Sweating response to passive stretch of the calf muscle during activation of forearm muscle metaboreceptors in heated humans

Amano, Tsuyoshi; Ichinose, Masashi; Nishiyasu, Takeshi; Inoue, Yoshimitsu; Koga, Shunsaku; Miwa, Masaichi; Kondo, Narihiko

doi:10.1152/ajpregu.00515.2013

Cited by 11 publications

(8 citation statements)

References 46 publications

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“…To determine the core temperature threshold for the onset of heat loss responses during the ischemic period, the occlusion period should be prolonged compared with the prevailing occlusion period (2-3 min) in the present study. To validate prolonged postexercise forearm occlusion, pilot studies were conducted using an occlusion period of 9 min in three subjects, which confirmed that the cardiovascular responses were similar to those of a shorter occlusion period (2-3 min) from a number of previous studies (1,3,5,11,23,29). Therefore, the postexercise forearm occlusion was sustained for 9 min during 2.5-11.5 min of passive heating in the present study.…”

Section: Methodssupporting

confidence: 84%

Modulation of muscle metaboreceptor activation upon sweating and cutaneous vascular responses to rising core temperature in humans

Amano

Ichinose

Inoue

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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The present study investigated the role of muscle metaboreceptor activation on human thermoregulation by measuring core temperature thresholds and slopes for sweating and cutaneous vascular responses during passive heating associated with central and peripheral mechanisms. Six male and eight female subjects inserted their lower legs into hot water (43°C) while wearing a water perfusion suit on the upper body (34°C). One minute after immersion, an isometric handgrip exercise--40% of maximum voluntary contraction-was conducted for 1.5 min in both control and experimental conditions, while postexercise occlusion was performed in the experimental condition only for 9 min. The postexercise forearm occlusion during passive heating consistently stimulated muscle metaboreceptors, as implicated by significantly elevated mean arterial blood pressure throughout the experimental period (P <0.05). Stimulation of the forearm muscle metaboreceptors increased sweating and cutaneous vascular responses during passive heating, and was associated with significant reductions in esophageal temperature threshold of sweating and cutaneous vasodilation (Δ threshold, sweating: 0.33 ± 0.05 and 0.16 ± 0.04°C, cutaneous vascular conductance: 0.38 ± 0.08 and 0.16 ± 0.05°C for control and experimental groups, respectively, P < 0.05). The slopes of these responses were not different between the conditions. These results suggest that muscle metaboreceptor activation in the forearm accelerates sweating and cutaneous vasodilation during passive heating associated with a reduction in core temperature thresholds and may be related to central mechanisms controlling heat loss responses.

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Section: Methodssupporting

confidence: 84%

Modulation of muscle metaboreceptor activation upon sweating and cutaneous vascular responses to rising core temperature in humans

Amano

Ichinose

Inoue

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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“…, ; Amano et al . , ; Avila & Buono, ; Binder et al . ) because of a priming effect (Avila & Buono, ).…”

Section: Methodsmentioning

confidence: 99%

Sweating responses to isometric hand‐grip exercise and forearm muscle metaboreflex in prepubertal children and elderly

Amano

Kai

Nakajima

et al. 2016

Experimental Physiology

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Edited by: Philip Atherton New Findings r What is the central question of this study?Non-thermal factors (e.g. muscle metaboreflex) contribute to the sweating response during exercise. Although it is well recognized that the sweating responses caused by core temperature elevation in prepubertal children and the elderly are attenuated compared with young adults, it is unknown whether non-thermal sweating is also attenuated in these populations. r What is the main finding and its importance?The non-thermal sweating response during isometric hand-grip exercise and isolated muscle metaboreflex were attenuated in prepubertal children compared with young adults in a non-uniform manner over the body, but only during the muscle metaboreflex in the elderly. This may explain the maturation-and ageing-related decline of sweating during exercise.The purpose of the present study was to investigate sweating responses to isometric hand-grip (IH) exercise and muscle metaboreflex in prepubertal children and the elderly. In hot conditions (ambient temperature, 35°C; relative humidity, 45%), 13 healthy young adults, 10 prepubertal children and 10 elderly subjects (aged 20.4 ± 1.2, 11.4 ± 0.5 and 63.5 ± 3.1 years, respectively) repeated a three hand-grip exercise protocol that consisted of 1 min IH exercise at 15, 30 or 45% of maximal voluntary contraction (MVC) followed by 2 min postexercise forearm occlusion. Local sweat rates (SRs) on the forehead, chest, forearm, thigh and palm were continuously measured (ventilated capsule method). The forehead SR in prepubertal children during IH exercise at 45% MVC was significantly lower than that of young adults (0.26 ± 0.22 and 0.08 ± 0.15 mg cm −2 min −1 for young adults and children, respectively; P < 0.05) but not of the elderly at any exercise intensities. The SR on the chest (0.22 ± 0.22 and −0.01 ± 0.05 mg cm −2 min −1 for young adults and children, respectively), forearm (0.14 ± 0.12 and 0.03 ± 0.04 mg cm −2 min −1 ) and thigh (0.13 ± 0.10 and 0.02 ± 0.03 mg cm −2 min −1 ) during postexercise occlusion at 45% MVC was significantly lower in children than in young adults (P < 0.05). Elderly subjects showed a significantly lower SR on the forearm (0.04 ± 0.04 and 0.01 ± 0.02 mg cm 215 Non-thermal sweating in prepubertal children and the elderly (P < 0.05). These results suggest that sweating responses to IH exercise and muscle metaboreflex were underdeveloped in prepubertal children and that ageing attenuates the response to the muscle metaboreflex in a way that is not consistent across the body.

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“…However, there have been no studies examining the effect of hypocapnia on thermoregulatory responses during exercise. Thermoregulatory responses can be modulated by exercise (23,47) as well as by exercise-associated nonthermal factors, e.g., central command, muscle mechanoreflex, and muscle metaboreflex (2,3,31,44). It remains to be seen whether hypocapnia continues to attenuate thermoregulatory responses in exercising humans despite the possible influences of exercise and/or nonthermal factors.…”

mentioning

confidence: 99%

Effect of voluntary hypocapnic hyperventilation on the relationship between core temperature and heat loss responses in exercising humans

Fujii

Honda

Komura

et al. 2014

Journal of Applied Physiology

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Two thermolytic thermoregulatory responses, cutaneous vasodilation and sweating, begin when core temperature reaches a critical threshold, after which response magnitudes increase linearly with increasing core temperature; thus the slope indicates response sensitivity. We evaluated the influence of hypocapnia induced by voluntary hyperventilation on the core temperature threshold and sensitivity of thermoregulatory responses. Ten healthy males performed 15 min of cycling at 117 W (29.5°C, 50% RH) under three breathing conditions: 1) spontaneous ventilation, 2) voluntary normocapnic hyperventilation, and 3) voluntary hypocapnic hyperventilation. In the hypocapnic hyperventilation trial, end-tidal CO2 pressure was reduced throughout the exercise, whereas it was maintained around the normocapnic level in the other two trials. Cutaneous vascular conductances at the forearm and forehead were evaluated as laser-Doppler signal/mean arterial blood pressure, and the forearm sweat rate was measured using the ventilated capsule method. Esophageal temperature threshold was higher for the increase in cutaneous vascular conductance in the hypocapnic than normocapnic hyperventilation trial at the forearm (36.88 ± 0.36 vs. 36.68 ± 0.34°C, P < 0.05) and forehead (36.89 ± 0.31 vs. 36.75 ± 0.31°C, P < 0.05). The slope relating esophageal temperature to cutaneous vascular conductance was decreased in the hypocapnic than normocapnic hyperventilation trial at the forearm (302 ± 177 vs. 420 ± 178% baseline/°C, P < 0.05) and forehead (236 ± 164 vs. 358 ± 221% baseline/°C, P < 0.05). Neither the threshold nor the slope for the forearm sweat rate differed significantly between the hypocapnic or normocapnic hyperventilation trials. These findings indicate that in exercising humans, hypocapnia induced by voluntary hyperventilation does not influence sweating, but it attenuates the cutaneous vasodilatory response by increasing its threshold and reducing its sensitivity.

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Sweating response to passive stretch of the calf muscle during activation of forearm muscle metaboreceptors in heated humans

Cited by 11 publications

References 46 publications

Modulation of muscle metaboreceptor activation upon sweating and cutaneous vascular responses to rising core temperature in humans

Modulation of muscle metaboreceptor activation upon sweating and cutaneous vascular responses to rising core temperature in humans

Sweating responses to isometric hand‐grip exercise and forearm muscle metaboreflex in prepubertal children and elderly

Effect of voluntary hypocapnic hyperventilation on the relationship between core temperature and heat loss responses in exercising humans

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