The team interviewed a group of adults who had been diagnosed with heart disease, and healthy adults -- both groups aged 40 to 68 -- about their levels of physical activity now and when they were younger.
The study showed that people who had been active their entire lives were 60 percent less susceptible to heart disease, but it also showed that people who started exercise in middle-age still reduced their risk by 55 percent.
"Our results suggest that a more active physical activity pattern is clearly associated with a reduced risk of coronary heart disease," said Dr. Dietrich Rothenbacher, lead researcher. "We also concluded that changing from a sedentary to a more physically active lifestyle, even in later adulthood, may strongly decrease coronary heart disease."
Those diagnosed with heart disease also had other high-risk factors such as smoking, diabetes and high blood pressure, although around 50 percent reported being moderately or very physically active during younger and older adulthood.
"We recommend that everyone does 30 minutes of moderate physical activity at least five days a week. You are never too old to start being active," said Alison Shaw of the British Heart Foundation. "But people who are unaccustomed to physical activity and not sure of what activity is right for them should discuss it with their (General Practitioner)."