Abstract

A simultaneous electromyographic (EMG) and cinematographic study was conductedon the tennis serve in comparison with the similar movement of overhand throwing. Three Japanese men (aged 21-23 a) served as subjects. One was a highly trained tennis player. The other two were untrained in tennis, but one of themwas a trained baseball pitcher. The motions were filmed from the side with a 16-mm high-speed camera. At the same time EMGs were recorded on seven muscles of the upper arm and trunk. In addition, the vibrational forces were recorded by a strain gauge attached to the racket. The EMG recordings and motion pictures filmed by cinecamera were synchronized by a flashing light. The results showed higher velocities for balls served and thrown by the trained subjects than by untrained. Although individual differences were found in muscle activities, similar muscle activities were observed between the serve and throwing action of each subject. The interesting finding was the existence of a silent period in muscle activities. Most of the observed muscles ceased their electrical activities during the first half of the forward swing in the serve performed by the tennis player and also during the first half of the throw performed by the trained baseball pitcher. Verf.-Referat