The purpose of this thesis was to explore the motivational processes that underpin adolescent exercise and sedentary behaviour. Grounded in Self-determination theory (SDT; Deci & Ryan, 1985), a series of four studies sought to address key methodological pitfalls within the extant SDT literature and utilise these developments to explore how motivation and its related cognitive processes relate to adolescent exercise and sedentary behaviour. In Chapter 2, through focus groups with 39 adolescents, the participants’ conceptualisation of exercise was explored to inform the interpretation of responses to exercise-related measures and the measurement of exercise behaviour. In Chapter 3, to facilitate the holistic measurement of need support, the Adolescent Psychological Need Support in Exercise Scale (APNSEQ) was developed and validated in two samples of adolescents (N=806). In Chapter 4, applying the new APNSEQ measure and the conceptual insight gained in Chapter 2, cross-sectional data from 388 adolescents supported the nomological network of variables proposed within SDT. However, the SDT model only explained a small amount of variance in behaviour. Thus, in Chapter 5 (N=257), a mediation model, where action planning, self-monitoring and habit mediate the relationship between autonomous motivation and behaviour was explored. Habit was a significant mediator of the relationship between autonomous motivation and exercise and sedentary behaviour, and need support was indirectly associated with self-regulation. Collectively, the four studies address some key conceptual and methodological issues present in the extant SDT literature, and apply these developments to offer a comprehensive exploration of the motivational processes that underpin adolescent exercise and sedentary behaviour. Through holistically considering the antecedents of motivation (i.e., need support, need thwarting, need satisfaction, and need frustration), as well as exploring the processes through which motivation influences behaviour, this thesis offers exciting routes for theoretically robust future research, as well as potential insights for intervention.
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|Number of pages||255|
|Publication status||Published - 2016|