To better understand mechanisms of physical activity (PA) behavior change in breast cancer survivors, we examined mediation of a successful PA behavior change intervention by social cognitive theory (SCT) constructs. Our exploratory study randomized 41 breast cancer survivors to receive the 3-month intervention (INT) or usual care (UC). We used the Freedman and Schatzkin approach to examine mediation of intervention effect on PA 3 months postintervention by changes in SCT constructs from baseline to immediately postintervention. Compared with UC, the INT group reported lower barriers interference (mean difference = −7.8, 95% CI [−15.1, −0.4], d = −0.67, p = .04) and greater PA enjoyment (mean difference = 0.7, 95% CI [0, 1.5], d = 0.61, p = .06). Barriers interference mediated 39% (p = .004) of the intervention effect on PA 3 months postintervention. PA enjoyment was not a significant mediator. Reducing barriers to PA partially explained our intervention effect.
Laura Q. Rogers, Southern Illinois University School of Medicine—Medicine, Springfield, IL; Stephen Markwell, Southern Illinois University School of Medicine—Surgery, Springfield, IL; Patricia Hopkins-Price, Southern Illinois University School of Medicine—Medicine, Springfield, IL; Sandy Vicari, Southern Illinois University School of Medicine—Psychiatry, Springfield, IL; Kerry S. Courneya, Faculty of Physical Education, University of Alberta, Edmonton, AB Canada; Karen Hoelzer, Department of Hematology and Oncology, Springfield Clinic, Springfield, IL; Steven Verhulst, Southern Illinois University School of Medicine—Statistics and Research Consulting, Springfield, IL.