Exercise reduces the risk of heart disease

In a study of 27,000 women followed for 11 years, researchers assessed various risk factors at different levels of physical activity.

"Regular exercise has a big effect in preventing strokes and heart disease," says Dr Samia Mora of Harvard Medical School. The changes in risk factors such as blood pressure and inflammation explained part of the benefit, but exercise can deeply affect the chance of future heart problems.

The women were aged 45 to 90 (average 55) and regularly reported their physical activity, weight, height, blood pressure and whether they had diabetes. They were divided into four groups:

Burning 1,500 kcal a week or more: more than 5 hours a week of moderate exercise, such as brisk walking.
Burning 600–1,499 kcal a week: 2 to 5 hours a week of moderate exercise.
Burning 200–599 kcal a week: 1 to 2 hours a week of moderate exercise.
Burning less than 200 kcal a week: considered inactive (the comparison group).

Compared with inactive women, the risk of cardiovascular disease was 41% lower in the most active group, 32% lower in the second group and 27% lower in the third. The study was part of the Women's Health Study, supported by the US National Heart, Lung, and Blood Institute and the National Cancer Institute.