Abstract: Depnding on telemetric EMG signal and image analysis methods, the research quantitatively analyzes 19 male gymnasts from Tianjin gymnastics team for their three kinds of horizontal bar chin-up actions, wide backhand grips, backhand grips and backhand neck-behind grips. The results show that: each of the three actions plays a dominant role in the development of gymnasts' latissimus dorsi and brachioradialis,with the mobilization of the motor unit rate being the highest; the three actions produce the same effects on developing trapezius muscle and the pectoralis major, with both discharge amount and degree of activation of the muscle being relatively stable; neck-behind wide backhand grips develop gymnasts' biceps and flexor carpi much better and the activation of motor unit rate is considerably higher than the other two kinds; the effect backhand grip on lexor carpi building is superior to the others and at last, the three horizontal bar chin-ups from backhand wide grip, grip to neck-behind grip develop flexor carpi power increasingly one by one.

Key words: gymnasts, horizontal bar chin-ups, EMG characteristics