The effect of heat exposure on performance of and recovery from high-intensity, intermittent exercise

Environmental heat is known to hamper aerobic performance. The purpose of this study was to examine the effect of heat on the performance of anaerobic exercise and the recovery from such exercise. Eleven trained men underwent two identical exercise-recovery protocols in neutral (22 degrees C, N) and hot (35 degrees C, H) conditions, in a cross-balanced order. Exercise consisted of a series of five 15 s bouts separated by 30 s of active recovery between bouts. The 60 min resting recovery was evaluated with a subsequent exercise series. Subjects were kept euhydrated with water. Peak power developed in the initial exercise series was higher in H compared with N (720 +/- 80 vs 664 +/- 74 W, respectively, p < 0.05). In the second series of exercise, peak power slightly improved in N but decreased in H (6.1 vs -4.1 %, respectively). Mean power was higher in the initial exercise series in H compared with N (636 +/- 83 vs 584 +/- 60 W, respectively, p < 0.05). No significant change occurred in the subsequent series of exercise. There was no difference in peak lactate following the initial series, nor in the decrease of lactate during recovery between the two conditions. Likewise, there were no differences in the changes in electrolyte concentrations and serum osmolality during recovery. VO2 and heart rate decreased following exercise in a similar manner in the two conditions. Rectal temperature increased similarly but remained elevated during H compared with N (p<0.05). In conclusion, the results of this study suggest that heat exposure may improve anaerobic performance but does not appear to affect the physiological responses during 60 min of recovery. Future research should examine the effect of more extreme heat stress, as well as shorter recovery periods.