2004 Fiscal Year Final Research Report Summary
Effects of environmental factors on heat tolerance during exercise.
| Project/Area Number |
15500428
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Sports science
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| Research Institution | University of Tsukuba |
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Principal Investigator |
HONDA Yasushi University of Tsukuba, Graduate School of Comprehensive Human Science, Associate Professor, 大学院・人間総合科学研究科, 助教授 (20165616)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIYASU Takeshi University of Tsukuba, Graduate School of Comprehensive Human Science, Associate Professor, 大学院・人間総合科学研究科, 助教授 (90237751)
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| Project Period (FY) |
2003 – 2004
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| Keywords | minute ventilation / esophageal temperature / skin blood flow / cooling |
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| Research Abstract |
We aimed to investigate the effects of environmental factors on heat tolerance during exercise and conducted the following three experiments.
1.We investigated the effects of brief leg cooling after moderate exercise on the cardiorespiratory responses to subsequent exercise in the heat. Following 40 min of ergometer cycling (65% of peak O_2 uptake) at 35℃ (Ex.1), seven male subjects immersed their legs in 35℃ (control condition:CONT) or 20℃ (cooling condition:COOL) water for 5 min and then repeated the cycling (as before, but for 10 min) (Ex.2). The results suggest that brief leg cooling during the recovery period may be effective at reducing thermal and cardiorespiratory strain during subsequent exercise in the heat.
2.We investigated whether the environmental factors affect the heat tolerance during exercise. Sixteen students exercised in the heat and the relationships among those physiological parameters, the climate conditions of their home towns and the usage of air-conditioner. The relationships between their heat tolerance index such as the sweat rate and increase rate of skin blood flow in the forearm and the climate data tend to be significant, suggesting the climate of the home town could affect the heat tolerance in the students.
3.We tested the hypothesis that during prolonged exercise in the heat, an increase in core temperature, not skin temperature, mediates an increase in minute ventilation (VE). Thirteen subjects exercised for 60 min on a cycle ergometer at 50% of peak oxygen uptake while wearing a suit per fused with water at 10℃ (T10), 35℃ (T35) or 45℃ (T45). The results suggest that during prolonged sub-maximal exercise in the heat, VE increases with core temperature and is unaffected by skin temperature or the rate at which core temperature increases.
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