Running Doesn’t Age Men (While Keeping Women Young). Here’s How We Know.
…And it’s good for your knees!
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Don’t you just love it when your interests come together?? Today’s post combines two recurring themes here at Range Widely: running, and critiquing science news.
Earlier this summer, social media kept feeding me headlines like this: “Why Running Helps Keep Women Young But Ages Men.” And this: “Men, Be Warned. Running Marathons Could Actually Age You.”
One thing I try to do regularly in this newsletter is give what I think of as cold takes — bringing nuanced context to unnerving headlines. In this case, I decided to chat with Alex Hutchinson, author of the utterly fascinating Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. (It’s basically a book I wanted to write, but I'm not sure anyone could've pulled it off as well as Alex.)
Alex, as a runner himself, made a Canadian national team; he also has a physics PhD, and keeps up with an otherworldly amount of exercise science. Below is our discussion about the harrowing headlines above.
David Epstein: So, Alex, in the first article I linked above, the author — a 42-year-old woman — complains of running injuries, and then writes: “At least I’m not a man.” The author then details apparent new research which found that running added a decade to the “vascular age” of men over 40. There’s a lot to unpack here, but can you start by sharing what we know (and don’t) about this study?
Alex Hutchinson: The headlines come from an abstract presented at the British Cardiovascular Society conference in early June by researchers from University College London. If you look at the press releases put out by the conference and the university, you see the headline is: “Endurance exercise may affect body's largest artery differently in men and women.” So it’s a viral story about how men and women are different, right?
Okay, that’s not really what caught everyone’s attention. The researchers looked at around 150 men and 150 women, all of whom were athletes over the age of 40 – mostly runners, plus a few cyclists and swimmers and so on. They used MRI scans to measure the stiffness of the aorta, the main artery that carries blood from your heart to the rest of your body. Compared to non-athletes, the men had significantly stiffer aortas, while the women didn’t.
That’s interesting, but it still probably wouldn’t have made waves if they hadn’t translated the stiffness findings into a “vascular age” that conjures up images of your hair going gray and teeth falling out as you stagger across the finish line of your marathon. What is this vascular age algorithm? We don’t really know, because – this is the key part – it’s just a conference presentation. There’s no paper to read, no references to scrutinize, and there’s been no peer-review process.
DE: So, we really don’t have anything to go on in terms of being able to assess this actual research. The best thing I can think of to do, then, is to share broader context. I know you could fill a book with this, but what do we know about the impact of habitual running on cardiovascular health and longevity?
AH: My favorite body of research is something called the National Runners’ Health Study, which was run by a guy named Paul Williams at Lawrence Berkeley National Laboratory and followed more than 150,000 walkers and runners for two decades —
DE: So just a bit more than the groups of 150 in this new report, huh?
AH: Yeah, just a bit. And in that giant study, you name the health condition, and running makes you less likely to get it: not just the obvious ones like heart disease, but also things like glaucoma, Alzheimer’s, brain cancer, and so on.
DE: Woaa, brain cancer. Didn’t know that one!
AH: I don’t want to sound like a multi-level marketer, but regular, vigorous exercise really does make your body work better and last longer in pretty much every way imaginable. And in most of Williams’ studies, there’s a clear dose-response effect: more is better.
Still, the trickier question is whether there can be too much of a good thing – whether running 5Ks is great, but running ultramarathons wears your heart out. Logic tells us that there’s a point of diminishing (or perhaps even negative) returns somewhere. My reading of the evidence is that this hypothetical point is way beyond what the vast majority of people would ever contemplate doing. But studying this stuff is hard, because you can’t run a study where half the volunteers are assigned to run marathons for the next two decades.
But there is one body of evidence that’s both clear and reassuring. Instead of asking people how much they exercise, you take an unfakeable measure of aerobic fitness (the most common is VO2max — a measure of how much oxygen your body can use while exercising), then wait a few decades to see who dies first.
DE: Sounds suspenseful…
AH: There have actually been several studies like this, and the conclusion is always the same: the fitter you are, the longer you’re expected to live. There’s no threshold where being a little bit fitter becomes a bad thing.
And, lest we forget, there’s more to living than not dying. I saw this great figure on Twitter recently, which drives home the importance of aerobic fitness for being able to live independently as we age.
DE: Wow, that’s a dire data visualization. It really hammers home the fact that less aerobic fitness translates to having to use more of your physical capacity for normal daily activities. (**Note to readers: there's an update about this chart at the bottom of the post.**) So if you don't keep aerobic fitness up, you just won't be able to do as much normal, daily stuff as you get older. And yet, “running is killing you” headlines seem to pop up with some regularity, at least over the last decade. Can you share what got that started?
AH: The general sentiment has been around for well over a century, and I think it’s fair to say that its enduring popularity has more than a bit to do with schadenfreude —
DE: You mean just non-exercisers wanting to believe that exercisers will have some negative outcomes for their efforts?
AH: Or just being relieved that the thing they’ve been feeling guilty about not doing for the last few decades was a bad idea after all. It’s the same reason I scan the headlines every morning hoping for news that flossing causes the common cold. But the running-is-bad stuff really took off in 2012 thanks to – note the parallels here – a non-peer-reviewed abstract at the American College of Sports Medicine annual meeting.
DE: Man. It’s frustrating when headlines like this go viral and the full report isn’t even available to scrutinize.
AH: Yeah, peer review is far from perfect, but it does help pump the brakes on big claims sometimes. In this case, this 2012 abstract analyzed 50,000 patients from the Cooper Clinic in Dallas, and concluded that a little bit of running was good for you, but any more than 20 miles a week wiped out the benefits and was no better – or perhaps even worse – than lying on the couch all day. That prompted lots of headlines like, in the Wall Street Journal, “One Running Shoe in the Grave.”
DE: Yikes…
AH: It’s the postscript that’s really important here. That conference data took another two years to make it through peer review, in part because there were some arguments about the appropriate statistical analysis. When it was finally published, the conclusions had changed!
DE: You’re kidding.
AH: Alas, I’m not. The new message was that even a little bit of running, like five minutes a day, has noticeable longevity benefits, but there was no longer any evidence that too much running is bad for you. As you can probably guess, the revised version of the results did not go viral like the original did.
DE: That’s really frustrating. In a previous post, I interviewed a misinformation researcher, and it’s scary how big an advantage bad information has over good information. Obviously, in this case we’re not talking about nefarious intent, but you’ve got a headline-making finding that could really influence people, and no data available for anyone to review. There’s no problem, I think, with scientists presenting and discussing preliminary work. In fact it’s great; they can get feedback and ideas. But it’s a problem when they issue a press release and it goes viral and distorts public understanding.
Anyway, since we can’t talk much about these reported new findings — which found that male runners had stiffer aortas — can you give us a little context for research on running and blood-vessel stiffening in general?
AH: In theory, you definitely want nice, flexible blood vessels. There’s been some research on coronary arteries (which branch off of the aorta near the heart), showing that longtime endurance athletes tend to have higher calcium scores, which are associated with stiffer arteries. In the general population, that’s bad news.
But there’s an additional twist. If you look more closely at the artery walls, you find that athletes tend to have smooth, hard, calcified plaques.
DE: Plaques being the buildup of cholesterol and other stuff that can cause heart disease?
AH: Right. So these calcified plaques make arteries stiffer, but they’re also stable. Non-athletes, in contrast, tend to have softer plaques made of a mix of calcium, fat, and other stuff. These are much more likely to break off and block an artery, which is the worst-case outcome.
DE: Then you have a heart attack or something, right?
AH: Exactly. In one recent study, 72 percent of the athletes’ plaques were the stable type, compared to 31 percent of the non-athletes. And another study published last month confirmed that athletes with high coronary artery calcification don’t seem to have an elevated risk of heart attacks. So that's a great example of a known risk factor whose meaning changes in a special population like endurance athletes.
DE: That’s really interesting. So you have a measure that is often bad — harder plaques — but when you look at the full context, the exercisers are much better off.
AH: Will the same thing turn out to be true for the latest study? Who knows, but when it comes to these sorts of secondary risk factors, I tend to default to something my running and journalistic mentor Amby Burfoot wrote a decade ago: if you really think there’s a problem, show me the bodies.
DE: Right. Runners live longer. Full stop.
But, ok, we’ve beat up on this new report a bit, so now let’s maybe give some brownie points to this study that we can’t yet read. It is definitely true that women are underrepresented as subjects of exercise science. One paper searched exercise physiology journals and found that two-thirds of subjects were male. So what do you think about the fact that this new work apparently reported on men and women separately?
AH: It’s great. This study had a 50-50 male-female split, and that didn’t happen by accident. Participation in competitive masters endurance sports skews heavily male, so it would likely have been much easier to recruit 250 men and 50 women for the study. But they didn’t do that, and that’s why they have the statistical power to observe that men and women seem to respond differently. This should be the model going forward.
DE: And despite this report, guys like you and I aren’t going to stop running due to this headline, even though I did find it a bit disconcerting. What advice would you give to someone who has just started running or is thinking about starting, and who reads one of the articles about this new research — or the inevitable next wave of headlines like this?
AH: If you’re just starting running, you shouldn’t have a care in the world. The levels of training that you’ll be able to tolerate are well below the level that anyone is debating.
DE: Haha, congrats — your aerobic capacity is too low to worry!
AH: The good news is that it will increase rapidly once you start running! Still, be sensible and listen to your body. Take rest when you need it. Start by aiming for a 5K as your first race, not a marathon.
If you eventually reach the point where you’re like, “I get no buzz from just one marathon, I need to do four in a row… through Death Valley,” then take a little time to think about what you’re looking for. You’re no longer doing this simply to improve your health, and some people believe you might be harming your health, so weigh that uncertainty against whatever satisfaction you’re gaining. Overall, I don’t believe there’s anything to worry about, but I keep in mind what Paul Thompson, a leading sports cardiologist and former Olympic Trials marathoner, told me: If you want a life with no risk, go to bed in a dark room – alone – and stay there.
DE: You just reminded me of a quote by former NASA engineer Mary Shafer: “Insisting on perfect safety is for people who don’t have the balls to live in the real world.”
Ok but apropos of running and health in general, but not of this new report, what’s the latest on how habitual running impacts your knees? I frequently meet people who tell me they stopped running because of their knees. Granted, musculoskeletal injuries happen when you use your body, but I don’t think the causal connection between running and knee deterioration is anything like what most people assume.
AH: Now you’re just trying to get me worked up.
DE: Go to a dark, lonely room if you don’t want Range Widely to get you worked up.
AH: Seriously, this is the myth that will not die. We all know runners who’ve had to stop because their knees gave out. However, we also all know non-runners whose knees gave out (my dad is one), and we don’t tend to view that as proof that not running ruins your knees.
How can we resolve this battle of anecdotes? By doing studies. There have been lots of them, and the general conclusion is that habitual runners are no more likely to develop knee osteoarthritis than comparable non-runners, and may even be less likely to. That fits with a broader shift to seeing cartilage (the lubricant/shocks in your knee joint) as an active tissue that benefits from regular use. The bottom line is that nearly half of Americans will eventually develop knee osteoarthritis, so both runners and non-runners have to face that possibility.
DE: Finally, while I’ve got you here giving exercise-related advice, I want to ask a question totally separate from these headlines. Your utterly fascinating book, Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance, was a bestseller, but you wrote a book before that: Which Comes First, Cardio or Weights? It was less of a narrative journey, and more practical advice, and I found it really useful in terms of answering fundamental questions that a lot of exercisers (or prospective exercisers) have. So: which should come first, cardio or weights?
AH: I’ll give you three answers.
The common-sense answer is that you should start with whatever is most important to you, because you’ll have the most energy to devote to it. You’re not going to make big gains if you’re too tired to lift hard because you just rode the treadmill to exhaustion, bro.
DE: I prefer “brotein shake” when we’re talking gym, just fyi.
AH: The answer in my book is that you should start with whatever is most important to you, because of the way your cells signal to each other that they should adapt in response to the stress of a workout. Basically, there are two distinct signaling cascades, one that says “build bigger muscles” and the other that says “build more mitochondria to enhance endurance.” These two signaling systems interfere with each other, so once you’re in strength mode, it takes a little while to transition to endurance mode (and vice versa).
This cell signaling stuff was pretty new when I was writing Cardio or Weights, and it struck me as absolutely fascinating. It still does, actually. But in the real world of practical advice, I’ve come around to a third perspective, which is that you should do your exercises in whatever order fits best in your life and brings the most happiness. The extra percent or two that you gain by optimizing workout order is swamped by what you lose if you can’t stick to a consistent routine. Maybe this is the hard-earned wisdom that comes from having had a couple of kids since that book came out, but I now see that as the single most important thing to say about exercise: Do whatever will make you come back for more.
DE: Alex, thanks so much for sharing with us the database of exercise research that is your brain! If readers leave interesting exercise science questions below, I’d love to have you back sometime to discuss them.
**Update on the Chart**
After our discussion, Alex and I emailed about that VO2max chart above a little more. It's a little technical, but given this newsletter's recurring attention to number sense, I think it's worth including. Here's how it went:
DE: Hey Alex, I forgot I had one more question for you about the chart: I was pretty surprised to see "slowly climbing stairs" above the VO2max of an "average fitness" 50-year-old. Were you surprised by anything on there?
AH: DAMN...this is like a case study of the spotting bad numbers you've been writing about lately. I totally missed that. Looking at it again, I suspect there's a math error. Here's why:
You can look up the average energetic costs of pretty much any activity at this site, which is just a compendium of data from hundreds of studies. (Go to "Activity Categories" in the menu, select a category, then scroll through the lists.)
The values are given in METs, which in VO2max units are roughly equivalent to 3.5 ml of oxygen used per kilogram of bodyweight per minute of activity — or 3.5 ml/kg/min.
Using that conversion, most of the activities on the chart we discussed above are right on. Running at 6 mph, for example, is listed at about 10 METs, which is a VO2 of 35 — pretty much exactly what the chart above shows. The other activities are also pretty much in line with the data in the Compendium. But there's an exception: stair climbing.
In the Compendium's walking category, "stair climbing, slow pace" is listed as 4 Mets (14 ml/kg/min in VO2 max units), and "stair climbing, fast pace," is listed as 8.8 METs (30.8 ml/kg/min). In the chart we shared above, however, "slowly climbing stairs" looks to be around 31 ml/kg/min, and "briskly climbing stairs" is around 46 ml/kg/min — both significantly higher than the Compendium data. So specifically for stair climbing, the chart doesn't agree with the Compendium.
"Fast" and "slow" are subjective terms, so it's possible there's a study somewhere that backs this up, but given that (a) the rest of the data matched the Compendium perfectly, and (b) your Spidey sense was tingling when you looked at this part of the chart, I suspect this is a math error by whoever made the chart.
DE: It happens! I must say, while the chart above still doesn't bode well for aging adults with low aerobic fitness, I'm glad to see that stair climbing is a lower aerobic bar than depicted on that chart.
Thanks to Alex for answering my questions. Check out his excellent books for more doses of research-grounded exercise insight.
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Thanks for reading. Until next time…
David
Image credit: Sebastian Kaulitzki/Science Photo Library/Getty Images