The physical benefits of exercise
Longevity
Paffenbarger et al. (1986) examined the relationship between weekly energy expenditure
and longevity for a group of 16,936 Harvard alumni aged 35 to 70. They reported the
results from a longitudinal study which suggested that individuals with a weekly energy
expenditure of more than 2000 kcals on exercise reported as walking, stair climbing and
sports, lived for two-and-a-half years longer on average than those with an energy
expenditure of less than 500 kcal per week on these activities.
The possible reasons for the effects of exercise on longevity are as follows:
1 Reduction in blood pressure: physical activity has an inverse relationship to both
diastolic and systolic blood pressure. Therefore, increased exercise decreases blood
pressure. This effect is particularly apparent in those who have mild or moderately
raised blood pressure.
2 Reduction in weight and obesity: overweight and obesity are related to certain
cancers, hypertension and coronary heart disease. Exercise may help promote
weight loss/maintenance (see Chapter 15 for details of exercise and obesity).
3 Reduction in diabetes: exercise may be related to improved glucose control,
resulting in a reduction in the possible effects of diabetes.
4 Protection against osteoporosis and thinning bones: exercise may be protective
against osteoporosis, which is common among older women.
5 Reduction in coronary heart disease: the main effect of exercise is on the
occurrence of coronary heart disease and rehabilitation following a heart attack.Coronary heart disease
The effects of exercise on coronary heart disease have been examined by assessing the
consequences of both occupational activity and leisure activity. Regarding occupational
activity, Paffenbarger and Hale (1975) followed up 3975 longshoremen for 22 years.
Longshoremen have occupations that involve a range of energy expenditure. The results
showed that at the end of this period, 11 per cent had died from coronary heart disease
and that those longshoremen who expended more than 8500 kcal per week had a
significantly lower risk of coronary heart disease than those in jobs requiring less energy.
This difference remained when other risk factors such as smoking and blood pressure
were controlled. This relationship between occupational activity and coronary heart
disease has also been shown in samples of both men and women (Salonen et al. 1982).
Research has also evaluated the relationship between leisure-time activity and
coronary heart disease. Morris et al. (1980) followed up a group of middle-aged seden-
tary office workers over eight-and-a-half years and compared those who engaged in
sport with those who reported no leisure-time activity. The results showed that those
who attempted to keep fit showed less than half the incidence of coronary heart disease
at follow-up compared with the other subjects. This association has also been reported in
students in the USA (Paffenbarger et al. 1978, 1983, 1986).170 HEALTH PSYCHOLOGY