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Mediators of Physical Activity Behavior Change in the “Girls on the Move” Intervention

Robbins, Lorraine B.; Wen, Fujun; Ling, Jiying

doi: 10.1097/NNR.0000000000000359

Background The minimal effect of interventions to date on increasing young adolescent girls’ physical activity (PA) may be due to inadequate understanding of the mechanisms underlying behavior change, yet sparse research testing a PA intervention has examined the capacity of theories to explain PA, particularly when using objective measures.

Objectives The aim of the study was to examine whether constructs from the health promotion model and self-determination theory mediated changes in moderate-to-vigorous physical activity (MVPA) following a 17-week intervention.

Methods The study was a secondary analysis of data from a group randomized trial, including 12 intervention and 12 control schools in the Midwestern United States. Data were collected in 2012–2016. Girls (fifth- to eighth-grade, N = 1,519) completed surveys on perceived benefits and enjoyment of PA, PA self-efficacy, social support and motivation for PA, and barriers to PA and wore accelerometers.

Results The final path model had a good fit: χ2(4) = 2.48, p = .648; goodness-of-fit index = 1; comparative fit index = 1; root-mean-square error of approximation = 0; standardized root-mean-square residual = 0.01. For MVPA change from baseline to postintervention, enjoyment (B = 24.48, p < .001) and social support (B = 30.48, p < .001) had a positive direct effect, whereas the intervention had a positive indirect effect through enjoyment and social support (B = 9.13, p < .001). Enjoyment (B = −13.83, p < .001) and social support (B = −17.22, p < .001) had a negative indirect effect on MVPA change from postintervention to follow-up.

Discussion Enjoyment of PA and social support for PA may be important mediators of PA in young adolescent girls and warrant consideration when designing interventions.

Lorraine B. Robbins, PhD, RN, FNP-BC, FAAN, is Associate Professor, Michigan State University College of Nursing, East Lansing.

Fujun Wen, MEd, is Master’s Degree in Biostatistics Student, Michigan State University Department of Epidemiology and Biostatistics, East Lansing.

Jiying Ling, PhD, RN, is Assistant Professor, Michigan State University College of Nursing, East Lansing.

Accepted for publication December 1, 2018.

Research reported in this publication was supported by a 5-year grant (Award R01HL109101, $3,657,706) from the National Heart, Lung, and Blood Institute at the National Institutes of Health (PI: L. B. Robbins, Michigan State University College of Nursing). The funding agency was not involved in the study design; data collection, analysis, or interpretation; writing of the manuscript or the decision to submit it for publication. The content presented in this article is solely the responsibility of the authors and does not necessarily represent the official policy or views of the National Institutes of Health.

The authors thank the school administrators, nurses, teachers, and other staff members for their assistance during the time of the “Girls on the Move Intervention” study. Their commitment to promote the health of their students is laudable. We want to acknowledge several research team members for effectively managing their respective areas: Stacey Wesolek, who served as Project Manager throughout the intervention phase; Kelly Bourne, Project Manager after the intervention phase and Measurement Coordinator during all phases of data collection; and Patrice Patrick-Banks (Intervention Year 1) and Ann Kostin-McGill (Intervention Years 2 and 3), who served as Intervention Coordinators. We are also very grateful to the Michigan State University undergraduate and graduate nursing and kinesiology students for their assistance during the study. Lastly, we thank the young adolescent girls and their parents/guardians for allowing their daughters to participate.

The authors have no conflicts of interest to report.

Corresponding author: Lorraine B. Robbins, PhD, RN, FNP-BC, FAAN, Michigan State University College of Nursing, 1355 Bogue Street, C245, East Lansing, MI 48824 (e-mail:

Ethical Conduct of Research: This study adhered to strict ethical conduct of research. The study protocol was approved by the Michigan State University Institutional Review Board.

Clinical Trial Registration: Identifier NCT01503333; Date of registration: January, 4, 2012; Date the first participant was enrolled: September 2012;

Online date: March 15, 2019

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