Healthy for life: A randomized trial examining physical activity outcomes and psychosocial mediators

Abstract

Background: Researchers theorize that interventions increase physical activity by influencing key theory-based mediators (e.g., behavioral processes). However, few studies have been adequately powered to examine the importance of mediators. Purpose: This study examined both physical activity behavior and psychosocial mediators in a randomized trial specifically powered to detect mediation. Methods: Healthy, sedentary adults (n = 448; 70 % Caucasian, 87 % women, mean age was 43) were randomly assigned to either a 6-month print-based theory tailored physical activity intervention (n = 224) or a 6-month health/wellness contact control arm (n = 224). Results: The print intervention arm exhibited greater increases in physical activity than the control arm at 6 and 12 months (p