of Sport Sciences. All rights reserved.