Excess body fat lessens the metabolic response to cold exposure

Abstract

Extensive research has been conducted to study the effects of body fat on physiological responses under various environmental conditions. Experiments involving extreme situations, such as cold water immersion and cold air exposure wearing minimal clothing, are in greater abundance than those replicating more common human cold interactions. The purpose of this study was to measure the influence of percent body fat (%BF) on oxygen consumption [VO2 (mL•kg-1•min-1 )] and mean blood pressure [MAP (mmHg)] at rest and during exercise in an environment simulating cold winter conditions. Subjects included 30 healthy, male volunteers, age 19-42 years who were not regularly active prior to the experiment. Testing was completed in an environmental chamber set to a temperature of 5°C with 30%-50% humidity. Subjects were asked to wear a t-shirt, winter coat, winter gloves, and exercise pants. Oxygen consumption and blood pressure were measured inside the environmental chamber while subjects were seated quietly for five minutes and during a 5-minute, low-intensity exercise period. Results showed %BF was negatively correlated with VO2 at rest (r = -.552, p < 0.01) and during exercise (r = -.503, p < 0.01) and positively correlated with MAP (r = .402, p < 0.05) in the cold. This supports the notion that body fat attenuates the muscle activation caused by shivering, which is responsible for increased oxygen consumption. It also provides evidence for blood pressure elevations associated with excess body fat. The findings suggest that during typical outdoor winter exposure, those with higher %BF are less likely to exhibit the shivering response at a level of those with lower %BF. Advisor: Steven T. Devor