Non-thermal modification of heat-loss responses during exercise in humans

Kondo, Narihiko; Nishiyasu, Takeshi; Inoue, Yoshimitsu; Koga, Shunsaku

doi:10.1007/s00421-010-1511-x

Cited by 47 publications

(24 citation statements)

References 103 publications

(150 reference statements)

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“…It is believed that the SR at a given core temperature (thermal input) during exercise is greater than that at rest (e.g., passive heating) because an integrative nonthermal input would increase the SR during exercise in addition to thermal factors (21). Muscle metaboreceptors and mechanoreceptors R732 INTEGRATED CONTROL OF NONTHERMAL SWEATING are known to provide afferent inputs from working muscles, and it has been reported that each reflex can induce sweating independently (20,23,39).…”

Section: Perspectives and Significancementioning

confidence: 99%

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

Amano

Ichinose

Nishiyasu

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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-Activation of muscle metaboreceptors and mechanoreceptors has been shown to independently influence the sweating response, while their integrative control effects remain unclear. We examined the sweating response when the two muscle receptors are concurrently activated in different limbs, as well as the blood pressure response. In total, 27 young males performed passive calf muscle stretches (muscle mechanoreceptor activation) for 30 s in a semisupine position with and without postisometric handgrip exercise muscle ischemia (PEMI, muscle metaboreceptor activation) at exercise intensities of 35 and 50% of maximum voluntary contraction (MVC) under hot conditions (ambient temperature, 35°C, relative humidity, 50%). Passive calf muscle stretching alone increased the mean sweating rate significantly on the forehead, chest, and thigh (SRmean) and mean arterial blood pressure (MAP), but not the heart rate (HR), from prestretching levels by 0.04 Ϯ 0.01 mg·cm 2 ·min Ϫ1 , 4.0 Ϯ 1.3 mmHg (P Ͻ 0.05), and Ϫ1.0 Ϯ 0.5 beats/min (P Ͼ 0.05), respectively. The SRmean and MAP during PEMI were significantly higher than those at rest. The passive calf muscle stretch during PEMI increased MAP significantly by 3.4 Ϯ 1.0 and 2.0 Ϯ 0.7 mmHg for 35 and 50% of MVC, respectively (P Ͻ 0.05), but not that of SRmean or HR at either exercise intensity. These results suggest that sweating and blood pressure responses to concurrent activation of the two muscle receptors in different limbs differ and that the influence of calf muscle mechanoreceptor activation alone on the sweating response disappears during forearm muscle metaboreceptor activation. nonthermal factors; group III and IV muscle afferents; thermoregulation; sympathetic nervous system; sweat gland THE SWEATING RESPONSE DURING exercise is controlled not only by core and skin temperatures (thermal factors) but also by exercise-related (nonthermal) factors, such as afferent inputs from working muscles. It is well known that group III muscle afferents are stimulated predominantly by mechanically sensitive muscle mechanoreceptors, whereas group IV muscle afferents are stimulated mainly by chemically sensitive muscle metaboreceptors. Activation of muscle metaboreceptors by postexercise muscle ischemia (PEMI) under normothermic and mildly hot conditions induces sweating (2, 4, 22, 38). Additionally, Kondo et al. (23) reported that activating the muscle mechanoreceptors by passive limb movement for 2 min evoked slight sweating under hot conditions. Furthermore, the muscle mechanoreflex increases the sweating response during passive recovery (passive limb movement using a tandem ergometer) compared with inactive recovery (resting) after cycling (20,39). These studies suggest that the isolated activation of muscle metaboreceptors and mechanoreceptors can independently affect sweating responses. However, the sweating response is presumably controlled by integrative mechanisms, based on afferent signals from muscle metaboreceptors and mechanoreceptors because physiological integrative control h...

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Section: Perspectives and Significancementioning

confidence: 99%

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

Amano

Ichinose

Nishiyasu

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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“…In a wet, windy environment with an ambient temperature of 5°C, so long as exercise intensity is fairly high, for example, a strong pace of walking, there is no change in core body temperature or rate of energy expenditure compared with thermoneutral conditions (129). Indeed, during periods of man-hauling, sweating and peripheral vasodilation occurs, necessary to dissipate the excess heat produced (60). However, if the work rate is lower, even though this still represents walking at a standard pace (129), core temperature decreases by around 1°C while rate of energy expenditure rises (probably primarily due to shivering; Ref.…”

Section: Polar Temperaturesmentioning

confidence: 99%

100 Years Since Scott Reached the Pole: A Century of Learning About the Physiological Demands of Antarctica

Halsey

Stroud

2012

Physiological Reviews

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The 1910–1913 Terra Nova Expedition to the Antarctic, led by Captain Robert Falcon Scott, was a venture of science and discovery. It is also a well-known story of heroism and tragedy since his quest to reach the South Pole and conduct research en route, while successful was also fateful. Although Scott and his four companions hauled their sledges to the Pole, they died on their return journey either directly or indirectly from the extreme physiological stresses they experienced. One hundred years on, our understanding of such stresses caused by Antarctic extremes and how the body reacts to severe exercise, malnutrition, hypothermia, high altitude, and sleep deprivation has greatly advanced. On the centenary of Scott's expedition to the bottom of the Earth, there is still controversy surrounding whether the deaths of those five men could have, or should have, been avoided. This paper reviews present-day knowledge related to the physiology of sustained man-hauling in Antarctica and contrasts this with the comparative ignorance about these issues around the turn of the 20th century. It closes by considering whether, with modern understanding about the effects of such a scenario on the human condition, Scott could have prepared and managed his team differently and so survived the epic 1,600-mile journey. The conclusion is that by carrying rations with a different composition of macromolecules, enabling greater calorific intake at similar overall weight, Scott might have secured the lives of some of the party, and it is also possible that enhanced levels of vitamin C in his rations, albeit difficult to achieve in 1911, could have significantly improved their survival chances. Nevertheless, even with today's knowledge, a repeat attempt at his expedition would by no means be bound to succeed.

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“…HUMAN ECCRINE SWEAT GLANDS respond to both thermal and nonthermal drives (26,27), and their secretions serve a wide range of secondary functions, such as facilitating tactile and thermal sensitivity, increasing contact friction (grip), and reducing the risk of tissue damage (55). The main nonthermal drive to sweating in resting individuals is mental stress or arousal, referred to here as psychogenic sweating (32).…”

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confidence: 99%