Written by: Rebecca Ladouceur
Graphics by: Jaimini Patel
Introduction
The brain is arguably the most important organ in the body, as it is essential in nourishing and regulating all of our body’s structures and functions. Our brains are what allow us to focus on our favourite sports, process and laugh at jokes on our favourite sitcoms, and enjoy the taste of our favourite desserts. One of the most beneficial ways we can strengthen the brain is through exercise. By moving the body on a regular basis, not only can we improve our lifestyle, but we can improve cognitive efficiency and help slow down the aging process. In addition, exercise plays a role in increasing mood and regulating the stress response. This article takes a deeper look into the types of physical activity and how exactly they can optimize the brain’s functioning.
Two Types of Exercise
Physical activity can be broadly split into two categories - endurance and resistance exercise. Endurance training , also known as aerobic training, is defined as any action that brings the heart and breathing rate up. Examples of endurance activities include running, swimming, cycling, dancing, and walking. On the other hand, resistance training, also called anaerobic training, is defined by exercising muscles against a resistance, causing them to contract (6). Different types of resistance exercises can be done with dumbbells, resistance bands, medicine balls, weight machines, and even one’s own body weight.
In this article, we will be examining four ways that physical activity positively affects the brain: in facilitating plasticity and growth, in slowing down aging, by increasing mood, and by strengthening the stress response.
Cognition/Plasticity
Exercise has numerous positive effects on increasing neural connections and strengthening brain functions. Exercise has been shown to stimulate the growth of new connections between cells in the cortex of the brain, thereby promoting neural intermingling and strengthening signals. A UCLA study demonstrated how exercise promotes the maturation of new growth factors in the brain to grow new neural connections (1). Specifically, resistance exercise has been shown to improve cognitive abilities through creating new connections within the hippocampus (8). In fMRI studies comparing the brains of athletes versus non-athletes, scientists have consistently found that the prefrontal cortex, the section of the brain responsible for thinking, focus, and attention, is bigger (6). Overall, scientists have concluded that regular aerobic and anaerobic exercise for at least six months has led to significantly larger brain regions (the prefrontal and temporal cortex) and improved mental functioning (6). These larger brain regions brought about by exercise mean a greater capacity for executive functioning and reasoning, thinking, and memory, among others.
Aging
Through aging, memory declines seem almost inevitable, however exercise can help slow down this process. As we get older, the hippocampus, the area of the brain responsible for spatial orientation and memory, naturally decreases in size. As a result, neuronal memory connections can be lost in a process called neurodegeneration, leading to an increased risk for dementia and impaired memory (4). Seeing as aerobic training increases the size of the hippocampus, scientists have correspondingly seen improvements in memory, actually reversing hippocampal volume loss in adulthood (4). Because of the role exercise also plays in enhancing neurogenesis and brain plasticity, exercise can be a viable tool in delaying or treating cognitive decline. Rat and human studies have demonstrated how long-term exercise is helpful in delaying cognitive decline due to hippocampal degeneration and dementia (2).
Mood
Scientists have found that long-term exercise helps to improve mood, with benefits lasting up to 24 hours after a bout of exercise (3). Serotonin is a neurotransmitter that is most notably responsible for improving mood. Regular exercise can boost serotonin levels, leading to uplifted and positive feelings after exercise (3). Additionally, exercise can reduce the production of uptake molecules, meaning
serotonin can be present for longer periods of time in the brain (3). In a review of the current literature, it has been consistently shown that performing aerobic exercise everyday reduces the risk of developing mood disorders, many of which are thought to be caused by a lack of serotonin (7). Not only can exercise lead to feelings of happiness right after a workout, these
benefits have a chronic effect on staying happy.
Stress response
Everyone experiences stress, whether it be day-to-day acute stress, or chronic stress due to too much homework piling up. Studies researching the HPA axis and the stress response have found strong evidence as to how exercise can help to reduce stress. The HPA (hypothalamic-pituitary-adrenal) axis is a system in our body that is responsible for regulating our stress response through the release of cortisol, also known as the stress hormone. Seeing as exercise is a physiological stressor on the body, it is able to activate the HPA axis and its associated hormones, namely cortisol (5). With consistent exercise, we are able to practice how we face stressful situations and release cortisol to fight them. This means that when we are faced with future stressors, our bodies will be better equipped to release cortisol to face that stressor (5). Exercise trains our bodies for the “fight” in the common saying “fight-or-flight response”, and allows us to be better able to fight stressors coming our way!
Conclusion
Hundreds of studies have focused on the many benefits exercise has on brain structure and function. Both aerobic and anaerobic exercise have proven to be beneficial in many aspects, notably in cognition, aging, mood, and the stress response. Although this article is only scratching the surface of the numerous benefits of exercise, we hope that it has convinced you to increase your activity levels in your day-to-day life.
References
Armstrong G-FGB. How Exercise Affects Your Brain [Internet]. Scientific American. Scientific American; 2018. Available from: https://www.scientificamerican.com/article/how-exercise-affects-your-brain/
Basso JC, Suzuki WA. The Effects of Acute Exercise on Mood, Cognition, Neurophysiology, and Neurochemical Pathways: A Review. Brain Plasticity. 2017;2(2):127–52.
Cordeiro L, Rabelo P, Moraes M, Teixeira-Coelho F, Coimbra C, Wanner S, et al. Physical exercise-induced fatigue: the role of serotonergic and dopaminergic systems. Brazilian Journal of Medical and Biological Research. 2017;50(12).
Erickson KI, Voss MW, Prakash RS, Basak C, Szabo A, Chaddock L, et al. Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences. 2011;108(7):3017–22.
Genc A, Tur BS, Aytur YK, Oztuna D, Erdogan MF. Does aerobic exercise affect the hypothalamic-pituitary-adrenal hormonal response in patients with fibromyalgia syndrome? Journal of Physical Therapy Science. 2015;27(7):2225–31.
Godman H. Regular exercise changes the brain to improve memory, thinking skills [Internet]. Harvard Health Blog. 2020. Available from: https://www.health.harvard.edu/blog/regular-exercise-changes-brain-improve-memory-thinking-skills-201404097110
Hearing CM, Chang WC, Szuhany KL, Deckersbach T, Nierenberg AA, Sylvia LG. Physical Exercise for Treatment of Mood Disorders: A Critical Review [Internet]. Current behavioral neuroscience reports. U.S. National Library of Medicine; 2016. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5423723/
Penttila N. How Does Exercise Affect the Brain? [Internet]. Dana Foundation. Dana Foundation; 2020. Available from: https://www.dana.org/article/how-does-exercise-affect-the-brain/
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