First, a point of clarification. There are different modalities of exercise: endurance training, resistance training, mobility work, and high-intensity interval training also known as HIIT. All have proven benefits for your body and all have their place in your training regiment. But for the purpose of today’s discussion, we will be focusing on steady-state cardio, also known as endurance training, which, if you are training for a marathon, bike race, or triathlon, should occupy the largest portion of the time you spend training. So when I say exercise, know that I am referring to cardiovascular exercise.
Oftentimes, we tend to think of exercise and physical activity more broadly for the physical benefits they can provide us - of which there are many. Exercise has wide-ranging benefits for basically the entire body, including improved cardiovascular health, lower blood pressure, increased lung capacity, increased muscular strength and endurance, improved bone density, enhanced flexibility and balance, improved insulin sensitivity, improved hormone regulation and digestion, and improved immune system function. This is not an exhaustive list but rather a sampling of some of the most prominent benefits affecting a variety of systems. However, one often overlooked benefit is that which cardiovascular exercise has on our brains. Frequently thought of as a separate entity, the brain is as much a part of our body as any of the other aforementioned organs and systems. And it, like the rest of your body, enjoys a whole host of benefits as a result of cardiovascular exercise. These benefits are, of course, dose-dependent. That is to say, the more cardiovascular exercise you do, the more pronounced these benefits will be. So an individual doing cardiovascular exercise five days a week would see greater benefit than a person doing only two days of cardio.*
*One caveat is that there is a dose-dependent benefit of exercise but this benefit levels off as you do greater and greater amounts of exercise. Another way of expressing this is what’s known as the law of diminishing returns. So if you are a sedentary individual and you start doing exercise three days a week, you will likely see a great return on your time investment. However, if you are already working out for 14 hours a week, increasing the training load to 16 hours will provide negligible benefit, if any.
So what happens to our brain when we exercise?
If you have ever worn a heart rate monitor while exercising, you will know that one of the first things that occurs is that your heart rate increases to compensate for the uptick in oxygen consumption by the body. This increase subsequently causes the rate of blood flow to increase, delivering more oxygen to tissues that are using more oxygen to power your muscles. But what you might not have realized is that the brain also benefits from this increase in oxygenated blood circulating throughout your body.
Not only this, but a single session of exercise will see increases in levels of neurotransmitters such as dopamine, serotonin, and noradrenaline. These neurotransmitters increase your mood immediately following the workout (acutely) and in the following weeks (chronically). Coincidently, these are the same neurotransmitters whose levels tend to be lower in those individuals suffering from Major Depressive Disorder (MDD). In a study done by researchers at the Amsterdam Academic Medical Center and the Center of Research on Psychological and Somatic Disorders (CoRPS), Department of Medical and Clinical Psychology at Tilburg University in the Netherlands, they examined the differences between using traditional antidepressant medications versus running as an intervention for depressive and anxiety disorders. Running therapy involved 16 weeks of supervised, 45-minute outdoor running sessions with a target of two to three sessions per week, in line with US Centers for Disease Control/American College of Sports Medicine recommendations. The results were very promising: Remission was defined as no longer meeting the criteria of a current depressive or anxiety disorder via CIDI (Composite International Diagnostic Interview) at week 16. On intention-to-treat analysis, this requirement was met by 44.8% of patients taking antidepressants and 43.3% of those in the running therapy group. However, running therapy patients showed significant improvements in weight, waist circumference, systolic and diastolic blood pressure, heart rate, and heart rate variability. This is to say that the benefits of regular running, given that an individual is able to adhere to regular running, can be comparably effective to taking antidepressant medications, but with additional health benefits that come from running.
Apart from the short-term effects that exercise has on mood and focus, it also has long-term neuroprotective effects on the brain that can help delay the onset of neurodegenerative diseases such as dementia and normal cognitive decline associated with aging. It does this by increasing the size of two key brain regions; the hippocampus, responsible for learning and consolidation of memory, also known as the conversion of short-term memories to the long-term and the prefrontal cortex, responsible for a wide range of functions from emotional regulation to planning and decision-making as well as balance between systems such as regulation of sympathetic and parasympathetic branches of the autonomic nervous system. Exercise itself unfortunately cannot prevent neurodegenerative diseases but having larger and more robust hippocampal and prefrontal cortical regions can delay the onset of these diseases. Essentially, you can think of exercise as putting money in your neural bank. When there is more “money” in the bank to withdraw, the amount of time before you will notice the effects of neurodegeneration will be greater, leading to an overall increase in “health span” defined by Merriam-Webster as “the length of time in one's life during which an individual is in reasonably good health.”
If you are reading this blog, you likely either already engage in regular exercise or have in the past. If this finds you at a time when you are taking a break from training, consider it an invitation to get back on the horse and train regularly again. Your body and mind alike will thank you for it both now and as you age. If you're looking for guidance on how to get back into training after taking a break or you just finished a race season, check out my upcoming Off-Season Clinic.
- Coach Ethan
The Effects of Acute Exercise on Mood,Cognition, Neurophysiology, and Neurochemical Pathways: A Review (2017) || Basso, J.C., Suzuki, W.A. || Brain Plasticity 2 (2016/2017), 127-152. Download PDF: Basso, Suzuki, 2017
Acute Exercise Improves Prefrontal Cortex but not Hippocampal Function in Healthy Adults (2015) || Basso, J.C., Shang, A., Elman, M., Karmouta, R., Suzuki, W.A. || Journal of the International Neuropsychological Society (2015), 21, 791–801. Download PDF: Basso, et al., 2015
Phillips C. Brain-Derived Neurotrophic Factor, Depression, and Physical Activity: Making the Neuroplastic Connection. Neural Plasticity. 2017 ;2017:7260130. DOI: 10.1155/2017/7260130. PMID: 28928987; PMCID: PMC5591905. https://europepmc.org/article/MED/28928987
Josine E. Verhoeven, Laura K.M. Han, Bianca A. Lever-van Milligen, Mandy X. Hu, Dóra Révész, Adriaan W. Hoogendoorn, Neeltje M. Batelaan, Digna J.F. van Schaik, Anton J.L.M. van Balkom, Patricia van Oppen, Brenda W.J.H. Penninx, Antidepressants or running therapy: Comparing effects on mental and physical health in patients with depression and anxiety disorders, Journal of Affective Disorders, Volume 329, 2023, Pages 19-29, ISSN 0165-0327, https://doi.org/10.1016/j.jad.2023.02.064