The Influence of Ethnicity on Thermoregulation Following Acute Cold Exposure

Abstract

INTRODUCTION: It is well established that a combination of factors including ethnicity may influence an individual's response to cold stress. Previous work from our laboratory has demonstrated that when faced with a cold challenge, there is a similar response in heat production between Caucasian (CAU) and African American (AA) individuals that is accompanied by a differential response in core temperature. PURPOSE: To evaluate the influence of ethnicity (CAU vs. AA) on the thermoregulatory response following acute cold exposure (ACE-REC, 25°C air). METHODS: Five AA males (20.8 ± 0.5 y) and ten CAU males (25.6 ± 4.9 y) underwent pre-experimental testing to determine VO2max (AA=37.2 ± 0.1 ml·kg-1·min-1, CAU=44.3 ± 8.7 ml·kg-1·min-1) and body composition (AA=14.6 ± 5.4%, CAU=19.2 ± 5.0%). Subjects underwent a cold exposure trial that consisted of 120 min of exposure to 10oC air (ACE) followed by 120 min of recovery in 25oC air (ACE-REC). Rectal temperature (Tre) was measured via a rectal thermistor inserted 13 cm past the anal sphincter. Mean skin temperature (Tsk) was assessed with thermistors according to the equation of Ramanthan (1964). Oxygen consumption (VO2) was assessed via indirect open circuit spirometry. Tre and Tsk were measured continuously and if Tre < 35°C testing was terminated. RESULTS: ANOVA for ACE-REC revealed a significant main effect for Tsk across time (p <0.001) and Tre across time (p<0.001). In addition, a time × ethnicity significant interaction was revealed for Tre (p= 0.010) and VO2 (p = 0.019) during ACE-REC. CONCLUSION: Based on these data there was a differential response between CAU vs. AA across time for VO2 and Tre in the recovery phase following acute cold exposure.