How Exercise Affects Your Brain

You have probably heard people say something along the lines of “your brain is like a muscle.” That comparison certainly supports the brain training industry (by that I mean school) and keeps millions of youth around the world sitting at desks, doing math problems, writing essays, and dissecting unsuspecting amphibians - but is it true?

Interestingly, the brain-as-a-muscle comparison isn’t all that accurate. If you want to build your glutes, you have to flex your glutes but when it comes to your brain, a more coincidental approach is more accurate. Getting busy working your glutes will also directly benefit your grey matter. Yes, exercising your butt will make you smarter!

Exercise affects the brain in many ways. It increases heart rate, which pumps more oxygen to the brain. It aids the release of hormones which provide an excellent environment for the growth of brain cells. Exercise also promotes brain plasticity by stimulating growth of new connections between cells in many important cortical areas of the brain. Research from UCLA even demonstrated that exercise increased growth factors in the brain which makes it easier for the brain to grow new neuronal connections.

From a more feel-good perspective, the same antidepressant-like effects associated with the "runner's high" has been correlated with a drop in stress hormones. A study from Stockholm showed that the antidepressant effect of running was also associated with more cell growth in the hippocampus, an area of the brain responsible for learning and memory. The study went as far as to say “Thus, suppression of cell proliferation in the hippocampus could constitute one of the mechanisms that underlie depression, and physical activity might be an efficient antidepressant.”

Some Examples

Scientists are continuing to showing that everything from the “runner’s high” to the “yogi’s tranquility” can have profound effects on your brain. Here are just a few examples. 

1. Exercise Boosts Memory

The part of the brain that responds strongly to aerobic exercise is called the hippocampus. Since the hippocampus is at the core of the brain’s learning and memory systems, this finding partly explains the memory-boosting effects of improved cardiovascular fitness.

2. Exercise Increases Concentration

Exercise can actually help you focus and stay on task longer. During a study in Holland, they interspersed lectures with 20-minute long aerobics-style workouts and found that it improved the attention spans of the students. Then a large randomised controlled trial in the US looked at the effects of daily sports classes which spanned the entire school year. The students got fitter but they also became better at multitasking, ignoring distractions, and processing complex information.

3. Exercise Improves Mental Health

We’ve all heard of (or experienced) the runner’s high – that feeling of happiness and clarity that often follows exercise – well, it is real. It has even been observed in mice and evidence points to a pleasurable and pain-killing firing of the endocannabinoid system (also known as the psychoactive receptor for cannabis).

Science is also increasingly backing the yogi’s claim of the “relaxation response”. A 2010 study titled Stress reduction correlates with structural changes in the amygdala put participants through eight weeks of daily yoga and meditation practice. The study concluded “... participants reported significantly reduced perceived stress. Reductions in perceived stress correlated positively with decreases in right basolateral amygdala gray matter density.”

The researchers stated that exercise seemed as effective as antidepressant drugs and psychological treatments.

Another study showing exercise as a way to overcome depression is the 2013 meta-analysis which reported that exercise (aerobic and heavy lifting) was “moderately effective” in treating depressive symptoms. Of particular note is that the researchers stated that exercise seemed as effective as antidepressant drugs and psychological treatments.

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4. Exercise Enhances Creativity

Creative types through the ages have claimed that walking aided their creative process and lately, psychologists gave it empirical support. A 2014 paper titled “Give your ideas some legs: the positive effect of walking on creative thinking” showed that walking, either on a treadmill or around Stanford’s leafy campus, boosted creative thinking. Interestingly, it didn’t help convergent thinking which is generally defined as the ability to give the "correct" answer to standard questions that do not require significant creativity,

5. Exercise Slows Cognitive Decline

To get this benefit, workouts don’t even need to be extreme. Once again 30-45 minutes of brisk walking, three times a week, can help fend off the mental wear and tear and delay the onset of dementia. Walking FTW!

And if walking isn’t your jam then twice weekly sessions of weight lifting can have a visible neurological impact. Or how about some dancing? Studies show that dancing may also be restorative. Just an hour of dance a week, for six months, boosted elderly individual’s cognitive well being.

6. Exercise Improves Circulation

Because exercise usually increases the heart rate, it helps deliver more oxygen and glucose to the brain which stimulates the brain’s synapses by preserving the number of acetylcholine receptors found at the junction of muscle and nerve. This is observed in the fact that active people have more receptors in their brains than inactive people.

7. Exercise Aids Learning and Memory

Even moderate physical exercise, such as our old friend walking, can boost memory functions, learning, and the ability for abstract reasoning. It is not completely understood how this works, but improved oxygenation and nutrition for the brain are likely the major factors.

8. Exercise Builds More Brain Cells

Up until 1999 the brain was thought to be complete at birth and not capable of growing new brain cells, but a Salk Institute study showed that the adult human brain is capable of producing new cells (neurogenesis). Although we don’t understand how, the one thing that is sure is that physical exercise helps build brains. The theory is that exercise stimulates the production of a very aptly named brain protein known as Noggin and this protein initiates the production of neurogenesis and stem cells.

9. Exercise Prevents Disease

According to the National Institutes of Health, being physically active may help to delay or prevent the decline of cognitive function associated with age. People who stay seated are twice as likely as people who bust-a-move to develop diseases such as Alzheimer’s.

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Gone Mainstream

As the saying goes, you know something is legit when mainstream media gets in on the action. Ha ha!

Earlier in 2017 CNN published an article called Three Ways Exercise Benefits Your Brain and in that article they highlighted these three beneficial factors of exercise.

1. Boost Your Mental Fitness
2. Banish Stress for Good
3. Age With Grace

Let’s look what they said about each of those. 

In the article they laid out "boost your mental fitness" like this; there are about 86 billion neurons in your head, all designed to give orders to the rest of your body with the help of chemical messengers called neurotransmitters. These neurotransmitters regulate everything in your body from mood, to sleep, to memory, and even hunger.

Studies show that low levels of two of these neurotransmitters in particular, glutamate and gamma-aminobutyric acid (GABA), often lead to depression. But according to a study in The Journal of Neuroscience, moderate exercise can increase these levels which can result in increased resilience and a capacity to respond to mental challenges. All of this is directly connected to a concept known as "mental fitness" which sounds pretty darn good to me. 

Which is helpful if you're getting chased by a sabertooth tiger but not if you’re just sitting at your desk.

In terms of "banishing stress for good," the CNN article said that when you're stressed out your brain secretes the "fight or flight" stress hormone called cortisol. Cortisol is very helpful if you're getting chased by a sabertooth tiger and need to run for the hills but if you’re sitting quietly at your desk (with no tigers in sight) and your cortisol levels are still elevated, it can cause problems (like heart disease, diabetes, and hypertension).

The solution for this appears to be hitting the track, pumping some iron, or punching the heck out of the heavy bag. All of these activities are thought of as something called "controlled stress," which actually sharpens your brain's stress response, helping you turn stress off and on at more appropriate times.

And finally CNN addressed the “aging with grace” factor by pointing out that older adults who exercise actually have larger brain volumes than those who don't, according to a 2006 University of Illinois study. In that study, sedentary volunteers aged 60 through 79 participated in a six-month exercise program that met three times each week. Half of the volunteers did aerobic exercises such as walking (again with the walking) and the other half did stretching and toning exercises. At the conclusion of the study, the aerobic exercise group showed greater increases in brain volume when compared to participants who did toning and stretching exercises.

The icing on the cake? The hippocampus (which is associated with memory and learning) which usually shrinks with age, is larger in people who are gettin’ down with their bad selves! Now, this is unlikely to make you smarter but it will certainly help you remember the important stuff. If you have ever watched an aging loved one start to forget more and more of their former life and their family, you’ll know that this is an excellent reason to get fit - starting now!

How Does This Work?

Increased blood flow to the brain, surges of growth hormones, and massive expansion of the brain’s network of blood vessels.

Researchers are still working on the why and the how and are trying to determine the critical factors that make exercise so good for the brain but the focus seems to be on: increased blood flow to the brain, surges of growth hormones, and massive expansion of the brain’s network of blood vessels.

Neuroscientists have known since that 1999 study that brain-derived neurotrophic factor (BDNF) is released during aerobic exercise and that stimulates neurogenesis (the growth of new neurons) but more recently scientists have honed in on an exercise activated hormone called Irisin. And I gotta say, if you need one more reason to get fit, you can add Irisin to your list. In 2012 scientists discovered that Irisin has the ability to help maintain healthy body weight, improve cognition, and slow the aging process. Now that is a trifecta that I can get on board with. 

So, after listing all of these factors, we can see that the cognitive benefits are nearly as impressive as the physical benefits of exercise. This also reminds us that our brains and bodies don’t operate in isolation, independent of each other. What you do with your body and what we put in our body, benefits or harms your mental faculties as much as it adds or subtracts girth from your biceps or your ability to run a 10-minute mile. Being sedentary all day, every day, is as dangerous for your waistline as it is for your mind. So, don't wait. Find an activity and do it. Or, as we learned again and again today, just go for a walk.

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