To investigate the effects of exercise intensity on resting blood pressure (BP) in normotensive elderly subjects, 44 sedentary healthy subjects aged 60 to 79 years of age were studied during 6 months of walking exercise. Subjects were ranked according to maximal oxygen consumption and randomly stratified to groups that trained at 70% (n = 19) or 80% to 85% (n = 14) of maximal heart rate reserve, or to a control group (n = 11) that did not train. Initial BP was established during a 2- to 3-week control period. During the first 3 months, both exercise groups progressed to 70% of heart rate reserve for 40 minutes 3 times each week. The moderate-intensity group continued to train at 70% (45-minute duration) for an additional 3 months, whereas the high-intensity group progressed to training at 85% of heart rate reserve (35-minute duration). Maximal oxygen consumption increased (p < or = 0.05) during the initial 3 months in both exercise groups (25.2 to 28.1 ml.kg-1.min-1 and 26.3 to 29.3 ml.kg-1.min-1) and continued to increase (p < or = 0.05) after 3 additional months of training, but the increase was greater (p < or = 0.05) in the high-intensity group (28.1 to 29.4 ml.kg-1.min-1 and 29.3 to 32.8 ml.kg-1.min-1). Systolic BP decreased (p < or = 0.05) similarly at 6 months in both training groups (120 to 111 mm Hg and 120 to 112 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)