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Health Psychol. 2007 Nov;26(6):718-27.

Ongoing physical activity advice by humans versus computers: the Community Health Advice by Telephone (CHAT) trial.

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Division of Epidemiology, Department of Health Research and Policy, Prevention Research Center, Stanford University School of Medicine, 211 Quarry Road, Stanford, CA 94305, USA.



Given the prevalence of physical inactivity among American adults, convenient, low-cost interventions are strongly indicated. This study determined the 6- and 12-month effectiveness of telephone interventions delivered by health educators or by an automated computer system in promoting physical activity.


Initially inactive men and women age 55 years and older (N = 218) in stable health participated. Participants were randomly assigned to human advice, automated advice, or health education control.


The validated 7-day physical activity recall interview was used to estimate minutes of moderate to vigorous physical activity. Physical activity differences by experimental arm were verified on a random subsample via accelerometry.


Using intention-to-treat analysis, at 6 months, participants in both interventions, although not differing from one another, showed significant improvements in weekly physical activity compared with controls. These differences were generally maintained at 12 months, with both intervention arms remaining above the target of 150 min per week of moderate to vigorous physical activity on average.


Automated telephone-linked delivery systems represent an effective alternative for delivering physical activity advice to inactive older adults.

[Indexed for MEDLINE]

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