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We often hear how important exercise is for our physical health, the connection between exercise and good physical health seems obvious to us. What is less obvious is that exercise can also have a positive impact on our mental health. This post is going to explore the different ways in which physical exercise impacts our physical and mental health in ways you may or may not know about. In addition, this post is going to explore why exercise is good for us by looking at how exercise impacts our brains.
Mental Health Impact of Exercise
First let us look at some of the different mental health conditions that have been examined in relation to exercise.
Serious Mental Illness
A review and meta-analysis was conducted by Pearsall and colleagues on exercise interventions with individuals who have a serious mental illness . In this meta-analysis serious mental illness meant patients who had diagnoses or symptoms of schizophrenia, bipolar disorder, or schizoaffective disorder (when someone has both psychotic symptoms and mood symptoms such as depression or mania).
It is important to study those with serious mental illness as they have a higher risk of cardiovascular disease, diabetes, and metabolic problems (e.g., high blood pressure). These problems are thought to be due in part to genetics and due to lifestyle factors such as cigarette smoking, obesity, poor diet, and low levels of exercise.
In terms of overall findings, the Pearsall and colleagues’ meta-analysis found that while exercise interventions improved overall levels of physical activity, the interventions did not improve symptoms of schizophrenia, depressive symptoms, anxiety symptoms, body weight, or body mass index, or either mental or physical quality of life.
This is somewhat surprising, particularly when compared to other reviews or meta-analyses that found beneficial effects (as discussed below). Some potential reasons for these findings include the studies not using intense enough exercise programs or not being long enough to find beneficial effects. An alternative reason might be that those with serious mental illness experience symptoms that are too severe to be aided by physical exercise interventions. This does not appear to be what other research suggests, but it could be a possibility. While it is disenheartening to start off with a meta-analysis that found no results, it is important to always consider research that does not support your conclusion instead of merely ignoring it or avoiding it. So keep a questioning mind as we discuss other meta-analyses and reviews.
In contrast to the Pearsall and colleagues meta-analysis, a meta-analysis by Rosenbaum and colleagues of 39 randomized trials found that physical activity reduced depressive symptoms for those with mental illness . In addition, the meta-analysis found that physical activity reduced symptoms of schizophrenia and improved aerobic capacity, anthropometry (i.e., waist circumference, body weight, body mass index), and quality of life for those with mental illness. According to Rosenbaum and colleagues, they appear to have found positive effects for the impact of exercise on schizophrenia symptoms due to including several Chinese studies that were not included in other reviews.
As Rosenbaum and colleagues note, few interventions positively impact both physical and mental health symptoms with few risks of adverse effects. As such, physical activity appears somewhat uniquely suited as an intervention for those with mental illness.
Let us look at some more studies that examine the impact of exercise on depressive symptoms more specifically.
Silveira and colleagues  conducted a review and meta-analysis of studies that examined the impact of exercise interventions for patients with major depressive disorder. This meta-analysis found that physical exercise, particularly aerobic exercise, improved patients’ response to psychopharmacological treatment (i.e., medication). This relationship was impacted by the patients’ age and severity of symptoms; elderly patients and patients with mild depressive symptoms responded better to physical exercise compared to other groups.
A review by Mammen and Faulkner  looked at longitudinal studies that examined whether physical activity prevents later depressive symptoms. The final review included 30 studies, 25 of which showed that physical activity prevented later depressive symptoms. Most of these studies were determined to be high quality in terms of research design, which increases the confidence one has in the results.
This review also found that an individual does not necessarily have to engage in a lot of exercise to gain a benefit for preventing depressive symptoms. Some of the studies found that even 10 to 20 minutes of daily walking can prevent depressive symptoms and that even this low to moderate amount of walking cut the risk of depressive symptoms in half. It does appear overall that the more one walks, the greater the mental health benefit. However, this should give people encouragement that if walking for 30 minutes seems too overwhelming at first, starting with shorter walks or other physical activity can still yield positive mental health benefits.
So physical activity appears to help with depressive symptoms. Let us next explore how physical activity relates to depression’s close relative, anxiety.
A review of the impact of exercise on anxiety symptoms found that exercise improves anxiety symptoms by working through both physiological and psychological mechanisms . In terms of physiological mechanisms, exercise impacts the hypothalamic-pituitary-adrenal (HPA) axis and the monoamine system. The HPA axis is important for our body’s reaction to stress and dysregulation of the HPA axis has been associated with both depressive and anxiety problems. It is believed that exercise helps regulate the HPA axis by altering the release of stress hormones, which in turn helps reduce anxiety symptoms.
The monoamine system is another physiological mechanism that impacts anxiety symptoms. Monoamines refer to a class of neurotransmitters that include dopamine, noradrenaline, and serotonin. Research shows that monoamines, including dopamine and serotonin, are related to depressive and anxiety symptoms. Research has also shown that exercise increases serotonergic and noradrenergic levels in the brain, which is a similar mechanism as antidepressants. As such, exercise can serve as a natural ‘antidepressant’ that impacts both anxiety and depressive symptoms.
In terms of psychological mechanisms, a construct called ‘anxiety sensitivity’ appears to be associated with exercise. Anxiety sensitivity is characterized in part by a fear and avoidance of experiencing physical symptoms (e.g., racing heart, sweaty palms, shortness of breath). Exercise is believed to reduce the amount of anxiety sensitivity an individual has. This is likely in part due to individuals exposing themselves to the physical symptoms they are avoiding as a part of the exercise. Given that exposure is the recommended treatment for anxiety problems, individuals who exercise are in essence providing themselves with treatment for physical anxiety symptoms.
In addition to anxiety sensitivity, self-efficacy appears to be help explain the relationship between exercise and anxiety symptoms. Self-efficacy, which refers to a person’s perceived ability to succeed in a task, reduces a person’s perceived anxiety. Essentially, the more control a person generally feels that they have in life, the less anxiety they will experience. Exercise provides one way that people can feel like they have more control over their lives and as such helps improve mental well-being.
Lastly, exercise may help with anxiety symptoms as it is a good distraction from anxiety. When people are focused on working out, it takes away their ability to focus on anxious thoughts and feelings. While distraction is not typically the best way to deal with anxiety long-term, sometimes some distraction in the short-term allows us to better manage our emotions and behaviors.
Lots of really interesting ways in which exercise can positively benefit our mental health. Let us explore some other ways that exercise physically impacts our brain.
Physical Impact of Exercise on the Brain
First up is a concept called neurogenesis. Neurogenesis, or the growth of new cells, is a reason why exercise appears to be associated with improved mental health. A review of available research examined how physical training and mental training improve cognition by neurogenesis in the hippocampus, a brain area that is particularly involved with learning and memory .
The review found that physical activity, particularly aerobic exercise, increases the number of neurons produced in the hippocampus. In contrast, mental training by skill training (e.g., memory games) increases the number of cells that survive in the hippocampus, especially when the training goals are challenging. Overall, the review notes that the best performance occurs when both mental and physical training occurs as opposed to either one alone.
Related to neurogenesis is a protein called brain-derived neurotrophic factor (BDNF), which helps support the survival of existing neurons and encourages the growth of new cells and synapses. A review by Huang and colleagues examined the impact of physical exercise on BDNF .
The review found that experimental studies (i.e., ones that tested different conditions in a controlled setting) indicate that BDNF increases in response to acute and chronic aerobic exercise. In addition, most studies found that strength training has no impact on BDNF. Findings from observational studies (where no interventions are provided) were generally contradictory, although seemed to indicate that there was an inverse relationship between consistent physical activity and BDNF levels. Why the experimental and observational studies had opposite findings is not presently understood and needs to be explored more with additional research.
A review by Bherer and colleagues examined the impact of physical activity on cognition in older adults . As discussed in the review, while exercise is believed to have a direct impact on cognition, it can also impact cognition in indirect ways. For example, exercise leads to better sleep and reducing stress, which are in turn both related to cognition. Physical exercise has been associated with something called angiogenesis, which is the process which new blood vessels grow from already existing blood vessels.
In addition, the Bherer and colleagues review found that physical exercise is associated with neurogenesis in the hippocampus. While a lot of the research so far has been completed with animals, the studies suggest that exercise leads to changes in molecular growth factors such as BDNF, which plays an important role in neuroplasticity and protection of the neurons. In addition, exercise appears to be related to the production of insulin-like growth factor 1 (IGF-1), which is related to neurogenesis and angiogenesis.
The Bherer and colleagues review states that exercise is associated with other positive brain changes. For example, increased fitness has been associated with a reduced loss of grey and white matter in the frontal, prefrontal, and temporal regions in older adults. Another study found that increased fitness was associated with larger hippocampal regions, which corresponded to better spatial memory performance.
Taken together, these studies indicate that exercise can help improve cognitive performance on a variety of tasks and measures. Future research will have to disentangle the impact of other factors, such as diet, from the impact of physical activity.
Physical exercise improves our physical and mental health. This post examined some of the mental health benefits of physical activity, particularly for depression and anxiety, as well as some of the ways that physical activity impact our brain functioning.
Researching this topic has been interesting because clinically, while I have always known that exercise is good for you, rarely is much time in sessions spent discussing a client’s level of exercise. Clinicians tend to discuss exercise as a way to increase self-esteem and provide client’s with a sense of mastery. Less often do we see exercise as a way to specifically combat depressive symptoms or anxiety. Reading this research makes it apparent how important it is that we all engage in at least some physical activity every week, even if it is going for a brief walk around the neighborhood.
Engaging in physical activity every week should be prioritized for both good physical health and mental health. This is sometimes easier said than done, particularly when we are busy, stressed out, etc. Unfortunately, those are also the times we probably need the physical activity the most. If going to the gym and working out seems too overwhelming, start smaller, like taking a walk around the block. Eventually you can work your way up to more if you want to, but even taking 10 minutes to walk around and stretch your legs will likely help improve your mood.
No one is perfect at exercising, it is all about doing what we can, when we can and not beating ourselves up if we do not meet a goal we set. Living a healthy and balanced life is a daily commitment, so let us all try to take stock of our current exercise habits. If your exercise habits are not as good as you want them to be, try to make a 5 or 10% change over the next week and see what happens. Worst that happens is you learn what does or does not work for you. Good luck to us all!
 Pearsall, R., Smith, D. J., Pelosi, A., & Geddes, J. (2014). Exercise therapy in adults with serious mental illness: A systematic review and meta-analysis. BMC Psychiatry, 14(117). doi:10.1186/1471-244x-14-117
 Rosenbaum, S., Tiedemann, A., Sherrington, C., Curtis, J., & Ward, P. (2014). Physical activity interventions for people with mental illness: A systematic review and meta-analysis. The Journal of Clinical Psychiatry, 75(9), 964-974. doi:10.1016/j.jsams.2014.11.161
 Silveira, H., Moraes, H., Oliveira, N., Coutinho, E. S., Laks, J., & Deslandes, A. (2013). Physical exercise and clinically depressed patients: A systematic review and meta-analysis. Neuropsychobiology, 67(2), 61-68. doi:10.1159/000345160
 Mammen, G., & Faulkner, G. (2013). Physical activity and the prevention of depression: A systematic review of prospective studies. American Journal of Preventive Medicine, 45(5), 649-657. doi:10.1016/j.amepre.2013.08.001
 Anderson, E., & Shivakumar, G. (2013). Effects of exercise and physical activity on anxiety. Frontiers in Psychiatry, 4(27), 1-4. doi:10.3389/fpsyt.2013.00027
 Curlik, D., & Shors, T. (2013). Training your brain: Do mental and physical (MAP) training enhance cognition through the process of neurogenesis in the hippocampus? Neuropharmacology, 64(1), 506-514. doi:10.1016/j.neuropharm.2012.07.027
 Huang, T., Larsen, K. T., Ried-Larsen, M., Møller, N. C., & Andersen, L. (2013). The effects of physical activity and exercise on brain-derived neurotrophic factor in healthy humans: A review. Scandinavian Journal of Medicine & Science in Sports, 24(1), 1-10. doi:10.1111/sms.12069
 Bherer, L. (2015). Cognitive plasticity in older adults: Effects of cognitive training and physical exercise. Annals of the New York Academy of Sciences, 1337(1), 1-6. doi:10.1111/nyas.12682
The Clinically Relevant Insights Blog, part of ShawnWilsonPhD.com, shares news and research regarding psychology and wellness.