By Denise Mann
WebMD Health News
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Reviewed by Louise Chang, MD
Many studies have suggested that regular physical activity, including walking for just 30 minutes a day at a moderate pace, may improve health. But the new research says it's the intensity, rather than the duration, that makes the difference.
Specifically, fast walkers and joggers who exercised for two to four hours per week were up to 50% less likely to develop what's called metabolic syndrome. Participants who walked at a casual pace for about an hour a day made no difference in their risk to develop the syndrome.
Metabolic syndrome is the name for a cluster of risk factors that give rise to diabetes or heart disease. These risk factors include high blood pressure, high blood sugar, a high triglyceride (blood fat) level, a low HDL (good cholesterol) level, and belly fat.
The new study included more than 10,000 adults aged 21 to 98 from Copenhagen, Denmark. All the participants were quizzed on the amount of physical activity they did when the study started and were monitored for up to 10 years.
The findings appear online in BMJ Open.
Exercise Intensity Trumps Duration
When the study began, 1 in 5 women and slightly more than 1 in 4 men had metabolic syndrome. Among women, close to 1 in 3 with metabolic syndrome was inactive. By contrast, 1 in 10 of the women who were extremely physically active had metabolic syndrome. The findings were similar among men in the study.
After 10 years of follow-up, about 15% of participants without metabolic syndrome developed it.
The risk was much lower among those who reported doing vigorous exercise than their counterparts who reported being inactive or doing light exercise, the study shows.
"Our results confirm the role of physical activity in reducing [metabolic syndrome] risk and suggest that intensity rather than volume of physical activity is important," the study authors conclude.
The study did have some limitations. Namely, researchers did not look at participants' diets. Nutrition also plays a role in developing metabolic syndrome.
Quality vs. Quantity
"It's not just time spent exercising, but the quality of that time that helps with weight loss, weight maintenance, and improves health issues," says Neeru Jayanthi, MD. He is the medical director of primary care sports medicine at Loyola University Health System in Maywood, Ill. "People feel that anything is better than nothing and this study shows that is not true when it comes to risk of metabolic syndrome."
You have to sweat for it to count, he says. "Even gardening, if it creates a sweat and is done two to four [hours] a week, can help lower risk for diabetes and heart disease," he says.
Still, studies are split on the intensity vs. duration issue, says Scott Kahan, MD, MPH. He is the director of the National Center for Weight and Wellness in Washington, D.C. "Much research says that moving in any amount is healthful and some studies show that the greater intensity of physical activity is better."
The new findings support the latter. "They may further fuel this debate," he says.
"Try to move as much as you can in your life," Kahan says. "If you can move a little more or with more intensity whether at the gym or outside, that is a good thing. Small steps go a long way."
SOURCES: Scott Kahan, MD, MPH, director, National Center for Weight and Wellness, Washington, D.C. Neeru Jayanthi, MD, medical director, primary care sports medicine, Loyola University Health System, Maywood, Ill. Laursen, A.H. BMJ Open, 2012, study received ahead of print.
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