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Publication Abstracts

Comparison of Short-Term Aerobic Training and High Aerobic Power on Tolerance to Uncompensable Heat Stress

S. S. Cheung and T. M. McLellan
Aviat Space Environ Med 1999; 70:637-43

Abstract

This study investigated whether, in subjects of moderate aerobic fitness, short-term aerobic training could replicate the improved physiological responses to exercise-heat stress observed in individuals with a high level of aerobic fitness. Males of moderate (MF; <50 ml · kg-1 · min-1 V(dot)O2peak, n = 8) and high (HF; >55 ml · kg-1 · min-1 V(dot)O2peak, n = 8) aerobic fitness walked at 3.5 km · h-1 in the heat (40°C, 30% relative humidity) wearing nuclear, biological, and chemical protective clothing. Tests were conducted once on HF subjects and on MF subjects before (MF-Pre) and after (MF-Post) a 2-week program 6 d · week-1 of daily aerobic training (1 h treadmill exercise at 65% V(dot)O2peak for 12 d, 22°C, 40% relative humidity). The training significantly increased V(dot)O2peak by 6.5%, while heart rate (fc) and rectal temperature (Tre) rise decreased during exercise in a thermoneutral environment. HF had lower body mass and body fat content than MF, and V(dot)O2peak remained lower in MF pre-or post-training. In the heat, MF-Post had a decreased skin temperature (T(bar)sk) and an increased sweat rate compared with MF-Pre, but no changes were observed in fc, Tre, or tolerance time (TT). No significant differences during the first 60 min in Tre and fc were observed between the MF-Post and the HF subjects, though the HF subjects exhibited a lower T(bar)sk. The endpoint Tre, DeltaTre, and TT remained significantly higher in HF than in either the MF-Pre or MF-Post subjects. It was concluded that, in preparation for exercise in an uncompensable heat stress environment, short-term aerobic training offers little, if any, benefit and is not an adequate substitute for a high level of aerobic fitness resulting from habitual exercise and training.

Keywords: heat exhaustion, temperature regulation, anerobic fitness, aerobic training.

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Table of Contents for Volume 70, Number 7 of the ASME journal.