Stemming from the need for theoretical integration, this study aimed at individually testing and integrating self-determination theory (SDT) and self-efficacy theory (SET) to predict physical activity. University students (n = 225) completed questionnaires measuring constructs from SDT and SET as well as the Godin Leisure Time Exercise Questionnaire. Using path analysis, individual SDT and SET models and 2 hypothesised integrated models were tested. The preferred integrated model was selected on the basis of model fit indices. The selected integrated model was then compared with the individual theoretical models by examining the number of theoretical links that remained constant and the explained variance in the variables. Results revealed that the individual and integrated models were supported. The second integration model, which had self-determined motivation and confidence in equal agenic roles, had better model fit, χ^sup 2^(7) = 28.87, p < .001, comparative fit index = .95, root-mean-square error of approximation = .12, standardized root mean residual = .05, Akaike Information Criterion = 84.87, and was preferred over the individual theoretical models. Overall, integrating 2 motivational theories in physical activity research is feasible, and more studies are needed to enhance our understanding of physical activity participation.
Keywords: theory, exercise, motivation, confidence
Theory testing needs to increase in health behaviour research, including physical activity, because only 36% of health behaviour articles are theoretically driven (Painter, Borba, Hynes, Mays, & Glanz, 2008). In addition to individual theory testing, theory integration has been recently urged to advance the health behaviour literature, because integration will help reduce redundancy between theories and utilize each theory's strengths (Noar & Zimmerman, 2005). In the physical activity domain, motivational variables continue to consistently hold a strong link with this health behaviour (Pan et al., 2009). Because self-efficacy theory (SET; Bandura, 1997) and self-determination theory (SDT; Deci & Ryan, 2002) are two reputable motivational theories, this article purports to answer the current call for theory testing and integration using these theories in the context of physical activity.
Self-determination theory (SDT; Deci & Ryan, 2002) has received increased attention in the physical activity domain, and consequently, its use is encouraged for physical activity research (Wilson, Mack, & Grattan, 2008). In SDT, multiple constructs - autonomy support, psychological needs and motivation - explain the physical activity behaviour change process. This section describes each SDT construct, starting with autonomy support to the types of motivation. First, autonomy support refers to one's perception of his or her social environment to the extent to which it provides choices and options, acknowledges one's opinion, and provides rationale when suggesting choices. Higher levels of autonomy support will positively influence one's psychological needs for autonomy, competence, and relatedness. Autonomy "refers to being the perceived origin or source of one's own behaviour," in this case physical activity (Deci & Ryan, 2002, p. 8). Competence is defined as "feeling effective in one's ongoing interactions with the social environment and experiencing opportunities to exercise and express one's capacities" (Deci & Ryan, 2002, p. 7) and relatedness as the desire to feel connected to others in the physical activity context (Deci & Ryan, 2000). Satisfaction of these three psychological needs lead to greater levels of selfdetermined motivation.
Three main types of motivation are found within SDT: amotivation, extrinsic, and intrinsic. These types are represented by different regulations and are placed on a continuum: amotivation, external, introjected, identified, integrated, and intrinsic (Deci & Ryan, 2002). …