Exercise And Happiness

By Chris Douglas

Psychological processes are intimately linked to one’s physical condition. The state of one’s mind is connected to the biological state of the brain, and as such is also connected to the state of one’s body. Therefore, researchers have explored the connection between mood and exercise, one of the most frequently prescribed preventative measures for maintaining overall physical health.

Immediate Effect

Exercise produces multiple short-term psychological and physical benefits.During the course of prolonged aerobic exercise, the body releases endorphins, naturally produced chemicals with activity similar to that of opiates.^[1] These chemicals are thought to partially underlie the pain-reducing and mood-enhancing effects of continuous exercise.^[2] This effect has a rapid onset and occurs during and immediately after a single session of moderately intense exercise, and contributes to the feeling of well-being associated with physical activity.

Long-term Effects

In the long term, exercise is capable of inducing further psychological benefits. Population studies have shown exercise to reduce stress and improve overall mental state. One Finnish study found that exercise significantly reduced depression, repression of anger, and perceived stress.^[3] The positive effects were most pronounced when subjects exercised at least two to three times per week.^[4] Another study of an adolescent population confirmed these findings, showing exercise to reduce both symptoms of depression and overall stress, especially when the exercise was of at least moderate intensity.^[5] This positive influence is partially due to the immediate physiological changes mentioned above, but also arises from other mechanisms. One such mechanism is the increase in brain plasticity produced by consistent exercise.^[6] An increase in neural plasticity – the brain’s ability to grow and adapt to changing demands – is thought to improve learning and stave off mental diseases arising from lack of plasticity, such as depression and age-related cognitive decline.^[7],[8] Research has shown exercise to increase plasticity through two mechanisms: by adapting and strengthening connections between existing neurons and through by encouraging the development of new neurons, primarily in regions of the brain associated with learning and memory.^[9],[10] Consistent exercise can even counter the reduction in plasticity seen in normal aging, and encourage both neurogenesis and improved learning in the aged brain.^[11],[12]

Therapeutic Effects

All the above psychological benefits of exercise occur in normal, healthy populations, but exercise has also proven itself an effective treatment for specific disorders. Treatment studies have shown it to reduce symptoms of depression,^[13] and in one study, the results were comparable to prescription antidepressants.^[14] Studies have also shown it to reduce overall levels of anxiety.^[15] Finally, exercise has been shown to increase overall quality of life, both mental and physical, in people suffering from a terminal illness such as cancer.^[16]

Regular exercise is one of the best documented proactive behaviors for maintaining overall health, and consequently, it promotes mental health as well. Long term consistent exercise has been repeatedly shown to improve mental state, but there are immediate benefits after just one session. Overall though, the key to increased brain plasticity, reduced stress, and improved mood is a regular schedule of at least moderately intense exercise, adhered to on a consistent basis.

Resources

Physical Activity and Public Health -- A Recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine

CDC analysis of exercise and recommendations for activity levels in the average population.

Bibliography

• [1] Carr, Daniel B., Beverly A. Bullen, Gary S. Skrinar, Michael A. Arnold, and Michael Rosenblatt. "Physical Conditioning Facilitates the Exercise-Induced Secretion of Beta-Endorphin and Beta-Lipotropin in Women." New England Journal of Medicine 305, no. 10 (1981): 560-563.
• [2] Foley, Kathleen M., Ione A. Kourides, Charles E. Inturrisi, Robert F. Kaiko, and Charles G. Zaroulis. "/3-Endorphin: Analgesic and hormonal effects in humans." Proceedings of the National Academy of Sciences 76, no. 10 (1979): 5377-5381.
• [3] Hassmen, Peter, Nathalie Kolvula, and Antti Uutela. "Physical Exercise and Psychological Well-Being: A Population Study in Finland." Preventative Medicine 30, no. 1 (2000): 17-25. 
• [4] Hassmen, Peter, Nathalie Kolvula, and Antti Uutela. "Physical Exercise and Psychological Well-Being: A Population Study in Finland." Preventative Medicine 30, no. 1 (2000): 17-25.
• [5] Norris, Richard, Douglas Carroll, and Raymond Cochrane. "The Effects of Physical Activity and Exercise Training on Psychological Stress and Well-Being in an Adolescent Population." Journal of Psychsomatic Research 36, no. 1 (1992): 55-65.
• [6] Cotman, Carl W., and Nicole C. Berchtold. "Exercise: a behavioral intervention to enhance brain health and plasticity." Trends in Neurosciences 25, no. 6 (2002): 295-301.
• [7] McEwen, Bruce S. "Glucocorticoids, depression, and mood disorders: structural remodeling in the brain." Depression: Genetics, Pathophysiology, and Clinical Manifestations 54, no. 5 (2005): 20-23.
• [8] Cotman, Carl W., Nicole C. Berchtold, and Lori-Ann Christie. "Exercise builds brain health: key roles of growth factor cascades and inflammation." Trends in Neurosciences 30, no. 9 (2007): 464-472.
• [9] van Praag, Henriette, Gerd Kempermann, and Fred H. Gage. "Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus." Nature Neuroscience 2, no. 3 (1999): 266-270.
• [10] van Praag, Henriette, Brian R. Christie, Terrence J. Sejnowski, and Fred H. Gage. "Running enhances neurogenesis, learning, and long-term potentiation in mice." Proceedings of the National Academy of Sciences 96, no. 23 (1999): 13427-13431.
• [12] van Praag, Henriette, Tiffany Shubert, Chunmei Zhao, and Fred H. Gage. "Exercise Enhances Learning and Hippocampal Neurogenesis in Aged Mic." The Journal of Neuroscience 25, no. 38 (2005): 8680-8685.