Refining the Fitness Bell Curve

We know that premature death and multiple diseases are intensified by living a sedentary lifestyle. On the other side of the spectrum, scientists continue to grapple on the safe upper limit – where too much exercise could potentially become dangerous. But those two end points along with the exact sweet spot in the middle remain gray areas, and researchers are working to refine and define the bell curve as it relates to the ideal amount of exercise we should get for optimal longevity.

Two recent studies published in JAMA Internal Medicine bring us a little bit closer to the answer. The first study – conducted and published by researchers representing the National Cancer Institute and Harvard University among others – analyzed data from more than 661,000 adults. Researchers focused on weekly exercise routines along with death records spanning 14 years for those in the study group.

Current guidelines offered by government and health organizations recommend 150 minutes of moderate exercise each week. But is that too much, too little, or ideal for longevity? Researchers found, not surprisingly, that those who did not exercise were at the highest risk of early death. At the other side of the bell curve were those who exercised more than 10 times the recommended limits. But those who exceeded guidelines hit a plateau and had the same mortality risk as group members who met them.

Precisely meeting the guideline, or getting 150 minutes of moderate exercise per week, reduced their risk of dying by 31 percent compared to those who didn’t exercise. But tripling the recommended level of exercise reaped the strongest rewards, with those working out moderately for 450 minutes each week – primarily walking – reducing their risk of premature death by 39 percent over those who didn’t exercise.

The second study, also large in scale with 200,000 adult participants and also comparing death statistics, was conducted by Australian researchers. Results were also comparable when it came to longevity, exercise duration, and exercise intensity. Specifically, those meeting guidelines even if they did so through moderate activity, such as walking, substantially improved their lifespan. Researchers also noted that large amounts of intense exercise didn’t correlate to increased mortality.