TWO SERIES OF FIFTY JUMPS PERFORMED WITHIN SIXTY MINUTES DO NOT EXACERBATE MUSCLE FATIGUE AND MUSCLE DAMAGE

Skurvydas, A, Kamandulis, S, and Masiulis, N. Two series of fifty jumps performed within sixty minutes do not exacerbate muscle fatigue and muscle damage. J Strength Cond Res 24(4): 929-935, 2010-Previous studies have demonstrated that an exercise bout repeated prior to full recovery, within 2-6 days, does not impair muscle function to a greater extent and does not affect the repair process. The aim of this study was to examine whether repeated exercise performed 60 minutes after the first one exacerbates muscle fatigue and damage. Ten healthy, physically active males (21.1 +/- 1.4 years, 75.2 +/- 4.1 kg, 178.7 +/- 4.5 cm) performed 2 bouts of 50 continuous maximal intensity jumps with a 60-minute rest period. Peak quadriceps muscle force evoked by electrical stimulation at 15 (P15) and 50 (P50) Hz and maximal voluntary contraction force (MVCF) were measured 2, 30, and 60 minutes after bout 1 and bout 2. The results demonstrated a significant decrease in P15, P50, and MVCF during bout 1 (p < 0.05). The force did not recover within 60 minutes after exercising. After the second bout, the MVCF and P50 decreased to similar extent both immediately after and 30-60 minutes after the first one despite the fact that bout 2 was repeated with the voluntary and involuntary force still depressed. It was concluded that within 60 minutes repeated jumping exercise does not exacerbate muscle fatigue and muscle damage. From the coach's point of view it is of significance that the neuromuscular system appears to be well protected from frequently repeated muscle damaging exercise.