HOW DOES EXERCISE CHANGE THE BRAIN?

Exercise is associated with many improved health outcomes, including the reduction of over 40 diseases and conditions (including cardiovascular disease, diabetes, stroke, sarcopenia, hypertension, osteoarthritis, osteoporosis, DVT, some cancers & even heart failure) [1]. It has become common knowledge that exercise is one of the leading strategies to maintaining optimal health and longevity, with some studies now showing a reduction in all cause mortality by upwards of 30-35% [2]. Interestingly, more and more research is being done that not only reports the positive physiological results of exercise, but also the impact it has on our brain [3]. 

What are the implications of this? How can we use this to further improve our own health and even performance? 

Stick around as we break this down!

MEMORY & BRAIN VOLUME:

Aging is associated with the loss of brain volume, vasculature and cognition [4]. It can heavily impact the function of the prefrontal cortex portion of our brain, increase risk of vascular issues (such as high blood pressure, CVD, stroke, etc.) and is associated with memory loss [5]. 

Research time and time again shows a link between exercise and improved cognition and memory. It is hypothesized that this is due to the increase in brain volume that occurs as a result of exercise. BDNF or brain-derived neurotrophic factor, is a key protein in the brain that is responsible for many neurological functions, including processing, cognition and neuroplasticity (the brain’s ability to change) [6]. With exercise increasing the brain’s volume, it is said to support and protect the brain’s memory – pretty impressive! In fact, there are studies showing that shrinkage of the hippocampus (that is associated with memory loss) can be reversed through walking! [7]

NEUROGENESIS:

As touched on before, BDNF is a key protein in the brain. However, what we didn’t explain yet is that BDNF is one of many brain proteins that is connected with neurogenesis (developing new neurons in the brain!) [6]. In fact, exercise and physical activity has been associated with inducing the repair and creation of new neurons (neurogenesis) via the brain-derived neurotrophic factor BDNF. Exercise is literally growing your brain! 

NEUROTRANSMITTERS:

Exercise has also been shown to ramp up those feel-good hormones called endorphins. Every time we are active, a barrage of neurotransmitters (norepinephrine (NE), dopamine (DO), serotonin (5-HT) & acetylcholine (ACh) are rapidly discharged into the brain influencing your mood regulation [9]. This is one reason research has continuously shown physical activity to have a positive impact on anxiety & depression while reducing stress! [10-11].

INFLAMMATION IN THE BRAIN:

Research has shown an association between inflammation and brain disease/cell death, with more and more evidence emerging that high levels of inflammation negatively impact brain health & even exacerbate brain diseases [12]. Furthermore, a direct link has been shown between inflammation and neuron death and cognition in animal studies [13]. The proposed mechanism as to why exercise may reduce inflammation has to do with a special class of immune cells in the brain called “microglia” – which belong to a group of cells called “glia”. 

Microglia cells when activated are known to support and protect the brain, identifying and cleaning the system by the removal of dead cells, while also facilitating in a process we covered above – “neurogenesis”. This is all good and well when you’re young, however, as we age these cells have been reported to act a little differently. In fact, when inappropriately activated they can impair neurogenesis and increase brain inflammation! 

The good news is here, don’t you worry! 

Physical activity has been shown to counteract the damage these nasty microglia cells cause when inappropriate activation occurs, improving overall cognition.[14-15].

BLOOD VESSEL HEALTH AND FUNCTION:

Aging is associated with reduced vascular function, arterial stiffness and an increase in blood pressure, of which all negatively impact the brain’s ability to function properly [16]. Furthermore, arterial stiffness and brain hypoperfusion are emerging risk factors for Alzheimer’s and other brain diseases. There are multiple studies showing that exercise increases blow to the brain [17], including Tomoto et al., (2021) who conducted a randomized clinical trial (RCT) that concluded exercise reduced arterial stiffness & increased cerebral blood flow [18]. 

Conclusion

I hope by now you have learned that exercise has MANY positive benefits on our brain. This is one reason why physical fitness should be a LIFELONG pursuit!

Until next time,

REFERENCES:

1. Ruegsegger, G. N., & Booth, F. W. (2018). Health Benefits of Exercise. Cold Spring Harbor Perspectives in Medicine, 8(7), a029694. https://doi.org/10.1101/cshperspect.a029694
2. Reimers, C. D., Knapp, G., & Reimers, A. K. (2012). Does Physical Activity Increase Life Expectancy? A Review of the Literature. Journal of Aging Research, 2012(243958), 1–9. https://doi.org/10.1155/2012/243958
3. McGregor, G. (2021, February 8). How exercise affects the brain. Life Sciences. https://lifesciences.byu.edu/how-exercise-affects-your-brain
4. Colcombe, S. J., Erickson, K. I., Scalf, P. E., Kim, J. S., Prakash, R., McAuley, E., Elavsky, S., Marquez, D. X., Hu, L., & Kramer, A. F. (2006). Aerobic Exercise Training Increases Brain Volume in Aging Humans. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 61(11), 1166–1170. https://doi.org/10.1093/gerona/61.11.1166
5. Peters, R. (2006). Ageing and the brain. Postgraduate Medical Journal, 82(964), 84–88. https://doi.org/10.1136/pgmj.2005.036665
6. Binder, D., & Scharfman, H. (2004). Brain-derived Neurotrophic Factor. Growth Factors, 00(0), 1–9. https://doi.org/10.1080/08977190410001723308
7. Erickson, K. I., Voss, M. W., Prakash, R. S., Basak, C., Szabo, A., Chaddock, L., Kim, J. S., Heo, S., Alves, H., White, S. M., Wojcicki, T. R., Mailey, E., Vieira, V. J., Martin, S. A., Pence, B. D., Woods, J. A., McAuley, E., & Kramer, A. F. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017–3022. https://doi.org/10.1073/pnas.1015950108
8. Liu, P. Z., & Nusslock, R. (2018). Exercise-Mediated Neurogenesis in the Hippocampus via BDNF. Frontiers in Neuroscience, 12. https://doi.org/10.3389/fnins.2018.00052
9. Lin, T.-W., & Kuo, Y.-M. (2013). Exercise Benefits Brain Function: The Monoamine Connection. Brain Sciences, 3(4), 39–53. https://doi.org/10.3390/brainsci3010039
10. Hu, S., Tucker, L., Wu, C., & Yang, L. (2020). Beneficial Effects of Exercise on Depression and Anxiety During the Covid-19 Pandemic: A Narrative Review. Frontiers in Psychiatry, 11. https://doi.org/10.3389/fpsyt.2020.587557
11. Craft, L. L., & Perna, F. M. (2004). The Benefits of Exercise for the Clinically Depressed. Primary Care Companion to the Journal of Clinical Psychiatry, 6(3), 104–111. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC474733/
12. Sartori, A. C., Vance, D. E., Slater, L. Z., & Crowe, M. (2012). The Impact of Inflammation on Cognitive Function in Older Adults: Implications for Health Care Practice and Research. The Journal of Neuroscience Nursing, 44(4), 206–217. https://doi.org/10.1097/JNN.0b013e3182527690
13. Direct link shown between brain inflammation, neuron death, and cognitive changes in mice. (n.d.). National Institute on Aging. https://www.nia.nih.gov/news/direct-link-shown-between-brain-inflammation-neuron-death-and-cognitive-changes-mice
14. Casaletto, K. B., Lindbergh, C. A., VandeBunte, A., Neuhaus, J., Schneider, J. A., Buchman, A. S., Honer, W. G., & Bennett, D. A. (2021). Microglial correlates of late life physical activity: Relationship with synaptic and cognitive aging in older adults. Journal of Neuroscience. https://doi.org/10.1523/JNEUROSCI.1483-21.2021
15. Mee-inta, Zhao, & Kuo. (2019). Physical Exercise Inhibits Inflammation and Microglial Activation. Cells, 8(7), 691. https://doi.org/10.3390/cells8070691
16. Barnes, J. N., & Corkery, A. T. (2018). Exercise Improves Vascular Function, but does this Translate to the Brain? Brain Plasticity, 4(1), 65–79. https://doi.org/10.3233/bpl-180075
17. Querido, J. S., & Sheel, A. W. (2007). Regulation of Cerebral Blood Flow During Exercise. Sports Medicine, 37(9), 765–782. https://doi.org/10.2165/00007256-200737090-00002
18. Tomoto, T., Liu, J., Tseng, B. Y., Pasha, E. P., Cardim, D., Tarumi, T., Hynan, L. S., Munro Cullum, C., & Zhang, R. (2021). One-Year Aerobic Exercise Reduced Carotid Arterial Stiffness and Increased Cerebral Blood Flow in Amnestic Mild Cognitive Impairment. Journal of Alzheimer’s Disease: JAD, 80(2), 841–853. https://doi.org/10.3233/JAD-201456