NEW YORK (Reuters Health) — Regular exercise helps obese children shed more than just excess weight. It also reduces the likelihood of heart disease by improving the health of their arteries.“Atherosclerosis - also referred to as hardening of the arteries — starts during childhood in the presence of such risk factors as obesity and sedentary lifestyle,” Dr. Andreas Alexander Meyer, a pediatrician and pediatric cardiologist at the University of Rostock Children’s Hospital in Germany said in a statement.

“Regular exercise is one of the most important activities we can do on our own to reduce the risk and reverse the early development of atherosclerosis,” Meyer added.

Meyer and colleagues divided 67 obese teenagers into two groups. One group exercised for roughly one hour three times per week while the other group stuck with their normal routine. These subjects were compared with lean teens.

At study entry, the obese subjects already had early visible signs of hardening of the arteries, as well as thickening of the lining of the arteries where atherosclerosis begins.

After six months, tests showed that the exercisers had improved the flexibility of their arteries, allowing these vessels to carry more oxygen-rich blood. Moreover, the already expanded inner layer of their arteries had shrunk.

The exercisers also lowered their cholesterol levels and blood pressure and lost weight.

“We think that 90 minutes of exercise, three times per week is the minimum teens need to reduce their cardiovascular risk,” Meyer said in a statement accompanying the study appearing in the Journal of the American College of Cardiology.

A problem is “low perseverance and motivation” in overweight adolescents, Meyer added, noting that of 50 obese teens originally assigned to the exercise group, only 33 participated sufficiently to be included in analyses.

Clearly, obese teens will need support and encouragement from their parents and their doctor to stick with an exercise programme, Meyer and colleagues said.

Dr. Albert P. Rocchini, a pediatric cardiologist from the University of Michigan, who was not involved in the study, notes that these findings are important because they document the presence of harmful vascular changes in obese children.

“I would take this (study) as good and bad news,” Rocchini said in a statement. The bad news is that there is early evidence of heart disease, “but the good news is it’s not fixed and permanent. There’s something you can do to make it better.”