ABSTRACT
The purpose of this study was to determine the effects of water temperatures on respiratory regulation during head-out water immersion (HWI). A total of eight healthy young male and female subjects were immersed in water at temperatures of 25, 30, 36, 38, 40, and 42°C for 10 minutes, and breathing frequency, tidal volume, ventilation, oxygen consumption, heart rate, and sublingual temperatures were measured over a period of 40 minutes before, during, and after HWI at each water temperature. Both oxygen consumption and ventilation increased during HWI at any temperature. It was hypothesized that the increase in oxygen consumption at 25°C was due to the increase in tidal volume and that at 40 and 42°C was due to the increase in ventilation caused by the increase in breathing frequency. These results suggest that the respiratory regulation during HWI is closely related to the body temperature regulation in response to water temperatures.
ABSTRACT
This study was conducted to examine the effect of exercise training on heat-shock response, the protective response to heat, oxidative stress and other stresses characterized by elevated synthesis of heat-shock proteins (HSP), in strenuous exercise. Five untrained men (aged 20-21 ) participated in the study. The protocol included strenuous exercise to exhaustion by bicycle ergometer (1 st Ex), 4 weeks of training (a 2 km run three days per week) and a repetition of the strenuous exercise (2 nd Ex) . We measured VO<SUB>2</SUB> and VCO<SUB>2</SUB> with a respiratorygas analyzer, 70 kDa heat-shock protein (HSP 70) of mononuclear cells by western blotting, and rectal and mean skin temperatures by thermistors during the strenuous exercise. After 4 weeks of training, VO<SUB>2</SUB>max was increased significantly (p<0.05) . HSP 70 increased immediately after the exercise in 3 of 5 subjects in the 1 st Ex, but not in the 2 nd Ex. Rectal temperatures rose significantly after both the 1 st and 2 nd Ex (p<0.05) . Mean skin temperatures fell significantly after both the 1 st and 2 nd Ex (p<0.05) . There was no correlation between rectal and mean skin temperatures and HSP 70. We observed the heat-shock response during strenuous exercise and the attenuation of this response after 4 weeks of exercise training. These results suggest that exercise training may have suppressive effects on the heat-shock response during strenuous exercise.
ABSTRACT
The erythrocyte antioxidative defense system was investigated before and after a 12km run. The effect of exercise with a bicycle ergometer on this system was also examined one and seven days after the. 12km run. Five untrained healthy men, aged 18-21 years, participated in the present study. Plasma creatine kinase (CK) activity increased after running and reached a maximum on the next day (p<0.005) . Levels of the reduced form of glutathione (GSH) decreased by 24.6% after running (p<0.005), but by 7 days later the values recovered. Levels of lipid peroxides (LPO, expressed as thiobarbituric acid-reactive substances) fell slightly after running (13.4%, not significant), then showed a significant decrease on the next day (34.7%, p<0.005) and recovered by the seventh day. Neither glutathione peroxidase (GPX) nor glutathione reductase (GR) activities (with or without FAD) showed significant changes after the 12km run. Activities of catalase (CAT) were lowest after the exercise with a bicycle ergometer on the following day (p<0.05 vs. initial levels) . Levels of GSH, GPX, GR and LPO did not change after this exercise. The decreased level of GSH after the 12km run indicates the presence of oxidative stress, while moderate exercise with a bicycle ergometer does not affect the erythrocyte glutathione metabolism in untrained men. It is also suggested that catalase activity decreases after the repeated exercise.