Cooling Attenuates the Reduction in Muscle Performance During Repeated Three Consecutive Days of Strenuous Exercise.

Abstract

PURPOSE: Although many scientific publications have already pointed the benefit of muscle cooling for physical performance, most of them focused on acute beneficial effects on a subsequent muscle performance. The purpose of this study was to investigate whether local muscular cooling intervention attenuates the reduction in maximal anaerobic performance caused by maximal pedaling exercises for three consecutive days. METHODS: Six male volunteers participated in this crossover, randomized controlled study. They completed two 3-day consecutive cycling exercise tests under the two conditions (i.e., cooling and non-cooling). Each daily exercise test required two 6-min intermittent sprint cycling exertions separated by a 10-min passive rest. The 6-min sprint cycling consisted of three sets of 10-s maximal effort against a resistance of 7.5% body mass and 110-s active rest (no load pedaling). During the 10-min passive rest and the 20-min recovery phase after second sprint cycling, subjects in the cooling intervention were seated and their quadriceps muscles were covered with 2 cold packs (26×26 cm). Muscle performance was assessed by measuring average and peak power in 10-s maximal effort. In addition, maximum voluntary isometric contraction of the knee extensor muscles, the skin surface temperature of anterior surface of thigh, and serum markers of muscle damage and inflammation (i.e., creatine kinase and lactate dehydrogenase activities) were also evaluated. RESULTS: The peak power in non-cooling trial gradually weakened, as the day passed (day 1 vs. day 3, P<0.05). However, the cooling strategy completely inhibited a reduction of peak power throughout three consecutive days. On day 3, a significant smaller decrease in average power was observed by cooling intervention, compared to non-cooling condition (P<0.05). Furthermore on day 3, we found a significant greater value of maximum voluntary isometric contraction in cooling condition than the other (P<0.05). Increases in creatine kinase and lactate dehydrogenase activities were also suppressed by cooling intervention during three consecutive days of exercise test. CONCLUSION: These results suggested that simple cooling strategy using ice packs contributed to alleviate accumulative fatigue imposed by intensive exercise for three straight days.