BIOMECHANICS OF THE OI-TSUKI IN ZENKUTSU-DACHI

Abstract

The punch studied herein is the oi-tsuki (lunge punch) in zenkutsu-dachi (front stance). A common description found for this skill is as follows. In the zenkutsu-dachi position the knee and hip of the front leg are flexed. The rear leg is extended at the knee with the hip joint in outward rotation. The rear foot is dorsiflexed at the ankle and directed forward and outward. The outward rotation of the ankle is between 20 and 45 degrees. Weight distribution on front and rear feet is 60 and 40 percent. The length of the stance is twice the width of the karateka's shoulders. The fist with which the punch is delivered is placed at the waist, forearm supinated. During the forward motion in zenkutsu-dachi the rear leg slides forward and at the same time the fist is accelerated as the forearm extends at the elbow and the arm flexes at the shoulder. The fist starts at the waist with the closed palm upward and as the fist is moved forward, the forearm pronates until the closed palm is downward when the arm is fully extended.