We examined whether increased blood flow during acute exercise would change human skin-gas nitric oxide (NO) or not. Nine healthy male students (21.2±1.9 years; mean±SD) volunteered as the subjects, and none of them were smokers. The subjects performed the repetitive wrist flexion-extension exercise at 25% maximal voluntary contraction at a pace of a time per second until voluntary exhaustion. The skin-gas samples were obtained by covering the non-dominant hand for 3min with a polyfluorovinyl bag in which pure nitrogen gas was introduced, and collected in a sampling bag at rest and after exercise (2- 5, 12-15, 22-25 min). The skin-gas NO concentration was measured by a chemiluminescence analyzer. The peripheral blood flow in the skin surface of the middle fingertip and blood pressure were measured at rest and after exercise (0, 10, 20 min). The mean (±SD) time to exhaustion of the repetitive wrist flexion-extension exercise for the subjects was 131.1±28.5 sec. The peripheral blood flow in the skin surface of the middle fingertip significantly increased immediately after the exercise compared to the resting values (p<0.01), no significantly higher levels were remained 10 and 20 min after the exercise. Similarly, the skin-gas NO concentrations significantly increased immediately after the exercise compared to the resting values (p<0.01), although no significant change was observed 12-15 and 22-25 min after the exercise.
　These results suggest that the repetitive wrist flexion-extension stimulates vascular endothelial NO production by increases in shear stress during the exercise and increases skin-gas NO concentrations.

DESCENTE SPORTS SCIENCE Vol.29/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE