It may take at least two hours per week of aerobic exercise such as walking, biking, or swimming — preferably in sessions lasting for more than half an hour — to get the HDL benefit. That's according to a new research review published in the Archives of Internal Medicine.
The reviewers, who work at the University of Tokyo, included Satoru Kodama, M.D. They pooled data from 25 studies on aerobic exercise and HDL cholesterol. Together, the studies included some 1,400 adults, some of whom were assigned to get aerobic exercise for at least eight weeks. Participants weren't told to diet.
On average, participants worked out nearly four times per week, with each workout lasting for about 40 minutes.
Participants who got at least two hours per week of aerobic exercise had a modest rise in their HDL cholesterol level. Unlike LDL ("bad") cholesterol, a rise in HDL ("good") cholesterol is considered positive for heart health.
Based on other research, the reviewers estimate that the gains in HDL cholesterol levels translate to a 5% drop in men's heart disease risk and more than a 7 percent drop in women's heart disease risk.
"This is potentially of substantial importance in public health," write Kodama and colleagues. However, they say the benefit may be less than that from drugs that boost HDL cholesterol.
The CDC recommends that people get at least 30 minutes of moderate-intensity physical exercise at least five days per week.
Many people find it hard to devote long periods of time to exercise. So Kodama's team tried to figure out whether several short sessions would raise HDL cholesterol.
They concluded that workouts needed to last more than half an hour to improve HDL cholesterol. However, further research is needed to confirm that finding.
Exercise intensity didn't affect the findings. That is, it didn't matter whether participants got vigorous exercise or worked out at a gentler pace.
The HDL benefits were greatest in people who weren't obese and those with high levels of total cholesterol. The reasons for those findings aren't clear.
Don't know your cholesterol levels? A simple blood test can give you that information. Then you and your doctor can make a plan to improve your cholesterol profile, if necessary.
By Miranda Hitti
Reviewed by Louise Chang, M.D.
©2007 WebMD, Inc. All rights reserved