Exercise is the omnipresent treatment adjunct for physical health. It is a prescription that is hard to escape, as even a routine visit to your physician will attest. But while the virtues of exercise may appear to be self-evident for the body, is there a rational scientific explanation of the mechanisms by which exercise is effective in mental health and well-being, and in particular for stress reduction?
The Research Evidence
Among the most significant evidence linking exercise to an increase in the ability to cope with emotional stress is the Nicholson, Fuhrer, & Marmot (2005) study of 5,449 cardiovascular disease patients, whose results confirmed an earlier study by Pelham, Campagna, Ritvo, & Birnie (1993). Both studies provided evidence that, among patients suffering from physical or psychiatric disorders, exercising increased motivation to be well while decreasing negative mood states.
In a study (Perna, Antoni, et al., 1998) among men and women rowers to verify the effects of a cognitive-behavioral stress management program, exercise was shown to reduce negative mood states and the level of cortisol. The rowers experienced significant reductions in depressed mood, fatigue, and cortisol level when compared to other individuals in the control group.
What Type of Exercise Is Most Beneficial?
When the available evidence is analyzed, no one type of exercise appears to be the “best” for stress reduction. Rather, personal preference and the enjoyment of the physical activity of exercise appear to be the two most important factors for mental health benefits. High-intensity aerobic activity does not appear to be necessary to achieve the mental health benefits of exercise (Doyne, Schambless, & Beutler, 1983; Martinsen, 1993; Blumenthal et al., 2002), unlike exercise prescribed for physical fitness, where aerobic activity and high-exertion for at least twenty minutes appear to be required for optimal results.
What Makes Exercise Effective in Stress Management?
As you might guess, since there is no hard-fast indicator of efficacy as too many individual factors cannot be precisely measured, theories abound as to what exactly makes exercise work in improving mood and reducing stress. Here are the three that are most widely accepted among researchers.
According to the Anesthetic Pain Relief Theory, the vigorous exercise of running, jumping, or weight lifting generates multiple minor traumas to skin, muscles and bones. These micro-traumas trigger the release of the body’s own painkillers, opioid substances such as endorphins and endocannabinoids. In addition to reducing the pain provoked by micro-traumas, these morphine-like substances also generate an unmistakable and very pleasurable sense of well-being (also known as the exercise high).
According to the Stress and Relaxation Hormone Theory, deficiencies in the hormones norepinephrine and serotonin signal the onset of depression. Exercise appears to increase the levels of both hormones, thus restoring their adequate levels and lifting the individual’s mood to correspondingly higher levels.
According to the Rebound Restorative High-Quality Sleep Theory, stress affects the quality and quantity of sleep and is in turn exacerbated by sleep deprivation. With respect to work stress, higher levels of stress at work appear to be closely correlated with sleeplessness at night and sleepiness during daytime (Dahlgren, Kecklund, & Akerstedt, 2005). Exercise has been shown to be very effective in improving the quality of sleep. Thus, exercising appears to indirectly reduce stress by increasing the quality of sleep.