1976 Volume 21 Issue 3 Pages 137-144
The motion-picture analysis administered to the skilled overhand pitchers has made it clear that in most of the subjects the upper extremity movement stops momentarily during the shift from the backswing to the forward swing, and in some subjects the upper extremity moves almost continuously during the same period. Most of the skilled overhand pitchers belonged to the former 'discontinuous type'; the rest, the latter 'continuous type.' The electromyograms were recorded from the shoulder girdle, the upper extremity, and the trnuk muscles of the skilled overhand pitchers who were requested to perform overhand pitching to the fullest of their ability, and were analyzed in terms of the functional mechanism of the muscles. 1) During the backswing of the upper extremity, the discharge patterns obtained from both of the two types indicated that the upper extremity was abducted slightly backward in the frontal plane, and for the 'continuous type,' the discharge pattern indicated that the upper extremity was abducted slightly forward in the frontal plane. 2) In the first half and in the middle of the forward swing of the upper extremity, both of the two styles showed the discharge patterns indicating that the trunk was rotated, and that in the first half, the upper arm was rotated with the elbow flexed. As for the 'continuous type,' the discharge pattern, in the first half and in the middle of the forward swing, indicated that the upper arm was lifted up, and at the same time horizontally abducted, but for the 'discontinuous type,' such discharge pattern appeared from the middle of the forward swing. 3) In the latter half of the forward swing of the upper extremity, the discharge patterns of both types indicated that the upper arm was depressed with the elbow flexed and with the forearm inwardly rotated. As for the 'discontinuous type,' the discharge pattern indicated that the upper arm was abducted in the frontal plane with force exerted backward, for the 'continuous type,' the discharge pattern indicated that force was exerted somewhat forward. In releasing the ball, the discharge pattern of the 'continuous type,' as in the 'discotinuous type,' indicated that the upper arm was abducted in the frontal plane with force exerted backward.
