Aerobic Activity ly Increases HDL Cholesterol Levels

Hitting the treadmill, the bike trails, or donning your rollerblades can modestly increase high-density lipoprotein (HDL) cholesterol levels, according to the results of a new study. While not entirely surprising, the finding that regular aerobic exercise increases HDL cholesterol levels emerges from a new meta-analysis, with investigators also showing that exercise duration per session is the most important element of an exercise program.

Publishing the results in the of the meta-analysis in the Archives of Internal Medicine, Dr Satoru Kodama (Ochanomizu University, Tokyo, Japan) showed the effect of aerobic training resulted in a 2.53-mg/dL increase in HDL cholesterol levels. With each 1-mg/dL increment in HDL cholesterol levels associated with a 2% to 3% decreased risk of cardiovascular disease, exercise, by rough estimates, could result in a 5.1% and 7.6% reduction in cardiovascular disease risk in men and women, respectively, say investigators.

The value of increasing HDL cholesterol levels to reduce risk is widely accepted, the Japanese researchers write, but also point out that the results of aerobic exercise studies vary, often depending on the duration, intensity, or frequency of the exercise program, and the characteristics of subjects at baseline.

In this meta-analysis of 25 articles from 35 randomized control trials published between 1966 and 2005, Kodama and colleagues evaluated the effects of aerobic exercise on HDL cholesterol levels in adults aged 20 years and older. The sample size of the included studies was small, ranging from 9 to 200 subjects, for a total of 1404 subjects. The mean intervention period was 27 weeks, with the minimum intervention 8 weeks. The prescribed exercise intervention included a mean of 3.7 sessions per week, with each session lasting approximately 40 minutes. The mean estimated energy expenditure was just over 1000 kcal/week.

Across the studies, HDL cholesterol levels increased an average of 2.53 mg/dL in those randomized to an exercise program. For 21 studies in which the weekly estimated energy expenditure exceeded 900 kcal/week, the pooled change in HDL cholesterol levels was significant, but not significant in studies where energy expenditures were less than 900 mg/dL.

Additionally, for 25 trials in which subjects exercised for more than 120 minutes/week, the increase in HDL cholesterol levels was significant, but not significant for subjects who exercised less. Also, the effect of exercise was greater in those with total cholesterol levels > 220 mg/dL and those with a body mass index (BMI) < 28 kg/m2.

In univariate analysis, the investigators found that only exercise duration, and not frequency or intensity, was associated with increases in HDL cholesterol levels. When subjects exercised between 23 and 74 minutes per session, each 10-minute increase in duration was associated with a 1.4-mg/dL increase in HDL cholesterol.
Practice Pearls:

• The current meta-analysis demonstrates that the duration of exercise appears to be the most significant exercise-related factor in increasing HDL cholesterol levels, and patients who are less obese and have higher total cholesterol levels are more likely to benefit from exercise in terms of their HDL cholesterol levels.

Arch Intern Med. 2007;167:999-1008.

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