There is a common belief that children compared with adults are at a greater risk for exercise-induced heat illness. However, a limitation of previous studies involves different exercise intensities used in the comparison between children and adults. Dehydration impairs aerobic performance, but its effects on strength are not well understood. Sports drinks are often used as ergogenic aids. There is some evidence to suggest children have a greater reliance on exogenous carbohydrate compared to adults, which could require special considerations when children exercise in the heat. The overall purpose of this thesis was to compare physiological and metabolic responses during exercise in the heat between boys and men. Three studies were conducted to 1) compare the thermoregulatory responses of boys and men exercising in the heat at a fixed absolute metabolic heat production or a fixed metabolic heat production per unit of body mass; 2) compare the effects of 2% hypohydration or, euhydration with and without carbohydrate ingestion during exercise in the heat on subsequent strength in boys and men; and 3) examine the effects of exogenous carbohydrate on endogenous metabolism in boys and men exercising in the heat. Age and body size differences between boys and men did not influence thermoregulatory responses at a fixed metabolic heat production per unit of body mass. No differences in strength were observed among trials. When exercising in the heat, the relative contribution of ingested carbohydrate and endogenous substrate to total energy yield were not different between groups. These findings together have practical implications for boys and men who exercise in the heat. Specifically, moderate exercise in the heat is equally safe for boys and men. The effects of hypohydration and a carbohydrate drink compared to water on muscle strength performance following exercise in the heat are minimal. An important practical application is that carbohydrate intake spared endogenous fuels during exercise in the heat in both groups. / Thesis / Doctor of Philosophy (PhD) / Children may not adapt to temperature extremes as effectively as adults. Thermoregulatory differences may be due to variable exercise intensities prescribed in available child-adult comparisons. Dehydration affects aerobic performance, but its effects on strength are not well understood. Sports drinks are often used to offset dehydration and improve performance; however, the body may have a harder time using sugar drinks when exercising in the heat. The purpose of this thesis was to compare bodily responses of boys and men during exercise in the heat. Our findings have important practical implications for boys and men who exercise and play sports in hot temperatures. Specifically, exercise in the heat is equally safe for boys and men. The effects of hypohydration and a sports drink on muscle strength performance following exercise in the heat are minimal. Finally, although exercise in the heat may affect the use of a sugar drink, boys and men may use this drink to improve aerobic performance, while maintaining hydration levels.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20432 |
| Date | January 2016 |
| Creators | Tomedi Leites, Gabriela |
| Contributors | Timmons, Brian, Medical Sciences (Division of Physiology/Pharmacology) |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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