BLOOD LACTATE CONCENTRATION FOLLOWING EXERCISE - EFFECTS OF HEAT EXPOSURE AND OF ACTIVE RECOVERY IN HEAT-ACCLIMATIZED SUBJECTS

The purpose of this study was to examine the effect of ambient heat on the decrease in blood lactate concentration ([LA](bl)) during passive and during active recovery. Ten trained men performed six 1-min bouts of exercise at 100% VO(2)peak on a cycle ergometer, with 1-min rest b etween the bouts. Each subject exercised twice in thermoneutral (22 de grees C, 40% RH, TN), and twice in hot (35 degrees C, 30% RH, H) condi tions. Exercise was followed by either 40 min of passive recovery (sit ting) or by 20 min active recovery (cycling at 35% VO(2)peak) and 20 m in passive recovery, named thereafter, 'active recovery'. Capillary bl ood lactate was measured before, 1 min after, and every 5 min during r ecovery. Heart rate (HR), rectal and skin temperatures (T-re, T-sk) we re monitored continuously. VO2 was measured prior to exercise, during the last exercise bout, the first 10 min of recovery, and periodically thereafter. Post-exercise [LA](bl) was similar in all treatments (13. 5 +/- 1.8, 13.0 +/- 1.3, 14.8 +/- 4.1, 13.3 +/- 2.6 mmol 1(-1) for TN- active, TN-passive, H-active and H-passive, respectively). [LA](bl) wa s significantly lower during active, compared to passive recovery in b oth, TN and H conditions. Environmental heat did not independently aff ect [LA](bl) during passive or active recovery. Exercise resulted in a n elevation in T-re, in all treatments, with a significantly higher T- re during active recovery in H compared to the other sessions. Likewis e, no differences in HR and in VO2 were observed between H and TN cond itions during active nor during passive recovery. In summary, under th e conditions of this study, ambient heat does not affect the rate of d ecrease in [LA](bl). As in the TN condition, active recovery in the he at results in lower [LA](bl) However, this is accompanied by a higher T-re in ambient heat.