Comparison of man's responses to pulsed and unpulsed environmental heat and exercise.

Belding, Harwood S.; Hertig, B. A.; Kraning, Kenneth K.

doi:10.1152/jappl.1966.21.1.138

Cited by 15 publications

(4 citation statements)

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“…This response is thought to be related to the overriding nonthermal influence on core temperature regulation associated with the work/rest transitions (219,243). In support of this hypothesis, it has been shown that intermittent exercise results in a progressive increase in core temperature although the magnitude of increase in the postexercise elevation in core temperature is reduced with successive work/rest intervals (219,(243)(244)(245)(246)(247).…”

Section: Calorimetic Evidence For Nonthermal Modulation Of Whole-bodymentioning

confidence: 94%

Human thermoregulation: separating thermal and nonthermal effects on heat loss

Glen¹

2010

Front Biosci

103

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Human thermoregulatory control during heat stress has been studied at rest, during exercise and more recently during exercise recovery. Heat balance in the body is maintained by changes in the rate of heat loss via adjustments in skin blood flow and sweating. Independent of thermal control, the actions of nonthermal factors have important consequences in the control of heat loss responses during and following exercise. While the effect of these nonthermal factors is largely considered to be an inhibitory or excitatory stimulus which displaces the set-point about which temperature is regulated, their effects on human thermoregulatory control are far reaching. Many factors can affect the relative contribution of thermal and nonthermal influences to heat balance including exercise intensity, hemodynamic status, and the level of hyperthermia imposed. This review will characterize the physiological responses associated with heat stress and discuss the thermal and nonthermal influences on sweating and skin blood flow in humans. Further, recent calorimetric evidence for the understanding of thermal and nonthermal contributions to human heat balance will also be discussed.

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Section: Calorimetic Evidence For Nonthermal Modulation Of Whole-bodymentioning

confidence: 94%

Human thermoregulation: separating thermal and nonthermal effects on heat loss

Glen¹

2010

Front Biosci

103

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“…Previous studies have shown that intermittent exercise results in a progressive increase in core temperature, although the magnitude of this increase is reduced with successive work/rest intervals (1,8,21,28). Consistent with these previous findings, we showed that the additional amount of heat stored in the body subsequent to the first exercise/rest cycle (ϳ271 kJ) was Values are means Ϯ SE of sensitivity of evaporative heat loss responses to changes in mean body temperature for the 3 exercise or 3 recovery periods.…”

Section: Exercise Responsementioning

confidence: 98%

“…that baroreceptor modulation of sweating remains a controversial topic. Although a baroreflex attenuation of sweating has consistently been shown during inactive recovery from exercise (20,23), many studies do not support such a mechanism during nonexercise conditions (1,8,21,28). The reasons for this discrepancy remain unclear.…”

Section: Considerationsmentioning

confidence: 99%

Is there evidence for nonthermal modulation of whole body heat loss during intermittent exercise?

Kenny

Gagnon

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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This study compared the effect of active, passive, and inactive recoveries on whole body evaporative and dry heat loss responses during intermittent exercise at an air temperature of 30 degrees C and a relative humidity of 20%. Nine males performed three 15-min bouts of upright seated cycling at a fixed external workload of 150 W. The exercise bouts were separated by three 15-min recoveries during which participants 1) performed loadless pedaling (active recovery), 2) had their lower limbs passively compressed with inflatable sleeves (passive recovery), or 3) remained upright seated on the cycle ergometer (inactive recovery). Combined direct and indirect calorimetry was employed to measure rates of whole body evaporative heat loss (EHL) and metabolic heat production (M-W). Mean body temperature (T(b)) was calculated from esophageal and mean skin temperatures, and mean arterial pressure (MAP) was measured continuously. Active and passive recoveries both reversed the reduction in MAP associated with inactive recovery (P

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“…However, studies examining differences in core temperature between continuous and intermittent exercise have yielded conflicting results. In general, when the exercise periods are of long duration and/or performed under compensable conditions, continuous and intermittent exercise result in similar increases in core temperature (2,3,5,(13)(14)(15)22). In contrast, greater increases in core temperature have been reported during intermittent exercise consisting of short exercise-rest cycles performed under both compensable (4,17) and uncompensable (13) conditions.…”

mentioning

confidence: 99%

Exercise-rest cycles do not alter local and whole body heat loss responses

Gagnon

Kenny

2011

American Journal of Physiology-Regulatory, Integrative and Comp

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Previous studies have suggested that greater core temperatures during intermittent exercise (Ex) are due to attenuated sweating [upper back sweat rate (SR)] and skin blood flow (SkBF) responses. We evaluated the hypothesis that heat loss is not altered during exercise-rest cycles (ER). Ten male participants randomly performed four 120-min trials: 1) 60-min Ex and 60-min recovery (60ER); 2) 3 ϫ 20-min Ex separated by 20-min recoveries (20ER); 3) 6 ϫ 10-min Ex separated by 10-min recoveries (10ER), or 4) 12 ϫ 5-min Ex separated by 5-min recoveries (5ER In contrast, the slope of the SkBF response against esophageal temperature did not significantly change from the first to the last Ex (5ER: 51 Ϯ 23 vs. 54 Ϯ 19%/°C, P ϭ 0.848; 10ER: 53 Ϯ 8 vs. 56 Ϯ 21%/°C, P ϭ 0.786; 20ER: 44 Ϯ 20 vs. 50 Ϯ 27%/°C, P ϭ 0.432). Overall, no differences in body heat content and core temperature were observed. These results suggest that altered local and whole body heat loss responses do not explain the previously observed greater core temperatures during intermittent exercise. calorimetry; core temperature; heat stress; skin blood flow; sweat rate INTERMITTENT EXERCISE IS TYPICAL of many occupational and military activities. In most cases, the intermittent aspect of these activities is inherent to the task(s) being performed. However, intermittent exercise is also used by many health and safety industries (1, 18), as well as the US military (24), as a strategy to minimize the risk of exertional heat strain when these activities are performed in hot and/or humid environments.The benefit of exercise-rest cycles is to decrease the timeweighted average rate of metabolic heat production for a given task, which, when combined with sufficient recovery periods, should maintain core temperature below 38°C (1, 18). However, studies examining differences in core temperature between continuous and intermittent exercise have yielded conflicting results. In general, when the exercise periods are of long duration and/or performed under compensable conditions, continuous and intermittent exercise result in similar increases in core temperature (2,3,5,(13)(14)(15)22). In contrast, greater increases in core temperature have been reported during intermittent exercise consisting of short exercise-rest cycles performed under both compensable (4, 17) and uncompensable (13) conditions. Although the specific reason(s) for these discrepancies is unclear, studies that report greater core temperatures during intermittent exercise have consistently attributed this response to altered heat loss responses (4,13,17).It is surprising to note, however, that there exists relatively limited research that directly compares the control of heat loss responses between intermittent and continuous exercise, as most studies only examine core temperature responses. Ekblom et al. (4) attributed a greater increase in core temperature during intermittent exercise to a lower overall loss of body weight (i.e., evaporative heat loss), while Kraning and Gonzalez (13) implied reduced sk...

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Comparison of man's responses to pulsed and unpulsed environmental heat and exercise.

Cited by 15 publications

References 0 publications

Human thermoregulation: separating thermal and nonthermal effects on heat loss

Human thermoregulation: separating thermal and nonthermal effects on heat loss

Is there evidence for nonthermal modulation of whole body heat loss during intermittent exercise?

Exercise-rest cycles do not alter local and whole body heat loss responses

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