How the Three Pillars of Exercise Benefit Mental Health
We often hear that exercise is good for mental health, but why is this so? I was curious about the physiological mechanisms behind exercise's emotional boost, so I did some digging. Here's what I found out regarding the three pillars of exercise: cardio/aerobic exercise, resistance/strength training, and stretching/flexibility activities.
Cardio exercise refers to increasing one's heart rate, while aerobic exercise entails increasing oxygen intake. However, many activities achieve both of these goals at once. Running, jogging, walking, bicycling, swimming, dancing, and many other sports provide both cardio and aerobic exercise.
According to Sharma, Madaan, and Petty in an issue of the Journal of Clinical Psychiatry, cardio/aerobic exercise has been shown to reduce both anxiety and depression by doing the following:
- Increasing blood flow to the brain
- Influencing the hypothalamic/pituitary/adrenal axis, which modulates our reaction to stress
- Positively affecting parts of the brain that impact mood and motivation such as the limbic system, the amygdala, and the hippocampus
A report published by Harvard Medical School added that exercise augments the action of endorphins - chemicals released by the body that reduce the perception of pain and may improve mood. Cardio/aerobic exercise might also stimulate the production of norepinephrine, a chemical in the brain tied to a host of mental processes.
Resistance/strength training entails strengthening muscles through lifting free weights, using resistance machines, or doing push-ups and similar strength exercises.
O'Connor, Herring, and Carvalho wrote in the American Journal of Lifestyle Medicine that numerous studies have shown resistance/strength training can help reduce anxiety, improve mental functioning, enhance self-esteem, and improve sleep, although results for treating depression were mixed.
Interestingly, the mechanisms by which resistance/strength training impacts mental health are still tentative. Some have proposed this type of exercise affects the central nervous system to produce positive mental health benefits. Others suggest that resistance/strength training generates new brain cells, more blood vessels, and increased neurotransmitter output, all of which improves mental functioning.
For most people, yoga is the stretching/flexibility activity of choice, but a simple stretching routine is preferred by people who shy away from yoga and related activities.
The science behind this type of exercise and its relation to mental health is the least solid. While anecdotal reports indicate that yoga is marvelous for lifting people out of depression and finding a calmer way of facing life's challenges, there have been very few well-designed studies that provide real data to support this idea.
Still, an article in the Harvard Mental Health Letter states that a handful of high quality research studies show that yoga moderates our stress response systems, which can help reduce heart rate, blood pressure, and respiration in the face of extreme stress. This bodes well for people diagnosed with PTSD; thankfully, research is growing in this area.
Other good studies have indicated that yoga can ease depression and anxiety while improving energy and well-being. Unfortunately, I could not find any research on the impact of basic stretching on mental health. For those who are not interested in trying yoga (which is actually more than just stretching, but also focuses on breathing and may include other components that are unappealing to some), I would love to know whether taking 15 minutes a day to stay limber can improve our mental resilience as well.
Harvard Medical School (n.d.). Exercise and depression. Harvard Health Publications. http://www.health.harvard.edu/newsweek/Exercise-and-Depression-report-excerpt.htm
Harvard Medical School (2009). Yoga for anxiety and depression. Harvard Mental Health Letter. http://www.health.harvard.edu/newsletters/Harvard_Mental_Health_Letter/2009/April/Yoga-for-anxiety-and-depression
O'Connor, P. J., Herring, M. P. and Carvalho, A. (2010). Mental health benefits of strength training in adults. American Journal of Lifestyle Medicine, 4(5), 377-396.
Sharma, A., Madaan, V., & Petty, F. D. (2006). Exercise for mental health. Primary Care Companion to the Journal of Clinical Psychiatry, 8(2), 106.