By now we’ve all heard it – by “we” I mean those of us who are drawn to strenuous exercise – and by “it” I mean the damage to health purportedly inflicted by that very exercise. That is, you can have too much of a Good Thing––the Good Thing in this case being the kind of prolonged intense effort that produces the runner’s high, a sense of satisfaction in your degree of fitness, and often the pride that comes with busting through the pain barrier in a hard workout.
The science says that if your hope is for a longer or higher quality life, you’re probably kidding yourself. I speak of the sinister “U-shaped curve” correlating strenuous exercise with mortality. The upright on one side of the “U” represents the high mortality of sedentary folks, and the opposite upright represents the high mortality of super-exercisers––to include you, perhaps. In the valley between are found those whose more moderate exercise habits confer a longer life span, if not the level of fitness you enjoy and crave.
Perhaps the most influential research on the association between exercise and mortality appeared in the results of the Copenhagen City Heart Study, published in the Journal of the American College of Cardiology in 2015. The abstract concludes, “the findings suggest a U-shaped association between all-cause mortality and dose of jogging as calibrated by pace, quantity, and frequency of jogging. Light and moderate joggers have lower mortality than sedentary non-joggers, whereas strenuous joggers have a mortality rate not statistically different from that of the sedentary group!” (The exclamation point is mine.)
Before you start thinking of ways to throw shade at the American College of Cardiology, take note of the carefully chosen word “suggest” in the conclusions. There were more than 5,000 subjects in the study and the authors marshal an impressive array of confidence intervals by way of validating the evidence. Even so, the Background section of the abstract does say that “the ideal dose of exercise to improve longevity is uncertain.” Continue reading “Running into an early grave: more is worse. No, wait! More can be good . . .”