Sage Journals: Discover world-class research

Abstract

Normal human core body temperature is regulated within a narrow range. Deviations from this range can have serious consequences in both health and disease. However, it is difficult to efficiently manipulate body heat content because of the high heat capacity of the body and the low thermal conductance of the body surface. Mammals have evolved vascular adaptations of the nonhairy skin to enable enhanced heat loss. These include arteriovenous anastomoses that bypass the nutritive capillary beds to shunt the blood into retia venosa which serve as radiators. We have quantified the area-specific heat loss from glabrous skin (palms and face) and nonglabrous skin (upper arm, back, thigh, and abdomen). Results show that the heat loss from the nonglabrous skin does not change appreciably over the course of exercise in the heat, whereas the heat loss from the glabrous skin rises to values more than five times that of the nonglabrous skin. The application of a mild vacuum increases the heat loss from the glabrous skin by an additional 33%. The effect of cooling of these different skin areas on the heart-rate response to a fixed exercise load was significantly greater for the glabrous than the nonglabrous skin. The intermittent application of vacuum cooling to the palms of individuals exercising in a hot environment had the effects of lowering the rate of rise of core temperature and enhancing performance. The vacuum-enhanced heat exchange via the glabrous skin is a disruptive technology for several reasons. It forces re-formulation of the models of human thermoregulation that are used to design thermal protective gear. It offers an effective means of treating heat and cold stress. It provides an insight into controversies about the effects of temperature on human athletic performance, and offers a means of enhancing strength and work volume training responses that are more effective than performance-enhancing supplements such as anabolic steroids. There are many potential applications of vacuum-enhanced cooling of the glabrous skin in medicine, occupational health and safety, and sport.

Get full access to this article

View all access options for this article.

References

Grahn

, Cao

, HC

Heller

. Heat extraction through the palm of one hand improves aerobic exercise endurance in a hot environment. J Appl Physiol., 2005; 99:972–978.

Grahn

, Cao

, Nguyen

et al. Work volume and strength training responses to resistive exercise improve with periodic heat extraction from the palm. J Strength Cond Res., 2011[Epub ahead of print].

Ruxton

, Wilkinson

. Thermoregulation and endurance running in extinct hominins: Wheeler's models revisited. J Hum Evol., 2011; 61:169–175.

van Beek

, Supandi

, Gavai

et al. Simulating the physiology of athletes during endurance sports events: Modelling human energy conversion and metabolism. Philos Trans A Math Phys Eng Sci., 2011; 369:4295–4315.

Brothers

, Wingo

, Hubing

et al. Methodological assessment of skin and limb blood flows in the human forearm during thermal and baroreceptor provocations. J Appl Physiol., 2010; 109:895–900.

Grahn

, Dillon

, Heller

. Heat loss through the glabrous skin surfaces of heavily insulated, heat-stressed individuals. J Biomech Eng., 2009; 131:071005.

Amorim

, Yamada

, Robergs

et al. Palm cooling does not reduce heat strain during exercise in a hot, dry environment. Appl Physiol Nutr Metab., 2010; 35:1–10.

Walker

, Zupan

, McGregor

et al.

Is performance of intermittent intense exercise enhanced by use of a commercial palm cooling device?

J Strength Cond Res., 2009; 23:2666–2672.

Grahn

, Brock-Utne

, Watenpaugh

et al. Recovery from mild hypothermia can be accelerated by mechanically distending blood vessels in the hand. J Appl Physiol., 1998; 85:1643–1648.

10.

Ereth

, Lennon

, Sessler

. Limited heat transfer between thermal compartments during rewarming in vasoconstricted patients. Aviat Space Environ Med., 1992; 63:1065–1069.

11.

Kwon

, Robergs

, Kravits

et al. Palm cooling delays fatigue during high-intensity bench press exercise. Med Sci Sports Exerc., 2010; 42:1557–1565.

12.

Rowell

. Human cardiovascular adjustments to exercise and thermal stress. Physiol Rev., 1974; 54:75–159.

13.

Yamazaki

. Vasomotor responses in glabrous and nonglabrous skin during sinusoidal exercise. Med Sci Sports Exerc., 2002; 34:767–772.

14.

Herman

, Lee

. Functional energetic landscape in the allosteric regulation of muscle pyruvate kinase. 1. Calorimetric study. Biochemistry., 2009; 48:9448–9455.

15.

Herman

, Lee

. Functional energetic landscape in the allosteric regulation of muscle pyruvate kinase. 2. Fluorescence study. Biochemistry., 2009; 48:9456–9465.

16.

Herman

, Lee

. Functional energetic landscape in the allosteric regulation of muscle pyruvate kinase. 3. Mechanism. Biochemistry., 2009; 48:9466–9470.

17.

Grahn

, Murray

, Heller

. Cooling via one hand improves physical performance in heat-sensitive individuals with multiple sclerosis: a preliminary study. BMC Neurol., 2008; 8:14.

Enhancing Thermal Exchange in Humans and Practical Applications

Abstract

Abstract

Get full access to this article

References