Electronic Thesis and Dissertation Repository


Doctor of Philosophy




Dr Harry Prapavessis


The importance of physical activity in the overall health promotion and primary prevention of cardiovascular disease risk factors and metabolic diseases in children is well established. Nonetheless, interventions to increase physical activity among this population have been largely unsuccessful. The main objective of the research in this dissertation was to explore the suitability of self-efficacy and basic psychological needs for physical activity prediction and intervention in children. Item generation and psychometric evaluation of psychological questionnaires occurred in study 1 (Chapter 2). Using a prospective design, study 2 (Chapter 3) established task efficacy, barriers efficacy, competence, and autonomy as significant predictors of self-reported physical activity (R2 = 20.3%, p < 0.05). Examining objective minutes in physical activity, autonomy accounted for 8% of the variance associated with moderate activity, while competence accounted for 9.4% of the variance associated with vigorous activity. Relatedness was unrelated to any physical activity outcome. In study 3 (Chapter 4), salient predictors from study 2 were targeted to increase physical activity in a sample of under-active children via a novel motivational interviewing inspired intervention protocol. The intervention significantly increased autonomy and competence but not physical activity. Overall findings provide initial construct validity and reliability evidence for the measures, and describe relationships between self-efficacy, psychological needs and physical activity in children. The brief intervention shows promise for affecting competence and autonomy, however, appears insufficient to increase physical activity.

ethics 1.pdf (51 kB)
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ethics 2.pdf (52 kB)
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CCF04062011_00000.jpg (1102 kB)
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