Effects of differing heat and humidity on the performance and recovery from multiple high intensity, intermittent exercise bouts

The aim of this study was to determine the effects of different conditions of heat and humidity on two multiple bouts of high intensity cycling with 60 min recovery between each bout. Eight males (age: 25.5 +/- 1.8 yr, height: 179.0 +/- 3.7 cm: weight: 72.3 +/- 4.0 kg; (V)over dot O(2)peak: 51.5 +/- 2.4 ml x kg(-1) x min(-1), Peak Aerobic Power: 366 +/- 13 W) volunteered for this study. After undertaking (V)over dot O(2)peak testing, all participated randomly, in three consecutive 30 s Wingate tests in three different environmental conditions being: Normal (22 degrees C/30% RH), Wet (30 degrees C/85% RH), and Hot (40 degrees C/40% RH). Subjects were then monitored for the 60 min post-exercise period after which time they repeated the Wingate tests and were again monitored for 60 min. Blood samples were taken pre, immediately post exercise, and at 1, 5, 10, 15, 30, 45, and 60 min into each of the recovery periods and analysed for lactate, pH, and hematocrit. Heart rate was monitored continuously throughout exercise (5 s average) and recovery (60 s average). Weight was measured pre exercise and at 15, 30, 45, and 60 min post-exercise. Urine samples were collected at the same time and analysed for osmolality. The results of the experiment indicated that environmental conditions had no effect on the performance of either series 1 or 2 Wingate tests. Neither were there any changes in weight throughout the three conditions or across the condition. Post exercise pH levels were lower than pre exercise values (p<0.0001) and the reverse was true for blood lactate levels (p<0.0003). We conclude that anaerobic exercise is not unduly affected by hot or humid conditions when subjects can re-hydrate according to decreases in body weight.