Leisure time moderate- to vigorous-intensity physical activity saves lives

The 2008 Physical Activity Guidelines for Americans recommended a minimum of 75 vigorous-intensity or 150 moderate-intensity minutes per week of aerobic activity for substantial health benefit and suggested additional benefits by doing more than double this amount. However, the upper limit of longevity benefit or possible harm with more physical activity is unclear. A total of 661 137 men and women (median age, 62 years; range, 21-98 years) and 116 686 deaths were included in this study.  Median follow-up time was 14.2 years.

Compared with individuals reporting no leisure time physical activity, the authors observed a 20% lower mortality risk among those performing some but less than the recommended minimum recommended hours per week, a 31% lower risk at 1 to 2 times the recommended minimum, and a 37% lower risk at 2 to 3 times the minimum. An upper threshold for mortality benefit occurred at 3 to 5 times the physical activity recommendation; however, compared with the recommended minimum, the additional benefit was modest (31% vs 39%). There was no evidence of harm at 10 or more times the recommended minimum