Just 10 minutes of exercise a week might be better than no physical activity in terms of mortality risk, according to a study in the British Journal of Sports Medicine. And very high levels of exercise are more protective.

Researchers studied 88,000 US adults aged 40 to 85 who participated in the National Health Interview Surveys and provided information about their weekly leisure-time physical activity. During a median 9 years' follow-up, 9% died.

After adjustment for BMI, smoking status, and other potential confounders, participants who had even a minimal amount of physical activity — 10 to 59 minutes a week — had a lower mortality risk than those who were inactive (hazard ratio, 0.82). The mortality benefit continued to grow with more activity — even when people exercised more than 1500 minutes, over 5–10 times the amount recommended by guidelines (HR, 0.54).

The authors conclude that promoting physical activity "of any intensity and amount is an important approach to reducing mortality risk in the general population."