“Exercised” and How to Get Society More Physically Active (with Dr. Daniel Lieberman)

We evolved to be physically active for two reasons and two reasons only — when it was necessary and rewarding. People went out to hunt and they went out together, or they danced or they played when it was useful for them. If we want to make physical activity more popular, we need to make it necessary and rewarding.

Welcome to the “BarBend Podcast,” where we talk to the smartest athletes, coaches, and minds from around the world of strength. I’m your host, David Thomas Tao, and this podcast is presented by barbend.com.

Today, I’m talking to Dr. Daniel Lieberman, Professor of Human Evolutionary Biology at Harvard and Chair of that department at Harvard University. Dr. Lieberman is also the author of numerous books, most recently one titled “Exercised — Why Something We Never Evolved to Do Is Healthy and Rewarding.”

Dr. Lieberman took time out of his busy teaching and research schedule to join us on the BarBend Podcast.

We discuss why humans evolved for a very different lifestyle than we live today, and why exercise has become something many people dread, while others embrace it in various forms. We also discuss which exercise modalities come most naturally to humans, and how we as a society can promote healthier living through better incentives and support structures around activity.

I do want to take a second to say that we’re incredibly thankful that you listen to this podcast. If you haven’t already, be sure to leave a rating and review of the BarBend Podcast in your app of choice. Now let’s get to it.

Professor Daniel Lieberman or just Daniel or just Dan, I’m…You have to forgive me, sometimes I have trouble addressing professors. I’m not in college anymore. It’s a real pleasure to have you on the show.

Today, we’re talking about your work in a book called Exercised. I’m curious, you’re someone with a lengthy and accomplished career in the biological sciences, why did you decide to pursue a book about exercise?

I study the evolution of human physical activity, and how and why our bodies are the way they are. It’s a topic I’ve been interested in a long time.

My previous book was called “The Story of the Human Body — Evolution, Health, and Disease.” It’s about mismatch diseases, how our bodies are poorly adapted for the world that we’ve created for ourselves, and why that makes us sick.

While I was finishing that book…This is a true story. There really was a moment. Sometimes a book starts with a moment, and this book really did.

I was finishing up that book. I was putting up the final touches on the book. I’ve got invited to Ironman in Kona. There is a medical conference that precedes the race every year. It’s the best medical conference on the planet, by the way. If you get a chance to go, it’s just awesome.

You get to watch the race. I’m not a triathlete. I love to run. I like to bike, but no way would I do that open water swimming. 2.4 mile of open water swimming is not for me.

Anyway, so I was having fun, and I enjoyed the race, but it’s crazy what those people do. To do that, 2.4-mile swim, 112-mile bike ride, then a marathon, in a little over 8 hours is just astonishing. That’s not a human accomplishment. Anyway, so I left that race feeling pretty astonished, and also very pleased not to be an Ironman.

Not long after, I was in Northern Mexico doing fieldwork with a Tarahumara, who are famous for their long-distance running. They have their famous races that are Ironman-like. They go on forever and ever, and I was wondering, what’s going on? Why does a small number of people do this?

I was collecting data. I talked to one elderly guy who actually raced. He was one of the racers, because most Tarahumara, by the way, do not run long distances.

It’s one of the myths about exercising, and one of them is that people who are uncontaminated by civilization can do whatever they want. Lift huge rocks over their heads and run ultra marathons. That’s just nonsense.

Anyway, so I asked this guy, like how he trained? Everybody had been asking before about training, didn’t really understand my question because they don’t train. They don’t have even a word for it. When I explained to him through this interpreter who was explaining this gringo, he runs five miles every morning to get fit, and whatever.

He looked at me and he said, “Why would anybody run if they didn’t have to?” Here’s a guy who runs 50, 60-mile races. Suddenly, I had that sudden realization that among the many things that are weird about the modern world, going to school, reading, wearing shoes, exercise is also one of them, because physical activity is moving. It’s using your body to do stuff.

Exercise is defined as voluntary discretionary physical activity for the sake of health and fitness. Not even these guys who run, like the Tarahumara, they don’t consider it exercise. It’s a form of prayer for them. They don’t do it for health and fitness. It’s a completely modern abnormal strange thing.

I had this sudden thought that weird exercise, about exercise, people are confused, anxious, ambivalent, fed up with being nagged about it. People who brag about it, it’s very off-putting.

People don’t know what to do. We’re exercised about exercise, and to start understanding that, to start unraveling that, we have to first understand that we’re asking people to choose to do something that’s inherently unnatural.

It’s not bad for you, but it’s inherently unnatural. Until we get that under our belt, we are never going to make any serious progress.

One thing that I find interesting, and I’ve been very fortunate to host well over 100 episodes of this podcast, and our audience is people who tend to enjoy exercise. Now it’s specific forms of exercise. It’s certainly not completing an Ironman. It might not be running 50, 60 miles, although we do have some listeners who do that.

This is a podcast that’s popular among people who like lifting heavy things. Oftentimes, when asked, “Why do you like lifting heavy things?” I hear the joking response, “Because it’s there. I want to pick up that heavy object because it’s there.” Some of these people do lift heavy rocks over their head.

As much as exercise can be arduous, it can be something that isn’t enjoyable, why is it that certain subsets of the population, you think, gravitate toward the expression of exercise or toward training as a hobby, as something they enjoy?

Once you start doing it, it’s rewarding and it’s fit. Also, it’s a luxury of the modern world. If you were a hunter-gatherer, you wouldn’t be lifting weights like that. It would be a stupid thing to do because bulking up like that requires you to consume way more calories than you otherwise would get. You don’t need to be that strong.

It’s maladaptive to bulk up to get totally ripped if you’re a hunter-gatherer. It’s nonsensical. Today, we do all kinds of things that are unnatural. We read. Nobody read until a few. I love to read. I run marathons, and nobody did that before, either. We’re capable of all kinds of wonderful things, but let’s be honest about them. They’re not natural.

Some of us choose to do them, and we get rewards for doing it. You get that dopamine hit from running a long distance or from lifting weights. That molecule tells you to do it again, do it again, do it again, do it again.

Dopamine doesn’t make you want to do it. Dopamine rewards you after you do it. For those people who aren’t fit, who aren’t strong, it’s not fun at all. [laughs]

Think about, “No pain, no gain.” That is not, for most people, an idea of a good time. It is for a very small set of people. All power to them. I’ve got nothing against it, but let’s not pretend it’s normal.

Let’s talk about that dopamine hit. Some people might call it a runner’s high. If you lift weights and you enjoy that as a hobby, it’s the feeling of lifting something you know you couldn’t have lifted previously, perhaps. In addition, there is this physical component.

It’s almost like we’re getting addicted to the exercise, if that becomes something we pursue. Is that a framework of thinking about it that you think would be appropriate?

Sure. We understand some of those mechanisms. When you’re physically active, you not only produce dopamine, you also upregulate the receptors. We all know the feeling. If you don’t exercise for a few days and you normally exercise, you drive your partner crazy. I get irritable and twitchy and just not happy in my body, etc.

That’s because I got all these hungry dopamine receptors and they want their hit. That’s what makes me addicted to it. The vast majority of us aren’t that far along. Most people aren’t at that level. By the way, just so you know, a runner’s high is totally different. Runner’s high is caused by endocannabinoids, the same stuff that’s in marijuana.

You not only produce the endocannabinoids, you also produce the receptors, which is why a runner’s high is way more amazing than anything you can get from smoking. It’s quite an exceptional thing. You have to do it to experience it, to really understand it.

Natural selection has created various mechanisms to reward us, but remember, here’s the key thing. It wasn’t optional in the past to do physical activity. We had to do them. There wasn’t as much selection to get people to do this kind of stuff, because you couldn’t not do it. [laughs]

If you weren’t physically active back in the Stone Age, you would die. Nobody would want to be around you. You’d be marooned on an iceberg or whatever.

We never evolved in the same way to get ourselves active. It’s just like we never evolved to diet. Nobody was overweight back in the day. People didn’t have to lose weight.

When you try to lose weight, you go into what’s called a starvation response. That’s an ancient adaptation to prevent you from losing weight. [laughs] You have to overcome that, which is why it’s so hard to diet.

Just as we never evolved to diet, we never evolved to do unnecessary huge amounts of physical activity. It can be enjoyable, it can be rewarding, but it’s hard for most people. There’s a small subset of people who’ve got it, and they’re doing just fine. I’m not worried about them. I’m not worried about most of your listeners.

I’m worried about the other 80 percent of Americans who are physically inactive, struggling to be more active. They see people like me who brag about their marathons or maybe people like you who brag about how much they can deadlift or whatever. It just pisses them off. It makes them irritated.

I call people like that exercists. We need to realize that it’s not working for them.

First off, I do appreciate you explaining the differences between a runner’s high and maybe the dopamine response that I was referencing from exercise. It’s not a BarBend Podcast episode unless I get schooled at least once on something. I really do appreciate that. That’s an interesting clarification.

Let’s talk a little bit about this 80 percent of the population that your work is really aimed at that you’re really concerned about. This is interesting. We have on this call two people who enjoy exercising talking about people who don’t enjoy exercising or about how difficult exercising can be.

One thing you focus on the book is not that there’s going to be a single flip-the-switch solution and suddenly everyone’s going to start exercising. You also talk a bit about the guilt complexes and how we will often guilt people or how people might feel guilty because they’re not as active.

What are some of the changes that, in your research, have come to mind or that you might start recommending at a societal level to get people more active in a way that’s actually conducive to long-term health?

Thanks for asking that question. It’s a really important question. I would say that the first thing to recognize…Here’s the example I like to use. We’ve all been in a mall or an airport or a subway stop, or something like that, where there’s an escalator next to a stairway.

Oftentimes, an elevator under the escalator and the stairway if it’s in a mall.

That too, whatever. All of us, no matter who you are, unless you’re a freak of nature, all of us have a little inner voice that say, “Take the escalator.” We all want to do that. I certainly have that.

The reason I take the stairway is that if anybody sees me taking the escalator, I’ll be called out as a hypocrite. I want to take the escalator, just like anybody else, even though there were no escalators in the Stone Age.

We shouldn’t shame people for that little inner voice. That’s a totally natural inner voice. Yet we do, we call them lazy. We make them feel bad about themselves. That’s the first thing.

The second thing is to recognize that when people get barraged with information about how much they should do and we read about elite athletes who are the fastest, the strongest, etc., most of our focus on exercise is on elite athletes and on performance and maxing out and doing as well as you can.

That has really little to do with most people. It’s off-putting, and it’s irrelevant to most people. The other thing is we also tend to focus on exercise for weight loss. It’s weight loss, weight loss, weight loss, weight loss. Everything’s viewed through the context of weight loss.

Yes, there are a lot of people who are struggling to lose weight, but that’s not the only reason to exercise. It’s a very narrow lens to think about it.

The final thing I would point out, and maybe the most important thing, is that we evolved to be physically active for two reasons and two reasons only, when it was necessary and rewarding. People went out to hunt, and they went out to gather, or they danced or they played when it was useful for them.

If we want to make physical activity more popular, we need to make it necessary and rewarding. Just telling somebody to just do it, to prescribe working out on a treadmill like taking cod liver oil, we know it doesn’t work. Let’s have people find ways to make it fun.

Prescribing it doesn’t make it fun. We know it doesn’t work. The evidence is in front of our faces. Let’s make it necessary and rewarding. One way to do that is through commitment contracts.

Think about school. School is a commitment contract. You went to my university, to Harvard. I don’t know what you paid or your parents paid or somebody paid.

A bit.

Some un-gobbedly amount of money, it’s like $60,000, $70,000 for people like me to torture you. I made you read books. I made you take exams. If you didn’t do well, I gave you a bad grade. Yet you paid for the privilege to be forced to do that. Why? Because we know that we don’t do this on our own.

You need a commitment contract, and you need a reward. It’s also fun. There’s clubs, there’s musical groups, there’s the dining hall, all the friends, all the people you can date, etc. All the things that are great about college make it rewarding and socially. We make it necessary, and we make it fun.

If we’re going to help people be more physically active, we need to take the exact same approach. We need a commitment contract model that will make it more necessary and more fun. If we do that, we can do much better. The problem is that that’s not our society’s approach. We commercialize it, and we medicalize it.

Think about a CrossFit workout. People who do CrossFit, it’s fun. It’s grueling, it’s horrible, you work out, you’re sore the next day, but you have all these people who are helping you out and cheering you on. You give encouragement. Also, because they’re expecting you to show up, you’re going to show up.

That’s one of the reasons why CrossFit and other kinds of group exercises or running groups or whatever, that’s why they work. It’s a commitment contract.

The term shared suffering is something that comes up often in CrossFit, shared being the operative word.

The problem is the suffering part. A lot of people don’t like the suffering part. That’s part of the virtue signaling of exercise. Why do we have to make it be suffering? It doesn’t have to be suffering. Just a walk around the block is a good thing for some people.

It’s part of this false virtue that we assign to exercise that is again for many people off-putting. If it works for you, that’s great, but for most people, it doesn’t.

Something else you talk about in your book, speaking of false virtues. I’m not sure if you would specifically categorize this as one of those. It’s overdoing it, the question of too much exercise.

I’m curious to what your research, and for those who haven’t read the book but hopefully after listening to this podcast will go pick up a copy, and we’ll also make that very easy to do in the show notes, what does your research suggest about over-exercising in that realm?

That’s a really interesting question. There’s a very, very small number of human beings, tiny fraction of the population that’s worried about exercising too much. It turns out, everybody I know, myself included, who studies physical activity and exercise, suspects there’s such a thing.

We don’t actually have any good data on it, partly because the numbers are so small.

If you, for example, look at dose-response curves, so exercise on the horizontal axis and health outcomes on the Y axis. If you get out to the really, really far right part of the graph where there’s too much exercise, there’s no evidence for a statistically increased rate of negative health outcomes from those individuals.

There are certainly trade-offs. People who do huge amounts of running might be more at risk of atrial fibrillation. They’re also at less risk of other kinds of heart disease. What’s the balance? Nobody really knows.

For those of you who are into weights, you should know that there are concerns about too much weightlifting because of cardiac hypertrophy.

We published a paper a few years ago which we showed that as people’s hearts gets thicker to respond to the peripheral resistance when you lift a huge weight, you’re pushing blood through your body against high resistance because you have to perfumes your brain.

When you’re doing that, just like any other…When you’re pushing with all that resistance, you have to thicken your heart wall. There is evidence that individuals who have really thick heart walls are more prone to heart disease.

Whether that comes from lifting or from hypertension is a big debate and I’m not going to get into it. I’m not a cardiologist.

What we do know is that individuals who engage in weightlifting don’t get the same kind of health…Only weightlifting and don’t do endurance, don’t get the same health benefit of people who add some endurance.

There’s a very famous study that was done in Finland. Finland is cool study, country that study this stuff because they keep nationalized healthcare. They have data on everybody, the entire country.

They did a fascinating study, the book is described in the book, where they looked at everybody in Finland.

They looked to all the Olympic athletes who did weight, your strength exercises, versus those who did endurance exercises, versus the country as a whole, and they looked at heart disease outcomes.

The people who did only strength training had lower rates of heart health and cardiovascular health than the average Fin, whereas CrossFit the people who did cardio were better off.

By not mixing it up, it is possible that you can overdo it especially if you do only one thing. That could lead to trouble. We’re talking about small samples, we don’t have a lot of evidence on that.

Variety in one’s diet is something you hear about a lot. Variety in one’s exercise is something that people who listen to this podcast have heard quite a bit.

Yeah. It has an evolutionary origin because we evolved to be endurance athletes. What humans are good at is not strength. [laughs] Some of us are stronger than others, but we’re not good at strength. We’re also not good at speed.

Usain Bolt, the fastest guy on the planet, is pathetic compared to most mammals. He’s fast compared to me.

I could never dream of running as fast as Usain Bolt, but my dog could probably outrun him. What we are good at is endurance, and that has affected our biology. I would argue that humans who do not engage in some degree of endurance compromise their health. They increase their vulnerability to a wide range of diseases.

We evolved to be jacks-of-all-trades, primarily endurance athletes, but we had to have some degree of strength too. When anybody goes over in one category and avoids the other categories, that’s probably less than optimal.

For all of the powerlifters and weightlifters listening in right now, cardio is not your enemy. We’ve said it on dozens of BarBend Podcasts before with various guests. [laughs]

I do want to talk a little bit more about something we talked about two questions ago, which is, basically, how do we create these contracts or these systems that don’t punish people or don’t guilt people for not exercising but can make exercise potentially more enjoyable, more accessible, and something that’s a little bit more baked into our lives?

You gave the example of one way CrossFit sort of does that, but the virtue signaling might also undermine the goals there. What are some other structures you could imagine in society that would reward people for activity in a way that’s a little bit more inclusive?

I can think of thousands of ways. Here’s one example.

Why not have in every town, in the town square or whatever, on Wednesday and Friday nights, music where people can dance and encourage people to come out and dance? Dancing is a fantastic form of exercise that people enjoy. It’s endurance too. It’s cardio. It’s great.

Why not have more clubs, like running groups or walking groups, in workforce? Your lunch break, why not have walk-with-your-boss kind of stuff? There’s so many ways that we can make social groups that can make people have opportunities to be physically active with each other in ways that are enjoyable.

For every kind of physical activity, we can have different kinds of social groups.

It have to be a societal thing because, obviously, we can’t legislate it. We can’t force people to exercise, just like you can’t prevent them from smoking. People have the right to be sedentary. Let’s, as a society, help each other compassionately by encouraging all these things.

One of the things I did in the book, one of my favorite parts studying the book was I went to the Bjorn Borg sports company in Stockholm. Bjorn Borg is the only company in the world that requires all its employees to exercise. If you don’t exercise, you’re [laughs] fired basically.

I was very curious about this, skeptical because it’s not my philosophy. I’m not into telling people what to do. I was amazed by how much the people in the company…They’re not all exercise addicts, a lot of them only exercise because their boss forces them to do, but they all grudgingly agree that it’s helpful for them. It’s extremely social.

For their Christmas party, instead of all getting drunk, they go for a run around Stockholm. [laughs]

No eggnog after? [laughs]

They have hot chocolate. That’s what I was told. They have hot chocolate afterwards.

That’s something.

The sky is the limit. We can all come up with fun…It makes the employees happier and healthier. I have another example. There’s a website called stickk.com. You guys want to check it out. It’s a commitment contract model where you can sign up. You can give them 1,000 bucks, which they’ll hold. You get interest on it.

You can designate a referee and then come up with a task like, “I want to walk 20 miles a week, or I want to run 20 miles a week,” or whatever. You can designate a referee. You can choose either a carrot or a stick. I have a friend, for example, whose stick is that if she doesn’t walk X number of miles a week, it sends $50 to the NRA.

She’s not a fan of the NRA, so it’s actually kept her physically active. She has never missed a week apparently because she doesn’t want [laughs] $50 to go the NRA. You could pick whatever charity you hate or like or whatever. That’s another example of a way that we can use collectively to help each other. That’s a silly one, but there are plenty of them.

It’s a powerful example. The NRA just announced their filing for bankruptcy. Clearly, something worked in the…

…universe. We could launch an entire podcast off of your ideas for more commitment contracts to get the world a little bit more active.

One thing I do want to ask before our time is up, are there any populations that you haven’t been able to study in your work, whether it’d be working in this book or previously in your career, that you would like to when it comes to how physical activity impacts their lives or the way that they express physical activity or do so in their daily lives?

I’ve been lucky. I had the chance to travel all over the place and see all kinds of amazing things and meet all kinds of amazing people. I can’t say there’s one population. There’s so many. [laughs]

I’m curious about so many different traditions out there. You can’t see them all. It takes time, and effort, and permits, and all that stuff. A lot of my research is by reading other people’s accounts. I’ve also been lucky enough to go and experience things myself, going hunting anywhere in Greenland.

There’s some things I didn’t even get a chance to put in a book, like I spent six weeks in India, looking for tribal runners in the Ghats mountains. That was amazing. We met all kinds of interesting characters.

I’m curious to see some of these Eastern traditions, like Buddhist monks who do amazing amounts of exercise as part of their spirituality. I could go on. There’s lots and lots and lots and lots of…The world is large and wide. There’re so many diverse ways that people use their bodies. I would have a hard time saying which ones I would most want to visit.

I’m getting a biology Anthony Bourdain vibe here. There might be a show there as well.

Oh gosh, post-COVID though.

Post-COVID, there definitely would be an audience for that. Professor, where is the best place for people to follow your work, to pick up the book? What are some other books or papers that you’ve been involved with that you’d like to encourage people to check out as well if they enjoyed Exercised?

The easiest thing to do is Google me. You can find my website, or go to Google Scholar. Most of your listeners know about Google Scholar. Get on Google and type in Google Scholar. You can type my name and you can get almost all of my papers, download them for free. The two papers I’m most famous for, one is the “Born to Run” paper in 2004 with Janice Bramble.

We argued that humans evolved to run long distances. That’s in the public domain. It’s easy to get.

In 2010, we published a paper, also on the cover of nature, about barefoot running, which got a lot of [laughs] big debate going. That’s what most people know me for. Exercised is available anywhere. Now, you can get on Amazon or whatever…

Go support your local bookstore, maybe it’s where…

Your local bookstore, that’s a good idea, but there’s lots of places to get it. I also published, a few years ago in 2013, a book called The Story of the Human Body — Evolution, Health and Disease. That’s about mismatched diseases, the story of human evolution, and stuff like that.

It’s a very different book. Those are both, hopefully, fun, popular reads and good ways to find out about how evolution matters. We often don’t think about evolution when we think about all of the things that we do. If you want to understand how and why we are the way we are, you have to understand that evolutionary story that got us there.

That evolutionary theory and evolutionary data are profoundly important for thinking about health and disease, and so many other aspects of being human.

Excellent. Thank you so much for joining us, really enjoyed this conversation. A lot to nerd-out on, and I’m sure our listeners are going to enjoy the dive. Find Exercised wherever you get your fine books. We appreciate your time.

My pleasure, thank you.