RESEARCH to PRACTICE

Physical Activity Improves Mental Health

Kevin R. Fontaine, PhD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 28 - NO. 10 - OCTOBER 2000

Mental health disorders such as depression and anxiety affect millions of people worldwide and are associated with increased morbidity and healthcare costs (1). Although several therapeutic modalities such as pharmacotherapy and psychotherapy appear effective in treating these disorders, evidence suggests that these treatments are underused (2). Physical activity (PA) has a positive impact on mental health and psychological well-being, and this finding has opened some important lines for further research. Emphasizing these benefits to patients is important.

Physical Activity's Positive Impact

PA appears to improve the symptoms of depression, anxiety, and, to a lesser extent, panic disorder (table 1). PA also increases patients' perceived energy level, self-esteem, and positive affect (3). Some PA correlates are ambiguous. For example, the relationship between PA and eating disorders is unclear, and frequent, intensive bouts of PA are considered secondary symptoms of some eating disorders (eg, anorexia nervosa).

TABLE 1. The Effect of Physical Activity on Mental Health
Trait or Disorder	Effect	Comments
Depression	Moderate	Decreases symptoms; efficacy similar to psychotherapy in patients with mild-to-moderate depression; unclear whether PA prevents onset of depression, but it may reduce symptom severity
Anxiety	Small-to-moderate	Reduces state anxiety but unclear whether it improves trait anxiety
Panic disorder	Small	Often produces transient increase in anxiety, but anxiety dissipates with time if patient adheres to regimen of activity
Energy/vigor	Large	Intensive PA increases perceived energy level; unclear whether regular PA influences habitual energy levels
Self-esteem	Small-to-moderate	Greatest improvement found in those with low self-esteem before PA
Positive affect	Small-to-moderate	Effect most pronounced if PA involves social interaction
Eating disorders	Unclear	Intensive PA or exercise may be symptom of an eating disorder
PA = physical activity

It is important to note, however, that much of the research conducted has not been optimal in terms of study design, sample size, and measurement. For example, relatively few studies used participants with diagnosed depression or anxiety disorders but instead relied on self-reporting (eg, symptom checklists and rating scales) (4). Moreover, many studies did not account for the potentially confounding or moderating effect of variables such as age, duration of disorder, health status, and social support. As a result, determining the independent effect of PA on mental health is difficult. Despite these limitations, the relative consistency of both epidemiologic and intervention studies suggests that PA is associated with improved mental health and psychological well-being.

Possible Mechanisms

The mechanisms by which PA improves mental health are not well established. Several psychological mechanisms (eg, distraction hypothesis, social interaction hypothesis) and physiologic mechanisms (eg, endorphin hypothesis, thermogenic hypothesis) have been proposed, but few have been supported by randomized, controlled trials (5). A model that postulates the interplay of biological, psychological, and social factors will be required to explain adequately the mechanisms underlying the effects of PA on mental health.

Implications for Practice

In addition to the well-documented benefits of PA on physical health, PA appears useful in treating depression and anxiety and in improving psychological well-being. Physicians should inform patients about these benefits and strongly encourage them to incorporate PA into their daily routines. The particular type of PA performed is less important than assisting patients in finding an activity that they can perform consistently. It should be emphasized that any PA is better than no PA. The benefits that PA conveys on mental health and perceived energy may be more immediate and dramatic to patients than are its effects on physical health.

Overall, the data suggest that (1) regular PA may alleviate symptoms of depression and anxiety; (2) PA appears as effective as psychotherapy for treating mild-to-moderate depression; (3) after an initial escalation of anxiety, over time PA appears to mildly reduce the symptoms of panic disorder; (4) intensive PA greatly increases perceived energy level; and (5) PA appears to mildly enhance patients' self-esteem and positive affect.

Where Do We Go From Here?

Although PA appears to have beneficial effects on mental health, several important questions remain. Among them are: (1) How and under what circumstances should PA be incorporated into therapy for patients with mental health disorders? (2) What are the long-term effects of PA on mental health disorders? (3) Does regular PA protect against developing mental health disorders?, and (4) What is the optimal PA prescription for various mental health disorders? Despite these questions, it appears that PA can play an important role in alleviating the pain and suffering of those afflicted with mental health disorders. Some additional resources may be found online (table 2).

TABLE 2. Online Mental Health Summaries and Information Mental Health Matters (http://www.mental-health-matters.com). Provides information on the diagnosis and treatment of mental health disorders. Mental Health: A Report from the Surgeon General (http://www.surgeongeneral.gov/library/mentalhealth/home.htm). In this December 1999 report, David Satcher, MD, PhD reviews research on mental disorders and summarizes the major treatment modalities, including physical activity.

References

1. Murray CJL, Lopez AD: Global mortality, disability, and the contribution of risk factors: Global Burden of Disease Survey. Lancet 1997;349(9063):1436-1442
2. Hirschfield RM, Keller MB, Panico S, et al: The national depressive and manic-depressive association consensus statement on the undertreatment of depression. JAMA 1997;277(4):333-340
3. Gauvin L, Spence JC: Physical activity and psychological well-being: knowledge base, current issues, and caveats. Nutr Rev 1996;54(4 pt 2):S53-S65
4. Fox KR: The influence of physical activity on mental well-being. Public Health Nutr 1999;2(3A):411-418
5. Paluska SA, Schwenk TL: Physical activity and mental health: current concepts. Sports Med 2000;29(3):167-180

Dr Fontaine is an assistant professor of medicine in the division of gerontology at the University of Maryland and at the Geriatric Research Education and Clinical Center in Baltimore. Address correspondence to Kevin R. Fontaine, PhD, Baltimore VA Medical Center, 10 N Greene St, Geriatrics (18), Baltimore, MD 21201; e-mail to Kevin@grecc.umaryland.edu.