Researchers had over 6,500 patients with an average age of 75 perform a treadmill stress test, where they ran as hard as they could until exhaustion. Their stress test results were measured in metabolic equivalents (METs), or the energy cost of an activity, and divided into three groups: most fit (10 or more METs), moderately fit (6 to 9.9 METs) and least fit (6 or fewer METs). For context, a 10-minute mile is roughly 10 METs.
Researchers tracked the participants for 10 years, until they would’ve been about 85. They found that 39 percent of the participants died. And their fitness levels 10 years earlier were predictive of who would survive: Individuals from the most-fit group—those at the fitness equivalent of running a 10-minute mile—were more than twice as likely to be alive 10 years later compared with the individuals in the least fit group, or those who would only been able to sustain a 15-minute mile.
Fitness level is very strongly associated with a patient’s risk for both cardiovascular disease, something which can obviously affect your risk of premature death, Seamus Whelton, M.D., assistant professor of medicine at Johns Hopkins School of Medicine, told Runner’s World. Higher fitness levels can also lower traditional stroke risks like high blood pressure, heart disease, and obesity, while also helping strengthen your immune system and lower inflammation.
The study did not take into account a change in fitness levels, but there’s no harm in improving your fitness, no matter your age. (Still, you should always consult with your doctor before starting a new exercise regimen.)
In fact, research has found that becoming more fit as you age can reduce your risk of stroke and improve your health in general. Individuals who started with low fitness level and became fitter cut their stroke risk by 60 percent and were 34 percent less likely to die over the course of the 35-year study.
This article originally appeared on Runner's World