Mental Benefits of Exercise

It is well accepted that exercise improves physical health but there are also many mental benefits of exercise. Exercise has been shown to be an effective treatment for depression, stress, anxiety and sleep disorders and in many studies has been shown to be as effective as any other psychiatric treatment including medication and psychological therapy. This article will provide a review of the psychological benefits of exercise and how exercise can improve mental health.

Can Exercise Improve Mood and Treat Mental Illness?

There have been a number of studies evaluating the psychological benefits of exercise and its effectiveness in overcoming mental health problems such as depressive and anxiety disorders. A selection of these studies is outlined below. However, it can now be quite confidently concluded that exercise is an effective treatment for depression and other mental health problems. Meta-analyses^1,2 (statistical analyses that combine the results of several studies to increase the confidence of a conclusion) conclude that exercise is an effective treatment for mental health and is at least as effective (and possibly more effective) as antidepressant medication and psychotherapy.

A selection of studies on the mental benefits of exercise are summarised below:

Blumenthal  and colleagues³ randomly assigned 156 depressed, over 50 year old adults to one of three treatment groups- exercise, medication, or combined exercise and medication. The participants assigned to the exercise group attended three supervised exercise sessions per week for 16 consecutive weeks. The exercise sessions lasted 45 minutes (including warm up and cool down) and comprised stationary cycling or walking/ jogging. Participants were instructed to exercise at 70 to 85% of maximum heart rate. At the end of 16 weeks, there were no significant differences between the three groups in improving depression. 60.4 percent of patients in the exercise group, 65.5% in the medication group, and 68.8% in the combined group no longer met the diagnostic criteria for depression.

A follow-up 6 months later⁴ showed that those people assigned to the exercise group were more likely to be partially or fully recovered and were less likely to have relapsed compared to the other two treatment groups. What was surprising was that those who were assigned exercise alone, reported greater mood improvements at 6 months follow-up than even those assigned to the combined medication and exercise treatment group. The researchers felt that that this may be because medication seemed to interfere with the beneficial effects of the exercise program.

In another study⁵, 83 depressed patients were randomly allocated to either an aerobic exercise group or a control group. Those allocated to the aerobic exercise group participated in three supervised sessions per week for 12 weeks. Each exercise session consisted of a warm-up routine and stretching exercises, followed by a running programme. Patients in both groups who were receiving either psychological or pharmacological treatment continued with their treatment during this period.

At the end of 12 weeks, there was a significant difference between the two groups in symptoms of depression and anxiety, favouring those participating in the exercise program. This difference applied even though a significant number in the exercise programme did not fully comply with the supervised program.

To determine whether exercise is beneficial for female adolescents with depression, researchers completed a crossover randomised trial on fifty-nine females aged between 18 and 20 years⁶. The subjects were either allocated to an exercise regimen or 'usual daily activities' for 8 weeks. After 8 weeks, subjects were then crossed into the alternate group (i.e, those in the exercise group were asked to stop exercising and participate in 'usual daily activities' while those in the 'usual daily activities' group were placed in the exercise group). The exercise program consisted of five 50-minute sessions per week of a mild intensity group jogging. The intensity of exercise was individualised at a level of less than 50% of maximal heart rate.

At the end of treatment three subjects dropped out due to lack of motivation, two attended less than three sessions per week, and 5 subjects continued to exercise despite being asked not to. This left data from 49 subjects to be analysed. The researchers found that those who were first placed in the exercise group experienced a significant decrease in depressive symptoms during the exercise period. When they were later asked to stop exercising, their depressive symptoms slightly increased but not to a statistically significant level. Those subjects who were placed first in the non-exercise group experienced no change in depressive symptoms in the first 8-weeks, but then reported significant improvements in mood when later placed in the exercise program. Throughout the program, levels of stress hormones (24 hour urinary cortisol and epinephrine/adrenaline) were also assessed and it was found that levels reduced significantly during exercise treatment but not during non-exercise treatment. The researchers concluded that a group jogging exercise was effective in improving mood and hormonal responses to stress in adolescent females.

76 adults with schizophrenia, bipolar disorder, major depression, or other mental disorders participated in an individualised, community-integrated “In SHAPE” health program that consisted of moderate exercise and dietary modification⁷. After 9-months, participants experienced a reduced waist circumference, increased satisfaction with fitness and improved mental health.

How Does Exercise Improve Mood?

There are a number of explanations as to the possible mechanisms behind the mental benefits of exercise. These can be characterised into psychological, social and physiological mechanisms^8,9.

Physiological Mechanisms

Thermogenic Hypothesis - this hypothesis proposes that a rise in core body temperature from exercise leads to improved mood. It is claimed that when the temperature rises in specific brain regions, such as the brain stem, this can lead to an overall feeling of relaxation and reduction in muscular tension.

Endorphin Hypothesis - this theory predicts that the mental benefits from exercise arise from an increased release of Beta-endorphins following exercise. Increased endorphins enhance the sensation of calmness and improve mood.

Monamine Hypothesis - according to this theory, the psychological benefits of exercise arise due to increases in monoamines (neurotransmitters). It is felt that exercise increases important mood enhancing neurotransmitters such as serotonin, dopamine and norepinephrine/ noradrenaline. Depression, anxiety and other mental health problems are believed to result from imbalances in these neurotransmitters.

Stress Hormone Hypothesis - depression, anxiety and other mental health problems are associated with imbalances in stress hormones such as cortisol and norepinephrine/noradrenaline. Some studies have shown that exercise can reduce levels of stress hormones⁶.

Anti-inflammatory Hypothesis - many mental health disorders such as anxiety, depression, and schizophrenia are associated with higher levels of inflammatory mediators. Exercise may be beneficial due to it 'anti-inflammatory' and health promoting effects¹⁰.

Psychological Mechanisms

Distraction Hypothesis - according to this hypothesis, exercise distracts you from worries and distressing thoughts. Because you spend less time preoccupied with such thoughts it leads to an improved mood.

Self-efficacy Hypothesis - self-efficacy refers to the confidence a person has in a specific situation. According to this hypothesis, exercise increases one’s self-efficacy and self-confidence which can explain some of the mental benefits of exercise.

Social Mechanisms

Social Interaction Hypothesis - according to this theory engaging in regular physical activity leads to increased social interaction. It is proposed that this increased social interaction has antidepressant effects leading to improved mood and reduced levels of depression and anxiety.

Some of the theories as to why exercise improves mood has support by research while others have little empirical support although seem pretty logical. It is likely that the mental benefits from exercise arise from a combination of the above. However, in the end it doesn't really matter why exercise improves mood, but just that it does.

What Type of Exercise Best Improves Mood?

Firm conclusions as to the type of exercise, intensity and duration that leads to most improvements in mood cannot be made at this stage. However, it seems that it doesn't really matter too much. Craft and Landers¹ concluded from their meta-analysis that the duration, intensity, frequency and mode of exercise had little influence on the effectiveness of treatment. Only the length of the exercise program was important, with programs 9 weeks or longer being associated with larger improvements in depression. The age, gender and severity of depression also didn't really matter. So exercise can be helpful for people of any age, sex or depression severity. However, one should take into account the health and physical capabilities of the person.

In summary, it seems that there are a number of mental benefits of exercise and when completed safely and at moderate intensity, can lead to a range of psychological and physical benefits. If you are suffering from a mental health problems such as depression, stress and anxiety, engaging in moderate intensity exercise 3 to 5 times a week for 30 to 60 minutes may be an extremely effective natural way to improve your mood.

References

1. Craft, L.L., Lnader, D.M. (1998) The effect of exercise on clinical depression resulting from mental illness: a meta-analysis. Journal Sport and Exercise Psychology, 20:339-357.

2. Lawlor, D.A., Hopker, S.W. (2001) The effectiveness of exercise as an intervention in the management of depression: systemic review and meta-regression analysis of randomized controlled trials. British Medical Journal, 322: 763-767.

3. Blumenthal JA, Babyak, MA, Moore KA, Craighead WA, Herman S, Khatri P, Waugh R, Napolitano MA, Doraiswami PM, Krishnan KR.(1999) Effects of exercise training on older adults with major depression. Archives Internal Medicine. 159:2349-56.

4. Babyak, M., Blumenthal, J.A., Herman, S., Khatri, P., Doraiswamy, M., Moore, K., Craighead, E.W., Baldewicz, T.T., & Krishnan, K.R. (2000) Exercise Treatment for Major Depression: Maintenance of Therapeutic Benefit at 10 Months. Psychosomatic Medicine. 62:633-638.

5. Veal, D., Le Fevre, K., Pantelis, C., de Souza, V., Mann, A., Sargeant, A. (1992) Aerobic exercise in the adjunctive treatment of depression: a randomized controlled trial. Journal of the royal Society of Medicine. 85 (9). 541-544.

6. Nabkasorn, C., Miyai, N., Sootmongkol, A., Junprasert, S., Yamamoto, H., Arita, M., Miyashita, K. (2005). European Journal of Public health, 16(2), 179-184.

7. Van Citters AD, Pratt SI, Jue K, Williams G, Miller PT, Xie H, Bartels SJ. (2009) A Pilot Evaluation of the In SHAPE Individualized Health Promotion Intervention for Adults with Mental Illness. Journal of Community Mental Health.

8. Craft, L.L., & Perna, F.M. (2004) The Benefits of Exercise for the Clinically Depressed. Primary Care Companion Journal of Clinical Psychiatry 6(3); 104-111.

9. Peluso MA, Guerra de Andrade LH. (2005) Physical Activity and Mental Health: The Association Between Exercise and Mood. Clinics 60(1): 61-70.

10. Cotman, C.W., Berchtold, N.C., Christie, L.A. (2007) Exercise builds brain health: key roles of growth factor cascades and inflammation. Trends in Neurosciences 30(9): 464-472.

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