This article was written by Scott Douglas and repurposed with permission from our partners at Runner’s World.
By now, you’ve probably seen reports in the mainstream press about a study published Monday in the Journal of the American College of Cardiology. Using data from the Copenhagen City Heart Study, the research looked at mortality rates in sedentary people and runners. Two takeaways widely reported are that those who reported the most (and most vigorous) running died at a greater rate during the study period than those who ran less, and that, as many media outlets have put it, “fast running is as deadly as sitting on the couch,” more ambitious runners “are doing themselves more harm than good,” etc.
Is this true? Here are a few things to keep in mind.
First, as Runner’s World Sweat Science columnist Alex Hutchinson wrote earlier today in a detailed analysis of the study and the reporting on it, the study uses a very small sample size for its analysis of varying mortality rates among runners.
You needn’t take Hutchinson’s word that the sample size is so small as to probably be insignificant. An editorial in the Journal of the American College of Cardiology makes the same point. The editorial also questions the study authors’ “somewhat arbitrary categorization of doses of jogging.” It’s also worth bearing in mind that the participants’ running volume, frequency, and pace were self-reported.
In addition, the study’s findings have only to do with mortality during the study period. Many mainstream articles, however, have broadened the conclusion to suggest more ambitious running is of equal health benefit to being sedentary. Such claims ignore the wealth of data that show that, while many of the health benefits of running accrue at modest amounts of mileage, in many studies, higher-mileage runners gain more benefits.
We at Runner’s World don’t think this one study is reason to change your approach to or appreciation of running. As Hutchinson has written, there’s obviously a threshold at which more running stops being beneficial, and a second threshold at which more will worsen your health. But there’s no consensus on where those thresholds are, and there’s scant evidence they’re at the low levels of mileage described in the new Journal of the American College of Cardiology study.
More from Runner’s World:
The (Supposed) Dangers of Running Too Much
The Benefits of Running—Proven
Your Runner’s Body