The effects of ethanol with and without exercise on the thermal balance of man in cold water
Date
1978
Authors
Fox, Glyn Robert
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Abstract
Experiments involving genuine and placebo ethanol consumption, with and without exercise, were performed by ten healthy young men so that the effects of ethanol in hypothermia might be assessed. A maximal level of hypothermia was induced by immersing subjects in 10°C water for a period of 45 minutes, (grand mean tympanic temperature equalled 34.4 ± 0.89°C at the termination of cold exposure). Ethanol was given 60 minutes prior to immersions at a standardized dose capable of producing moderately high Blood Alcohol Concentration (BAC), (grand mean BAC equalled 81.6 ± 11.79 mg · 100ml⁻¹ at the time of immersion). During the first 20 minutes of immersions performed with exercise, subjected pedalled a submerged exercise bicycle fitted with an ergometric device adjusted to a one kg load in the air, at a rate equal to 0.5 Hz.
The following physiological variables were studied: core cooling as assessed by rectal and tympanic temperatures, metabolic rate, skin temperatures at four sites, heart rate, blood pressure, BAC "decay" rate, and urine total volume and pH.
The following results were found:
1. prior to immersion, ethanol increased rectal cooling.
2. during cold-water immersion, ethanol without exercise reduced overall mean metabolic rate approximately 20%. This statistically significant reduction was of no physiological importance, since no ethanol-induced alterations of core cooling were found either with or without exercise. Exercise, either with or without ethanol however was found to increase tympanic cooling was approximately 75%, during the period of its performance.
3.the BAC rate of decay was increased during cold exposure. However, this increase probably reflected haemodynamic alterations induced by hypothermia, rather than an actual increase in the rate of ethanol elimination in the cold.
4. core rewarming rates were not found to be significantly altered by either ethanol or exercise.
5. for all physiological variables studied, placebo conditions (three subjects only) did not yield results significantly different from those found under control type treatment.