Human thermoregulatory responses to cold air are altered by repeated cold water immersion

Abstract

The effects of repeated cold water immersion on thermoregulatory responses to cold air were studied in seven males. A cold air stress test (CAST) was performed before and after completion of an acclimation program consisting of daily 90-min cold (18 degrees C) water immersion, repeated 5 times/wk for 5 consecutive wk. The CAST consisted of resting 30 min in a comfortable [24 degrees C, 30% relative humidity (rh)] environment followed by 90 min in cold (5 degrees C, 30% rh) air. Pre- and postacclimation, metabolism (M) increased (P less than 0.01) by 85% during the first 10 min of CAST and thereafter rose slowly. After acclimation, M was lower (P less than 0.02) at 10 min of CAST compared with before, but by 30 min M was the same. Therefore, shivering onset may have been delayed following acclimation. After acclimation, rectal temperature (Tre) was lower (P less than 0.01) before and during CAST, and the drop in Tre during CAST was greater (P less than 0.01) than before. Mean weighted skin temperature (Tsk) was lower (P less than 0.01) following acclimation than before, and acclimation resulted in a larger (P less than 0.02) Tre-to-Tsk gradient. Plasma norepinephrine increased during both CAST (P less than 0.002), but the increase was larger (P less than 0.004) following acclimation. These findings suggest that repeated cold water immersion stimulates development of true cold acclimation in humans as opposed to habituation. The cold acclimation produced appears to be of the insulative type.

Homeostatic Responses to Prolonged Cold Exposure: Human Cold Acclimatization

“…Also in agreement with the previous report, Bittel (5) observed that skin temperatures fell more during the coldexposure test after than before acclimation. In contrast to observations of Young et al (68), rectal temperatures did not fall as much during the post-acclimation cold-air exposure as before acclimation, but this may have reflected the warmer air temperature used for the standardized cold-air test. Bittel (5) calculated that the net effect of acclimation was a significant reduction in the heat debt that developed during cold-air exposure.…”

“…Following the eight week program of repeated cold-water immersion, cold-air exposure caused skin temperature to fall about 4 0( lower than before acclimation (68). Although skin blood flow was not actually measured, the greater fall in skin temperature during cold exposure was similar to the adjustments noted by others studying the Central Australian Aborigine, and suggests that a more pronounced cutaneous vasoconstrictor response to cold had developed.…”

Chronic intermittent cold stress and serotonin depletion induce deficits of reversal learning in an attentional set-shifting test in rats

“…We and others have found that catecholamine neurotransmitter systems in the brain can also be affected by cold stress. Acute cold stress has been shown to increase norepinephrine release (Yeghiayan et al 2001;Young et al 1986), and chronic (2-4 weeks) cold stress exposure has been shown to increase noradrenergic receptor sensitivity, enhance the noradrenergic response to acute stress, and sensitize the acute excitability of noradrenergic neurons in locus coeruleus (Gresch et al 1994;Jedema and Grace 2003;Ma and Morilak 2005;Mana and Grace 1997;Pardon et al 2003). In addition, a variety of stressors, including cold stress, also increase dopamine utilization, leading to a reduction in central levels of both catecholamines (e.g., Dunn and File 1983;Finlay and Zigmond 1997;Reinstein et al 1984).…”

Mechanistic insight into the norepinephrine-induced fibrosis in systemic sclerosis

“…In addition, the mental stress-induced serum NE levels are also higher in SSc patients than in normal individuals based on mental calculation stress tests, suggesting that SSc patients may have an impaired function of the neuro-endocrine-immune system due to stress 1 . Previous findings showed that serum NE levels in normal individuals were increased after cold exposure 2 , and serum NE levels increased after repeated cold-water immersions 3 , further indicate that emotional stress and cold exposure increase the systemic and/or local NE levels in SSc patients.…”