San Francisco, CA (updated) - What doesn't kill you is supposed to make you stronger, an adage that many a long-distance runner has clung to, but intriguing findings from a new study presented last week suggest the mortality benefits of running are best accumulated in shorter distances, specifically at less than 20 miles per week .
In fact, at longer distances, the researchers observed a U-shape relationship between all-cause mortality and running, with longer weekly distances trending back in the wrong direction, toward less mortality benefit.
"We were thinking that at some dose of running, things would level off, that we'd see that runners would have a reduction in mortality at certain distances and then it would kind of level off," Dr Carl Lavie (Ochsner Health System, New Orleans, LA), one of the study investigators, told heartwire. "The fact that it reached its plateau at such a low level is surprising, as is the fact that it didn't level off but actually went the other way.
We never had a point where runners did worse than nonrunners, but really, if you put it in almost a joking way, it showed that if you ran enough you got yourself back to the level of a couch potato. You lost the survival advantage."