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

Beth A. Lewis, David M. Williams, Brian C. Martinson, Shira Dunsiger, Bess H. Marcus

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


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 <.05). Additionally, behavioral processes were found to be an important mediator of physical activity behavior. Conclusions: 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.

Original languageEnglish (US)
Pages (from-to)203-212
Number of pages10
JournalAnnals of Behavioral Medicine
Issue number2
StatePublished - Apr 2013

Bibliographical note

Funding Information:
Acknowledgments This research was supported through a grant from the National Heart, Lung, and Blood Institute (R01 HL72947). The authors would like to acknowledge the incredible work by the research assistants including Kris Nozal and Jane Wheeler and the data programmer Alexander Kravchik. We would also like to thank the study participants without whom this study would not have been possible.


  • Exercise
  • Intervention studies
  • Mediators
  • Physical activity


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