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Thirty Minutes of Exercise Goes a Long Way

Posted - Jan. 12, 2004 at 3:20 p.m.



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WASHINGTON, Jan 12, 2004 (United Press International via COMTEX) -- Thirty minutes of daily moderate exercise may be all it takes to prevent weight gain, according to a study released Monday that contradicts earlier research recommending 60 minutes of activity a day.

As Americans delve into their New Year's fitness resolutions, they may discover they do not have to be in pain to gain. Researchers at Duke University Medical Center in Durham, N.C., found a half-hour of walking every day, or about 10 to 12 miles per week, will offset gradual weight gain from inactivity, and any further exercise leads to additional loss of weight and body fat.

In 2002, the Institute of Medicine recommended exercising 60 minutes each day for good health and weight loss.

The IOM's and other exercise recommendations are "confusing," lead researcher and exercise physiologist Cris Slentz told United Press International. "That's one of the reasons why we did this study."

The researchers took 120 sedentary individuals and randomly assigned them to one of four groups:

--no exercise,

--low-dose moderate exercise or the equivalent of 12 miles of walking per week,

--low-dose vigorous exercise or about 12 miles of jogging per week, or

--high-dose vigorous exercise equivalent to 20 miles of jogging per week.

The exercise was performed on treadmills, elliptical trainers or cycle ergometers in supervised settings. The study required no dietary changes.

"They just ate whatever they were eating," Slentz said.

Those in the no-exercise group showed a 1.1 percent weight gain while everyone else showed varying degrees of weight loss, depending on the amount of exercise they did. Those who did not exercise also experienced an average 0.8-percent increase in their waist measurement compared to waist decreases of 1.6 percent for the low-dose moderate group, 1.4 percent for the low-dose vigorous group and 3.4 percent for the high-dose vigorous group.

When it came to body fat mass, the inactive group saw a 0.5-percent increase while everyone who exercised experienced a drop: 2 percent for the low-dose moderate group, 2.6 percent for the low-dose vigorous group, and 4.9 percent for the high-dose group.

The study results suggest a little exercise goes a long way for people who are looking to leave the sedentary lifestyle behind. The findings are published in the Jan. 12 issue of Archives of Internal Medicine.

"The people who remained inactive gained weight and that's not surprising because that's what everybody in America is doing," Slentz said. "A calorie is a calorie."

The important thing to remember is moderate exercise effectively burns off calories, he added.

Slentz said the IOM recommendations were based on projected calculations and did not provide the whole picture.

Tim Church, medical director of the Cooper Institute in Dallas, a non-profit research and education center focused on preventive medicine, agreed.

"The American College of Sports Medicine, the National Institutes of Health, the Centers for Disease Control (and Prevention) and the American Heart Association -- they all recommend 30 minutes a day, five days a week," Church told UPI. "IOM kind of pulled that 60 minutes a day out of thin air. It was a giant public disservice by throwing it out there. There's just overwhelming evidence that 30 minutes a day is all it takes."

Church cautioned, however, that by exercising "30 minutes a day, five days a week, you're probably not going to lose weight," unless you cut calories as well.

Nevertheless, overall health benefits are tremendous, even if clothes do not feel any looser.

"Individuals who are fit but fat outlive individuals who are skinny but sedentary. The bottom line is you don't have to lose weight to benefit greatly from exercise," Church said.

Liz Applegate, a fitness and nutrition professor at the University of California at Davis, said people were discouraged by the 60 minutes daily recommendation.

"The Duke study shows, 'Hey, (30 minutes) works,'" Applegate told UPI. "It's more than just calorie burning."

Applegate said the body has its own unique thermostat for maintaining energy balances and control.

"If you take exercise out of picture, the thermostat just doesn't work very well. A sedentary lifestyle is detrimental to your health."

Church said the new findings show a little moderate physical activity could have big effects.

"It would change our whole healthcare system," he said.

CDC figures show 61 percent of the entire U.S. population is either clinically overweight or obese.

"We're not trying to make everyone marathon runners," Church said, adding that simple steps are key. "At lunch, you should walk to the deli. Take your dog for a walk. It's just about physical activity."

--

Katrina Woznicki covers medical research for UPI Science News. E-mail sciencemail@upi.com

Copyright 2004 by United Press International.

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