RALEIGH, N.C. — There's no need to run. Just going for a brisk walk — in the park, around the block or on a treadmill — may be enough to help keep your heart healthy, a small study suggests.
Don't miss these Health stories
More women opting for preventive mastectomy - but should they be?
Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.
- Larry Page's damaged vocal cords: Treatment comes with trade-offs
- Report questioning salt guidelines riles heart experts
- CDC: 2012 was deadliest year for West Nile in US
- What stresses moms most? Themselves, survey says
- More women opting for preventive mastectomy - but should they be?
The study, which indicates roughly two to three hours of mild exercise a week at a moderate intensity can significantly cut the risk of cardiovascular disease, supports earlier research.
The findings may encourage people who are reluctant to exercise, said Brian Duscha, the lead author of the research published in the October issue of the journal Chest.
"The classic question always is: What's the minimum amount I need to do to enjoy the benefits of it," Duscha said. "If you just walk 12 miles a week at a brisk pace, it's scientifically proven now that you will get some benefits."
The conclusions are based on a study at Duke University Medical Center of 133 middle-aged overweight sedentary men and women who were at risk for heart disease.
Broken into four groups, the volunteers either did not exercise, walked briskly for 12 miles a week at a moderate intensity, walked briskly or jogged slowly 12 miles a week at a vigorous intensity, or jogged 20 miles a week at a vigorous intensity.
The researchers studied two measurements of fitness — time to exhaustion and oxygen consumption. The better shape a person is in, the more oxygen can be consumed and used, Duscha said.
All the exercise groups saw fitness improvements. And when the two groups that walked 12 miles at differing intensity levels were compared, there wasn't a significant difference in peak oxygen consumption. There was an improvement for those who jogged vigorously 20 miles a week, an indication that the amount of exercise can be important.
As to the exercising volunteers' minimal weight loss — an average of 3 pounds over the eight-month study period — Duscha said that didn't matter. People who don't exercise and maintain the same diet will gain up to 4 pounds a year, according to an earlier analysis of the same study participants.
Even if you think you aren't gaining any benefits because you aren't losing weight, "don't stop exercising," Duscha said.
Dr. Robert Eckel, president of the American Heart Association, said the study supports what already is known: Moderate activity is certainly better than no activity. But, he noted that "even being more fit may have a better outcome long-term."
A large study based on medical records and questionnaires of more than 40,000 men middle-aged men a few years ago also suggested moderate exercise helps the heart.
Dave Brady, manager of Hyde Park Gym in Austin, Texas, said the findings from the Duke study weren't new but "absolutely right on." Walking 12 miles a week is a good start for people who are overweight and haven't done any exercise, he said.
"If people would just start walking they will get some type of benefit," said Brady.
© 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.