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Hey podcast listeners. We love it when you send us your questions — like, “Hey Freakonomics, what’s the best way to do this or that,” or “Hey Freakonomics, what’s the story with such-and-such.” Some of you are so smart … I’m not even sure you’re real.

JASMINE: Hey, Freakonomics. This is Jasmine.

Stephen DUBNER: All right, Jasmine, and what would you like to know today?

JASMINE: I want to know what is the best and most efficient form of exercise. I want to get the most benefit for the least amount of time invested. I don’t have that much money either. Also, I am kind of lazy. Thanks, Freakonomics!

All right, Jasmine. Let’s see if we can answer your question — the best, most efficient form of exercise. But let’s start by examining the premise. Maybe you don’t even need to exercise? Is exercise really as worthwhile as we think? We put this question to David Meltzer. He’s our kind of guy — a doctor and an economist, at the University of Chicago.

David MELTZER: I think there’s a lot of good evidence both observational as well as experimental that exercise really helps. The numbers I often cite are that even something as simple as walking for half an hour a day five days a week raises your life expectancy by a year and a half. And exercising more intensively than that on a daily basis can produce gains that are double that.

JASMINE: No offense, Freakonomics, but I could have told you that exercise is good for me!

O.K., I just wanted to make sure you’re not wasting what little time you have. As it turns out, Jasmine, your situation is pretty typical. Here’s Gretchen Reynolds. She writes the “Phys Ed” column for The New York Times:

Gretchen REYNOLDS: The most common reason that people give for not exercising is that they don’t have time.

And here’s what that means:

REYNOLDS: Most Americans are not exercising. The best statistics suggest that at least 80 percent of Americans are not meeting the most commonly used guidelines for exercise, which are those from the American College of Sports Medicine. And they suggest 30 minutes of moderate exercise most days of the week. The vast majority of Americans are not doing that.

JASMINE: Oh. Now, I don’t feel quite so bad.

DUBNER: All right, but that doesn’t mean you shouldn’t try to exercise.  So we took your question – “what’s the most efficient form of exercise” – and asked some people we thought could answer it. Here’s one of them:

Peter ATTIA: The right way to think about this is it’s the wrong question. And you know, if I’ve learned anything in my life, whenever I ask the wrong question it almost guarantees I will not find the right answer.

JASMINE: Ooh, what a meanie. Who is this guy?

His name is Peter Attia. He’s an M.D. and a nutrition expert and also a fitness fanatic, emphasis on the fanatic. Part of his exercise routine is flipping a tractor tire:

ATTIA: It’s a pretty heavy tire. It’s about 450 pounds. You’re never actually lifting the entire thing at once because you’re flipping it. I have a goal that I’m working really hard mostly for fun to get to, which is to break sixteen seconds on six flips of that tire.

And here’s why Dr. Attia thinks this question — “what is the most efficient form of exercise?” — is the wrong question.

ATTIA: If someone says to me because I get asked this question all the time, “What’s the least I can do for the most?” I really ask the person, what is it that you want? What’s your desired outcome? And it can be anything from “I want to run my first marathon in six months” or “I want to compete in a triathlon and it will be my first one” or “I want to take my game to the highest level because I’ve already been doing this for a while, but I want to get a little bit better.” It can also be something like “I want to look better in a bathing suit” or “I want to not get tired when I play with my kids.” Those are all actually really elaborate physical activities.

DUBNER: O.K., so Jasmine, what’s your exercise goal – you want to compete in a triathlon or just look better in a bathing suit?

JASMINE: Oh, I already look very good in a bathing suit. This is mostly for my heart. For my longevity.

Well, if you’re thinking longevity, there’s one exercise that Gretchen Reynolds really likes. The squat:

REYNOLDS: The squat will use almost all of the biggest muscles in your body, those in your upper legs, your back, your core. Those are also the muscles that you need to do things like get up out of a chair, which may sound facetious, but in fact, as you age, one of the best indicators of whether you will be independent well into your twilight years is if you can get up out of a chair. And if you can go up and down stairs.

JASMINE: That sounds pretty good. But how am I supposed to know what exercises do the most good?

O.K., so let’s talk about how exercise is actually measured. Here’s David Meltzer again:

MELTZER: The technical answer is exercise is probably best measured in terms of the total number of calories that you burn. And therefore, the efficiency of exercise in terms of calories burned per unit of time is commonly measured in something called the metabolic equivalent score, or METs. And they rank all the exercises that you could imagine doing from the most intensive to the least intensive. And the scale starts at one, and one is basically rest. And in the sort of standard scales that I’ve seen, the things that are right at the top are basically running and soccer, which presumably means running all the time, unless you’re the goalie. And then it works its way down. So things like running are a 10, jogging is a seven, golf is a four and a half.  Rest is a one. But it’s interesting because there are also some activities on the list that are things you might have to do anyway, like yard work. That’s a six.

JASMINE: Oooh, I don’t really like yard work. Is there anything else like that on his list that is a 5 or a 6 on the METs scale?

Well, square dancing is pretty good. And I’ll quote here from a list put out by the Centers for Disease Control: “playing guitar or drums in a rock band” or “fishing while walking along a riverbank.” Any of that sound good?

JASMINE: I am not into fishing.

DUBNER: Sorry?

JASMINE: I am not into fishing.

DUBNER: All right, let’s see what else … clogging is good … jumping jacks … digging ditches.

JASMINE: Yeah … let me think those over.

DUBNER: Fair enough. And when we come back – I’ll tell you about a really fast way to get in your daily exercise:

QUICKGYM VIDEO CLIP: With the ROM there is no time to get bored … by the time you think of an excuse, 4 minutes is up and you’re getting on with your day …

*      *      *

DUBNER: Hey, Jasmine. You still there?

JASMINE: I am still here.

DUBNER: And you’re still looking for the most efficient form of exercise?


DUBNER: O.K., so you could try an exercise commitment device – like joining a gym. The problem is, research shows that people who buy an annual gym membership overestimate how much they’ll use it by about 70 percent.

JASMINE: What a waste of money.

DUBNER: Agreed. Now, there’s another kind of commitment device – an app called GymPact, where you sign up for a certain amount of exercise and if you don’t follow through, you have to pay them.

JASMINE: I don’t like that one bit.

DUBNER: All right, Jasmine, I hear you. So you want the best, most efficient, most cost-effective exercise you can find. Based on what our three wise guests have figured out, let me offer you a little checklist. We’ll call it the three I’s. The first I: intensity. Here’s Gretchen Reynolds again:

REYNOLDS: And that means simply that you go very, very hard for a brief period of time, and that usually you have a short break, and you go very, very hard again. There are a number of studies that have looked at different forms of high-intensity interval training and have found that, for instance, you can do one minute of, say, hard bicycling and one minute of much easier bicycling. And if you do 10 of those intervals you get essentially the same physiological changes within your body as if you do about 90 minutes or two hours even of more common endurance training where you just go ride. It seems very clear that these intense bouts of exercise can improve your fitness and also improve your health just as much as longer bouts. But they have to be hard. They have to hurt.

DUBNER: Jasmine, are you ready for the pain?

JASMINE: Maybe. Maybe not. What is the second “I” in your checklist of three I’s?

DUBNER: Individualization. Here’s Peter Attia again, the tractor-tire-flipping doctor-nutritionist:

ATTIA: It kind of means using yourself as a guinea pig. You know, there’s a lot of questions that I think we wish science would answer. But sometimes they’re either not deemed high enough priority in a scientific community, or the scientific experiments that are carried out are done on such a heterogeneous population that you can’t necessarily extrapolate for yourself. And so one of the other things that I do when I work with people is we really sort of embrace this concept of self-experimentation, because at the end of the day if I was working with you, it’s really not that important what works for the population. It’s really more important what works for you, personally.

JASMINE: O.K., he doesn’t sound so mean anymore.

DUBNER: Agreed. And that leads us to the last “I” on the exercise checklist. If the first two are “intensity” and “individualization,” the third one is, “I… like to do it.”

Peter Attia, Gretchen Reynolds, and David Meltzer, all agree that the best exercise is … whichever one you’ll actually do:

REYNOLDS: Whatever you will do is certainly the best exercise.

MELTZER: Well, what do you actually like doing?

ATTIA: Do something that you actually enjoy. Do something that makes you better.

DUBNER: So what do you say, Jasmine – does that give you any ideas?  

JASMINE: I do have something in mind. But I would rather not say.

DUBNER: O.K., no problem. But if whatever you’re thinking about doing doesn’t work out, we’ve got one more option to offer you. David Meltzer told us about the ROM workout machine from a company called QuickGym.

QUICKGYM VIDEO CLIP: The best exercise machine is the one you’ll actually use, and the one that gives you a total body workout, in only 4 minutes, is the one you’ll use every day.

DUBNER: You sound like the kind of person who could really warm up to this machine, Jasmine. But let me warn you: it costs more than $14,000.

JASMINE: Ouch. Is it worth it?

Well, depends on who you ask. Here’s how David Meltzer sees it. Remember, when he’s not busy being a doctor, he’s being an economist:

MELTZER: Yeah, well I guess the economic logic of it is that it doesn’t require very much time at all to get a full day’s workout. So presumably if, you know, it took an hour to get a comparable workout, and it only takes you four minutes, it saved you 56 minutes. So presumably that’s worth your hourly wage, you know, five times a week over a year, you can price that out and amortize it, that’s probably worth quite a lot of money. Maybe you’ll even get a new sponsor for the show.

QUICKGYM VIDEO CLIP: With the ROM there is no time to get bored … by the time you think of an excuse, 4 minutes is up and you’re getting on with your day …

JASMINE: Hey Freakonomics, that’s pretty neat. Thank you for your help.

Thanks for the question, Jasmine. And I look forward to your next one.

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