Exercise Shown to Improve Lipid Profiles

Source: Tufts University
December 20, 2002 (Reviewed: December 16, 2004)

It's well established that physical activity can lower cardiovascular disease risk, in part due to its ability to improve lipid profiles. But it's not clear how much exercise is needed - and how vigorous it should be - in order to derive these benefits. Duke University researchers have examined the effects of varying amounts and intensity levels of exercise on plasma lipoproteins.

The 84 volunteers were middle-aged or older adults, sedentary, overweight or mildly obese (body mass index between 25 and 35), and had mild to moderate dyslipidemia. They were randomly assigned to one of three exercise groups or to a non-exercising control group. The exercise groups were: high amount/high intensity (equal to jogging about 20 miles per week at 65% to 80% of peak oxygen consumption); low amount/high intensity (equivalent to jogging 12 miles per week at 65% to 80% of peak oxygen consumption); and low amount/moderate intensity (equivalent to jogging 12 miles per week at 40% to 55% of peak oxygen consumption).

The volunteers exercised on stationary bikes, treadmills, or elliptical trainers under the guidance of a trainer, and used heart rate monitors. The activity duration and intensity was gradually increased over two to three months until prescribed levels were reached and then sustained for six months. Participants were counseled to maintain their body weight in order to minimize the confounding effect of weight loss. Lipid measurements were taken at baseline and at the end of the study.

How much vs. how hard

Researchers compared the effects of each of the exercises groups on 11 lipid variables, including triglycerides and concentrations of small LDL, LDL, ILD, large HDL, and large VLDL particles, and size of VLDL and LDL particles. (Except for HDL cholesterol and triglycerides, these lipid measurements are not part of a normal cholesterol panel.)

They found that intensity level (high or moderate) was less important than amount of exercise (high or low) in affecting lipid components. Exercise appears to increase the size of lipid particles, which may make them less susceptible to oxidation.

Although all exercise groups fared better than the control group, the only consistently significant improvements were in the high amount/high intensity group.

Clinical significance

This study offers insight into how exercise protects against cardiovascular disease, despite its seemingly small effect on cholesterol levels used in routine screenings. The author of an accompanying editorial points out that the combination of changes in the different lipid variables is probably beneficial, even if the role of each individual sub-fraction is not well understood at this point.

Patients should be encouraged to exercise and reminded of its heart health benefits, even if their efforts result in only modest changes in cholesterol readings.

Source

• Effects of the amount and intensity of exercise on plasma lipoproteins. WE. Kraus, JA. Houmard, BD. Duscha,  et al., New Engl J Med, 2002, vol. 347, pp. 1483--1492

Related Links
Managing Elevated Lipid Levels
The Metabolic Syndrome: Time for Action!
Exercise Shown to Keep Inflammation Markers in Check
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