We investigated the effects of the alternate activity in the synergistic muscles (AA) and the tremor (T) on 1) maximal muscle force, endurance performance and static work and 2) these parameters on the next day. Eight male subjects performed static contractions at an ankle joint angle of 110° or 130° plantar flexion under constant load of 10％ maximal voluntary contraction till exhaustion as a fatigue test on days 1 and 2. Maximal isometric force of the ankle plantar flexors and endurance time of the fatiguing exercise were measured, and the surface electromyograms were also recorded from the triceps surae muscles, i. e. lateral gastrocnemius (LG), medial gastrocnemius (MG) and soleus (SOL) muscle. Endurance time in the AA group was significantly longer than that in the T group on both days (p<0.05). The fatigue test significantly reduced the maximal force in both AA and T groups on days 1 and 2 (p<0.05), but the rate of decrease in the maximal force was greater in the T group than in the AA group. Endurance time and static work in the T group declined by 40% and 45% on day 2, respectively (p<0.05). However, no significant differences in these parameters in the AA group were found between days 1 and 2. The results suggest that the type of the alternate activity in the synergistic muscles may reduce the development of muscle fatigue and have little effect on the static work on the next day.

DESCENTE SPORTS SCIENCE Vol.21/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE