Exercise is Good for the Body, Even Better for the Brain

The impact of exercise on brain health is greater than anyone could have imagined.

Everything in our daily lives is marketed to us in one way or another, successfully or unsuccessfully. Exercise has been touted as the “cure all” for everything from obesity to mood swings. Yet truthfully it falls into the unsuccessful category.

An example that illustrates how exercise has been and continues to be marketed and why it fails to convert people to begin an active lifestyle is the Nintendo-64 (N64). In 1995 Nintendo launched the N64. When marketing their new machine they talked solely about its technical aspects and how it has a faster processor than the previous Super Nintendo. The launch of N64 was a failure because the marketing team failed to promote any of the relevant facts about the games or even that the N64 was the first gaming device to introduce 3D gaming for gamers. In other words, they sold the steak, not the sizzle.

Exercise and weight loss

Exercise has mostly been promoted as a way for people to lose weight and to improve cardiovascular health and physical fitness. Yet research has not found exercise to be an effective way to lose weight. Also the claim that “exercise is good for the heart” is a vague notion that is not going to appeal to young, otherwise healthy individuals who are not yet old enough to worry about their heart health.

A review of exercise intervention studies in 2001 at Queen’s University in Canada found that after 20 weeks the amount of energy expended during exercise had no correlation with weight loss. This does not mean that exercise doesn’t affect your body; it does. Exercise has been shown to increase muscle mass and improve your insulin sensitivity, setting you up to have a healthier body composition with less fat and more muscle tone.

Exercise alone does not result in weight loss. However, exercise alone does result in a gain in lean muscle mass. Muscles have mitochondria, which are the power plants of the cell, and use more energy (think calories) than fat cells. However, muscle weighs more than fat which is one of the reasons that exercise alone does not result in loss of weight.

So, while these benefits of exercise are good, they are not as compelling as the many other benefits of exercise, such as brain health — which is the topic of this article.

Exercise and our brain

Exercise is incredibly important for our health, but it’s real impact is not on our bodies, but on our brains. The brain’s primary purpose is to produce adaptable and complex movements. We know this because when we look at our evolutionary tree we see numerous examples of animals who have lost all or part of their brain as their dietary intake and mobility decreased. The most dramatic example of this is the lowly sea-squirt. Early on in its life a sea-squirt uses its brain and central nervous system (CNS) to move about the oceans in search of a good rock to attach itself to. Once it does, it no longer has to move around, so the first thing it does is to digest its own brain and CNS for energy.

Another more relatable example is the Koala. Koala’s today survive exclusively by eating the leaves of eucalyptus trees. For this reason they don’t need to move around much once they have found a suitable tree to call their home. This lack of mobility means Koala’s don’t have much use for their brain. What is interesting is that when we look at the ancestors of the Koala we see that they had much more active lifestyles and much more diverse diets. This required a larger brain than we see in today’s Koalas.

These, and other examples, strongly suggest that brains evolved for movement only to be later utilized for the variety of activities we use them for today, from art to science. Not having a big brain isn’t necessary if you aren’t going to move around much. It is a lot like not buying an expensive computer if you are only going use it to check email and browse the internet.

We maintain our bodies homeostasis by subconscious, negative feedback controls. By understanding the bidirectional flow of information between the brain and the body we can begin to understand why exercise is so important for brain health, in particular for learning. Movement is how the brain knows that something is happening and that it should pay attention. This is because for most of our existence, movement has been key to our survival. It is how we found food and avoided predators. So when you are moving it is in your best interest to be paying attention to where you are, where you were, and where you are going. You don’t want to get lost, starve to death, or get eaten! Remembering these things and learning from your experience will, in turn, make you more likely to find food, evade predators, and stay alive long enough to pass on your genes to the next generation. From your brain’s perspective, being sedentary means it is safe and you do not need to be as aware or as alert as when you are active.

Exercise and learning

The California Department of Education has shown consistently, that children with higher fitness scores, score higher on standardized tests.

Exercise primes the brain to learn faster. A meta-analysis of randomized controlled trials looking at the link between aerobic exercise and neuro-cognitive performance found that aerobic exercise is associated with “improvements in attention and processing speed, executive function, and memory.” The key to this phenomenon is a neurotransmitter called Brain Derived Neurotrophic Factor (BDNF). BDNF is what allows our brains to change as we learn new things. BDNF is what causes neurons to grow new branches and form new connections in the brain. It also protects them from the natural processes of cell death. The best way to increase levels of BDNF is aerobic exercise, exercise that requires an increase in oxygen consumption. One study found that 30–40 minutes of aerobic exercise increased BDNF by 32%. Although BDNF’s mechanism of action is difficult to understand, it is clear that BDNF is critical for the function and growth of neurons. Neurons are the crucial biological link between our thoughts, emotions, and movements. So the next time you need a brain boost, instead of making another pot of coffee, you might want to try jogging around the block.

Exercise and depression

Studies have shown that exercise not only boost dopamine levels but also increases the number of dopamine receptors in the reward center. Exercise won’t help you stay up late doing all the things you don’t want to do, like Adderall will, but it will help you have the willpower to get them done regardless of how rewarding it may be. Adderall increases the levels of the neurotransmitters serotonin, dopamine, and norepinephrine, the messengers in the brain’s reward and motivation pathways, and they are responsible for the regulation of emotions and feelings of pleasure.

Aside from its positive effects on dopamine and the reward system in our brain, exercise also increases levels of norepinephrine and serotonin. When dopamine, norepinephrine and serotonin levels are low, people become depressed. In 1999 James Blumenthal, a professor at Duke University, compared the effectiveness of exercise at treating major depression with the antidepressant Zoloft.

The results of the study found that 30 minutes of aerobic exercise, just three days a week was just as effective as Zoloft. But that’s not all, a 2006 study of over 19,000 dutch twins and their families found that exercisers were less depressed, less anxious, more socially outgoing, and less neurotic. If exercise were a drug it would be the closest thing to a silver bullet for some of the most common health problems people will confront throughout their lives.

Exercise and stress and anxiety

The last point about exercise and the brain has to do with stress. Exercise has been shown to help people learn and to better deal with stress and anxiety. Exercise is so good at improving your mood that it can sometimes help patients suffering from clinical depression for whom drugs and therapy have not been effective.

Now let’s go back to the very beginning, when humans were still climbing their way up the food chain. One of our ancestors is out hunting and gather, moving constantly, always on the lookout for predators or dangers that might harm them. All of a sudden you come across a snake. From experience you know that others who have been bitten by snakes have gotten sick and died. As a result your fight or flight response kicks in. This means the pituitary gland secretes an adrenocorticotropic hormone which causes the release of cortisol and adrenaline which increases your heart rate, relaxes your bladder, causes your face to become flush, and your pupils to dilate as you become singularly focused on the threat at hand ignoring everything else around you. The last thing that happens is your muscles contract and you begin to shake as your body prepares itself to either fight or flee whatever is threatening us. Once we’ve exerted enough effort to neutralize or avoid the threat at hand, our bodies come to rest and a signal is sent that lowers cortisol levels and returns our bodies to a more rested state.

Unfortunately, many people find themselves suffering from chronic stress which means they are constantly primed for a fight or flight response. Their body does not return to its more rested state. We have all heard that stress makes you fat and it does; the longer your body’s cortisol levels are elevated the more likely you are to be overweight. Research has shown that elevated cortisol levels are associated with increases in visceral fat which is linked to cardiovascular disease and metabolic syndromes, like type-2 diabetes. It’s not just our bodies that suffer as a result of chronic stress, our brains are also affected in negative ways.

Exercise reduces stress and lowers cortisol levels. By exercising in the morning you can lower your body’s cortisol levels for the rest of the day thereby improving your body’s ability to manage stress. Exercise is not just a substitute for drugs when things go wrong. Exercising when you are healthy can improve focus and your ability to learn things.

To use another metaphor, starting an exercise routine is like upgrading your computer one piece at a time. The first thing that happens when you start exercising is your fan starts working better, all the systems begin operating more efficiently, and you are better able to get the most out of what you’ve got. Over time your computers RAM gets upgraded, working memory increases, and the ability to perform tasks gets better. Eventually more permanent brain changes come about which are similar to upgrading your CPU. At this point you are now basically a brand new computer. Your overall cognitive abilities are enhanced and your abilities have expanded. It’s hard to imagine how you ever worked on your old computer after spending some time with a new one. At the same time there was no way for you to know how great an improvement it would be before you did it.

Conclusion:

Considering how little exercise is needed to improve our health, 30 to 40 minutes, 3 times a week, it’s hard to believe that “not having time” is a reasonable excuse for not working out. The fact that working out has been sold as a way to lose weight and build muscle is lost on those who don’t feel the need to or want to lose weight and are not interested in building muscle. The main reason people should exercise should be the fact that the benefits of exercise are so much greater than their superficial effects on the body; not just so that they can be skinny or look good naked.