This week, the Journal of the American College of Cardiology published an article called "Dose of Jogging and Long-Term Mortality," in which they conclude light and moderate jogging can help you live longer, but "strenuous jogging" is no better than being a couch potato.
The article quickly went viral, because it plays on what many folks want to hear: too much exercise can kill you. To come to this conclusion is rash. This study is by no means the last (or even the most accurate) word on the matter.
Alex Hutchinson, a blogger at Sweat Science with a PhD in physics and author of Which Comes First, Cardio or Weights?, analyzed this study (and its authors), and found it to be poorly designed. The sample size is tiny, for one thing, and inconsistent. The "less exercise" group is dramatically larger than the "strenuous" group, and they are imbalanced when it comes to age and gender. Furthermore, Hutchinson writes:
"Yes, the conclusion of the study (that "strenuous" jogging is as bad as being sedentary) is based on two deaths over more than a decade of follow-up. … Did the joggers die of heart disease, as the paper suggests they should? or were they hit by a car or struck down by cancer? We have no idea."
While Hutchinson and other experts acknowledge that there is likely an upper limit to how hard you should run, more (and better) research is needed to draw that line.
In the meantime, we'll rely on the mountains of studies supporting the health benefits of vigorous exercise. Here's a sample:
- "Larger training volume (exercise duration × intensity) is associated with greater mortality benefits. Furthermore, for a given training volume, engaging in higher intensity physical activity provides additional benefit," according to a 2012 study published by cardiovascular researchers in Montreal.
- Endurance athletes tend to live longer, according to studies like this one, which looked at the increased average longevity among Tour de France cyclists.
- HIIT interval training has been shown to be better than steady-state cardio for longevity.
- And, perhaps one of the most famous, groundbreaking studies on exercise and health, the Harvard Alumni Health Study, followed 13,485 men from 1977 to 1992 and tracked their physical activity and mortality rates. The researchers concluded that "vigorous activity clearly predicted lower mortality rates," more so than "light" and even "moderate" activities.