Researchers at the University of Michigan said the longitudinal study involved healthy women ages 40 to 60 who worked full time. Researchers collected data on women living in the Midwest at three intervals, including one-month and one-year periods.

Michelle Segar said the findings, published in Women's Health Issues, are counterintuitive -- and instead of prescribing exercise to prevent disease, healthcare providers who emphasize physical activity as a means of enhancing quality of life might better facilitate long-term participation among healthy women, making disease prevention more likely.

Segar said research indicates that women are more committed and are more likely to plan exercise into their daily lives if they know that exercising will make them feel better immediately by reducing stress and improve well being.

"Because research shows that exercise is effective for maintaining weight but less so for losing weight, we think that women who exercise to lose weight may not see results," Segar said in a statement.