It’s never too late to start exercising to improve your health, even if you’re about to retire, according to a study.

People who took up exercise over a four-year period were more than three times as likely to be healthy agers as those who did nothing, according to the study of 3,454 people in England whose average age was 64. Active adults who continued to exercise during that time were seven times as likely to be healthy agers as those who were consistently inactive.

The study, published yesterday in the British Journal of Sports Medicine, is one of the first to focus on how exercise affects health in the elderly. Physical inactivity is the fourth leading risk factor for premature death -- after smoking, excessive drinking and obesity -- causing an estimated 3.2 million deaths globally, according to the World Health Organization.

“This study supports public health initiatives designed to engage older adults in physical activity, even those who are of advanced age,” the researchers, led by Mark Hamer at University College London, said in the published paper.

Participants, taken from the English Longitudinal Study of Ageing, described the frequency and intensity of regular physical activity from 2002 and every subsequent two years until 2011. Any participants with existing chronic disease were excluded.

Healthy aging was measured through absence of major disease and disability, mental health, cognitive abilities and ability to maintain social connections.

The study was funded by the U.S. National Institute on Aging and a consortium of U.K. government departments coordinated by the Office for National Statistics.