Dec. 13 (HealthDay News) -- Computer-generated phone call reminders are an effective, low-cost method to encourage sedentary adults to exercise, a new Stanford University School of Medicine study suggests.

The yearlong study of 218 people over the age of 55 found that regular phone reminders by either health educators or an automated computer system were equally good at nudging the participants into a regular 150-minute per week exercise regimen.

"This is the first study to directly compare the efficacy of a physical activity program delivered by a computer versus humans and found them to work similarly well," study author Abby King, a professor of health research and policy and a senior investigator at the Stanford Prevention Research Center, said in a prepared statement. "Theoretically, [computer reminders] could be delivered to anybody around the country, or around the world, and could save time and money."

At the start of this study, 80 percent to 85 percent of the participants said they would prefer or need a live human voice to prompt them to exercise. The results showed that wasn't true. After six months, the group receiving calls from people and the group receiving computer calls were doing the same amount of exercise. After one year, there was little difference between the two groups -- 157 minutes per week for those who received computer calls and 178 minutes a week for those who received human voice calls.

A control group that received no reminder calls averaged 118 minutes of exercise a week.

The study was published in the current issue of Health Psychology.

SOURCE: Stanford University, news release, December 2007