I used to think running was a panacea. “If the furnace is hot enough, anything will burn, even Big Macs,” as the fictional miler Quenton Cassidy once said. Then, about a decade ago, there was a big surge of doubt about the health effects of running. Most prominent was the suggestion that even modest amounts of running might damage your heart—“One Running Shoe in the Grave,” as the Wall Street Journal put it—but running was also accused of broader sins like promoting inflammation, causing muscle loss, and wreaking havoc on blood sugar levels.
As a runner and a journalist, I spent a lot of time trying to understand these claims, and reevaluating my own understanding of running’s health effects—a process that continues to this day. Part of that process involved going back to the original research that led us to believe that running is healthy. And to be honest, the evidence wasn’t as clear as I’d assumed. Does running (or aerobic exercise more generally) really improve health markers, or is it just that healthy people are more likely to choose to run? Do the benefits max out after a few minutes per…
