Factor Analysis Test of an Ecological Model of Physical Activity Correlates

Objectives: The fit of measured variables into a social-ecological model of correlates of physical activity is rarely tested. In this study, we examined the factor structure of correlates of moderate/vigorous physical activity (MVPA) within a hypothesized social-ecological model. Methods: We measured 46 possible personal, social and environmental correlates of MVPA in 2779 adolescents participating in the Project EAT-2010 study. Confirmatory (CFA) and exploratory factor analyses (EFA) were used to determine the factor structure. Associations of factor scores with self-reported MVPA were calculated with linear regression. Results: A 6-factor CFA model did not show adequate fit. Eight factors were identified using EFA (Root Mean Square Error [RMSEA] 90% CI: 0.053 to 0.055; CFI = 0.82). A factor representing the mix of personal and social correlates showed the strongest association with MVPA. Conclusions: The 8-factor model supports independent clustering of possible environmental correlates of MVPA, but indicates that social and personal correlates may not cluster independently. The factor most strongly correlated with MVPA represented a mix of personal and social correlates. Future work will be needed to better understand how mechanisms for developing physical activity work within and across levels of the social-ecological framework.