. "3. Physiological Responses to Excercise in Heat." Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations. Washington, DC: The National Academies Press, 1993.
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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations
FIGURE 3–2
Relationship of steady-state core temperature responses during exercise at three metabolic rates to the environmental conditions. SOURCE: Sawka and Wenger (1988), used with permission. Redrawn from Lind (1963).
the environment. During exercise with a substantial metabolic requirement, the prescriptive zone might be exceeded, and there is a further elevation of steady-state core temperature.
As stated, within the prescriptive zone, the magnitude of core temperature elevation during exercise is proportional to the metabolic rate (Nielsen, 1938; Saltin and Hermansen, 1966; Stolwijk et al., 1968). Although the relationship between metabolic rate and core temperature is strong for a given individual, it does not always hold well for comparisons between different individuals. Åstrand (1960) first reported that the use of relative intensity (percentage of maximal oxygen uptake), rather than actual metabolic rate (absolute intensity), removes most of the intersubject variability for the core temperature elevation during exercise.
METABOLISM
Metabolic Rate
The effects of acute heat stress on a person's ability to achieve maximal aerobic metabolic rates during exercise have been thoroughly studied. Most
