MICHELE NORRIS, host:
If having no time is one of your excuses for skipping that morning exercise, consider this, new research shows that taking just three 25-minute walks a week is enough to improve fitness, at least a bit.
NPR's Allison Aubrey has the details.
ALLISON AUBREY: There was a time when people walked everywhere. Seventy-four-year-old Jean Pearman remembers as a child walking to school, to church.
Ms. JEAN PEARMAN (Resident, Washington D.C.): We walked to the movies. We walked back from the movies. We walked to get a trolley(ph). It's part of my life.
AUBREY: Pearman says she misses that healthy way of life. So why is that these days from her home in Washington D.C., she's riding the bus to get around town and not getting much exercise at all.
Ms. PEARMAN: Lazy. Just absolutely lazy. I should have been being doing it.
AUBREY: Getting some exercise. But Pearman says after falling out of the routine, she's not exactly sure how to work it back in.
Dr. TIM CHURCH (Director, Preventive Medicine Research Lab, Pennington Biomedical Research Center, Louisiana State University): I hear that all the time in my business. As you know I want to become physically active, I have no idea where to start.
AUBREY: Tim Church directs the Preventive Medicine Research Lab at Louisiana State University in Baton Rouge. He says Jean Pearman's story is very similar to the nearly 500 women who were volunteers in his latest study. Many of them like Pearman were retired schoolteachers. All of them had become overweight and were living very sedentary lives.
Dr. CHURCH: The number one cause of death in women is cardiovascular disease. And as you reach the menopause, your risk for cardiovascular disease skyrockets.
AUBREY: One way to reduce this risk is to exercise regularly. But exactly how much - or how little - exercise is enough to protect older women who haven't yet made physical activity a priority.
To answer this question, Tim Church divided his volunteers into groups. Some women were instructed to walk on a treadmill three times a week for about 25 minutes at a time. That's just over an hour for the whole week.
Other women were pushed a little harder riding a bike or treadmill for three hours per week.
Dr. CHURCH: We were surprised when we found out that, you know, the 71 minutes a week not only prevented a loss of fitness, but it's actually resulted in an increase in fitness.
AUBREY: Now even after six months, none of these women lost weight or saw a drop in blood pressure. But the main benefit was important: The women improved their aerobic fitness. This means they were able to move a little longer and faster without becoming winded.
Exercise physiologist Glenn Gaesser at the University of Virginia says building this aerobic capacity is incredibly important to health in preventing heart attacks and strokes, even if the scale shows you're not dropping any pounds.
Mr. GLENN GAESSER (Exercise Physiologist, University of Virginia): Aerobic fitness alone is a key predictor of longevity. Whether or not, the individual loses weight or improves any other risk markers associated with disease.
AUBREY: That's assuming people keep exercising. The study also shows: The more you do, the better off you are. In Church's study, women who biked or walked on treadmills for three hours per week ended up significantly more fit about twice as fit as those who exercised for just 71 minutes a week.
I-Min Lee is a professor of medicine at Harvard. She says that's great news in terms of fitness, but:
Dr. I-MIN LEE (Professor of Medicine, Harvard University; Researcher, Brigham and Women's Hospital): If you want to control your weight, given what we typically eat in an American diet, you might need 60 or even 90 minutes of physical activity a day.
AUBREY: Hearing about the study, Jean Pearman says she wants to hop off her bus and start walking again. She remembers how good exercise makes her feel.
Ms. PEARMAN: You're lighter. Your attitude is different, also. If you have a tremendous attitude - look at me, I look great. And every woman wants to look that way.
AUBREY: Pearman says she plans to start her new routine tomorrow.
Allison Aubrey, NPR News, Washington.