15 minutes of walking can do some good

BATON ROUGE, La., May 21 (UPI) -- Walking or bike riding for as little as 15 minutes a day improves the fitness of postmenopausal women who are sedentary, found a U.S. study.

The study examined 460 women who were randomly placed into one of four groups: a control group that did no exercise and groups that exercised 72 minutes, 135 minutes or 191 minutes per week.

The study, published in the Journal of the American Medical Association, found the more exercise performed the greater the increase in fitness, which was expected. However, the lowest-exercise groups also saw improvements in fitness.

"The surprising news is that the lowest exercise group showed significant improvement," Dr. Timothy Church of the Pennington Biomedical Research Center in Baton Rouge, La., said in a statement.

"We continue to recommend 30 minutes a day of walking at least five days a week, but the data suggests just doing something -- even 15 minutes a day -- is better than nothing."