Benefits of exercise
Research has shown that exercise and physical activity is just as beneficial to our minds as it is to our bodies. In fact, engaging in physical activity can actually decrease symptoms of depression (Foley et al., 2008) and anxiety (Broman, Berman, Rabian & Webster, 2004). These benefits have been shown to be enjoyed by people of all ages from university aged students (Tyson et al., 2010) to adults even in their nineties (Sjӧsten& Kivelӓ, 2006).
One of the key characteristics of depression, and a common experience among people experiencing mental health problems, is a lack of energy. This can cause exceptional difficulties when attempting to introduce more physical activity to one’s daily routine. While it may sound counter-intuitive, engaging in regular physical activity can actually increase energy levels. For example, one recent study tested just how effective exercise is at doing so. Researchers asked one group of participants to engage in a low-intensity exercise for twenty minutes, three times a week, on a stationary bicycle. A second group of participants was also asked to do that same exercise, but at a higher intensity rate. When compared to a group that engages in no physical activity, participants in both groups reported feeling more vigorous after completing an exercise session. Additionally, by the third week, all participants in both groups reported lower levels of daily fatigue, compared to participants who engaged in no physical activity. What this shows us is that engaging in even a moderate level of activity (defined as hitting at least 50% of your maximum target heart rate, for twenty minutes a day, three times a week) is enough to see an increase in your levels of energy (Dishman et al., 2010). It is important to keep in mind that while you may not experience increased energy levels after the first day, within a few weeks, levels of fatigue should be reduced.
Another main feature of some mental illness is poor sleep. It is important to understand that when not engaging in sufficient levels of physical activity, our body retains the excess energy. This can prove falling asleep difficult and increase the chances of becoming more easily agitated, irritated or anxious. This excess energy can also lead to having a difficult time sitting still or concentrating. Expending some of the built up energy on exercise, this will make falling asleep at the end of a day much easier and further decrease the risk of depression. Researchers associated with the American Sleep Disorders Association and the Sleep Research Society completed a study to determine if exercise did help improve sleep and quality of life. For ten weeks, adults suffering from depression aged sixty to eighty years old were placed into either a low-intensity or high-intensity exercise programme over ten weeks. At the end of the ten week period, both groups showed a significant improvement in their subjective sleep quality, and depressive symptoms. In addition, they reported that their overall quality of life had also improved (Singh, Clements & Fiatarone, 1997).
As stated above, excess energy increases the likelihood of experiencing anxiety and agitation. By reducing excess energy, the body is less likely to jump into a stress response, which ultimately leads to anxiety. The stress response, also called a fight, flight, or freeze response, is both a psychological and physiological response to real and perceived stressors. When this response occurs, epinephrine (adrenaline) and cortisol surge through the blood stream. This leads to an increase in heart rate and blood pressure, a slowing of the digestive tract, reduced immune system functioning, while blood flow is directed towards muscles and away from organs to aid in fighting or fleeing. Because of the effects of epinephrine and cortisol, when the body enters the stress response the brain is unable to focus on small items and tasks, and can only focus on the big picture items. This is explains a common complaint of being unable to think clearly or focus while anxious. During our ancestral hunter-gatherer days, this response always ended in some sort of vigorous physical activity; either fighting the threat or running away from it as quickly as possible. Thus, when engaging in physical activity or exercise, the body is able to metabolise the stress hormones and allow the fight or flight response to run its course. Even low intensity exercise is enough to reduce cortisol levels in the blood stream (Hill et al., 2008). When someone is in this heightened state for a long period of time, they will likely find it difficult to sleep, experience weight gain, become ill more often than usual and become easily irritated. Thus, using exercise as a coping tool to manage stress will shorten the experience of a stress response, and decrease stress levels in the future.
Additionally, when exercising, the activity of specific brain chemicals such as dopamine and serotonin is activated (Meeusen & De Meirleir, 1995). These are the chemicals in the brain that, when increased, make us feel good and soothed. Although it is not completely known how dopamine and serotonin affect symptoms of depression, research has repeatedly shown a strong correlation between low levels of dopamine and serotonin and an increased risk of experiencing depressive symptoms (Nutt, 2008). One of the most common types of antidepressants prescribed today are Selective Serotonin Reuptake Inhibitors (SSRI). This drug works by targeting the receptors in the brain that control when and how often serotonin is absorbed. However, because these drugs only target Serotonin, and not dopamine, dopamine levels are remaining the same even though serotonin levels are being increased. Participating in physical activity will allow the release of both dopamine and serotonin into the blood stream, bringing both of these levels back into balance, and decreasing the experience of depressive symptoms.
Engaging in regular physical activity can also improve our memory (Foley et al., 2008). When we regularly engage in physical activity, our brain begins to activate growth in a part of our brain called the hippocampus. The hippocampus is responsible for creating and maintaining memories. One study in particular found that adults who engaged in aerobic exercise regularly for a year experienced a 2% increase in the size of this region of the brain, while adults who engaged in no physical activity experienced a 1.4% decrease in size. While this percentage may sound small, it shows that exercise alone can have an impact not only on our brain’s ability to retain information, but it physically effects the growth and size of certain brain regions. It may also help explain why people who experience depression and anxiety tend to have difficulty recalling information(Thomas et al., 2012).
Exercise is also a great tool to help reduce stress levels, as it provides an opportunity to engage in a non-ruminative activity. Rumination occurs when someone obsessively focuses on their distress and the situations, thoughts, and emotions associated with it. For example, when someone reruns a recent argument through their head; focusing on the stress following this argument and imagining the various scenarios the event could have followed. Rumination is also a key factor in depression and anxiety disorders (Nolen-Hoeksema, 2000). Thus, because most exercises require a high level of focus, the brain does not have the time and energy to engage in other activities such as rumination. This allows someone suffering from rumination a welcome break from their anxieties, worries and depressive symptoms.
Adults who do not engage in physical activity tend to lack the ability to properly interpret their own bodily sensations. For example, someone who experiences a high level of anxiety can misinterpret an increased heart rate as meaning that something is wrong with them, or that something in their environment is wrong. This occurs because the only time they have experienced this sensation was while under stressful circumstances and do not figure in the fact that there may be some other reason for that feeling. This happens often in people who suffer from anxiety or panic disorders. The sensation of an increased heart rate often becomes associated with the possibility of an oncoming panic attack, or fears of experience a heart attack. If a person who experiences these types of misinterpretations begins an exercise regime, they will quickly learn that when exercising, their heart begins to increase as a result of increased physical activity. This allows the person to learn that an increased heart rate can also be associated with other situations and decrease how strongly that person responds the next time their heart rate is elevated.
Another helpful aspect of engaging certain types of exercise is that it promotes deep breathing. When experiencing anxiety or stress, breathing becomes shallow and quick. Exercises such as yoga and tai chi encourage deep breathing throughout the practise. Deep breathing helps to slow the heart rate and in turn lowers the stress response, even while not engaging in exercise (Hayano et al., 1994).
Broman-Fulks, J., Berman, M., Rabian, B., & Webster, M. (2004). Effects of aerobic exercise on anxiety sensitivity. Behaviour Research and Therapy, 42(2), 125-136.
Dishman, R.K., Thom, N.J., Puetz, T.W., O’Connor, P.J., & Clementz, B.A. (2010). Effects of cycling on vigor, fatigue, and electroencephalographic activity among young adults who report persistent fatigue. Psychophysiology, 47 (6) 1066-1074.
Foley, L., Prapavessis, H., Osuch, E., De Pace, J., Murphy, B., & Podolinsky, N. (2008). An examination of potential mechanisms for exercise as a treatment for depression: A pilot study. Mental Health and Physical Activity, 1, 69-73.
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Hill, E.E., Zack E., Battaglini, C., Viru, M., Hackney, A.C. (2008). Exercise and circulating cortisol levels: the intensity threshold effect. Journal of Endocrinological Investigation, 31(7), 587-591.
Meeusen, R., De Meirleir, K. (1995). Exercise and Brain Neurotransmission. Sports Medicine, 29(3), 160-188.
Nolen-Hoeksema, S. (2000). The Role of Rumination in Depressive Disorders and Mixed Anxiety/Depressive Symptoms. Journal of Abnormal Psychology, 109(3), 504-511
Nutt, D.J. (2008). Relationship of Neurotransmitters to the symptoms of major depressive disorder. The Journal of Clinical Psychiatry, 69(Suppl E1), 4-7.
Singh, N. A., Clements, K. M., & Fiatarone, M. A. (1997). Sleep, sleep deprivation, and daytime activities: A randomized control trial of the effect of exercise on sleep. Sleep, 20(2), 95-101.
Sjӧsten, N., & Kivelӓ, S. (2006). The effects of physical exercise on depressive symptoms among the aged: a systematic review. International Journal of Geriatric Psychiatry, 21, 410-418.
Thomas, A.G., Dennis, A., Bandettini, P.A., & Johansen-Berg, H. (2012). The effects of aerobic activity on brain structure. Front. Psychology, 3:86. doi: 10.3389/fpsyg.2012.00086
Tyson, P., Wilson, K., Crone, D., Brailsford, R., & Laws, K. (2012) Physical activity and mental health in a student population. Journal of Mental Health, 19(6), 492-499.