Self-determination Theory and the psychology of exercise

Abstract

The purpose of the Self-determination Theory is to explain motivation and behaviour based on individual differences in motivational orientations, contextual influences, and interpersonal perceptions. The theory has shown utility in explaining the antecedents and processes that underpin exercise behaviour. This review will provide an overview of the theory and its application in explaining health-related exercise motivation, behaviour, and outcomes. Recent innovative research using the theory in exercise contexts will also be reviewed in two key areas: advances in measurement and theoretical integration. Based on this evidence, recommendations for future investigations will be made advocating the development instruments to measure self-determined motivation from first principles, the adoption of experimental and intervention designs to better infer causal links between self-determined motivation and behaviour, further investigation of the role of implicit self-determined motivation in predicting behaviour, and the integration of the Self-determination Theory with other theories of motivation, e.g. the Theory of Planned Behaviour and the Achievement Goal Theory, to provide complimentary explanations of self-determined motivation in exercise contexts. Based on the evidence, the Self-determination Theory demonstrates considerable efficacy in explaining exercise motivation and behaviour. Future research should adopt these recommendations to develop the theory further with a view to informing intervention and practice.

Keywords:

• self-determination theory
• autonomy
• intrinsic motivation
• locus of causality
• theoretical integration

Notes

1. We have identified two mechanisms or processes that are prevalent in research that has applied the Self-determination Theory to exercise behaviour: mediation and moderation. Mediation refers to the transfer of the effect of one variable (usually called a predictor or independent variable) on another (usually referred to as the outcome or dependent variable) by a third variable (the mediator). A series of conditions must be met for a variable to qualify as a mediator. The independent variable must be significantly correlated with the dependent variable and the mediator must be significantly correlated with the independent variable. The mediator must also have an independent effect on the dependent variable. Most important, the inclusion of the mediator as a predictor of the dependent variable must reduce or attenuate the effect of the independent variable on the dependent variable for mediation to occur. For a clear explanation of mediation effects, the reader is directed to Baron and Kenny (1986). Moderators refer to variables that interact with, or alter, the effect of one variable on another. Therefore, a moderator changes the effect that one variable has on another. There are numerous ways that a moderator can be evaluated in psychological research. The most prominent is testing for interaction effects using multi-factorial designs and analysed using ANOVA models or moderated multiple regression analysis. Another approach would be to split a sample based on the high and low values on a moderator variable and analyse the relationship or system to be moderated in each sub-sample using regression or correlation analysis. Further reading on moderation and interaction effects can be gleaned from Aiken and West's (1991) classic treatment on this subject.