Fitness research shows that when a computer talks the talk, even couch potatoes can be persuaded to walk the walk. Researchers at Stanford University, who studied sedentary people for a year, found that automated exercise reminder phone calls had about the same get-up-and-go power as calls from human counselors.

"The recording had a very nice, kind of cheerleader voice. It sounded very natural," said study participant Rita Horiguchi, who was initially disappointed to be assigned to get computer calls. "She would say things like, 'That's very good. I think you can go a little farther next week.' So I would do a little bit more.'"

Horiguchi was one of 218 adults over 55 in the San Francisco Bay area who took part in the study, known as Community Health Advice by Telephone, or CHAT. The goal was to get them out walking at a brisk pace for 30 minutes most days, or engage in some other medium-intense activity, for a total of about 150 minutes a week.

The group was divided into three: people who got no calls, people who were called by trained health educators and people who got computer calls. The automated calls were interactive — i.e. press "1" if you reached your goal last week — and participants got prerecorded advice on how to overcome challenges.

Exercise levels were measured with devices that estimate physical activity and intensity.

A lot of participants thought they'd need a real human to get motivated.

But in fact, after a year, both of the called groups were topping 150 minutes of exercise a week. Those who got computer calls averaged 157 minute while human-called participants logged an average 178 minutes. The no-call group averaged only 118 minutes.

Lead author Abby King, a senior investigator at the Stanford Prevention Research Center, said the study shows that alternative ways can be used to encourage inactive people to become more physically active.

Results of the study, funded by the National Institute on Aging, are in the current issue of the journal Health Psychology.

The 62-year-old Horiguchi has worked with computers for decades as a programmer and systems analyst among other things but considers herself a "people person."

And to her surprise, she found herself in tune with computer coaching.

"I think it started growing on me immediately. Maybe my mind was more open than I thought it was," she said.

Gender didn't make a difference on call responsiveness, with both men and women doing well with the computerized version, King said.

Researchers are now looking at how to combine people and machines for a cost-effective model that still provides a human touch and are looking at other tech reminding possibilities such as text messages.

Dr. Rachelle Bernacki, an assistant professor of medicine at the University of California, San Francisco, who was not involved in the research, said she was impressed at how much the computer-generated calls worked.

"I still think they weren't as good as calls with a human, but there's only a 20 minute difference," she said. "In terms of a cost-benefit ratio, obviously having a computer call is going to be a lot cheaper."