Do intrapersonal factors mediate the association of social support with physical activity in young women living in socioeconomically disadvantaged neighbourhoods? A longitudinal mediation analysis

RESEARCH ARTICLE a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 Do intrapersonal factors mediate the association of social support with physical activity in young women living in socioeconomically disadvantaged neighbourhoods? A longitudinal mediation analysis Anouk Middelweerd1, Saskia J. te Velde1, Gavin Abbott2, Anna Timperio2, Johannes Brug3, Kylie Ball2* 1 Department of Epidemiology & Biostatistics and the EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, the Netherlands, 2 Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong Victoria, Australia, 3 Amsterdam School of Communication Research, University of Amsterdam, Amsterdam, the Netherlands * OPEN ACCESS Citation: Middelweerd A, te Velde SJ, Abbott G, Timperio A, Brug J, Ball K (2017) Do intrapersonal factors mediate the association of social support with physical activity in young women living in socioeconomically disadvantaged neighbourhoods? A longitudinal mediation analysis. PLoS ONE 12(3): e0173231. https://doi. org/10.1371/journal.pone.0173231 Editor: Hajo Zeeb, Leibniz Institute for Prvention Research and Epidemiology BIPS, GERMANY Received: September 11, 2016 Accepted: February 18, 2017 Published: March 16, 2017 Copyright: © 2017 Middelweerd et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Due to ethical restrictions related to patient consent, data cannot be made publicly available. Data are available upon request following approval from the Deakin University Faculty of Health Human Research Ethics Committee. Interested researchers may contact Kylie Ball () to request data access. The Ethics Committee can be contacted via Ms Jane Moschetti or Ms Penny Andrews, email . Abstract Background Levels of physical activity (PA) decrease when transitioning from adolescence into young adulthood. Evidence suggests that social support and intrapersonal factors (self-efficacy, outcome expectations, PA enjoyment) are associated with PA. The aim of the present study was to explore whether cross-sectional and longitudinal associations of social support from family and friends with leisure-time PA (LTPA) among young women living in disadvantaged areas were mediated by intrapersonal factors (PA enjoyment, outcome expectations, selfefficacy). Methods Survey data were collected from 18–30 year-old women living in disadvantaged suburbs of Victoria, Australia as part of the READI study in 2007–2008 (T0, N = 1197), with follow-up data collected in 2010–2011 (T1, N = 357) and 2012–2013 (T2, N = 271). A series of singlemediator models were tested using baseline (T0) and longitudinal data from all three time points with residual change scores for changes between measurements. Results Cross-sectional analyses showed that social support was associated with LTPA both directly and indirectly, mediated by intrapersonal factors. Each intrapersonal factor explained between 5.9–37.5% of the associations. None of the intrapersonal factors were significant mediators in the longitudinal analyses. PLOS ONE | https://doi.org/10.1371/journal.pone.0173231 March 16, 2017 1 / 14 Longitudinal mediation analysis social support and physical activity in young women Funding: The READI study was funded by the Australian National Health and Medical Research Council, ID 374241. AM is supported by the Philips and Technology Foundation STW and Nationaal Initiatief Hersenen en Cognitie NIHC under the Partnership program Healthy Lifestyle Solutions (grant no. 12014) and Albert Renold Travel fellowship from the European foundation for the Study of Diabetes. Analyses for the current paper were part of the MeMo International Exchange program funded under Marie Curie Actions (FP7PEOPLE-2009-IRSES-247630). KB is supported by an NHMRC Principal Research Fellowship, ID 1042442. AT is supported by a National Heart Foundation of Australia Future Leader Fellowship, Award ID 100046. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Conclusions Results from the cross-sectional analyses suggest that the associations of social support from family and from friends with LTPA are mediated by intrapersonal factors (PA enjoyment, outcome expectations and self-efficacy). However, longitudinal analyses did not confirm these findings. Introduction Although the positive health effects of physical activity (PA) are well known [1–4], only approximately 30% of the Australian adult population meet the recommended guidelines of at least 30 minutes of moderate-intensity PA per day. [5] Only 48.7% of young Australian women aged 18–24 years meet the recommended PA guidelines and the percentages tend to decline substantially in older age groups. [5, 6] Previous research has shown that PA levels decrease during the transition from adolescence into adulthood. [6, 7] Life events that occur in young adulthood, such as leaving school and home, getting married or having children, may be associated with disruption in PA during this life stage [7], especially for women. [8, 9] Furthermore, women living in the most socioeconomically disadvantaged areas already are less physically active than those from more advantaged neighbourhoods, and thus are even more at risk of adverse health outcomes resulting from age-related declines in PA. [10] In order to minimise reductions in PA in young adults living in disadvantaged neighbourhoods, we need to understand the determinants of PA in this population group. Various social-cognitive and ecological-based models have been published which aim to predict and understand health behaviours.[11] These models and theories describe a range of potential behavioural determinants, e.g. environmental factors such as availability and sociocognitive factors such as self-efficacy and social support. Often used theories and models are the Social Cognitive Theory (SCT)[12–14] and socio-ecological models [15]. These models postulate that the social environment influences health behaviours, such as PA, both directly and indirectly (i.e. through self-efficacy). That the social environment is indeed an important determinant of PA has been confirmed in observational research.[16–18]Moreover, self-efficacy, or similar constructs, is a key construct within various social cognitive theories and has consistently positively been associated with PA. [18, 19] Outcome expectations, another key concept in the SCT, represent one’s beliefs about the consequences and perceived benefits of one’s behavior such as participating in PA and has consistently been associated with PA. [20] In additio (...truncated)