THE INFLUENCE OF ETHNICITY ON THERMOSENSITIVITY DURING COLD WATER IMMERSION

Abstract

PURPOSE This investigation evaluated the influence of ethnicity, Caucasian (CAU) vs. African American (AA), on thermosensitivity and metabolic heat production (HP) during cold water immersion (20 degrees C) in 15 CAU (22.7 +/- 2.7 yr) vs. 7 AA (21.7 +/- 2.7 yr) males. METHODS Following a 20-min baseline period (BASE), subjects were immersed in 20 degrees C water until esophageal temperature (Tes) reached 36.5 degrees C or for a maximum pre-occlusion (Pre-OCC) time of 40 min. Arm and thigh cuffs were then inflated to 180 and 220 mm Hg, respectively, for 10 min (OCC). Following release of the inflated cuffs (Post-OCC), the slope of the relationship between the decrease in Tes and the increase in HP was used to define thermosensitivity (beta). RESULTS ANOVA revealed no significant difference in thermosensitivity between CAU and AA (CAU = 3.56 +/- 1.54 vs. AA = 2.43 +/- 1.58 W.kg(-1). degrees C(-1)). No significant differences (p > 0.05) were found for Tsk (CAU = 24.2 +/- 1.1 vs. AA = 25.1 +/- 1.1 degrees C) or HP (p > 0.05; CAU = 2.5 +/- 0.8 vs. AA = 36.5 +/- 1.8 W.kg(-1)). However, a significant (p < 0.05) main effect for ethnicity for Tes was observed (CAU = 36.7 +/- 1.8 vs. AA = 36.5 +/- 1.8 degrees C). CONCLUSION These data suggest, despite a differential response in Tes between AA and CAU groups, the beta of HP during cold water immersion is similar between CAU and AA. Therefore, these data demonstrate that when faced with a cold challenge, there is a similar response in HP between CAU and AA that is accompanied by a differential response in Tes.