Contributions of epidemiology to exercise science and cardiovascular health.

Much important information about the cardiovascular benefits and hazards of exercise requires the methods of epidemiology, i.e., the study in human populations of frequencies and distributions of disease in terms of time, place, and personal characteristics. The key techniques are comparison and contrast, but epidemiological analyses of physical activity and cardiovascular health often must rely on circumstantial evidence to assess cause-and-effect relationships. The study procedures must be designed to meet rigorous epidemiological principles: statistical association, temporal sequence, consistency, persistence, independence, dose-response relationship, specificity, alterability, repeatability, and confirmation of findings. Through measurement and contrast, study procedures aim to determine whether physically active persons experience a lower incidence of cardiovascular disease than do persons more sedentary. Based on these principles, current evidence indicates that exercise induces protective benefits against coronary heart disease that enable most persons to approach their potential longevity.