Biomechanical analysis of volleyball overhead pass

In volleyball, the overhead pass is an important skill for passing a ball and making a set to attackers. In the present study, we analysed the overhead pass motion and involved muscle activity with special attention to the stretch-shortening cycle (SSC). Electromyogram was recorded from the wrist and elbow joint flexors and extensors. The movement period when the ball touched the hand was divided into the pull and push phases with the moment when the ball was at the lowest position. In the pull phase, although the wrists were extended, the activity of wrist flexor muscle was higher than the extensor muscle in both skilled and unskilled groups. And the activity in the wrist flexor muscle in the pull phase was higher in the skilled participants than that of the unskilled participants. Thus, the skilled participants pushed the ball by utilising the SSC of the wrist, while the unskilled participants did this in a less degree. In addition, the kinetic chain was observed from elbow to wrist in the skilled participants. We conclude that it is important for an overhead pass that the wrist flexor muscles accumulate elastic energy during the pull phase which is then released in the push phase.