Exercise intensity and the post-exercise elevation in esophageal temperature.

Abstract

In order to examine the effects of exercise intensity on the post exercise elevation in esophageal temperature (DeltaTes), 8 male subjects performed 15 minutes of treadmill running exercise at 3 different exercise intensities, subthreshold (70% VO2max), threshold (84% VO 2max, and suprathreshold (93% VO2max), followed by an upright 45 minute recovery period. In addition, the effects of exercise intensity on the internal temperature threshold for cutaneous vasodilation (Tdil ), as well as post exercise blood pressure, cutaneous blood flow (SkBF) and cardiovascular conductance (DeltaCVC), were examined. Significant differences (p < 0.05) in DeltaTes were found between the 3 exercise intensities during exercise, as well as between suprathreshold (0.91°C), and threshold (0.56°C)/subthreshold (0.44°C) intensities during the recovery period. The elevated DeltaTes remained significantly above pre-exercise values for the entire recovery period for all 3 exercise intensities. Exercise intensity also demonstrated an effect on Tdil during exercise where significant differences were found between the 3 exercise intensities (0.26°C, 0.47°C, 0.84°C for subthreshold, threshold, and suprathreshold intensities respectively). However, no significant correlation was found between Tdil, and post exercise DeltaTes. Finally, a state of hypotension with respect to pre-exercise was observed during recovery from suprathreshold exercise. This could explain the significantly higher post exercise elevation in DeltaTes from subthreshold and threshold exercise.