Study on the Prevention of Heat Casualty during Exercise Under Hot Environment by WBGT
【Supercategory：7. DESCENTE SPORTS SCIENCE Subcategory：7.13 Vol.13】
Ambient temperature is only one component of environmental heat stress, and humidity, wind velocity, and radiant heat should also be considered and recently WBGT (Wet Bulb Globe temperature) has been used to assess the degree of heat stress during exercise. In this experiment, the effect of exercise intensity was studied under varied WBGT.
Six male subjects repeated 20 min exercise by a bicycle ergometer at metabolic rate of 250 W/m² three times with 5 min rest period at WBGT 22, 26, 30 and 32.5°C. Heart rate, oxygen intake, oxygen pulse, mean skin temperature, esophageal temperature, body weight, thermal sensation and rating of perceived exertion of the subjects were measured.
The results obtained are as follows
1) Significant differences were found on heart rate and oxygen pulse under 30 and 32.5°C of WBGT compared to those under 22°C of WBGT. The values of oxygen intake were not different by WBGT.
2) Esophageal temperature and mean skin temperature under 30 and 32.5°C of WBGT were significantly higher than those of under 22°C of WBGT.
3) The body weight loss and % body weight loss under 26, 30 and 32.5°C of WBGT were significantly higher than those of under 22°C of WBGT.
4) Thermal sensation and rating of perceived exertion under 30 and 32.5°C of WBGT were significantly higher than those of under 22°C of WBGT.
5) There is a high risk of heat casualty at WBGT avobe 26°C, and the upper limits of prescriptive zones for exercise at metabolic rate of 250W/m² is 30°C of WBGT on an average.
DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
Six male subjects repeated 20 min exercise by a bicycle ergometer at metabolic rate of 250 W/m² three times with 5 min rest period at WBGT 22, 26, 30 and 32.5°C. Heart rate, oxygen intake, oxygen pulse, mean skin temperature, esophageal temperature, body weight, thermal sensation and rating of perceived exertion of the subjects were measured.
The results obtained are as follows
1) Significant differences were found on heart rate and oxygen pulse under 30 and 32.5°C of WBGT compared to those under 22°C of WBGT. The values of oxygen intake were not different by WBGT.
2) Esophageal temperature and mean skin temperature under 30 and 32.5°C of WBGT were significantly higher than those of under 22°C of WBGT.
3) The body weight loss and % body weight loss under 26, 30 and 32.5°C of WBGT were significantly higher than those of under 22°C of WBGT.
4) Thermal sensation and rating of perceived exertion under 30 and 32.5°C of WBGT were significantly higher than those of under 22°C of WBGT.
5) There is a high risk of heat casualty at WBGT avobe 26°C, and the upper limits of prescriptive zones for exercise at metabolic rate of 250W/m² is 30°C of WBGT on an average.
DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
| Researcher | Akira Yorimoto*1, Seiichi Nakai*2, Taketoshi Morimoto*3 |
|---|---|
| University or institution | *1 Shiga Prefectural Junior College, *2 Kyoto Women's University, *3 Kyoto Prefectural University of Medicine |
Keywords
heat casualty, WBGT (Wet Bulb Globe temperature), heat stress, exercise intensity