Effects of ephedrine/xanthines on thermogenesis and cold tolerance.

This paper reviews the use of ephedrine (E) and xanthines (X) to improve thermogenesis and cold tolerance. Recent experiments in cold-exposed subjects have shown that the beneficial effects of ingesting an E/caffeine (C) capsule on metabolic rate (M), heat debt, deep body core temperature (Tre) (P < 0.05) is entirely comparable to that observed with an E/C/theophylline (T) capsule. Although T has been reported to reduce the drop in Tre in several studies, these improvements are difficult to explain in the absence of changes in M. A theobromine-based commercial sports bar (Cold Buster) has been similarly shown to reduce the drop in Tre. However, such a claim could not be confirmed in our lab, even in two studies performed under different environmental conditions. Despite an increase in M in some studies, C had no effect on Tre in the cold. It is concluded that E/X represent, at the moment, the best pharmacological agents to enhance cold thermogenesis and to delay the onset of hypothermia in humans.