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cortisol responses to stress and that optimism appeared to be an important
moderating factor for this eff ect.

Exercise

Many scientific studies have demonstrated that moderate exercise leads to

improved physical and mental health. Good physical fitness has been shown

to delay death, particularly from causes such as cardiovascular disease and

cancer, while poor physical fitness is associated with early death by numer-
ous medical conditions (Blair et al., 1989). Moderate exercise also tends to
improve emotional well-being. In a large study of subjects from 15 member
states of the European Union, subjects who were physically active reported
better mental health than those who were sedentary (Abu-Omar, Rutten &

Robine, 2004). Exercise has also been shown to be effective as a means to
improve mild depressive symptoms among otherwise healthy individuals
and as a means to reduce the severity of depression in young adult, middle-
aged, and older subjects diagnosed with major depressive disorder. A meta-

analysis has found that exercise is as effective as cognitive behavioral therapy

for reducing mood-related symptoms in patients suffering from depression
(Manber, Allen & Morris, 2002). In a randomized controlled treatment study
of middle-aged men with major depression, 16 weeks of aerobic exercise was

as effective in reducing the symptoms of depression as was either 16 weeks
of treatment with the antidepressant sertraline or 16 weeks of exercise plus
sertraline (Babyak et al., 2000).
Aerobic exercise also appears to decrease anxiety in healthy individuals
and in patients with anxiety disorders (Broman-Fulks, Berman, Rabian &
Webster, 2004; Fremont & Wilcoxon Craighead, 1987; McAuley, Mihalko &
Bane, 1996; Salmon, 2001), particularly those who misinterpret and catastro-
phize anxiety-related physical symptoms (e.g., rapid heart rate, sweating).
When “anxiety sensitive” individuals exercise regularly and vigorously, they
can learn that physical signs of physiological activation and arousal are not
dangerous. Regular exercise has also been shown to improve cognition and
memory and to exert a protective effect in elderly individuals with and with-

out Alzheimer’s disease (Colcombe et al., 2004; Friedland et al., 2001; Lau-
rin, Verreault, Lindsay, MacPherson & Rockwood, 2001). Although there are
relatively few well-controlled studies of exercise and mental health, on the
whole it appears that moderate exercise is associated with both physical and
psychological well-being (Paluska & Schwenk, 2000). In formerly sedentary
elderly adults, daily exercise such as 30 minutes of walking for just 6 months
leads to improved executive function and attention and also increases associ-
ated activation of prefrontal and parietal cortices.
The positive effects of exercise on physical and mental health are likely

due to its impact upon the stress response, allostasis, and allostatic load.

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