Objective: 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. The objective of this study was to evaluate the influence of ethnicity (CAU vs AA) on the thermoregulatory response after acute cold exposure (ACE-REC, 25 degrees C air).
Methods: Five AA males (20.8 +/- 0.5 years) and 10 CAU males (25.6+/-4.9 years) underwent pre-experimental testing to determine Vo(2max) (AA = 37.2 +/- 0.1 mLxkg(-1)xmin(-1), CAU = 44.3 +/- 8.7 mLxkg(-1)xmin(-1)) and body composition (AA = 14.6 +/- 5.4%, CAU = 19.2 +/- 5.0%). Participants underwent acute cold exposure that consisted of 120 minutes of exposure to 10 degrees C air (ACE) followed by 120 minutes of recovery in 25 degrees C air (ACE-REC). Rectal temperature (T(re)) was measured via a rectal thermistor. Mean skin temperature (T(sk)) was assessed with thermistors. Oxygen consumption (Vo(2)) was assessed via indirect open circuit spirometry. Rectal temperature and T(sk) were measured continuously, and if T(re) < or = 35 degrees C, testing was terminated.
Results: Analysis of variance for ACE-REC revealed a significant main effect for T(sk) across time (P < .001), T(re) across time (P < .001), and Vo(2) across time (P < .001). In addition, a significant time x ethnicity interaction was revealed for T(re) (P = .008), T(sk) (P = .042), and Vo(2) (P = .019) during ACE-REC.
Conclusions: Based on these data, there is a differential response between CAU and AA across time for Vo(2), T(re), and T(sk) ACE-REC.