TUESDAY, May 29 (HealthDay News) -- Regular exercise seems to help boost levels of high-density lipoprotein (HDL), the "good" cholesterol, say Japanese researchers.

A low level of HDL cholesterol is an independent risk factor for cardiovascular disease.

The analysis, which reviewed 25 studies published between 1966 and 2005, assessed the effects of aerobic exercise on HDL cholesterol in a total of more than 1,400 adults ranging in age from 23 to 75. The studies lasted an average of 27.4 weeks. On average, participants exercised 3.7 sessions per week for 40.5 minutes each session, burning an average of 1,019 calories per week.

The combined findings showed that exercise resulted in an average increase in HDL cholesterol of 2.53 milligrams per deciliter. The minimum amount of exercise required to change HDL cholesterol levels was 120 minutes a week or 900 calories burned. Exercise had a greater impact in people with a higher total cholesterol level (220 milligrams per deciliter or greater) and in people with a body mass index (BMI) of less than 28 (obesity begins at a BMI of 30).

"In a previous observational study, every 1-milligram per deciliter increment in HDL cholesterol level was reported to be associated with a 2 percent and 3 percent decreased risk of cardiovascular disease in men and women, respectively," the review authors wrote.

"If this observation were applied to our results, the increase in HDL cholesterol level by exercise determined by this analysis would, by a rough estimate, result in cardiovascular disease risk reduced by approximately 5.1 percent in men and 7.6 percent in women."

The authors noted that their analysis showed that only exercise duration, not frequency of intensity, was associated with a changed in HDL cholesterol levels.

The article was published in the May 28 issue of the journal Archives of Internal Medicine.

More information

The American Heart Association has more about HDL-C.