While it is not a surprise that aerobic exercise increases HDL levels, researchers have not been able to say just how much HDL levels can be increased by exercise, or which forms of exercise are the most effective at doing so. A study conducted a few years ago by Japanese researchers appears to shed some light on these questions.
In a meta-analysis, investigators from Tokyo evaluated the effect of exercise on HDL levels. They included data from 35 randomized trials assessing the effect of exercise on HDL levels in adults. While exercise regimens varied among these studies, on average patients in these studies exercised for 40 minutes, three to four times per week, and the effect on HDL was measured after eight to 27 weeks.
Across the studies, participants had increases in HDL cholesterol averaging about 2.5 mg/dL. This increase in HDL cholesterol was only modest, but was statistically significant. Furthermore, since cardiac risk is thought to drop by two to three percent for each 1 mg/dL increase in HDL, a 2.5 mg/dL rise in HDL may actually amount to a substantial reduction in risk.
Perhaps the most interesting finding from this study is the observation that the duration of exercise sessions - and not the frequency or intensity of exercise - correlated the best with rises in HDL levels. The investigators report that in research subjects exercising for at least 20 minutes, each additional 10-minute increase in exercise duration increased HDL levels by an additional 1.4 mg/dL.
From this study, if you want to increase your HDL level, you ought to exercise at least three to four times per week, and the exercise sessions ought to last for at least 20 minutes (though 40 would be better). In fact, increasing the duration of your exercise sessions by pacing yourself judiciously (that is, by going slower if necessary), appears to be the best way to translate exercise into higher HDL levels.
Kodama S, Tanaka S, Saito K, et al. Effect of aerobic exercise training on serum levels of high-density lipoprotein cholesterol. Arch Intern Med 2007; 167:999-1008.