Restricted Blood Flow Exercise on Vascular Function in African Americans With and Without Parental Hypertension

Abstract

In the Surgeon General Report on Physical Activity and Health, resistance exercise is a recommendation. A popular modality in increasing muscle strength is the restriction of blood flow (RBF) during exercise. A concern is the hypoxic exercise may adversely affect the vascular function. Equivocal findings have been found regarding RBF exercise on the blood vessels in healthy disease free individuals. How RBF exercise influence vascular function in healthy individuals at risk for cardiovascular disease (CVD) has not been addressed. PURPOSE: To determine the effect of RBF exercise on lower leg vascular function in healthy individuals at risk for developing hypertension. METHODS: Seven healthy young adult African-Americans with a parental history of hypertension, and 7 similar subjects without a parental history of hypertension served as volunteers. One leg was randomly chosen for a 3-week period of low intensity training with 30% of the 1-repetition maximum load, 3 times per week under conditions of partial RBF (occlusion pressure of systolic blood pressure plus 1/3) and the other leg was the untrained control. Calf blood flow was measured using the method of venous occlusion strain-gauge plethysmography. Resting and reactive hyperemic blood flow (flow-mediated dilation) was made in both limbs, and flow was calculated by the slope of volume over the first cardiac cycle using commercial software. RESULTS: Baseline reactive hyperemic flow-mediated dilation (FMD) was less in the subjects with a parental history of hypertension than the subjects without a parental history of hypertension (P< 0.05). After training, motor strength increased in the trained and untrained control muscles of the groups with and without a history of hypertension (P< 0.05). Lower leg hyperemic response of FMD decreased in the trained legs of both groups (P< 0.05). Pooling of pre-training and post-training values showed a larger decrement of FMD in the subjects without a parental history of hypertension than with a history of hypertension (P< 0.05). CONCLUSION: RBF exercise is associated with an increase muscular strength and a decrease in endothelia function. RBF exercise may need to be cautiously prescribed to the general population with and without risk for CVD. This work was supported in part by grant 2 G12 RR003048 the RCMI Program.