February 12, 2015

Bad Science: Is Running As Bad For Your Health As Being a Couch Potato?

There’s been a new scientific article about running making the rounds lately, and it’s causing a bit of an uproar. In short, the 2012 Copenhagen City Heart Study was recently republished in the Journal of the American College of Cardiology, and all the media articles that have picked up on the results are using some form of the hyperbolic headline: “Running will kill you faster than sitting on the couch.” Um, what?! I don’t by any means consider science to be one of my strong suits, but I decided to do some digging to figure out what was going on here. (And to make sure I have solid ammunition when yet another person tells me I’m hurting myself by running marathons. Aha, you’ve been “scienced!”)

So first of all, I think it’s worth some time to click through to the study and look at the actual abstract written by the researchers (aka, before the media got to it and tried to create a controversial headline). Here’s a direct quote:

“People who are physically active have at least a 30% lower risk of death during follow-up compared with those who are inactive. However, the ideal dose of exercise for improving longevity is uncertain.”

The first part seems to logically hold up to me, so I’m not going to waste much time investigating. But the second part says that the researchers are “uncertain” about what the best level of activity is. So… where is this “running is as bad as being sedentary” headline coming from? Turns out, it’s not really in the data – it’s more in the interpretation.

Runner’s World did a great response to the new headlines in this great article by Alex Hutchinson: The Supposed Dangers of Running Too Much. In addition to a ton of other salient points, one thing I found really interesting was that a new author was added to the 2015 republication of the study. James O’Keefe wasn’t listed as an author in 2012 when the results were first published (and didn’t cause an uproar). Yes, Dr. O’Keefe is evidently a cardiologist and former elite runner, but a quick Google search reveals that he keeps publishing pieces on how running is bad for you. To me, that sounds like he might have a bit of a bias in the results he wants to find, in order to back up his own beliefs – and as I learned a few weeks ago in Ben Goldacre’s awesome TED talk on Battling Bad Science, it’s not hard to manipulate data if you’re looking for a certain result. Even if you’re not trying to do that, basic social psychology has shown numerous times that it’s much easier for someone to see what they want to see.

Melbourne Marathon Mimosas
Rather than share a picture of the now-hackneyed gorilla playing basketball, I’ll instead share this: on the Melbourne Marathon course, I unintentionally chose to see the “Free Mimosas” sign instead of the 18 mile marker sign before it that meant I still had more than an hour until the finish line. And I was much happier that way!

Speaking of the data integrity front, it’s also important to note that this wasn’t a completely controlled study where the only variable between the groups was their exercise level. In fact, when Hutchinson digs into the data, he finds that the “controlled” sedentary group had an average age of 61.3; meanwhile, the “variable” exercising groups in the study had an average age in their 30s and 40s. With that kind of a discrepancy in the controls, I don’t even trust this data to tell me that exercising at all is better than being sedentary – you’re comparing apples to oranges.

But all that aside, my biggest issue with this study is the sample size. The data basically found that 2 out of the 40 participants who were classified as “strenuous joggers” died during the ten year study (5.0%), but that only 7 out of the 576 participants who were classified as “light joggers” died during the study (1.2%). Meanwhile, 128 of the 413 participants who were “sedentary” died (31.0%). Even if the rest of the study design were valid, I’ll take my chances (trying to) run fast rather than not running at all!

But with sample sizes that small, the results are ridiculously invalid – if two more people in the “strenuous jogging” group had died, we’d be up to 10%, whereas if two fewer had died, we’d be at 0%. Fluctuation that high makes it pretty evident what a terrible sample size that is, especially since the study didn’t look at cause of death (Did those two people die of a heart attack? Get hit by a bus while running? Or were they killed in a plane crash, sitting on their butts? We don’t know!). In all, I think this research is trying to find causation/correlation using a data set that may be valid… but definitely doesn’t have information to really draw any conclusions. (Or at least not the ones that the researchers want to draw.)

And if this study can pull from a limited data set, so can I. There have been a whole bunch of occasions where I’ve been injured or sick, and running long distance has somehow cured me (e.g., recovering from a nasty cold by running the New Hampshire Marathon in the rain, the miraculous flexibility my arm regained after running 20 miles). Personally, I choose to believe that running is good for my mind and good for my body, and I don’t intend to stop anytime soon unless there’s hard evidence to indicate otherwise.

PS – Ben Greenfield points out in his awesome podcast that perhaps we ought to examine the health habits of the slower joggers who are “running to eat”. You know – those runners like me who meet in groups to run to brunch, run to the cassoulet, or run the day after a beer festival (coming this weekend). It’s a lot easier to eat back the calories you burn running than you think, so perhaps we should look at the correlation between slower-paced casual runners and how much they eat after they run? Physiology might dictate that the harder you run, the hungrier your body is for food after, but my own anecdotal evidence hasn’t shown that to be the case – I am starving after a friendly group run and chatter!

Which leads me to how very excited I am getting to go run my 107th marathon, the Lost Dutchman in Phoenix this weekend. My tailbone has healed significantly since my fall on Saturday, and now there isn’t really any movement that causes shooting pain; it’s just a little more sore than usual when I’m walking around. I haven’t tried running yet, but my physical therapist (who I’m still seeing for my arm) told me that basically I couldn’t hurt it any further by running instead of resting; it just might hurt while I’m running. So… Tylenol for the win? And of course some margaritas after 😉


9 thoughts on “Bad Science: Is Running As Bad For Your Health As Being a Couch Potato?”

  1. Studies with weak conclusions or questionable methods often get hyped. I pay attention to studies like this, but research in this area is still in its infancy. There was a better, but still inconclusive study of endurance athletes a couple years ago. When I started seeing a new doctor, he said he’d be remiss if he didn’t make me aware of the study, but he wasn’t recommending that I make any changes at this time.

    1. I agree – I think it’s definitely important to be aware of the research and stay abreast of new developments. I just hate how the media oversensationalizes things, and that the vast majority of people don’t research it (honestly, myself included with many studies!) so faulty studies seem like fact.

  2. Oh science, coming from a science background, I understand how easily it is to interpret scientific results in order to get the story desired. However, misinterpreting the results is completely uncalled for and creates false assumptions (such as the entire vaccination issue right now). Thanks for breaking it down!

    1. I love when you provided insight on the vaccination issue that helped to sway me! I really admire those who are good at science – that’s definitely not me, though I try to stay informed.

  3. Laura, that is quite silly to think that running will do you harm to your health. I’m guessing this type of debate would be talked about a lot in a cardiology class. Which is what I’m actually studying for and it would be quite logical to know that running does help prevent different type of diseases.

  4. I saw some of the media coverage from that study, and I was also pretty frustrated. It’s very well known that running is excellent for your health. Of course there are people who over-train, but to insinuate that it’s as bad as being a couch potato is really frustrating!

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