Effect of postprandial thermogenesis on the cutaneous vasodilatory response during exercise.

To examine the effect of postprandial thermogenesis on the cutaneous vasodilatory response, 10 healthy male subjects exercised for 30 min on a cycle ergometer at 50% of peak oxygen uptake, with and without food intake. Mean skin temperature, mean body temperature ((T) over bar (b)), heart rate, oxygen uptake, carbon dioxide elimination, and respiratory quotient were all significantly higher at baseline in the session with food intake than in the session without food intake. To evaluate the cutaneous vasodilatory response, relative laser Doppler flowmetry values were plotted against esophageal temperature (T-es) and (T) over bar (b). Regression analysis revealed that the (T) over bar (b), threshold for cutaneous vasodilation tended to be higher with food intake than without it, but there were no significant differences in the sensitivity. To clarify the effect of postprandial thermogenesis on the threshold for cutaneous vasodilation, the between-session difference in the T-es threshold and the (T) over bar (b), threshold were plotted against the between-session difference in baseline T-es and baseline (T) over bar (b), respectively. Linear regression analysis of the resultant plot showed significant positive linear relationships (T-es: r = 0.85, P < 0.01; <(T)over bar>(b): r = 0.67, P < 0.05). These results suggest that postprandial thermogenesis increases baseline body temperature, which raises the body temperature threshold for cutaneous vasodilation during exercise.