The positive effects of exercise in reduction of blood cholesterol level can persist weeks after cessation of exercise, suggesting a long-term bodily adaptation, according to a presentation at the 50th annual scientific sessions of the American College of Sports Medicine.

An American group randomized 182 sedentary, overweight men and women at risk for diabetes and cardiovascular disease into 3 groups for an 8-month exercise program: high amount/vigorous intensity exercise (caloric equivalent of 20 miles of jogging per week), low amount/vigorous intensity (equivalent of jogging 12 miles per week); low amount/moderate intensity (equivalent of walking briskly for 12 miles per week).

All training programs lasted 8 months. Possible persistence of positive effects was assessed through blood tests at baseline and at 1, 5, and 14 days after stopping the exercise program. Exercise was carried out on cycle ergometers, treadmills, or elliptical trainers in a supervised setting. In order to determine the role of exercise alone, participants maintained diet during the course of the study.

Both men and women in the high amount/vigorous intensity group maintained improvements in high-density lipoprotein cholesterol level and particle size for the entire 14 days after program cessation. A previous study by the same research group had demonstrated that exercise can increase the size of high-density lipoprotein cholesterol particles. Other research has shown that smaller particles are associated with atherosclerosis and larger particles can be protective against the disease.

In the low-amount exercise groups, men and women maintained lower levels of triglycerides 1 day after exercise cessation, but only men sustained this benefit over the full 14 days of the detraining period.

More research is needed to understand the mechanisms behind the body’s metabolic adaptations to exercise, as well as why the long-term triglyceride benefits only occurred in men, said presenter Johanna Johnson, Ph.D. Nonetheless, the research group believes that the new data correlating the amount and intensity of exercise with benefits in blood lipid levels is very useful, given the very low attention paid previously to the subject.

The research group, led by cardiologist William Kraus, M.D., conducted the current work as part of the 5-year trial Studies of Targeted Risk Reduction Interventions through Defined Exercise (STRRIDE); the overall results are currently entering publication.

Johnson pointed out that compared with most exercise studies, the STRRIDE regimen was longer and more intense. Participants were given individualized exercise programs based on their weight and level of fitness, and they were required to exercise a specified number of minutes per week at a designated intensity.