#218 - AMA #38： Can you exercise too much？
Episode Stats
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Summary
In this episode, we take a deep dive into the question of whether or not there is such a thing as too much exercise. We discuss the data, the controversy, and some of the best evidence on the topic.
Transcript
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Hey everyone, welcome to a sneak peek, ask me anything or AMA episode of the drive podcast.
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I'm your host, Peter Atiyah. At the end of this short episode, I'll explain how you can
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access the AMA episodes in full, along with a ton of other membership benefits we've created,
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or you can learn more now by going to peteratiyahmd.com forward slash subscribe.
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So without further delay, here's today's sneak peek of the ask me anything episode.
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Welcome to ask me anything episode number 38. I'm joined once again by Nick Stenson. In today's
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episode, we dive in really deep to this question around exercise and if there is such thing as
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too much exercise. Obviously we talk a lot about exercise on this podcast and that's for pretty
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obvious reasons. Namely, it's perhaps the single most important tool we have to live longer and
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live better. However, we often get asked a lot of questions about the optimal dose of exercise for
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longevity. So it's a topic where there's a lot of confusion in the literature and we've even had
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previous guests on the podcast who disagree with each other on what those answers ought to be with
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respect to the dose of exercise. So for this AMA, we compiled all the questions that you've asked around
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this and we've now taken the hard look at this. So which studies say what things, how contradictory
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are the results? And we do this primarily by looking at the so-called J curve. The J curve meaning that as
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you go from being sedentary to being active, your risk of all cause mortality declines. But then
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something paradoxical seems to happen, which is after bottoming out, it starts to uptick again,
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the so-called J, suggesting that once you go beyond a certain point, that is to say, once you exercise
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beyond a certain point, your risk no longer stays low, but actually starts to go back up.
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Now, this episode took a lot of time. In fact, we were going to record this episode about two
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months earlier, but I just didn't feel we had done a deep enough dive. So we delayed it. And the reality
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of it is there's so much here that we just can't discuss in a podcast because the podcast would be
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too many hours. So what we do is we talk about everything in summary. We deep dive into a handful of
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studies. We discuss some of the illustrative critiques on all sides, but really, if you want
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to see this at the deepest level, I would encourage you to look through our show notes where we're going
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to link to all of the analysis has been done on each of the studies. So if you're a subscriber and
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you want to watch the full video of this podcast, you'll find that on the show notes page. Also,
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if you're not a subscriber, you can watch a sneak peek of this on YouTube. So without further
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delay, I hope you'll enjoy AMA number 38. Peter, how are you doing? I'm good, Nick. How are you?
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I'm doing good, man. You ready for another AMA? Sure am. All right. Well, this one I think is on
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a topic you're a little more excited about than maybe the fruits and vegetables one, looking at
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exercise. So there's been no shortage of things that you've spoken about exercise and how positive
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you are on it. You've often talked about how it's one of the most potent things we have
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in the toolkit for longevity. And whenever you talk about it, we get a lot of questions from
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subscribers. A lot of people wondering how should they think about exercise? Like what is the optimal
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dose of exercise for longevity? And I think we see this anytime we do an exercise podcast because
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you have your four pillars of exercise. And so people are always wondering, how do I get everything
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in? How much should I be working out? I think some of the confusion can also come from past guests,
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maybe having different opinions. I think when you look at the literature, it also doesn't quite agree
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with each other. You know, so if you take someone like Alex Hutchinson and you take maybe the AMA you
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and Bob did on VO2 max, and you talked about how important that was. And then you have a podcast like
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we did with James O'Keefe where he and his research talks about a J curve. It's kind of hard for
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subscribers at times to understand the literature, right? How do you get an elite VO2 max when some
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of the other research says the best thing you can do is play badminton? You know, those two things
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don't quite add up. And so what we did for this one is we compiled all these questions around this
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to really try and answer the core question, which is what is the optimal dose of exercise for longevity?
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And quick disclaimer is, we're not looking at what is the minimum dose, which I think gets written about
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a lot. And I know we've done weekly emails, kind of responding to articles that are like 10,000 steps,
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10 minutes of walking a day, all these little things are all you need to do. So we're going to focus on
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that core question is like, what is the optimum dose? So before we get into those types of questions
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that we compiled, anything you want to add to what I just said to set the stage?
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Yeah, I would add that we're also going to explore, can you do too much? Because most things in biology
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occupy a Goldilocks space, not too much, not too little. Clearly, that's the case with nutrition,
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too much nutrition, just look around you, too little nutrition. Well, that's frankly, the problem that
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lots of parts of the world still experience and have historically experienced a lot of. So
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with exercise, I think that's less clear. And that's a topic we also want to really get into
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today. And even if that's not relevant to the majority of the population, in other words,
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even if majority of people aren't in the situation where they're butting up against potential limits
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of exercise, in terms of crossing from being benefit to risk, I think it's a very important
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question, nevertheless, and it might speak to some of the mechanistic insights around exercise.
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And of course, for those people who do want to push the limits, it probably gives us some insight
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So maybe we just start with one of the first questions. And it's something that you've covered
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before, so we don't have to go into it in an insane amount of detail. But I think it might be
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helpful for people just to set the stage on why they should care about this and why it's worth
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putting in the time to exercise. How is exercise so beneficial, not only for our healthspan,
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but also for our lifespan. And you kind of tried to summarize in a cartoon you put on Instagram
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the other week at this point, which kind of looked at the guy in the doctor's office and
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the doctor asked him, like, what would you rather do exercise one hour a day or be dead 24 hours a
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day? And so anything that you can kind of do to set the stage on why this is so important and why
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people should make the time for it should put the effort in to understand this.
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To your point, I think at this point, there's really no need to spend time discussing this
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beyond just stating that regardless of which chronic disease you're looking at, whether
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it be ASCVD, cancer, type 2 diabetes, Alzheimer's disease, all cause mortality, it doesn't matter.
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Exercise is going to reduce the toll of mortality across all of those things. The mechanisms by
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which it does it can be interesting. So it can improve lipids, it can reduce inflammatory markers,
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it can reduce flow-mediated shear stress in arteries. In cancer, truly, it's a little bit less
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clear. I suspect much of the benefit in cancer comes through the metabolic benefits of exercise.
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So we know, for example, that the second leading environmental or modifiable risk of cancer
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after smoking is in fact obesity. And as I probably talked about another podcast, I think it's really
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less the adiposity of obesity that's the problem and the metabolic consequences of obesity that are
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found in many but not all obese patients. Obviously, diabetes is probably one of the most clear places
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where you just dramatically see an improvement. And this, of course, has to do with glucose disposal and
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insulin sensitivity within the muscle. And again, I think the list just goes on and on and on,
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but there really isn't any ambiguity here. And again, we should sort of celebrate this fact
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because there's a ton of ambiguity in a lot of things that pertain to lifespan and healthspan.
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It's actually nice for once to have a slam dunk.
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I think what would also be helpful for people is another term I've heard you mention before
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internally as you think about your exercise and how you plot out how you tackle this problem is
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METs. So do you want to let people know what a MET is and then why it can be beneficial
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in looking at a variety of different exercises?
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I do talk about it a little bit. And I think most people have heard of this idea of a metabolic
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equivalent or a MET. And it's basically an energy currency in the body. We think about energy
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currency and sort of ATP, but you know, that's on such a cellular level. This is kind of a global way
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to think about it. One MET is the energy cost of being alive at rest. So obviously not a whole lot.
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Worth noting that one MET is equivalent to 3.5 milliliters per minute per kilogram of oxygen
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utilization. And that relationship for the most part just holds. So in other words, if you are doing
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10 METs of exercise, you are consuming 35 milliliters of oxygen per minute. And that becomes
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relevant as we start to think about VO2 max. Now, when you want to get a sense of what certain
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activities look like, and again, so much of what we talked about on this podcast, even what we've
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already gone through, like I glossed over some of the details of the benefits of exercise in the show
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notes, we will include so much on that. So that if you really want to go deep on every single,
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you know, aspect of health span and lifespan and the mechanism for each, we've got all of that in
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great references. But again, when you want to think about how many METs do you get doing various
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things? Well, again, sitting there doing nothing is one MET. Walking your dog might be three METs.
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Going for a slow bike ride, kind of 10 miles an hour or less, four METs. Mowing your lawn might be
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five and a half METs. Playing golf, four and a half METs. Resistance training vigorously, six METs.
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So you kind of get a sense. Now, where does this go? Well, rowing at 100 watts, which really isn't
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that much of a killer effort, you're at seven METs. Now you can look at the speed change, right? So
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once you're running six miles an hour, which is a 10-minute mile, and that's still a jog, you're
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almost at 10 METs at that point. Once you're running 10 miles an hour, six-minute mile,
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this is a pace that a fit person can hold for a while, but most people couldn't hold for very
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long, you're at about 14 and a half METs. So you get the sense of the non-linearity of this,
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meaning 14 METs versus seven METs, you wouldn't hold seven METs for, or you wouldn't hold 14 METs
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for half the time you'd hold seven METs. Just to double click on it, METs you get per activity
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is per an hour of activity? No, it's all normalized per time. So if you're running a six-minute mile
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pace, for an hour, we would say you did 14 and a half MET hours of work. So here's the way to
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think about it. It's the difference between watts and joules, if you think about it. If anyone who's
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a cyclist will think of things that way. On a bike, your power meter tells you instantaneously how much
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work you're doing. That's wattage, which is really joules per second. And then you multiply that over the
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total time that you do it, you take it back to total energy. So the MET is an instantaneous
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measurement and you normalize it over time to give the total volume. So the work that's done
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is really the MET hour. So for example, if you, I don't know, do a hike for six METs worth of activity
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or six METs worth of exertion, and you do it for 45 minutes, that would be four MET hours of work
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done. Peter, when people think about their METs, how is it that knowing how many MET hours you're
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putting out, how is that helpful to someone as they think about exercise on a whole?
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You know, look, I think for most people, it's not. Truthfully, I'm probably one of the few people
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who tracks my MET hours per week. I don't do it down to the Nat's ass. I just mean, I have a
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spreadsheet where I'm basically putting in my activity, the amount of time I spend doing it at
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various different intensities. And I can, at the end of the week, say, look, I'm doing 100 MET hours
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per week during this phase of my training. During this phase of my training, it might be 80. Back in
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the old days, it was 200 MET hours per week. It was a much greater workload. If you're doing one thing
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that's tied to a power meter, like in cycling, you know, we tend to keep track of kilojoules and
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normalize power and power. So all of these things are just sort of ways to track the work you're
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doing. Now, I think it partially becomes relevant when you want to evaluate the research because the
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research has to be able to take into account not just how much time you're exercising, but what's
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the intensity of that exercise. It would be very difficult to provide guidance if we didn't know
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this. For example, do we want to say just the amount of distance you run a week tells us everything
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we need to know? Are two people who are running 15 miles per week experiencing the same metabolic
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benefit or harm? Well, certainly not. One could be running them all at 10-minute mile pace. One might
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be, I mean, just imagining this, one might be running them all as 400 all-out repeats. So you have to have
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some way to kind of normalize that. And in the case of the latter, you would probably see a much higher
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met hour because of the intensity. And so with that kind of background, now we're going to kind
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of get to the core of what we get asked about. And so the first question is, to the best of our
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knowledge, are we even able to say if there is a minimum efficient or most effective dose of exercise
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when you look at met hours per week? Is that something that, is that our understanding?
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