, Volume 45, Issue 2, pp 203-212
Date: 15 Nov 2012

Healthy for Life: A Randomized Trial Examining Physical Activity Outcomes and Psychosocial Mediators

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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.


This study examined both physical activity behavior and psychosocial mediators in a randomized trial specifically powered to detect mediation.


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).


The print intervention arm exhibited greater increases in physical activity than the control arm at 6 and 12 months (p < .05). Additionally, behavioral processes were found to be an important mediator of physical activity behavior.


It is important for researchers and practitioners to focus on increasing behavioral strategies for physical activity adoption. Future studies should examine other potential mediators of physical activity.

Trial Registration Number: NCT00142688