The purpose of this study was a investigate the endothelial function of prehypertensive during dynamic exercise. Hypothesis of this study was to impair the endothelial function in prehypertensive compared to normtensive during dynamic handgrip exercise. Eleven healthy prehypertension (24±2 yrs) and ten healthy normotensive (25 ± 2 yrs) were recruited in this study. Participants were performed dynamic handgrip exercise in one contraction per second at 30% of maximum voluntary contraction for three minutes. Vascular (blood vessel diameter, blood flow) and cardiar response (stroke volume, heart rate and cardiac output) were measured at rest and during exercise. Flow mediated dilation (FMD) was decrease significantly in prehypertensive less than normotensive (p<0.05) at rest, and vasodilation of prehypertensive was reduced significantly less than normitensive during exercise (p<0.05). All the cardiovascular responses were aot significantly different at rest and during exercise between prehypertensive and normotensive. These results suggest that endothelial function is impaired in prehypertensive compared to in normotensive
