Wednesday, February 18, 2015

Study on running highlights danger of studies

A study recently concluded that intense running might be as unhealthy as a sedentary lifestyle with little or no exercise.  It proposes that optimum longevity is achieved by running around 2.5 hours a week, distributed over three days, and at a pace no faster than a 8.5 minute mile.  This study then produced a large number of headlines such as "Fast running is as deadly as sitting on couch, scientists find."  Problem:  The study has too little data to make any such conclusion.  And it doesn't separate correlation and causation.  For example, people who are sedentary might be so because they are already unhealthy, having some existing health problem that prevents them from exercising.  In addition, too few intense runners died to conclude anything.  Further, it's possible that intense runners are also living on the edge in other ways that increase mortality.  The study and its shortcomings is analyzed by Justin Wolfers in the New York Times.  The editors of the journal publishing the study also point out its limitations.

This is probably a good example of a very limited and potentially useless study that is blown out of proportion by the media.  The media--internet, radio, television--are a pipe and must be filled with content of some sort.  And people are paid (poorly) to quickly misunderstand a study, translating it into one or two pages maximum as a way to attract an audience (clicks or page views).  Often the misunderstanding is intentional based upon bias (e.g. confirmation bias and ideology).  And the study itself is produced by people are need to publish in order to further their academic careers.  The public attention is a benefit for them (as long as they aren't outright lying or egregiously mistaken or biased).

So what should one conclude?  My intuition, from what I've read through the years, is that people who push themselves hard (e.g. running extremely fast over short distances or moderately fast over long distances) are a bit more likely to suffer injuries and death.  Why?  Because they're pushing their bodies to the limits and that can lead to an injury of some sort.  E.g. we probably increase our odds of having a heart attack by running or even walking a marathon.  But as long as one does not push too hard, the benefits of moderate exercise most likely far outweigh the risks.  On the cardiovascular side, one should probably increase one's heart rate at least three times a week.  In that sense, the recommendations of the study are probably good:  run three times a week, at a moderate pace, for about an hour, for a total of three hours a week.  This is probably a great way to maintain mental and physical health.