Feeling down is something we can all relate to right now. The pandemic has left us with less social contact and more stress. One study in the Journal of the American Medical Association (JAMA) reported an increase in serious psychological distress by almost 10%, from 3.9% in 2018 to 13.6% in 2020. So now would be a good time for all of us to take inventory – how are we feeling?
The answer to this question can relate to your general attitude about life, how you manage stress, your confidence, and your outlook for the future.
Benefits of Exercising for Mental Health
Exercise is known to be part of your physical health, but it can also be a key part of your mental health. The positive impact of exercise on improving mood is not a new phenomenon, but recent research validates our experience and helps us understand how this works in the body and brain.
Some major benefits of exercise for your mental health include:
1) Reducing depression and anxiety, stress, and symptoms associated with Attention Deficit Hyperactivity Disorder (ADHD), Post-traumatic Stress Disorder (PTSD), and trauma.
2) Increasing alertness, cognition, and confidence,
3) Reducing the risk for Alzheimer’s disease and dementia,
4) Improving sleep, and
5) Increasing social interaction
The scientific literature is clear that working out can improve mental health. Below are a few takeaways for exercise prescription from the experts:
- Even a simple 12-week resistance and walking program can significantly reduce Post-Traumatic Stress Disorder (PTSD) symptoms, as well as depression, waist circumference, body weight, and body fat percentage.
- Aerobic sessions (elevated heart rate for 20 minutes) on a stationary bike can significantly reduce PTSD symptoms*.
- Due to individual differences in hormones and aerobic training, exercise programs should include periodization (increasing and decreasing intensity throughout the year) to avoid overtraining, and be tailored to individual needs.
- Exercise outdoors when possible, as studies show people tend to exercise for longer and are more likely to continue when compared to exercising indoors (see Coon et. al, 2011 for review).
- Physicians recommend starting with 20 minutes, 3 times per week to depressed patients.
- Exercise at 60% of maximum heart rate (or effort) can elicit the elevated cortisol response needed for positive adaptations for stress (see below for discussion, also Lasby et al 2013).
- Exercise at 70-80% for short bouts (5-10 minutes) can be effective for improving mood and euphoria.
- Exercise an average of 30 minutes per day elevates serotonin (chemical released by the brain) levels and improves processing of emotions.
Read more below about each of the positive effects of exercise.
Depression & Anxiety
Associations between loneliness and mental health problems are present in both adolescents and adults. Exercise can mediate the symptoms of many mental health disorders such as depression and anxiety (and Stubbs et. al, 2017). Many studies have reported this result, showing exercise improves anxiety and depression symptoms in rats, as well as symptoms of Major Depressive Disorder (MDD) in humans. For example, one study showed primary care outpatients with low activity levels were 6.0 times more likely to be severely depressed than patients with more normal activity levels.
A physical education survey from 2007 observed that physical exercise can reduce anxiety symptoms, with lower anxiety levels in the group that achieved better aerobic fitness.
There are several ways the body benefits from exercise to reduce stress. Cortisol is a hormone released during exercise as well as psychological stress. However, the differences can teach us about how exercise helps us adapt to cortisol, releasing small amounts in a controlled environment. This gives us more protection when encountering life’s stressful situations.
For example, research shows cortisol levels in the bloodstream are elevated for up to 2 hours post exercise. Aerobic exercise over 60% of max heart rate has been shown to elicit an adaptive response to cortisol, as measured by blood plasma and saliva. While both physical and psychological stress cause a release of cortisol, trained individuals are more able to convert active cortisol into inactive ‘cortisone’ during psychological stress (see Hejnen et. al, 2016 for review). This process is protective against the harmful effects of cortisol, including hypertension, hyperglycemia (high blood sugar), major depressive episode, and anorexia.
In addition, exposure to cortisol from physical but not psychological stress is accompanied by an increase in growth hormone, and blunts the response to cortisol levels and negative events in major depression.
ADHD, PTSD, & Trauma
ADHD (Attention Deficit Hyperactivity Disorder) is an executive function and self-regulation disorder defined by both neurological and behavioral characteristics (see ‘What is ADHD’ at cdc.gov). Since this disorder affects emotional processing, verbal and working memory, as well as social skills, it is important to mediate symptoms. Children with ADHD are more likely to develop occupational, educational, and relationship impairments if left untreated. Medication can be effective, but 20% of children experience some adverse side effects.
Physical activity has been shown to be associated with reducted anxiety and mood disorders for which people with ADHD are at risk, as well as physical benefits such as reducing risk of obesity and chronic disease. For example, one study from 2016 in children ages 6-12 showed that a 10-week after school program with 60 minutes of exercise per day improved cognitive and behavioral outcomes such as hyperactive symptoms, verbal working memory, and visuospatial memory. Short bouts (5-minute relay) of intense exercise of 65-85% have also been shown to improve attention and performance for participants with ADHD on a computer game by 30% as compared to their peers who did not do the relay, and by 40% compared to children with no ADHD symptoms.
Other systematic reviews of the literature have also concluded exercise can be effective for reducing depression, and that active games and sports for children can be an affordable and accessible way for all ages and backgrounds to learn social skills with peers and adults.
PTSD & Trauma
Studies in humans show that exercise reduces symptoms of Post-Traumatic Stress Disorder (PTSD) and other trauma, associated with an increase brain-derived neurotropic factor (BDNF), These studies also show that even a 12-week resistance and walking program significantly reduced PTSD symptoms, as well as depression, waist circumference, body weight, and body fat percentage.
Another study from 2014* showed 89% of participants showed significantly reduced PTSD symptoms after 2 weeks of aerobic sessions on a stationary bike. A study looking at interventions in military veterans also suggests exercise is a potential help in reducing PTSD and recommend continuing research into long-term effects.
Reduces Risk for Alzheimer’s and Dementia
Exercise can also help mediate and reduce risk for Alzheimer’s and Dementia. The increases in blood pressure associated with exercise allow blood to circulate through the blood brain barrier.
Studies in recent decades have shown the positive effects of exercise on health and brain function, specifically in the brain area known as the hippocampus involved in learning and memory. Existing (and growing) brain cells can then receive nutrients and remove waste, preventing the cell death associated with these diseases (see Malkiewicz et. al, 2019 for review).
Alertness, Cognition, & Confidence
Exercise has also been shown to modulate mood (also Sparling et al., 2003). Chemicals called ‘neurotransmitters’ are released in response to physical stress (i.e. exercise) as well as to psychological stress and play a crucial role in the beneficial effects of aerobic exercise on mood (see Hejnen et. al, 2016 for review).
Specifically, these neurotransmitters result in increased amounts and time a chemical called Brain-derived neurotropic factor (BDNF) is circulating in the brain (also Ferreira-Vieira et al., 2014). BDNF is positively correlated with cognitive performance, and increases our ability to learn. In contrast, decreases in BDNF have been observed following psychological stress in rats*, as well as humans.
Other studies show exercise resulted in higher alertness, decreased impulsiveness, and increased reaction speed. In addition, physical activity also improved the performance of children on tasks that require attention.
Mechanisms – Dopamine & Serotonin
Exercise also helps modulate hormones such as serotonin and dopamine, two of the chemicals involved in increasing mood, concentration and alertness, outlook, and confidence. For example, serotonin, a neurotransmitter important for emotional processing and memory, increases in the brain following acute exercise due to increases in blood pressure and permeability through the blood-brain barrier. In studies done with rodents, serotonin levels stayed elevated in the cerebral cortex and brainstem following 30 minutes daily of swimming for 4 weeks for up to a week (also Meeusen and De Meirleir, 1995).
Increases in dopamine in other brain areas such as hypothalamus, midbrain, and brainstem have also been shown in animals in response to aerobic exercise. Physical stress has also been shown to be associated with increases in dopamine (also Heyman et al., 2012) in humans, further supporting the beneficial effects of exercise on memory and mood. One study from 2016 showed intense exercise of 65-85% of heart rate max is associated with improved attention. It also notes a correlation with increase serotonin, dopamine, and another chemical epinephrine, which has been corroborated by other peer-reviewed research studies* and literature.
In contrast, psychological stress can increase serotonin levels to the point of depletion, and is associated with decreases in BDNF in the hippocampus.
Increases in Confidence
Exercise increases confidence, which is also lacking in many common mental health disorders. This boost in confidence comes from following through on an aspect of your life that you can control, such as increasing the amount of weight you can lift or miles you can run, versus something you cannot directly control like the weight on the scale.
Called ‘self-efficacy’, research shows exercise improves this feeling for the general population* (also Brown et. al, 1992*, see Craft et. al, 2004 for review). Improvements in self-efficacy have in turn been shown to be associated with decreases in depression.
Exercise also improves sleep, as well as muscle strength, cardiovascular function, hypertension, and diabetes, and can even reduce mortality in women (also van der Kooy K, 2007).
Another study in 2014 with inpatients* given 3, 30-min resistance training programs and a pedometer walking program, found significant improvements in depressive symptoms, waist circumference, sleep quality, and sedentary time. Thus, the benefits of exercise extend beyond sleep to multiple aspects of physical health.
Improves Social Interaction
Exercise is also typically associated with an increase in social interaction, which, when lacking, has been shown to be as detrimental to health as smoking. One 1991 study with elderly adults showed that social contact can be just as effective as exercise for reducing depression symptoms, but exercise also reduces pain, weakness, and shortness of breath. One recent study from 2021 showed participation in sports improved depression symptoms more than medication alone, as well as showing additional benefits for multiple aspects of physical health.
*Only available on PubMed.
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