BACKGROUND: Older adults make up the fastest growing segment of our population. It is estimated that by the year 2030, elderly people will make up 22% of the United States population. A large portion of older adults suffer from one or more chronic conditions that could be improved by regular physical activity, therefore research in this age group is needed.

DESIGN NARRATIVE: The Cooperative Lifestyle Intervention Program (CLIP) is designed to test the effects of a physical activity intervention and a weight loss intervention on mobility disability of 300 older (60-79 years) overweight/obese men and women who have evidence of cardiovascular disease or the metabolic syndrome. The public health relevance of the trial lies in the fact that the interventions will be delivered in conjunction with four Cooperative Extension Centers in counties surrounding Winston-Salem, North Carolina. CLIP will be designed as a three arm randomized controlled trial. The three 18-month treatments will include: (1) a basic health education-based control condition, (2) a group treatment program for physical activity, and (3) a lifestyle intervention designed to intervene on both sedentary behavior and weight loss. The primary aim is to compare the effects of the three treatment arms on 18-month change in performance on a six-minute walk test, a valid and reliable measure of mobility disability. Secondary aims include changes in cardiovascular risk factors, adiposity, cardiovascular fitness, physical activity, and health-related quality of life. Analyses will also be conducted to determine whether changes in the primary outcome are mediated by changes in constructs from social cognitive theory.