Reviews and synthesizes the scientific literature on the physiological changes of ageing and how regular physical activity affects the ageing process. This analysis features recent theories on ageing and their effects on such medical conditions as cardiorespiratory disease, musculoskeletal diseases, metabolic health, mental function and well-being. The author provides physiological evidence that exercise is effective for reducing the risks of many diseases, maximizing independence and improving the quality of life for the elderly. He also discusses the economic and social consequences of an ageing society.