Regardless of the location of the activity, research indicates an association between
physical fitness and health status. Blair et al. (1989) examined the role of generalized
physical fitness and health status in 10,224 men and 3120 women for eight years and
reported that physical fitness was related to a decrease in both mortality rates (all cause)
and coronary heart disease.
Exercise may influence coronary heart disease in the following ways:
1 Increased muscular activity may protect the cardiovascular system by stimulating the
muscles that support the heart.
2 Increased exercise may increase the electrical activity of the heart.
3 Increased exercise may increase an individual’s resistance to ventricular fibrillation.
4 Exercise may be protective against other risk factors for coronary heart disease
(e.g. obesity, hypertension).
The physical benefits of exercise have been summarized by Smith and Jacobson (1989)
as: (1) improved cardiovascular function; (2) increased muscle size and strength and
ligament strength for maintaining posture, preventing joint instability and decreasing
back pain; (3) improved work effort; and (4) changing body composition.
The psychological benefits of exercise
Research also indicates that exercise may improve psychological well-being. These effects
are outlined below:
Depression
Research using correlational designs suggests an association between the amount of
exercise carried out by an individual and their level of depression. Much of the reviews
into this association have stressed the correlational nature of the research and the
inherent problems in determining causality (e.g. Morgan and O’Connor 1988). However,
McDonald and Hodgdon (1991) carried out a meta-analysis of both the correlational
and experimental research into the association between depression and exercise. They
concluded that aerobic exercise was related to a decrease in depression and that this
effect was greatest in those with higher levels of initial depressive symptoms. In an
attempt to clarify the problem of causality, McCann and Holmes (1984) carried out an
experimental study to evaluate the effect of manipulating exercise levels on depression.
Forty-three female students who scored higher than the cut-off point on the Beck
Depression Inventory (BDI) were randomly allocated to one of three groups: (1) aerobic
exercise group (one hour of exercise, twice a week for ten weeks); (2) placebo group
(relaxation); (3) no treatment. After five weeks, the results showed a significant reduction
in depressive symptomatology in the exercise group compared with the other two subject
groups supporting the relationship between exercise and depression and suggesting a
causal link between these two variables; that is, increased exercise resulted in a reduction
in depression. However, the authors report that subsequent exercise had no further
effects. Hall et al. (2002) also used an experimental design to explore the relationship
EXERCISE 171