Why do you exercise? It might be to lose weight, maintain or improve your health, reduce stress, or perhaps a combination of all of these. But what is actually motivating you is simpler than that. As Dr. Gary Wenk reveals in his book “Your Brian on Exercise”, you exercise because your brain needs you to move, and it will do everything it can to motivate you to do it.
He provides fascinating insights into exactly what is happening to our brains when we go jogging, lift weights, swim laps, or take a walk, as well as what happens when we don’t. He’ll also answer questions we all have about exercise vs diet to lose weight and perhaps, most importantly, how much exercise is enough.
Bio: https://psychology.osu.edu/people/wenk.6
Phil Stieg
We all know that exercise is good for our bodies, but do our brains benefit as well? Does it make us think faster, clearer, or even make us smarter? Can it help with depression, reduce pain, or help fight off dementia? In his book “Your Brain On Exercise”, Dr. Gary Wenk reveals exactly how your muscles are connected to your mind and what happens in our brains when we work out, take a brisk walk, or even just do some gardening. Dr. Wenk is with us today to help us understand why exercise is so important to our mental health. And he has some very practical advice and simple steps on how to do this for anyone who just needs a little push to get started.
Gary, thank you so much for being with us today.
Gary Wenk
My pleasure. Thanks for the invitation.
Phil Stieg
Let’s start with a basic question – how is exercise related to the function of the brain?
Gary Wenk
Oh, my, that’s. I love that question. The. The brain has two primary functions. One is survival, which means going out and finding food and trying to avoid becoming someone else’s food. And the other is procreation. And that’s actually what started me on writing the book, was that link between eating, foraging and exercise and aging. Because it turns out that those two primary functions is what we use movement for. We need to move around find food, and we need to move in order to find mates for procreation, the two primary functions of the brain.
Phil Stieg
And, as you go on to explain – there’s a cost for all this movement. Correct?
Yeah, So there’s this fascinating link between the, the need to move to find food and the cost of finding that food every day. Let’s begin with probably the most profoundly obvious thing you’re going to hear all day. The older somebody is, the more likely they are going to die. Now, we all know that. It’s true of every organism on the planet.
So you have to ask the question, what am I doing every day as I move around and look for food and mates that is killing me day by day, slowly by slowly, moment by moment. And the answer is, we eat.
We have to eat every day. And in the process of eating, we need to breathe in oxygen to obtain the energy. So we are all carbon bond energy consumers, all of us on the planet. We gobble up these carbon molecules as carbohydrates, proteins and fats. We break them in half inside our mitochondria, inside the cells, and we get energy. It’s pretty inefficient. In the process, we release a lot of heat. And muscles in particular, have a lot of mitochondria use a lot of carbon bond energy and they generate a lot of heat for us. This is why big bodybuilders are out there walking in skimpy shirts in winter weather. It’s not because they have big egos, they’re just really hot. We are constantly generating heat in the process of getting the energy we need to survive and move.
Every day we have to eat to stay alive. And in the process, we generate these horrible things that are called free radicals. Oxygen free radicals. Every breath of air does this. And that production of energy is what ages us.
Phil Stieg
Most of our listeners probably understand that their brain controls their muscles through electrical impulses. But I think they’d really be surprised at the extent to which muscles talk back to the brain through a variety of chemicals.
Gary Wenk
One of the things that surprised me the most was how muscles end up acting very much like many of the other endocrine glands that we have in the body. Various organs, such as, you know, the thyroids, release hormones. The adrenal glands release hormones. Well the muscles would do the same thing. They produce chemicals that they release that communicate with the rest of the body and in particular, the brain. And why are they talking to the brain? That became interesting as well.
One great example that comes up often with my students was the runner’s high. It’s one of the most studied and one of the most interesting things. But in sort of unpacking that in the book, I think it told the story, the entire story in miniature, as an example of how muscles talk to brain and what the brain’s listening for.
We, we’ve heard of the runner’s high. It’s when people go out and run a very long distance, usually many, many miles and all of a sudden people develop this euphoria. That drew the attention of scientists many years ago. And the first thing they discovered was that the body is releasing endogenous morphine like compounds, opiates that they called endorphins. And those they said inaccurately enter the brain and produce euphoria. Well, it turns out endorphins are incapable of crossing the blood brain barrier. So there’s a little snag.
But then we learn many years later that the brain makes its own endorphins in response to that long exercise. Now, about 10 years ago, we discovered that there’s such a thing in the body as cannabis like compounds. We call them endocannabinoids. Well, it turns out that the runner’s high is much more related to the release of endocannabinoids. So essentially a runner’s high is a marijuana high.
That makes a lot of sense. But the question you need to ask is why would the body release these two compounds? What do they usually do for us? Well, the endorphins reduce pain. The endocannabinoids are there to act as analgesics, pain reduction and anti inflammatories.
So why would the body release those two things? And the answer is pretty simple. It has everything to do with the fact you’ve just ran 15, 20, 25 miles, you have produced one heck of a lot of damage on your body, and the body is responding by doing what it does — protecting you — producing analgesics and anti inflammatories to compensate for the stupid behavior it just saw you perform of running 20 miles . Because all drugs have many actions in the brain, you felt some euphoria. It was not for a good reason. People become addicted to this just as they can morphine and opiates and cannabinoids and long distance runners really do become addicted to that high.
But it tells us something. Muscles talk to brain to say we’ve been injured. Release a chemical to help us compensate for that. And that’s what’s going on.
Phil Stieg
That’s what I find most striking in your book, is how the individual needs to balance the need for exercise, the desire for exercise, but then the high cost of exercise for the brain, but also for other parts of your body, your joints, your heart and all that. Talk a little bit about how that linkage works and what the end message is.
Gary Wenk
Well, the linkage is all of those chemicals that the muscles release. And we know that in response to high intensity training, it can actually cause cell death in the body and brain. So it’s actually not a good thing to have released.
So in the book I make the point that extreme exercising is not a good thing. It harms the body too much. It induces muscles to release hormones like lipocalin and cathepsin that we should not be releasing that are probably doing harm. So there is an optimum amount of use and an optimum amount of exercise. And I think that may explain why you will never ever see an animal in the wild exercise. I mean, look out your window. What’s that squirrel doing? They’re looking for food, looking for mate. But they’re not out there lifting weights or just running in circles, you know, to make themselves look trim. You know, only humans do this. It’s a unique phenomenon for us.
Phil Stieg
Well, do you think that the reason humans do that is also part of the evolutionary process where early on humans had to hunt and forage for food. Now, because of our sedentary society, we don’t have to do that. But people feel this innate need to get exercise. Is it an evolutionary process?
Gary Wenk
I think you’re right. And it also. It’s a very communal process. Exercise, as I define it in the book, is something that we do with others frequently, so it has that value. But we also know just walking alone in the woods, people have studied that, and even that’s beneficial. So many things we do that we call exercise have no obvious benefit to us in terms of our survival, but they do bring pleasure in other ways, and those factors can’t be ignored. The issue is, I think my point was just don’t take it to extreme.
I have many of my students who. I have swimmers who swim four or five hours a day, day. And they have zero body fat. They also eat 4,000 calories a day. They look great at age 20, but by the time they, you know, hit their 60s and 70s, it’s going to take a toll on their body.
I love to make the example if you took two individuals who were genetically identical twins and you have one of them, you know, become a swimmer or a marathon runner and who had to eat 4,000 calories a day and ask the question, which one of the twins lives longer?
Twin studies have been done on these kinds of questions. We know the answer. The person who didn’t consume all those carbon bonds lives a lot longer. So that’s why moderation is so important.
Phil Stieg
You kept early on in the book referring to exercise is good as long as it’s done in moderation. But it took you about 100 pages to define what moderation meant to you. Can you explain to me what moderate exercise means?
Gary Wenk
There are lovely definitions online. I’m sure we all both had to look that up. And indeed, usually it means that it’s not for a long duration. That would be one of the keys. It’s not against strong resistance. Just simply walking with gravity is probably going to be good enough. It was going out for a walk, a light jog, but these long jogs where you’re pounding on your joints.
I have runners who claim they’ve seen studies that there’s no inflammation in the joints. Well, the runner’s high and the chemicals involved in that high clearly indicate there’s damage. You may not be able to feel it, but it’s there and the body noticed it. So it’s simply not getting to the point where you can’t keep up a conversation while you’re doing it. That’s a nice indicator, I think. Go out and do it with somebody else, be social, talk to them while you’re doing it. If you can’t, then you’re probably doing too much for your body.
Phil Stieg
You talked about, gender differences and testosterone in men and why that’s bad.
Gary Wenk
Yes, testosterone has the ability. And we’re going back to mitochondria again. Mitochondria, these little organelles inside every cell of our body. They generate ATP, which you should view as little batteries, and that’s energy. And we have to do it all day long in order for muscles to move and our brains to think. And we all do it quite well.
Well, if you happen to have testosterone in your body, the testosterone has an effect on mitochondria. It’s called uncoupling. And what that means is it essentially makes the mitochondria less efficient at producing energy, ATP, and that translates as more heat.
So we break our carbon bonds and our fats, carbohydrates and proteins, and more of the energy is lost as heat waste. That’s why men are always so much warmer than women. They usually have more muscle, but their muscles have more mitochondria. And essentially they generate a lot more heat thanks to the testosterone.
We’ve seen from looking at the other animals and humans, obviously, that all males of all species always die before the females in their species. Well, it turns out that testosterone and the uncoupling process not only wastes heat, but it generates a lot more free radicals. And so men simply age faster. And the big. You’re gonna love this. The bigger the muscle, the. The more active the muscle, the more calories they eat, the more oxygen they have to breathe, the faster they die. So there’s a cost for looking good in a tiny shirt in the winter and that’s it.
But there’s one more thing that is really depressing for women about this, and that’s that men can lose weight by just sitting in a chair. They don’t have to do anything. Their bodies waste so much energy they don’t even need to exercise. So if there’s ever a competition between a man and a woman to lose weight, the man’s going to win because he can literally just sit there, whereas the woman’s going to have to move around and burn some calories.
Phil Stieg
That was the other interesting thing too is if you look at this as a brain centric issue, the brain craves sugar. So why don’t humans just start devouring more sugar to feed the brain’s need, which is obviously bad for the rest of the body. What’s going on?
Gary Wenk
Oh, it’s a great story. It actually explains why there’s Dunkin Donuts in every corner.
The brain can only use glucose. That’s true. So our brain’s main desire is to get us to eat sugar. There’s an evolutionary history to this. Our brain evolved in a world where fat, salt and sugar was rare to come by. In fact, if we came across some of fat, you ate it to completion. And salt especially, in fact, people would find salt concentrations on the crust of the earth and they would settle there. The cities in England that end in -wich –W I C H are actually there, like Greenwich, Sandwich and others, because that refers to the fact there’s salt here. And so they made towns there. And the other thing was sugar, very rare in the environment. So our brain finds them appealing.
Why? Well, fat is a concentrated form of energy. And if you found it, you ate it to completion because you needed the energy. And sugar we’re rewarded with because there’s a special receptor in our tongue. And when we eat it, our brain rewards us by releasing actually dopamine, a nice reward molecule transmitter in the brain. And it tells us, go do that again.
And the interesting thing about rewards that are produced by food is that and actually everything is that they’re very ephemeral, they are brief. So you eat some sugar and the brain gives you a very brief little pulse of dopamine and you go, wow, that was great. And then the brain’s going, go do it again. Go do it again.
So foods give us this ephemeral plus, you know, just charge in our brain thanks to endorphins, enkephalins and also dopamine. But essentially we really want sugar, but there’s another reason for it. And I’ll go back to the Dunkin Donuts example.
Every morning humans wake up and what we find is we would really like some simple carbohydrates. We tend to eat bagels and toast and cereals and sugar coated things. And there’s a reason we choose that. It’s not random. In the hours before we wake up, we are dreaming a lot. We call it REM sleep. And the brain is very, very, very active at that time. And some people, it’s more active during dreaming than when they’re awake. And we are burning up ATP and our brain wakes up and it is sugar depleted. And it will tell us ”Go find simple sugars”. Well, donuts are a great choice place to find some sugar. And also I think the brain uses, if I remember right, about the equivalent of 12 donuts of sugar worth of sugar every day. So it needs a lot of sugar. That’s one thing it’s craving for us.
The other thing is that during dreaming we are using up a lot of a certain transmitter called acetylcholine. And we are also producing a lot of another transmitter that people might have bumped into called adenosine. Adenosine is an interesting transmitter. It turns off acetylcholine neurons.
Why does that matter? Well, it turns out when you wake up in the morning, you need your acetylcholine neurons to do things like paying attention. So we wake up and we’re not very attentive. So one of the best things we can do in the morning is to block the adenosine so the acetylcholine neurons can wake up and become active.
So what’s the best drug out there for a blocking adenosine? Caffeine! So caffeine and donuts are the two optimal things that our brain wants us to go get first thing in the morning. And it will reward us with some euphoria. We will be attentive, and we will think fast. And then for a few hours we’ll be great and then it’ll all crash.
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Narrator
Movement can affect the brain in a variety of ways. Studies focusing on people with movement disorders like Parkinson’s have revealed that group exercise which combines social engagement with movement – even sports like boxing – can be beneficial.
Dance instructor
…Sitting tall? Seven .. eight .. going in One …Two …
Narrator
These are not typical dance students. The class you are listening to is part of a pioneering program designed for people with Parkinson’s Disease.
This program is called “Dance for PD” and has been running at the Mark Morris Dance Center in Brooklyn, New York since 2001. David Leventhal directs the program…
David Leventhal
When we started 20 years ago, we had no idea whether dance would be accessible or appropriate to people with Parkinson’s. Things that people with Parkinson’s struggle with are addressed head on in dance. So the idea was, let’s take professional dancers, put them in the same room with people living with Parkinson’s and see what happens.
I taught the first class, and I saw people who came into the room struggling with walking, struggling with rigidity, struggling with their balance, struggling with things like facial expression – all aspects of movement. In the course of the first 20 minutes of class, I saw transformation happen. I saw people moving with more fluidity. And I saw people dancing with each other and connecting with each other, people who may have been experiencing quite a bit of social isolation in their lives, coming together and finding a connection nonverbally, just being able to look at someone’s eyes and dance with them, to mirror their movements, to do something meaningful together as a community.
Participant 1
My hands are so stiff, I can’t straighten my hand out. Just start moving gently and all of that stiffness goes away.
Participant 2
There is something magical that takes place in there. I’m not sitting there thinking about my body. I’m just trying to move.
Participant 3
At first I didn’t want to do it because I thought I’d be associated with a lot of people in the stage of Parkinson’s that I didn’t want to be at, and that would be discouraging to me. But I finally went, and I’ve never regretted the decision.
David Leventhal
We start class in a circle, so everyone is dancing together, everyone is equal, and we’re all sort of mirroring each other. Some people need to go a little slower, some people choose to do only certain movements. But there is a sense of a unified body moving together, and everybody is entraining to that circular environment, to the circular community.
This class is about dance and music and community. And in this class, people are given an opportunity to shed their “Parkinson’s persona”, and to really think of themselves as dancers.
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Phil Stieg
I really want to highlight. Can you give me the top myths about the magic of movement, the benefit of exercise, and the excessive levels of exercise that a lot of people take to? You know, I mean, I go to Central park and people are running 20 miles – which you would say is bad.
Gary Wenk.
One of the myths out there is that exercise will treat depression. It will not. It is reckless for anyone to suggest that because if it delays someone from getting appropriate medical therapy and effective pharmacotherapy of some kind, then you’ve done them a disservice by telling them that “just exercise and it’ll all go away”.
Now exercising, if you get rid of the body fat, that will help because the pro inflammatory molecules that fat cells release go to the brain and reduce neurogenesis. That actually leads to the depression associated with obesity. And that also is why obese people are very hard to treat with antidepressants. So that’s a big one right there.
The other myth is that I’m going to be able to go to the gym and exercise off my fat. Oh my goodness. You remember there was an NBC TV show, I quote in the book, “The Biggest Loser”, where the guy, he was, he had, you know, very large people exercise and then get on diets. And after doing this many years, he was quoted as saying the exercise never meant anything, it was just part of the entertainment. The only thing that ever worked was the diet.
We do not have muscles that have evolved to be efficient energy utilizers. They use what they need. Yeah, they have a lot of mitochondria, but so do a lot of other tissues like your liver and your brain. No, you’re not going to be able to exercise off the fat. You need to stop eating. That’s another big one.
Phil Stieg
I want to make sure everybody understands that you spent a lot of time talking about the neurochemistry, the different receptors, and that. I want to give equal opportunity for you to highlight the negative impact of inflammation and all the inflammatory agents and their effect not only on the brain, but also on your heart and all of your blood vessels.
Gary Wenk
Oh, my. Thank you for that. You know, inflammation. I started studying brain inflammation back in the 1980s, and at that time, my reviewers at the NIH told me that I was crazy. Everybody knows that there’s no inflammation in the brain. It’s a protected structure. Today, 40 years later, now, it’s like there’s inflammation everywhere!
Yes, inflammation plays a huge role. It is the consequence of oxidative stress. It is meaning it’s a consequence of eating and breathing. And if you want to see you know, what oxidative stress looks like, just cut an apple in half and set it out on the countertop. Fruits and vegetables are protected from oxygen. In fact, I usually begin my lectures with the statement that humans are essentially a big sack of fluids with a feeding tube going down the center. The surface is covered in dead skin, and the inside is covered with mucus. Now, ask yourself why –
Phil Stieg
– that’s attractive (laugh)
Gary Wenk
Yeah, because essentially, it’s protecting us from oxygen. Oxygen is horribly toxic to our cells. The job of hemoglobin is to keep the oxygen levels low enough in our blood that it doesn’t outright kill us. So here we are protecting ourselves from oxygen. If you look at, like, that apple, it’s covered in coating to protect its insides. So are bananas, and so are peaches. And it goes on and on and on. They protect themselves from the oxygen.
The oxygen damage produces inflammation in us. And those inflammatory proteins go into the brain. They kill cells, they prevent neurogenesis, and they actually accelerate neurodegenerative changes in the brain that we now realize are at the basis of Parkinson’s and Alzheimer’s, similar diseases. And all of that seems to be made worse because we eat too much and we develop too many fat cells and they’re too big. So, the cost of inflammation is very high.
Phil Stieg
What advice do you give to our listeners regarding “Nutraceuticals” – those dietary supplements the supposedly promote brain health?
Gary Wenk
Oh, my goodness. Let’s begin with the popular nutraceuticals that are out there now that you see advertised every night on the news to make you smarter. So without mentioning their products, they have been sued by the FDA for their commercials. They had to take away the claims of data that were all false. Their claims are entirely false. It’s entirely placebo. They are useless. They’re expensive, and they will not help anyone. But people are – they’ve seen it in advertisements and they just – they believe it!
Phil Stieg
Well, they prey upon people’s desperation when they feel like they’re losing their memory.
Gary Wenk
They do. And, you know, we all feel that way, but these things are not going to help. Better is to lose the weight. We’ve seen that in animal studies. Hard to do it in humans, but you can prove it in animals easily. If you want to feel younger and more intelligent in a way, more cognitive active, then lose the fat. That’ll do way more.
Phil Stieg
So your recommendation would then be. I think that with all of this is that this is not something that you start at 60, but something you start in your 30s — or even earlier.
Gary Wenk
Actually, that would be the recommendation, but this is not a death sentence. This is not that negative. Actually, from animal studies, we found that you can really start at any age. As soon as you stop consuming so many carbon bonds, you’re going to slow down the aging process. And you will feel better at any age. Really, just do it. It’s pretty simple to say. Very hard to do.
Phil Stieg
Dr. Gary Wenk, thank you so much for publishing your book, “Your Brain On Exercise.” It highlights how we’re really at the beginning of our understanding of marvelous complexity not only of the brain, but also its relationship with all the other organs in our body. Thank you so much for being with us.
Gary Wenk
My pleasure. Thanks.
