The study of the normal human individual provides an important baseline for the study of disease. Exercise physiology is particularly important because an exercise situation provides a unique opportunity to study how different functions are coordinated and integrated. In fact, most functions and structures are in one way or another affected by acute and chronic (i.e. training) exercise. There is unanimous agreement that regular exercise is essential for optimal function of the human body. It is evident that extrinsic factors, such as diet and exercise habits, are reflected in the morbidity and mortality statistics, especially in aging. Both healthy individuals and those with chronic illnesses and functional handicaps can improve their performances and, therefore, their quality of life by increased physical activity. In my opinion, epidemiological research has established that physical inactivity from a medical viewpoint is a risk factor threatening health and an optimal life style. Adverse effects of non-competitive exercises are very small in comparison with health benefits.