Adaptations in the structural and/or functional properties of cells, tissues and organ systems in the human body occurs when exposed to various stimuli. While there is unanimous agreement that regular physical activity is essential for optimal function of the human body, it is evident that extrinsic factors, such as diet, smoking, exercise habits, are reflected in the morbidity and mortality statistics of the population. Ageing is obligatorily associated with reduced maximal aerobic power and reduced muscle strength, i.e. with reduced physical fitness. As a consequence of diminished exercise tolerance, a large and increasing number of the aged population will be living below, at or just above 'threshold' of physical ability, needing only a minor illness to render them completely dependent. Physical training can readily produce a profound improvement of functions essential for physical fitness in old age. Adaptation to regular physical activity causes less disruption of the cells' internal environment and minimises fatigue which enhances performances and the economy of energy output during daily physical activity. Regular physical exercise reduces the risk of premature mortality in general, and of coronary heart disease, hypertension and diabetes mellitus. Physical activity also improves mental health and is important for health and optimal function of muscles, bones and joints. The most recent recommendations advice the people of all ages to include a minimum of 30 minutes of physical activity of moderate intensity, such as brisk walking, on most, if not all, days of the week.
Keywords: Exercise; aging; exercise training; optimal function; therapeutic agent.