The relationship between exercise and mental well-being has been a recent topic of discussion in the medical community. It has long been suggested that routine exercise has indisputable physical benefits, specifically with improvements to cardiovascular and respiratory health. But could it also be true that exercise can benefit the brain? Recent studies suggest the answer may be yes!

What exactly does exercise do to the brain?

In an article published by Harvard, which cited several medical studies, the brain exhibits structural changes in response to regular aerobic exercise; this includes a larger hippocampus (a part of the brain critical for learning, memory, navigation and stress regulation), increased synaptic size and density, increased vascular density, and increased rate of neurogenesis, or new cell growth. Another avenue of brain changes concerns brain derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). Both BDNF and VEGF promote the proliferation and survival of new neurons, or brain cells. In other words, they are like food, or fertilizer, for our brains. An inadequate amount and polymorphisms in BDNF and VEGF have been associated with depression. However, exercise upregulates the production of both! BDNF synthesis occurs with an increase in local neuronal activity; VEGF synthesis occur with hypoxia, which is to say that although being out of breath when you exercise may not feel great, it means you are doing it right! All these structural brain changes point to one result: a better functioning and more engaged brain.

How does that effect my mental state?

For starters, regular aerobic exercise has been shown to reduce cortisol levels in the body. Cortisol is commonly known as “the stress hormone”, because it is naturally released when we are anxious, depressed, not sleeping, or in other words, stressed! Cortisol is a natural steroid produced by our body, but prolonged exposure to it can lead to many harmful results. For example, it can cause body wide inflammation and can weaken our immune systems. This is why we may be prone to more illness when we are under significant or prolonged stress. Luckily, exercise is natural way to reduce our body’s cortisol levels. And reduced cortisol levels means our mood gets a boost, anxiety is reduced, sleep is improved, and we are better able to focus during the day.

So, how should I exercise?

Aerobic exercise has been cited several times as the best way to boost mental and physical health. It may help to first define aerobic exercise vs anaerobic exercise. Aerobic exercise is physical activity commonly referred to as “cardio”. It is any exercise that increases your heart rate and respiratory rate to meet the needs of your muscles to sustain the activity for a period of time, usually 10 minutes or longer. This can be a multitude of activities: jogging, biking, swimming, dancing, and hiking are a few. Alternately, anaerobic exercise is usually more stationary, and is often used by non-endurance athletes to build muscle mass. It can increase heart rate and respiratory rate, but it does not require continual movement, and therefore, does not require sustained elevated heart rate and respiratory rate. This can include activities like weight-lifting, sprinting and jumping. In short, aerobic exercise requires low to moderate exertion for a longer time, while anaerobic exercise requires higher intensity exertion for a shorter time.

Can I get a prescription for that?

Absolutely! The best way to exercise aerobically is any way that will get you to 65%-85% of your maximum heart rate, and keep it there for a minimum of 20 – 30 minutes per session, at least 3 times/week. Studies actually show that 30 – 45 minute sessions 3 – 5 times/week are optimal for treating depression, and a minimum of 90 minutes of aerobic exercise per week can prevent depression relapse. So, to start, use your heart rate as a guide during your activity. To calculate your maximum heart rate, subtract your age from 220. That is your maximum heart rate. Then multiple that number by 0.65 (65%) and by 0.85 (85%) to get your optimal heart rate range, in beats/minute. 65% of your maximum heart rate is considered moderate intensity activity, and 85% of your maximum heart rate is considered vigorous intensity activity. Once you have your range, you know what you are aiming for. You can find your pulse, or heart rate, in your wrist or neck, count the beats for 60 seconds, and that is your current heart rate in beats/minute. It is good to practice this before you get started in your activity. Heart rate monitors and most Fitbits are another great way to easily monitor your heart rate.

The example below can serve as a guide:

A 30 year old male or female would have a maximum heart rate of 190 beats/minute.

(220 – 30 (age) = 190)

His/her target heart rate range would be 123.5 beats/minute to 161.5 beats/minute.

(190 x 0.65 = 123.5 and 190 x 0.85 = 161.5)

This means, that he/she should engage in any activity that gets his/her heart rate to somewhere between 123.5 beats/minute and 161.5 beats/minute. He/she should maintain that level of activity for a minimum of 20 minutes, (though 30 is better) on at least 3 days out of every week.

You may find as you continue exercising that the level of activity at which you start, will eventually not get you into your target heart rate range anymore. This means that you are improving and that your body and brain are changing to meet your needs! It also means you will need to change up your activity to continue getting your heart rate up!

How long will it take to see results and are there side effects?

Exercise is optimized as a treatment when it is done consistently and over time. Exercise actually takes about the same amount of time to begin “working” as can treatment with an antidepressant medication, which is about 2 – 4 weeks. This doesn’t mean the first 2 – 4 weeks of treatment are not effective, it just means the changes in your brain and body start small, and it may take some time before we recognize those changes in ourselves. Additionally, exercise has been shown in several studies to be equally effective as standard antidepressant treatment, and in the patients who continued to exercise at least 90 minutes/week after treatment ended, there was a lower rate of depression relapse. The other good news? Exercise has some great side effects aside from just looking and feeling better; it can improve sleep, lower blood sugar, and reduce your risk of many illnesses that often present in comorbidity with depression including cardiovascular disease, hypertension, diabetes mellitus, osteoporosis, dyslipidemia, obesity, and several cancers.

To summarize:

Aerobic exercise, when done 30 minutes at a time, at least 3 times a week, at an intensity that gets your heart rate between 65% and 85% of your maximum heart rate, can significantly change your brain in a way that reduces depression and anxiety, improves sleep and daytime focus, and decreases your risk for other common illnesses. It provides a mean for you to be in control of your own treatment, and quite simply, it works!! Happy exercising!!

For further research or more information, please check out the articles I referenced in this post.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3674785/

https://www.health.harvard.edu/blog/regular-exercise-changes-brain-improve-memory-thinking-skills-201404097110

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3311131/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3876165/

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