The effect of exercise-induced elevation in core temperature on cold-induced vasodilatation response in toes.

Cold-induced vasodilatation (CIVD) has been proposed as a potential protective mechanism against cold injuries during exposure of extremities to a cold environment. The purpose of this study was to evaluate the effect of exercise and the associated elevation in core temperature on toe skin temperatures during immersion of the foot in cold (8 degrees C) water. Subjects (N = 8) participated in two trials. In one, they conducted an incremental exercise to exhaustion (exercise) on a cycle ergometer, which was followed by immersion of the right foot in 8 degrees C water. In the second trial (control), immersion of the foot in cold water was not preceded by exercise. Upon completion of the exercise in the exercise trial, and at the onset of the immersion of the foot in cold water, tympanic temperature was 0.6 degrees C (P < 0.01) higher than pre-exercise levels. There was a significant increase (P < 0.05) in the number of CIVD waves, but not their amplitudes, in the exercise trial compared to the control trial. A CIVD response occurred in 57.5% of all toes in the exercise trial, and in only 27.5% in the control trial. Additionally, 50% of subjects exhibited CIVD in at least one toe in the control trial, and 87.5% during the exercise trial. It is concluded that exercise, and particularly the associated elevation in core temperature, enhances the frequency of the toe CIVD responses, and can therefore potentially act as a protective mechanism against cold injury.