The value of physical fitness in preventive medicine

Physical conditioning induces many favourable changes in the body, including an increase of maximum oxygen transport, a decrease of body fat, a strengthening of muscles, tendons and bones, an improvement of blood lipid profile, and a better balance between oxygen demand and supply in the myocardium. The preventive value of such changes is often seen in measures of perceived health or their practical consequences. Industrial fitness programmes apparently reduce the use of medical services (physician visits and hospital days), with gains of productivity, a lessening of absenteeism, and a lower employee turnover. Techniques such as the Canadian Health Hazard Appraisal questionnaire suggest a general reduction in 'risk-taking' behaviour among exercise-class participants, with a substantial reduction in their 'appraised' age. There is little evidence that regular moderate exercise can alter the response to acute disease, but both theoretical considerations and epidemiological data suggest the value of physical activity in preventing manifestations of ischaemic heart disease, obesity and maturity onset diabetes, cholecystitis, hypertension, certain neuroses, and age-related pathologies. A fit individual is also at a lesser risk of industrial injury, and is capable of living independently for a longer fraction of his or her old age. It is concluded that physical activity is one of the more useful tactics of preventive medicine; the current challenge to both research workers and policy makers is to carry this message beyond the white-collar executive to such target groups as blue-collar workers, ethnic minorities, housewives, the elderly and the handicapped.