ABSTRACT
The use of theory and theoretical frameworks is widespread in the psychology of physical activity (‘exercise psychology’). A theory allows for the specifying of relations among key variables with the key purpose being to explain and predict behaviour. This chapter covers three commonly used individually focused theories in the psychology of physical activity that reflect an emphasis on motivation, attitudes and self-confidence: Self-Determination Theory (SDT), including related theoretical frameworks on intrinsic motivation; the Theory of Planned Behaviour (TPB); and Social Cognitive Theory (SCT), including self-efficacy. Self-Determination Theory is an important perspective for the study of motivation in physical activity, and helps in the understanding of the different types of extrinsic motivation that might exist in physical activity. The Theory of Planned Behaviour has consistently predicted exercise intentions and behaviour across diverse settings and samples; attitude is a strong predictor of intention, but subjective norms less so. However, the theory has limitations. The key construct in Social Cognitive Theory is self-efficacy, and this acts as both a determinant and an outcome in physical activity. Self-efficacy has several sources.
