March 13 (HealthDay News) -- Just 10 minutes to 30 minutes of exercise a day can improve the quality of life for sedentary, overweight or obese women, American researchers suggest.

The analysis studied hundreds of women, average age 57, who took part in the Dose Response to Exercise in postmenopausal Women (DREW) study, first reported in 2007. These newly released secondary results focused on quality of life among 430 women who were randomly assigned to four groups -- three groups did various amounts of exercise (70, 135, or 190 minutes per week), while the fourth group did no exercise.

Most of the exercise was divided into three or four sessions per week. When they weren't doing the organized exercise sessions, the women wore pedometers.

All the women in the exercise groups reported a statistically significant improvement in social functioning compared to women in the non-exercise group, according to the study authors. In addition, women who did more exercise also showed improvements in general health, vitality and mental health.

The women who did more exercise also showed improvements in physical functioning and fewer limitations in work or other activities due to physical problems and fewer limitations due to emotional problems. There was no statistical improvement in pain.

Specifically, after six months of exercise, the women improved almost 7 percent in physical function and general health, 16.6 percent in vitality, 11.5 percent in performing work or other activities, 11.6 percent in emotional health, and more than 5 percent in social functioning.

"This has not been shown in a large controlled study before," principal investigator Dr. Timothy S. Church, researcher director at Pennington Biomedical Research Center, said in a prepared statement. "This is the first large controlled study of postmenopausal women to look at the effect of exercise training on the quality of life. It shows that exercise gives you energy and makes you feel better."

The findings were presented Thursday at the American Heart Association's Conference on Nutrition, Physical Activity and Metabolism, in Colorado Springs, Colo.

"While the women who participated in the highest exercise group saw the greatest improvements in most quality of life scales, the women in the lowest exercise group also saw improvements," study co-author Angela Thompson, a research associate at Pennington Biomedical Research Center in Baton Rouge, La., said in a prepared statement.

"The public health message is tremendous, because it provides further support for the notion that even if someone cannot exercise an hour or more daily, getting out and exercising 10 to 30 minutes per day is beneficial, too," she said.

"Walking a little bit every day will help tremendously. Walk with your mother, a neighbor or friend. A little physical activity will improve your quality of life," Thompson said.

While some of the women did lose weight during the study, Thompson said the self-reported improvement in quality of life wasn't dependent on shedding excess pounds.

Not only does exercise improve an older woman's quality of life, it improves balance and builds stronger bones, Church noted.

"Start exercising for small amounts of time, and then gradually work up to 150 minutes a week. A little is better than nothing," he said.

SOURCE: American Heart Association, news release, March 13, 2008