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UBC Theses and Dissertations

Examining physical activity, healthy eating, and non-smoking behaviours during adolescence : a test of the expectancy-value model Sabiston, Catherine Michelle


The general purpose was to explain adolescents' physical activity, healthy eating, and non-smoking behaviours using an expectancy-value (EV) model approach. Possible differences in the model for boys and girls were also examined. The first study (boys: n=211; girls: n=329) used the EV model to examine health behaviours, and the integration of physical self-concept into the motivation framework. The second study (boys: n=419; girls: n=438) further tested the EV model to better understand healthpromoting behaviours, and examined the unique effects of parent and best friend influences. For both studies, structural equation modeling procedures found the EV model provided a good fit to the observed physical activity and healthy eating data. The models accounted for an R² of 0.41-0.57 for physical activity and R² of 0.29-0.59 for eating behaviour, and provided partial support for the EV model. Logistic regression models examining non-smoking behaviour showed support for the EV model tenets across the studies. In both studies, there were a number of mean-level and covariant gender differences for the health behaviour variables. Differences in the strength of the parameters and prediction in the models for boys and girls were also evident. There are conceptual and practical implications associated with this research. First, gender-specific models may benefit further inquiry into adolescents' health-promoting behaviours and subsequent intervention strategies. Additionally, physical activity, healthy eating, and non-smoking behaviours show only weak interrelationships (r=.01- .26) and the models are unique in the predictive power and independent predictors. These findings suggest that independent strategies focused on enhancing health behaviour motivation during adolescence are necessary.

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