The effects of four levels of activity on heart rate, blood pressure, cardiac index, total peripheral resistance index (TPRI), norepinephrine (NE) spillover rate, insulin sensitivity, and levels of lipids and some hormones were studied in 12 normal subjects. The randomized periods were (1) 4 weeks of below-sedentary activity, (2) 4 weeks of sedentary activity, (3) 4 weeks of 40 min of bicycling three times per week, and (4) 4 weeks of similar bicycling seven times per week. Exercise three times per week reduced resting blood pressure by 10/7 mm Hg (p < .01) and it was reduced by 12/7 mm Hg after exercise seven times per week (both p < .01). This was associated with reduction in TPRI, an increase in cardiac index, and cardiac slowing. At the highest level of activity, NE spillover rate, an index of sympathetic activity, fell to 35% of the sedentary value (p < .001) in eight of 10 subjects. In two other subjects NE spillover rate rose, although blood pressure and TPRI were reduced. Metabolic changes included lowering of total cholesterol, but high-densitv lipoprotein level was unchanged. Insulin sensitivity rose by 27% after exercise three times per week, icut –ec“ Ted to sedentary levels with seven times per week exercise. Maximum oxygen uptake inceasec i crly with activity. Exercise performed three times per week lowers blood pressure and should reduce ardiovascular risk. The same exercise seven times per week enhances physical performance with little further reduction in cardiovascular risk factors. Exercise is potentially a major nonpharmacologic method oflowering blood pressure.