The psychological benefits of exercise

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EXERCISE 171
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
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172 HEALTH PSYCHOLOGY
between exercise and affect with 30 volunteers rating their affective state every minute
as they ran on a treadmill. The results showed improvements in affect from baseline
to follow up which supports previous research suggesting that exercise is beneficial.
However, the results also showed a brief deterioration in mood mid-exercise. The authors
suggest that although prolonged exercise may improve mood this dip in mood may
explain why people fail to adhere to exercise programmes.
Anxiety
Research has also indicated that exercise may be linked to a reduction in anxiety. Again,
there are problems with determining the direction of causality in this relationship, but it
has been suggested that exercise may decrease anxiety by diverting the individual’s
attention away from the source of anxiety.
Response to stress
Exercise has been presented as a mediating factor for the stress response (see Chapters 10
and 11). Exercise may influence stress either by changing an individual’s appraisal
of a potentially stressful event by distraction or diversion (e.g. ‘This situation could be
stressful but if I exercise I will not have to think about it’) or may act as a potential coping
strategy to be activated once an event has been appraised as stressful (e.g. ‘Although the
situation is stressful, I shall now exercise to take my mind off things’).
Self-esteem and self-confidence
It has also been suggested that exercise may enhance an individual’s psychological wellbeing by improving self-esteem and self-confidence. King et al. (1992) report that the
psychological consequences of exercise may be related to improved body satisfaction,
which may correlate to general self-esteem and confidence. In addition, exercise may
result in an improved sense of achievement and self-efficacy.
How does exercise influence psychological well-being?
Many theories have been developed to explain the factors that mediate the link between
exercise and psychological state. These reflect both the physiological and psychological
approaches to the study of exercise. For example, it has been argued that exercise
results in the release of endorphins, the brain’s natural opioids (Steinberg and
Sykes 1985), and increases in the levels of brain norepinephrine, which have been
hypothesized to be a cause of depression. It has also been suggested that improved
psychological state is related to the social activity often associated with exercise and
the resulting increased confidence and self-esteem. Any reduction in levels of depression
may be related to greater social contact, improved social support and increased selfefficacy.
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