Exercise: more is better, and the harder the better

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Great article in the Wall Street Journal about Paul Williams’ National Runners’ Health Study. As I wrote last summer:

What Williams really emphasizes in his recent studies is the “dose-response” relationship between running and health: the farther and faster you run, the greater the benefits.

But this isn’t a very popular message among public-health advocates, who are struggling to convince people to do any exercise at all, let alone worry about how hard they go, according to WSJ’s Kevin Helliker:

In Dr. Williams’ study of more than 100,000 runners over nearly 20 years, stepped up exercise was found to have some powerful benefits. But his research is controversial. While Dr. Williams is well respected by other exercise scientists, he is shunned by those in the public-health field. Dr. Williams is routinely excluded from committees charged with formulating exercise guidelines, and his grant proposals are often rejected as irrelevant because few exercisers want to hear the word “more.” Public-health officials also worry that touting Dr. Williams’s research could discourage the sedentary from doing any exercise at all, or lure them off the couch with goals too lofty to engender success.

It’s an interesting dilemma, but ultimately I believe in simply telling the truth, even if it makes the message more “complicated.” More exercise is better, and if you’re simply meeting the standard exercise guidelines, you’re leaving a lot of potential benefits on the table:

A number of [Williams’] studies have taken direct aim at current exercise guidelines, by comparing the benefits of mere compliance with the benefits of running far beyond them. A Runners’ Health study published in the journal Stroke last spring found that men and women who ran more than eight kilometers a day had a 60% lower risk of stroke than those who ran at the guideline levels. An article published in September in the journal Atherosclerosis found that those Runners’ Health participants who exceeded guideline levels had a 26% lower risk of coronary heart disease than those who ran at guideline levels.

4 Replies to “Exercise: more is better, and the harder the better”

  1. I always find your thoughts on these studies fascinating. Of course, my interest always goes towards the elite application. What does Williams mean by “more” and “hard”? Someone like me running 8miles at 7min mile pace…is that more (yes it is more than 8k a day, at least) and hard, or is it relative to the individual?

    Also, I wonder what your thoughts are on this article:
    http://www.sciencedaily.com/releases/2010/01/100104122310.htm?sms_ss=email

  2. First question: I think you’re maxing out on the benefits relative to Williams’ cohort. (At least I hope you are, because you’re currently running longer and faster than I am!) Looking back at the most recent study of his that I have on hand (the one on running and glaucoma), he looked at both racing speed and volume.

    For speed, the subjects were divided into five groups; the slowest had 10K bests of greater than about 47 minutes, while the fastest (who were so healthy that had no reported cases of glaucoma) had bests of less than 33:20. For training volume, the four groups ranged from less than 2 km per day to greater than 6 km per day. So you’re way beyond the max that his study looked at.

    Second question: I’m just about to post this in a separate post, because I think it’s important, but Amby Burfoot did a fantastic deconstruction of that running shoe study here, making pretty much all the points I wanted to make.

  3. I think you are absolutely right that the MAXIMUM benefit comes from doing a large volume of physical activity, as well as a large volume of high intensity physical activity. I don’t think that will ever be in dispute. However, the maximum reduction in mortality and other deleterious outcomes, is achieved by simply moving from being totally inactive, to being just slightly active.

    There is a great graph in this paper (http://tiny.cc/gw0B9) by Bill Haskell and Steve Blair, that shows that once you’re at least a little bit physically active, the benefits of further increases in physical activity or intensity are quite marginal. There are still benefits, but they are much smaller than the initial benefit of becoming even slightly active (the graph is based on x-sectional data, but the principle of diminishing returns is pretty well established from training studies, so I’m willing to bet we’d see similar results in intervention studies).

    This is why it’s so tricky for public health advocates. It’s true that the absolute best thing is to be extremely active, but that is unattainable for most people, so they do absolutely nothing at all. So it might be time to advocate for a more manageable increase in physical activity (or even simply reducing the time spent being sedentary), which is still likely to result in tremendous health benefits, albeit slightly lower than the ideal. Frankly, we’ve been telling people to do the “ideal” scenario for a long time, and it hasn’t done much good.

    On a side note related to John’s second question, I think remember Benno Nigg and some of the other HPL profs at Calgary arguing that cushioning could be a big cause of running injuries (it was a few years back, so it’s a bit blurry). It was heavy on biomechanics which is not my forte, but their arguments made a lot of intuitive sense.

    Travis

  4. Interesting thoughts, Travis. I definitely appreciate the public health dilemma — there’s an extent to which the message has to be tailored for different audiences. But on the other hand, I think we need to be careful not to create different truths for different people. The biggest marginal gain is going from sedentary to active, and that should be acknowledged. But further gains accrue as you get more (and more vigorously) active — that’s also true, and acknowledging that doesn’t have to detract from the previous message.

    The figure from the Haskell paper is interesting. As you say, getting off the couch is the biggest and most important step. Still, from the “barely active” to the “meeting the guidelines” group, it looks like you decrease your mortality risk by another ~30% (from 0.7 to 0.5). And “meeting the guidelines” is just the minimum benchmark against which Paul Williams measures his results. It would also be interesting to know how a similar graph would look for “quality of life while aging” benchmarks instead of all-cause mortality, CVD and cancer. That was a point that came up in the debate around that study that purported to show that being overweight decreased mortality.

    Ultimately, I’d agree that the primary focus of our public health efforts should be on motivating the sedentary to be active in any capacity. But I often hear from people who are firmly convinced that exercise beyond the standard guidelines is counterproductive, and I think that’s an unfortunate case of misinformation.

    As for Benno Nigg’s work, the blog post by Amby Burfoot actually mentions some related research (where the shock-absorbing properties of your leg depend on how cushioned you expect the surface to be). The arguments make sense to me too, at least on a theoretical level. For practical purposes, my current thoughts are pretty similar to Burfoot’s conclusions: run in the lightest shoe you can stay healthy in, and don’t believe anyone who tells you they have a universal cure for running injuries. (Maybe I should start a website called Running Injury Panacea!)

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