The influence of repeated bouts of high-intensity veloergometric exercise on low frequency fatigue and recovery of quadriceps muscle at different muscle length

The aim of this study was to establish the effect of one day training exercise on the time-course of muscle recovery after high-intensity veloergometric exercise in untrained subjects (males, age 25.4 ± 1.7 years, n=12) what causes muscle fatigue, especially low frequency fatigue (LFF). Subjects performed three, 1 min exercise bout at approximately 130% VO2max with a 4-min rest period between each work bout. The same experiment (second experiment) was repeated 48 h after the first experiment. After first and second experiment exercises muscle contraction force induced by stimulating the muscle at 20 Hz and 50 Hz frequencies and changes in the maximal voluntary contraction force were established. The contractile force was measured at knee-joint angles of 135o and 75o. The results of the experiments carried out have shown that 1) the exercise repeated 48 h after applying the first experiment brought about no changes either in muscle resistance to LFF (irrespective of muscle length at which muscle contraction force was registered) or in the time-course of changes in LFF after the exercise; 2) following exercises of both experiments LFF was significantly greater at a shorter muscle length though the time-course of muscle recovery after exercise did not depend on muscle length.