Sedentary older adults can help lower their risk of heart disease if they start exercising, a new study confirms.

Researchers examined data on more than 1.1 million people aged 60 and older without any history of heart disease who had two health screenings between 2009 and 2012. Most were physically inactive at the first screening, and almost four in five of these people remained sedentary throughout the study period.

Compared to adults who were continuously inactive, those who started exercising one to two times a week were 5% less likely to have events like a heart attack or stroke, during the follow-up period. When sedentary people started exercising three or four times weekly, their risk of cardiac events dropped by 11%, and boosting exercise from none to at least five times a week was associated with a 9% risk reduction.

“The most important message from this research is that older adults should increase or maintain their exercise frequency to prevent cardiovascular disease,” said Kyuwoong Kim, lead author of the study and a researcher at Seoul National University in South Korea.

“While older adults find it difficult to engage in regular physical activity as they age, our research suggests that it is necessary to be more physically active for cardiovascular health, and this is also true for people with disabilities and chronic health conditions,” Kim said in a statement.

Researchers used South Korea’s National Health Insurance Service database to determine there were almost 115,000 cardiovascular disease events like heart attacks and strokes in the study population.

The link between increased physical activity and falling risk of cardiovascular disease in older people held true even for those with disabilities and chronic conditions such as high blood pressure, high cholesterol levels, and Type 2 diabetes, researchers report in the European Heart Journal.

During both health screenings, participants answered questions about their lifestyle habits and activity levels, indicating how often they got at least 30 minutes a day of moderate exercise, like walking or gardening, and how often they got at least 20 minutes a day of vigorous exercise like running or cycling.

Only 22% of inactive people increased their physical activity by the time of the second health check, the study found.

And 54% of the participants who had been exercising five or more times a week at the time of the first screening had become inactive by the time of the second. Those who were moderately or vigorously active more than five times a week at the first check and then became continuously inactive at the second check had a 27% increased risk of cardiovascular problems.

The study wasn’t designed to prove whether or how any amount of exercise or change in activity levels might directly reduce the chance of having a heart attack or stroke.

One limitation of the study is that researchers relied on participants to report their own exercise levels, which might be unreliable. It’s also possible that results from this Korean population might not apply to people from other racial and ethnic groups.

Adults 65 and older should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity, according to recommendations from the World Health Organization. Ideally, people should exercise in at least 10-minute intervals.