What exercise does for your brain

My friends are extraordinary people. The people I’m attracted to are very driven and highly intelligent (and perhaps more than a little neurotic). The majority of them are also passionate about exercise.

“Exercise” is maybe too mild a term for this group: they are athletes devoted to a sport (either professionally or as committed amateurs), or they are coaches who are as relentless about training themselves as they are their students. To a person, they freely admit that this activity is essential for their mental well-being.

Cognitive therapy. Photo taken by gymjones.com
My own cognitive therapy. Photo taken by gymjones.com

And while I believe that their lives are very stressful, they handle stress remarkably well. They seem to be very resilient when bad stuff happens to them. This is an anecdotal observation on my part, but it interested me enough to go read about the effects of exercise on the brain. Here’s what I found:

1. Exercise makes your brain smarter

Neurons, unlike many other cells in the body, don’t regenerate. When they die, they die. However, there are several ways you can stimulate neuron growth as an adult in some regions of your brain: having an enriched environment, constantly learning new things, and regular exercise.

Animals that engage in exercise have been reliably shown to undergo a sustained increase in adult neurogenesis in the hippocampus in comparison with control animals that do not engage in exercise. For example, mice given free access to a running wheel for 2–4 months have more than twice the number of new cells in the subgranular zone of the dentate gyrus in comparison with control mice (no access to a running wheel). Similar results have also been obtained in rats.These increases are observed whether animals are housed in small social groups or individually. Increases in adult neurogenesis can be observed as early as 3 days after the start of exercise (unpublished observations) but are more reliably observed after at least a week of exercise. –Ernst et al., 2006

Exercise can even get around the bad effects of some mutations. For example, it’s recently been shown that the effects of the CHD7 mutation (that causes CHARGE syndrome, associated with learning disabilities, mental retardation, and a high risk for autism) can be reversed in rats if they’re allowed unlimited access to exercise wheels.

Newborn neuron in the brain of an adult mouse. Haikun Liu, German Cancer Research Center
Newborn neuron in the brain of an adult mouse. Haikun Liu, German Cancer Research Center

2. Exercise helps relieve depression
Perhaps you’ve noticed this in your own experiences. Sad? Go take a half-hour brisk walk or lift weights. See how you feel afterwards.

However, if you want more than anecdotal evidence, there are numerous studies showing how exercise helps alleviate symptoms of depression and stress (see Rimmer et al. 2012 for a meta-review of clinical studies on the effects of exercise on depression).

3. Exercise enhances your ability to cope with stress
A recent paper showed a remarkable difference between exercisers and non-exercisers. The authors looked at two groups of mice: one group was allowed to exercise as much as they wanted to for 6 weeks, the other group was kept sedentary. At the end of this period, both groups were exposed briefly to cold water as a stress stimulus. The “runner” group’s brains not only showed more neurons compared to the sedentary group, but that neurons typically activated by stress were actually suppressed when exposed to cold water, while the sedentary mice had no such control over their stress reactions. The authors summarize their findings (with a lot of jargon):

Our results resolve the seemingly contradictory findings that running can decrease anxiety while increasing the number of new excitatory neurons and excitatory connections in the ventral hippocampus, a potentially anxiogenic region (Adhikari et al., 2010,2011; Fanselow and Dong, 2010). By increasing GABAergic inhibition in the hippocampus in response to stress, running may serve to calm excitatory circuitry that might otherwise produce an overly anxious state. These findings suggest that the hippocampus of runners may be fine-tuned to respond to different environments optimally (Glasper et al., 2012).

So, in other words, regular exercise alleviates anxiety and increases resilience.

If all this isn’t enough to convince you that exercise is good for the brain, consider this last point:

4. Exercise helps your brain age “gracefully”

Neurodegeneration is a normal part of aging, but dementia isn’t necessarily inevitable. Exercise has been shown to significantly improve your chances of maintaining a healthy brain as you age:

“It is becoming apparent that successful brain aging is possible if people maintain certain healthy lifestyle habits throughout their lives. These lifestyle factors include: the number of calories ingested, composition
and quality of diet, physical as well as mental exercise, not smoking, active social life, effective use of technical innovations for social communication, maintenance of an active emotional life, and control of a stressful lifestyle” –Mora, 2013.

Physical exercise has even been shown to delay the onset of Alzheimer’s disease and to alleviate its effects to some degree (Mora 2013).

Now, if you’re already stressed and overworked, the idea of adding yet another thing to your life may seem completely overwhelming. But you don’t have to become a professional athlete in order to gain the benefits from exercise. Start small. Twenty minutes of walking a night will significantly improve your mood, and it’s not a huge commitment**. Take a few minutes away from gaming to take care of your brain. Do what you enjoy. If walking isn’t your thing, dance or bike or do martial arts. You’ll find that your body will adapt to this over time, and you’ll begin craving more exercise; add to your routine gradually and above all, be consistent.

(Many thanks to Dr. Kathleen Burke for her insightful comments).

**Remember, this isn’t about weight loss or trying to look a certain way (if those are your goals, you need to take a different approach), but rather physical and mental well-being.

Further reading:
Carl Ernst, Andrea K. Olson, John P.J. Pinel, Raymond W. Lam, and Brian R. Christie. 2006. Antidepressant effects of exercise: Evidence for an adult-neurogenesis hypothesis? J Psychiatry Neurosci 31(2): 84–92.

Mora F. 2013. Successful brain aging: plasticity, environmental enrichment, and lifestyle. Dialogues in Clinical Neuroscience – Vol 15 . No. 1.

Rimer J, Dwan K, Lawlor DA, Greig CA, McMurdo M, Morley W, Mead G
E. Exercise for depression. Cochrane Database of Systematic Reviews 2012, Issue 7

9 thoughts on “What exercise does for your brain

  1. Mark July 6, 2013 / 9:28 am

    excellent post! very informative… this studies opens our eyes on how marvelous our brain in which we always take for granted.. Ive wonder if there is a study on comparing the cognitive ability of the athletes students versus non athletes students.. anyway again excellent post!

  2. Jennifer Raff July 7, 2013 / 7:54 am

    Thank you very much! Great question. I’ll see if I can find any studies on this.

  3. cakmn August 20, 2013 / 9:46 pm

    Interestingly, most of what you wrote about exercise could also be said about something that seems to be the exact opposite – meditation, which is typically practiced as a sedentary (in)activity that both depends upon and facilitates relaxation.

    Relaxing the “brain” – the mind – makes us smarter, or at least more capable of becoming smarter and more wisely applying what we know.

    Relaxation of our thought patterns and emotional patterns that we otherwise tend to get stuck in can help relieve depression and help us discover joy, and it can also help cope with stress because it helps one see things more clearly in a larger perspective.

    I don’t know of any research into meditation helping one’s brain age more “gracefully,” but everything else I think I know about meditation – from reading and, more importantly, from decades of experience – suggests that it’s likely to be beneficial in this manner, too.

    There are also many other benefits to one’s health and well-being that can be gained through meditation, as well as through exercise.

    Also, practicing meditation by sitting quietly is just that – practice. That may be as far as many people go with it, but one can actually carry meditation into and through life – busy activities, noise, commotion, turmoil and all. The essence of meditation can become the essence of one’s behavior in life.

  4. Doug August 20, 2013 / 11:17 pm

    Great article. Exercise is extremely important. I often cringe (a little) at articles written by people who have clearly studied mostly under a reductionist (allopathic) paradigm. Rarely do I read articles where the author talks about exercise as a nutrient. It’s almost always looked at as a form of therapy to treat what ever ails you. The fact is, is that exercise is an essential nutrient that your body must get daily in order to express health. Your body cannot express health without it. Movement is actually the most important nutrient for us, even more important than the more known nutrients we consume. I might not agree with you on everything (your allopathic view on vaccines for example), but you are definitely on the right track with this article. As a doctor, besides getting my patients to eat healthier, increasing their daily movement is one of my main goals. Thanks for the article!

  5. Victor Venema August 30, 2013 / 5:45 pm

    “Twenty minutes of walking a night will significantly improve your mood…”

    I am tempted to ask: does it have to be at night? 🙂

    And is that the recommendation for mice or humans?

  6. David Colquhoun September 27, 2013 / 12:15 pm

    Hmm. I’m all for exercise. I’ve done lots, from boxing to marathon running, to mountain walking. I enjoyed them all, But I’m skeptical about the quality of many studies that purport to show exercise is a panacea for almost everything. It has become the latest fashionable magic bullet, for things which are otherwise difficult to cope with, like depression for example. It’s more likely that people who aren’t too depressed will run, i.e. improvement in depression cause an inclination to run, rather than running causing an improvement in depression. It’s a causality problem.

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