Effect of radiation on thermoregulatory response

Abstract

The purpose of this study was to investigate the effect of radiation on thermoregulatory response during exercise. Some healthy male subjects dressing shorts and shoes remained seated resting for at least more than 40 min, and performed 20 min or more of cycle ergometer at several intensities in climatic chamber. The dorsal aspect of trunk was irradiated by infrared heater with main emissivity intermediate-infrared (MIR; 3.5μm) regions . Esophageal (Tes) and skin (Tsk) temperatures, local sweat rate (SR), local skin blood flow (SkBF), heat flax (HF), heart rate (HR), oxygen consumption (VO₂) were measured continually throughout the experiment. Body weight loss was measured at the end of experiment. All experiments were conducted in winter season. Thus the subjects were not naturally heat acclimated. In the condition with radiation, vasodilation was promoted by irradiation. SR increased since start of exercise. Tsk of upper back achieved about 40°C. HF increased in a direction toward ambient from body. So Tsk of upper back decreased, and Tes reached a constant value. These data suggest that thermoregulation may be affected by radiation. [Jpn J Physiol 54 Suppl:S229 (2004)]