It would be pretty awesome if running fast for four hours per week was the same as sitting on a couch all day. In fact, data from the Copenhagen City Heart Study found that to be mostly true. But should you trust their conclusion and abandon all intense running in favor of watching Netflix all day?
The study followed more than 1,000 joggers and more than 400 healthy, but sedentary, non-joggers, and tracked their death rate between 2001 and 2014. The joggers were separated into groups based on their running intensity. Light jogging was defined as running at a speed of about 5 miles per hour for less than 2.5 hours per week, while strenuous jogging was defined as running at a speed of 7 miles per hour or faster for more than four hours per week.
During the years of the study, light joggers were 78% less likely to die than other participants. Based on the results, the study concluded that strenuous joggers were equally as likely to die as sedentary non-joggers. It seems pretty straightforward: light joggers had the lowest death rate, and non-joggers and strenuous joggers had higher death rates. But if you dive deeper into the specifics of the study, the data doesn’t look as convincing.
The biggest problem with the study is that the sample size was much too small to discern a direct relation between running intensity and death. Of the 40 strenuous joggers, only two participants died. That’s right, just two. So while the death rate of the strenuous joggers might have been equal to the sedentary, non-joggers, two is not a number that holds a ton of statistical credibility. Also, there were many other factors could have had a major effect on the study’s results, including age, gender, overall health, and how a participant actually died. Did he get run over by a car? If so, that probably didn’t have anything to do with how hard he was running (unless he was running in the middle of a street).
Studies that analyze the effects of running or the intensities of workouts are extremely beneficial to the fitness world, but it does some good to be wary of studies that make extremely strong claims…such as sitting on the couch and intense running are equally likely to kill you. What can we take away from this study? A little running can probably do most people some good. And try to stay out of the streets.