We all know exercise does your body good, but it can also do the same to the mind.
Illustration by Heidi Wong
In modern times, we often exercise for the sole goal of achieving and maintaining a fit and healthy body. Exercise is framed as a good way to lose weight, but this may not be a big motivator for some, especially those who are already at a healthy body weight. While our motivation levels cycle, our running shoes take up residence in our closets and couches remain comfortably, well, comfortable. If the physical health benefits of exercise were not a good enough reason to exercise, there is now mounting evidence that your mental health is directly linked to your physical health and activity level.
While the media ensures we are aware that obesity rates are climbing, we may not notice that mental disorders are also more prevalent. In 2011, the Centers for Disease Control and Prevention reported that 11% of American citizens over the age of 12 take antidepressants and that the overall prevalence of these medications has risen 400% since 1988. Depression is sometimes referred to as a disease of modernity. We now eat more than ever and move less than ever. According to the World Health Organization, 50% of women and 40% of men in the United States are not getting enough physical activity.
As chronic stress and loneliness increase, sleep and physical activity diminish. It is no surprise that both our mental and physical health is declining and that younger generations are at increased risk of depression. This is not surprising, as being overweight and inactive has been repeatedly linked to depression. We are increasingly isolated, unhappy, and medicating to avoid these feelings. While working out is commonly seen as an activity for only the physical body, exercise has real effects on our emotional and social well-being.
During intense physical exercise, runners may experience runner’s high, a euphoric feeling caused by exercise-induced endorphins. Johnathan Fox/Flickr (CC BY-SA 2.0)
Most people have heard of runner’s high, a euphoric feeling caused by endorphins released during intense physical exertion. Neurotransmitters called endocannabinoids are released and they produce a rewarding feeling. They also help with mood modulation and stress reduction, and can change pain perception. Numerous studies endorse exercise as a viable treatment option for depression. Review papers from 2001, 2009, and 2016 evaluated the attempts to quantify and validate this option, despite how difficult it is to measure happiness and exercise ‘doses’. Researchers use the Beck Depression Inventory and other tools to measure and compare the efficacy of standard treatment (psychological or pharmaceutical) to exercise. Multiple trials found that exercise produced a large positive clinical effect on par with cognitive therapy and pharmacological treatments.
One specific study showed that just 30 minutes of walking three times per week significantly lifted a major depressive’s mood. However, these sessions must be rigorous in order to be effective, which means that the heart rate should be at 70-85% of the heart rate reserve. In these cases, exercise reduced depressive symptoms in half of the study participants in just 12 weeks. A similar recovery rate is observed with pharmacological treatments. Interestingly, those who participated in exercise had a reported lower relapse rate at the 10-month follow up session. Although the mechanism is not fully understood, these antidepressant and anxiolytic effects of exercise may be due to more than physical biology. Exercise training is theorised to confer enduring resilience to stress, both mental and physical. Non-professional runners report emotional and psychological improvements including relief of tension, improved self-image, and even increased creativity while running. A form of self-hypnosis and naturally released neurotransmitters may result in these stress-busting and creativity-boosting effects.
People who are obese have higher incidences of depression and anxiety, which may be due to bullying, self-esteem issues, or unhealthy behaviours. While exercise alone is a poor choice if your goal is weight loss, those that engage in regular exercise alongside eating healthily find it easier to maintain a healthy weight. People who maintain a healthy weight through food choices and exercise report improved self-esteem, self-confidence, levels of energy and physical activity, general mood, and physical health. On top of those benefits, just 30 minutes of running during the week boosts sleep quality, mood, and concentration. In light of all this evidence, doctors have begun prescribing physical activity for depression and anxiety alongside accepted medications and therapies.
Physical activity can also improve brain function by changing its physiology, including both the structure and physiochemical makeup of the central nervous system. While endorphins modulate mood and reduce stress, they are often dysregulated, imbalanced, or not properly registered by receptors in those suffering from various mental disorders including anxiety, depression, bipolar disorder, and schizophrenia. Serotonin is implicated in depression but the full mechanism is more complex. Depression is described as being stress-related, behaviourally linked, and a biochemically heterogeneous disease. Some examples of new biochemical markers of mental disturbance includes the neurotransmitter GABA, or MOA-A, an enzyme which breaks down serotonin. Today, mental disorders are understood to be as much related to innate biology as internal emotional states. This means that some people are predisposed to depression because of their brain structure or chemical imbalances. The hippocampal region, which is related to learning, memory, and emotion, is smaller in depressed people and reduces in size over time. There is a known correlation between the length of depression and decreased hippocampal size and neural degeneration.
Exercise has been shown to induce neurogenesis and is positively correlated with overall brain health. This is reported to stem from increased blood flow via increased blood vessels, strengthened neuronal synaptic structures and potentials, and the induction of growth factor cascades, which all protect the brain from neurodegeneration. Brain-derived neurotrophic factor (BDNF) is one such growth factor and it enhances neural cell survival and activity. Exercise induces neurogenesis in the dentate gyrus and hippocampal subregion, which is implicated in cognitive aging. General aerobic exercise also increases brain volume, especially in more aged adults. The positive correlation of physical exercise, brain growth, and neuroplasticity means that cardiovascular fitness is beneficial for cognition in general, including decreasing the risk of Alzheimer’s disease and dementia.
Intense physical exertion at 70-85% of the heart rate reserve has a therapeutic effect on people with depression. Nicole/Flickr (CC BY-NC 2.0)
Physical exercise combats depression by altering both the emotional and physical mind. As there is an intimate mind-body connection, mental health also affects physical health. People with depression report somatic (body) responses and experience increased fatigue, insomnia, nausea, and back pain compared to the general population. Major depressive disorder is also correlated with accelerated bodily ageing and serious co-morbidities, including cardiovascular disease and diabetes. Cardiovascular fitness and exercise have been shown to help keep the body healthier for longer. Those who exercise regularly have decreased risk of depression, cancer, and chronic diseases including diabetes, arthritis, and hypertension.
By adding exercise to your life, even just the minimum amount, you can extend your life by years, and these are likely to be years with greater physical, emotional, and mental wellbeing. Happy people also live longer. These outcomes are resultant not only from physical movement, but also new habit patterns. Exercise can be a keystone health habit, which precedes the adoption of other healthy behaviours like getting more sleep and making healthier food choices. Among current runners, three out of four previous smokers have quit the habit.
The effects of exercise on the body are apparent, but research suggests that a sound body and sound mind are related. While we still have a lot to learn about mental health disorders, exercise is a sustainable and low-risk activity that regulates both our physical and mental health.
Edited by Ena Music.
