Exercise and Depression

Studies show the benefits of physical activity in treating and preventing depression.

According to the IHRSA Institute on Exercise and Health's Wellness Research Newsletter, the 1996 Surgeon Generals Report on Physical Activity and Health reported that mental disorders posed a significant public health burden in the United States. Studies by the National Institute of Health (NIH) and other groups have estimated that more than 5 percent of Americans--some 17 million people--suffer clinical depression. Another 5 percent experience milder symptoms of being "blue." In all, depression costs the nation $43 billion each year in medications, professional care and lost school and workdays.

Exercise helps in the avoidance and treatment of depression in several ways. It releases endorphins--the body's own mood-elevating, pain-relieving compounds--while reducing levels of the stress-depression hormone cortisol in the bloodstream. Exercise also boosts self-esteem by yielding positive feelings of accomplishment and autonomy.

Researchers haven't established a direct-causal relationship between exercise and mood elevation. Still, the prevailing hypothesis holds that the chief effect of regular physical activity (i.e., higher levels of cardiorespiratory fitness) produces key, life-coping psychological benefits such as enhanced mood, self-esteem, confidence and cognitive functioning.

Intensity May Be the Key

Preliminary results from a major study on depression conducted at Duke University demonstrate that acute doses of physical activity--rather than sustained regular exercise--may be the most effective way to reduce feelings of depression, anger and fatigue. The study is part of a larger, five-year study comparing different treatments for depression: a four-month exercise program, drug therapy or a combination of exercise and medication.

Kathleen Moore, a researcher in the department of psychiatry and behavioral sciences at Duke University Medical Center, reported that the Duke study was the first to test the benefits of acute exercise on a group of people actually diagnosed with clinical depression. In the study, 55 participants over the age of 50 completed a 60-question Profile of Mood Survey (POMS) to assess baseline mood. Then they walked on a treadmill for up to 14 minutes at a maximum, exhaustive effort. After exercising, they completed the survey again. Participants experienced an 82 percent reduction in feelings of depression, tension, fatigue, anger and confusion.

Lead Study #1

R.K. Dishman. Physical Activity and Public Health: Mental Health. QUEST 1995.

47:362-385. American Academy of Kinesiology and Physical Education.

This paper reviews the available literature on the effects of physical activity on depression and anxiety. The author locates a central shortcoming inherent in most of the studies (i.e., the absence of hard evidence of physiological mechanisms coherent with biological or cognitive theory about the cause and treatment of depression and anxiety). Still, the author's overall conclusion is that physical activity does positively affect depression and anxiety.

Although more conclusive studies need to be undertaken, researchers have offered both physiological and psychological explanations for the effects of exercise on anxiety or depression. The most common physiological explanations involve the action of endorphins within the central nervous system, the elevation of the body and brain temperature, the distraction hypothesis (that "time out" from worry can trigger relief from depression) and the mastery hypothesis (that the completion of an important task brings a sense of well-being).

Lead Study #2

D.M. Landers. The Influence of Exercise on Mental Health. President's Council on Physical Fitness and Sports Research Digest.

December 1997; 2 (No. 12).

In this review of the meta-analysis (a study across all of the relevant literature on a subject) on exercise and depression, Landers found that exercise seemed to significantly reduce feelings of anxiety. The literature suggested that exercise produced the greatest positive effects both when it was aerobic, lasting for more than 10 weeks, and when subjects had an initially lower level of fitness or higher level of anxiety.

Since the early 1900s, more than 100 studies have examined the relationship between exercise and depression. The findings suggest that exercise produces a greater antidepressant effect when training lasts longer than nine weeks and involves more frequent sessions undertaken at a greater degree of intensity and duration. The research also shows that exercise decreases depression more than relaxation training or casual recreation, while producing a roughly similar effect on depression as psychotherapy. Exercise may be a positive adjunct for treatment of depression since it provides additional health benefits that behavioral interventions do not.

Other Significant Findings

Exercise as Prevention

T.C. Camacho. Physical Activity and Depression: Evidence From the Alameda County Study American. Journal of Epidemiology; July 15, 1991; 134 (2).