The overall goal of this project is to conduct a multi-disciplinary investigation of acute and chronic life style and physiologic changes among demographic subpopulations resulting from involvement in a senior exercise program of either high or low intensity. People over 60 years of age will be recruited on a volunteer basis for an exercise program that will last for one year. Participants in the study will be recruited from a program for students over 60 at The Ohio State University, a retirement apartment complex, and various senior citizen centers throughout the Columbus area in association with local YMCA's. Participants will exercise at low intensities (less than 50% of the heart rate range (HRR) or high intensities (greater than 50% of the HRR) and the frequency of the exercise sessions will be three times per week. Each subject will serve as his/her own control. Repeated measures will be taken on aerobic and anaerobic capacities, body composition, daily activity levels, myocardial performance, blood lipoprtein concentration, blood platelet adhesiveness, life satisfaction, and mental status. The most common pattern of measurement will be at three month intervals from initiation of the exercise program to the end of the twelfth month of exercise. A separate analysis of each perameter as it relates to the intensity of exercise and acute versus chronic effects of exercise will be performed. In addition to the individual analyses, multivariate analyses of variance for repeated measures will be used with selected variables that show high correlations or meaningful results.