It is proposed to study the effects of exercise training on resting, ambulatory (8-hour), and exercise blood pressure in 150 middle-aged, sedentary, moderately overweight men. The proposed study takes advantage of an existing clinical trial designed to determine the different effects of weight loss through caloric restriction and weight loss through increased physical activity on lipoprotein metabolism. In this, "parent" study, 150 sedentary men aged 30-59 with Metropolitan relative weight 115-135 % will be randomly assigned to one of three groups: control, caloric restriction, or exercise. Both treatment groups will lose one-third of excess body fat through the two different methods over nine months. Complete data on body composition, exercise capacity, lipoprotein level and composition, and dietary intake will be available from the parent study. This application will enable the principal investigator to measure resting, ambulatory (8-hour), and exercise blood pressure in the same subjects. While not hypertensive, the subjects of the parent study will be at higher risk for hypertension, because they are overweight, which is important from a public health perspective. Resting blood pressure is expected to fall in response to weight loss, but it is hypothesized that exercise training will result in a significantly greater fall due to other cardiovascular effects. Specifically, training is expected to result in lower catecholamine and blood pressure levels during submaximal exercise; it is expected that this effect will generalize to lower ambulatory (i.e., mean daily) blood pressure in the exercise group. Ambulatory blood pressure will be obtained using the Remler M-2000 semi-automatic recorder, a tested and reliable device. Resting blood pressures will be carefully determined using random-zero sphygmomanometers. Blood pressure during and after a standard exercise treadmill test will be determined using a standard manometer. Catecholamines at rest and during submaximal exercise will be determined by high performance liquid chromatography. All measures will be made at baseline, six months, and one year. There is a growing interest in the nonpharmacologic treatment and in the prevention of hypertension due to the economic cost and possible toxicity of drug treatment. This study could be an important beginning to the exploration of the inter-relationships among exercise, weight loss, resting blood pressure, and ambulatory blood pressure in man.