Restoration of thermoregulatory response to body cooling by cooling hands and feet

Abstract

Deep body temperature fell progressively by 0.5-1.4 degrees C during 3-h immersions in 29 degrees C water. Both in unacclimatized volunteers and, to a lesser degree, in divers in cold-water training, cooling the hands and feet for 1 h in 12 degrees C water during such immersion caused sensation of cold, shivering, and rise in metabolic rate; it caused body temperature to rise in unacclimatized subjects and halted its fall in divers. Tissue conductances generally fell a little in divers but rose in unacclimatized subjects, probably because of muscle blood flow associated with the greater shivering in the latter. Soaking the skin for 4 h produced no major changes in cutaneous thermal sensation assessed in the forearm, though with seawater it sometimes reduced cold sensation and with distilled water sometimes reduced warm sensation, a little. It is concluded that uniform skin temperature of 29 degrees C often induces insufficient heat-gain reflexes to maintain body temperature and that cooling of the extremities can restore adequate thermoregulatory response.

Thermophysiological Significance and the Role of Local Clothing in Ambient 10.DEG.C. Environments.

“…In contrast, when the lower extremities of the body are uncovered, the veins tend to gather around the arteries and hence the venous blood is warmed. As a result, the venous blood warms the core body temperature and the blood in the venous returning to the thoracic and abdominal regions does not lower the core body The present results found in Experiment 1 were in agreement with the results found by Van Someren et al (1982), who demonstrated that when only the hands and feet are submerged in 12°C water, while the entire body is submerged in 29°C water, the core temperature of the subjects ceased to fall and commenced to rise slightly. temperature.…”

Effects of fluctuating skin temperature on thermoregulatory responses in man.

“…The total transient increase in discharge from cold receptors on cooling often tends to be larger than the transient decrease on comparable warming, both in first-order and second-order cold fibres (Hensel &r Zotterman, 1951;Dykes, 1975;Davies et al 1983) Kenshalo, 1976 (Kenshalo & Duclaux, 1977 Whatever their precise neurophysiological basis, the present results provide evidence that one factor in insidious core cooling during immersion in water at 29 0C is a low level of thermoregulatory response associated with maintenance of a stable skin temperature around this level. We have previously reported that even distribution of temperature between the trunk and extremities is a factor in the inadequate thermoregulatory response seen in this situation, since cooling the hands and feet improves the response (van Someren et al 1982). Both temporal fluctuations in skin temperature, and spatial gradients with lower temperatures on the extremities than the trunk, are usual during exposure to cold air.…”

“…The drop in deep body temperature could be explained partly by the lack of stimulation of cold receptors in the extremities that takes place when people are exposed to cold air. Cooling of the hands and feet whilst the rest of the body remained immersed in water at 29 'C improved thermoregulatory response, with increased heat production, vasoconstriction and consequent stabilization of or increase in core temperature (van Someren et al 1982).…”

Proceedings of the Physiological Society and the Societa Italiana Di Fisiologia, 11‐13 July 1985, Oxford Meeting: Communications

“…The data also demonstrate that subcutaneous fat is a relatively constant and significant proportion (78-9 + 7-1 %) of the total neutral fat as imaged by NMR in these subjects. People immersed in water at 29 'C show falls in core temperature, sometimes to below 35 TC, with little shivering or sensation of cold (Hayward & Keatinge, 1979;van Someren, Coleshaw, Mincer & Keatinge, 1982). This is due in part to lack of cold stimulation to the extremities that is normally present in cold air, since cooling the hands and feet with the remainder of the body still in water at 29 'C restores thermoregulatory responses (van Someren et al 1982).…”