Thermal and metabolic responses of high and low fat women to cold water immersion

Background: At rest during cold exposure, the amount of body fat plays an i mportant role in the maintenance of core temperature. High fat (HF) individ uals would therefore have an advantage as compared with their low fat (LF) counterparts. Since females usually have a higher amount of body fat than m ales they are expected to maintain core temperature at a lower energy cost. Methods: The purpose of the present investigation was to dichotomize femal e subjects by percent fat (LF = 20.5 +/- 2%, n = 6 vs. HF = 30 +/- 3%, n = 6) to elucidate the thermal and metabolic responses during acute exposure t o 17 degrees C water for 120 min. The following variables were measured: re ctal temperature (Tre; degrees C], mean skin temperature (Tsk; degrees C), oxygen consumption ((V) over dot O-2; ml.kg(-1).min(-1)), and tissue insula tion (l; degrees C.m(2).W-1). The experiment-wise error rate was set a prio ri at p = 0.05. Results: Unexpectedly, only one of the variables demonstrat ed a main effect for fat (p < 0.05). Tre demonstrated a significant (p < 0. 05) group by time interaction. However, Tsk and I demonstrated a main effec t for time (p < 0.05). While (V) over dot O-2 demonstrated an increase acro ss time, these changes were non-significant (p > 0.05). It appears that the HF group demonstrated a similar thermal (I and Tsk) and metabolic ((V) ove r dot O-2) response as compared with the LF counterparts. However, the LF g roups maintained a lower Tre as compared with the HF subjects. Perhaps lean er subjects or colder water temperatures would elucidate the value of body fat in females, and demonstrate a differential response with respect to fem ales Varying in percent body fat.