How Physical Exercise Benefits Your Brain
A large body of evidence has demonstrated that physical exercise affects brain plasticity, and influences your cognitive abilities and wellbeing. The studies done on molecular and epigenetic levels have confirmed that exercise induces structural and functional changes in the brain, determining enormous biological and psychological benefits.
According to WHO (2010), physical exercise is a sub-classification of physical activity that is planned, structured, repetitive, and has a final or an intermediate objective, the improvement or maintenance of one or more components of physical fitness. The WHO has defined physical exercise quite accurately. But, what is under-appreciated is that exercise also benefits the mind, improves memory and cognitive functions, while delaying cognitive decline linked to aging. (1)
Studies in young and older adults showed that exercise enhances cognitive functions, improving memory, efficiency in attentional processes, executional control, and academic achievements. Moreover, it has been shown that people who practice physical exercise regularly are less depressed and anxious than those who do not.
How Does Physical Exercise Keep Your Brain Healthy
1. Structural and functional effects
According to study reports, structural changes in the human brain were indicated by increased gray matter volume in the frontal and hippocampal regions. Other studies have shown an increased level of brain-derived neurotropic factors (BDNF). BDNF is a protein that helps in the production of new brain cells and protection of existing ones. (2) Moreover, exercise increases blood flow and improves glucose and lipid metabolism that serves food to the brain. (3)
2. Concept of cerebral reserves
It is a mechanism that might explain why the neurodegenerative changes despite being similar in nature and extent, vary in people in terms of severity of cognitive aging and dementia.
There are two types of reserves recognized; brain reserve and cognitive reserve. Brain reserve is about the protective ability of anatomical features of brain such as brain size, neuronal density, and connectivity of synapses. Cognitive reserve is based on efficiency of connectivity among neuronal circuits.
According to this concept and taking into account all the evidences it could be said that physical exercise is an environmental factor that permits to gain reserves. This reserve helps in protecting and preserving the cognitive function in old age. (3,4)
3. Epigenetic Mechanism
Epigenetics account for how genes interact with environment to produce the phenotype (to express themselves). Several molecular processes underlying epigenetic mechanisms have been demonstrated to be involved in keeping brain healthy.
It is a process by which methyl groups are added to the DNA molecule. It plays a key role in long-term memory. DNA methylation affects gene expression by repressing gene transcription. Here it is important as it relieves the repressive effects of memory suppressor genes to favour the expression of memory consolidation genes. Several evidences have shown that physical exercise is able to coordinate the action of genes involved in consolidation processes. (5)
Histone modifications are chemical changes in the histone proteins (like methylation, acetylation) that occur after translation process. Studies show that histone acetylation is a requisite for long-term memory.
There are specific enzymes that take part in these changes regulating gene expression. It has been evidenced that four weeks of exercise induced an increase in the activity of enzymes involved in acetylation and deacetylation of histones, determiming an increase in the expression if BDNF. (6)
micro RNAs are small, single stranded RNAs that are able to inhibit the expression of some genes. They participate in cell division, differentiation, synaptic plasticity, and memory consolidation process in the brain. Recent studies have showed that physical exercise can reduce the harmful effects of traumatic brain injury and aging on cognition by regulating the expression of specific microRNAs. (7)
4. Release of protein cathepsin B
Researchers at NIH’s National Institute of Aging conducted a study involving 40 healthy young adults aged between 19 and 34 years. The protein cathepsin B levels were compared in people after four months of physical exercise to those who did not exercise. A significant increase in cathepsin protein levels was observed in individuals who performed regular exercise. They found an association between increase in cathepsin B and the ability of the participants to recall and accurately draw a complex assemblage of lines and geometric shapes, that is often used to assess visual memory. (8)
5. Lowering the oxidative stress
It was shown that there was an abnormal oxidative stress in people with depression or bipolar disorder. Physical exercise especially that of high intensity reduces oxidative stress and improves mood. (9)
What Kind of Physical Exercise is Beneficial for Brain Health
Aerobic and anaerobic exercise - difference
Aerobic and anaerobic exercises have different effects on cognitive functioning. While performing aerobic exercise there is enough oxygen intake needed to carry out the activity without using additional energy from other sources such as muscles. Here, the ATP is synthesized continuously by aerobic mechanisms, adjusting intensity of exercise (from low to high), duration, and oxygen availability. Examples of aerobic exercise are jogging, running, cycling, swinging, spinning, and dancing.
In contrast, during anaerobic exercise the oxygen intake is not enough to supply the energy demands of your muscles so the body starts using muscle ATP reserves and producing ATP from anaerobic mechanism that is lactic acid. Examples of anaerobic exercise are weight lifting or sprint 100m.
The success of physical exercise programs depend on several factors such as intensity, frequency, duration, and whether the exercise is performed alone or in group. (1)
Benefits of aerobic exercise
Chronic aerobic exercise is linked with neuroplastic changes, an improvement in cognitive functions, and increased feeling of wellbeing. Acute aerobic exercise aka single bout exercise have also been shown to improve cognitive functions but the effects were generally small. Acute exercise of moderate intensity enhances mood and general wellbeing in people with major depression, increase working memory and cognition.
A study by Brown et. Al showed that high intensity exercise in elderly gives greater benefits to cognitive functions.
For psychological benefits, in cases of anxiety and depression most benefits are achieved by longer training programs of several months as compared to shorter programs lasting for some days for training sessions of over 30 minutes. (10)
Yoga and other anaerobic exercises in which there is rhythmic abdominal breathing, enjoyment, repetitive movements and no relative competition provides positive mood changes. (11)
Exercise means different things to different people. There is no doubt that exercise is important for a healthy body and brain. But it should be noted that physical exercise must be tailored to the individual. Even physical exercise when excessive, may be harmful, when it becomes compulsive and brings about addictive behaviours.
1. Mandolesi L, Polverino A, Montuori S, Foti F, Ferraioli G, Sorrentino P and Sorrentino G (2018) Effects of Physical Exercise on Cognitive Functioning and Wellbeing: Biological and Psychological Benefits. Front. Psychol. 9:509. doi: 10.3389/fpsyg.2018.00509
2. Hötting, K., Schickert, N., Kaiser, J., Röder, B., and Schmidt-Kassow, M. (2016). The effects of acute physical exercise on memory, peripheral bdnf, and cortisol in young adults. Neural Plast. 2016, 1–12. doi: 10.1155/2016/6860573
3. Mandolesi, L., Gelfo, F., Serra, L., Montuori, S., Polverino, A., Curcio, G., et al. (2017). Environmental factors promoting neural plasticity: insights from animal and human studies. Neural Plast. 2017, 1–10. doi: 10.1155/2017/7219461
4. Stern, Y. (2002). What is cognitive reserve? Theory and research application of the reserve concept. J. Int. Neuropsychol. Soc. 8, 448–460. doi: 10.1017/S1355617702813248
5. Deibel, S. H., Zelinski, E. L., Keeley, R. J., Kovalchuk, O., and McDonald, R. J. (2015). Epigenetic alterations in the suprachiasmatic nucleus and hippocampus contribute to age-related cognitive decline. Oncotarget 6, 23181–23203. doi: 10.18632/oncotarget.4036
6. Maejima, H., Kanemura, N., Kokubun, T., Murata, K., and Takayanagi, K. (2018). Exercise enhances cognitive function and neurotrophin expression in the hippocampus accompanied by changes in epigenetic programming in senescence-accelerated mice. Neurosci. Lett. 665, 67–73. doi: 10.1016/j.neulet.2017.11.023
7. Saab, B. J., and Mansuy, I. M. (2014). Neuroepigenetics of memory formation and impairment: the role of microRNAs. Neuropharmacology 80, 61–69. doi: 10.1016/j.neuropharm.2014.01.026
8. Exercise Releases Brain-Healthy Protein -NIH director's blog.
9. Urso, M. L., and Clarkson, P. M. (2003). Oxidative stress, exercise, and antioxidant supplementation. Toxicology 189, 41–54. doi: 10.1016/S0300-483X(03) 00151-3
10. Weinberg,R.S.,andGould,D.(2015).Foundationsofsportandexercisepsychology, 6th Edn. Champaign, IL: Human Kinetics.
11. Berger, B., and Motl, R. (2001). “Physical activity and quality of life,” in Handbook of Sport Psychology, eds R. N. Singer, H. A. Hausenblas, and C. Janelle (New York, NY: Wiley), 636–670.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
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© 2018 Sherry Haynes