ROUNDHOUSE KICK WITH AND WITHOUT IMPACT IN KARATEKA OF DIFFERENT TECHNICAL LEVEL

The purpose of this study was to compare two different Karate roundhouse kicks performed by athletes of different technical level. The combination of high movement velocities and a high technical difficulty, qualify these actions as a good model to quantify the ability of a Karateka to execute complex movements. The first kick, directed to the face, entails a strong braking action to avoid the impact (NI), the other, directed to the chest, is concluded by an impact (IM). Technical aspects and the role of muscular co-activation as joint protector were investigated in six top level Karateka (KA) and six practicing karate amateurs (CO), by estimating joint kinematics and neuromuscular activity patterns. KA presented a faster execution for both tasks, prevalently due to a faster knee extension, supported by a low co-activation of the antagonist Biceps Femoris. This behaviour confirms that elite KA tend to lower the co-activation of antagonist muscles during fast movements, partially in contrast with the antagonists possible role in maintaining knee stability. The NI task, requiring higher technical competence and entailing a high target, is performed by KA athletes using a peculiar technique, based on a wide hip flexion-extension range, with a peak hip ab-adduction occurring earlier than in CO. A lower co-activation presented by CO during knee flexion is presumably due to their difficulty in mastering this complex kick