Decades of being a couch potato can be reversed within two years if you take up regular exercise, according to a new study.

Researchers found that frequent aerobic activities such as walking, running and swimming in middle age can cancel out the increased risk of heart failure brought on by years of sitting in front of the television.

“The key to a healthier heart in middle age is the right does of exercise, at the right time in life.” said Benjamin Levine, of the Texas Health Presbyterian Hospital Dallas.

“We found the optimal dose of the right kind of exercise to be four to five times a week, and the sweet spot in time- when the heart risk from a lifetime of sedentary behaviour can be improved- is late-middle age”

Aerobic exercise strengthens the heart and other muscles and helps the body use oxygen effectively.

The study, published in the American Heart Association’s journal Circulation involved 53 adults ages 45-63- sessions involved various exercise including four by fours- four minute sets of high intensity exercises, done four times interspersed with three minute breaks.

The researchers found that exercising two or three times per week did not do much to protect the heart against ageing. However, four or five sessions was almost as effective at protecting against ageing as the regimes of elite athletes, they said.

“People need too make an exercise programme part of their personal routine, just like thy brush their teeth”said Dr Levine.