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Article Excerpt
The Transtheoretical Model (Prochaska & Marcus, 1994) has been widely used as a framework for understanding exercise behavior change. The purpose of this study was to clarify equivocal research findings reported for model predictions when examining stage movement over time rather than static stages and to provide some evidence of the construct validity of transitional stages. Participants were female (n = 285) and male (n = 243) undergraduates (M age = 19. 9 years, SD = 2. 7) who completed previously validated questionnaires twice, separated by 9 weeks, that assessed stage of change, exercise behavior, processes of change, pros and cons of exercise, and exercise self-efficacy. Participants were classified into one of five transitional shift groups based on their responses at baseline and follow up: (a) stable sedentary, (b) stable active, (c) activity adopters, (d) activity relapsers, and (e) perpetual preparers. Results of a 5 (group) x 2 (time) repeated measures (RM) analysis of variance (ANOVA) examining exercise behavior revealed a significant interaction (p < .001) and supported transitional stage classification, with activity adopters and stable actives increasing exercise over time and relapsers decreasing activity. Separate 5 (group) x 2 (time) RM ANOVAs examining model constructs revealed no significant interaction for cognitive processes of change; however, activity adopters and stable actives reported significant (p <. 01) increases in the use of behavioral processes over time, while only the activity relapsers and perpetual preparers reported decreases. Activity relapsers also reported significant (p <. 05) decreases in the pros of exercise. No significant interactions were found for the cons of exercise behavior Unlike findings reported in cross-sectional studies, increases in self-efficacy did not accompany increases in exercise stage. The findings strongly support examination of stage movement classifications rather than static stages, as these transitions provide greater insight into the mechanisms of exercise behavior change.
Key words: decisional balance, processes of change, self-efficacy, transtheoretical model
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The relationship between physical inactivity and increased risk for cardiovascular disease has prompted a wealth of research exploring physical activity correlates and determinants. The investigation of theoretically based interventions designed to increase physical activity across the lifespan has logically followed. Yet, current statistics indicate that 15% of American adults are completely sedentary, and less than 50% meet recommended guidelines for achieving the health benefits associated with physical activity (Macera et al., 2005). Likewise, certain subgroups are less likely to engage in physical activity (Lethbridge-Cejku, Schiller, & Bernadel, 2004). The greatest declines in physical activity are reported in the transitional years from middle to high school and in those just graduating from college and entering the work force (King et al., 1992; U.S. Department of Health and Human Services [USDHHS], 2000). Those in college are at particular risk for decreases in physical activity levels (Calfas, Sallis, Lovato, & Campbell, 1994). Less than half report engaging in recommended levels of vigorous physical activity, and less than 20% engage in moderate intensity at recommended levels (Centers for Disease Control and Prevention [CDC], 1997). Thus far, interventions specifically targeting college students have met with some short-term success (Sallis et al., 1999); however, they appear to be less successful over the long term (Calfas et al., 2000). Clearly, a better understanding of the mechanisms of physical activity behavior change is needed, if activity changes are to occur and be maintained.
The Transtheoretical Model (TTM) of behavior change (Prochaska & DiClemente, 1983) has been applied to physical activity (Prochaska & Marcus, 1994) to explain behavior change over time and provide a framework for physical activity intervention research (e.g., Cardinal & Sachs, 1995; Marcus, Simkin, Rossi, & Pinto, 1996; Sallis et al., 1999). The model suggests behavior change occurs over time in stages and the mechanisms of change include the cognitive and behavioral processes in which individuals engage at different stages of change. Additionally, individuals will weigh the pros and cons of engaging in physical activity and will generally experience increased self-efficacy as they advance through the stages of physical activity behavior change. Finally, while less examined in the physical activity domain, temptation to return to sedentary behavior patterns lessens at the later stages of the model (Hausenblas et al., 2001). Five stages are proposed, including precontemplation, contemplation, preparation, action, and maintenance. Relapse back to prior stages is not uncommon and is further incorporated into the model, suggesting the dynamic nature of the stages (Cardinal, 1998). A sixth stage, transformation, or termination, has been proposed, and initial research has supported the presence of this stage in which an individual adopts regular physical activity for the lifespan and is no longer at risk of becoming sedentary or irregularly active (Cardinal, 1999; Cardinal & Levy, 2000, Fallon & Hausenblas, 2004).
Cross-sectional studies have generally supported the model's stage constructs and the relationship of its constructs of self-efficacy, decisional balance, and change processes to stage of behavior or motivational readiness to change (Cardinal & Kosma, 2004; Cardinal, Tuominen, & Rintala, 2004; Gorely & Gordon, 1995; Marcus, Selby, Niaura, & Rossi, 1992). While cross-sectional studies support the relationship of model constructs to the various stages of physical activity behavior, longitudinal studies are needed to better explain the specific mechanisms of activity adoption, maintenance, and relapse within the model.
Although fewer in number, some studies have examined the model constructs over time. Differences accompanying stage movement in processes of change have been reported over 6 months in middle-aged adults (Marcus et al., 1996) and over 6 weeks in middle-aged and older adults (Pinto, Lynn, Marcus, DePue, & Goldstein, 2001). Over longer periods of time (e.g., 3 years), little support for the processes of change predicting exercise behavior change in adolescents has been found (Nigg, 2001). Significant differences in decisional balance constructs (i.e., pros and cons of exercise) have been reported between a small sample (N = 52) of college students classified as exercise maintainers and exercise relapsers, over an 8-week period (Sullum, Clark, & King, 2000), and support has been found for the pros of exercise predicting forward stage movement in a larger sample (N = 683) of adults over two consecutive 9-month periods (Plotnikoff, Hotz, Birkett, & Courneya, 2001).
Self-efficacy, a construct receiving perhaps the most research support as a correlate of exercise behavior (Sallis & Owen, 1999), has been reported to significantly predict stage movement in the early stages of exercise behavior (Plotnikoff et al., 2001) and show no differences between those moving from the early stages to the preparation and action stages (Pinto et al., 2001). Nigg (2001) found that self-efficacy did not predict exercise behavior change; however, baseline exercise behavior significantly predicted self-efficacy over a 3-year period. As Nigg acknowledged, the long time lag of the study limited the ability to examine construct relationships, as individuals may have progressed and relapsed through multiple stages over such an extended period.
Together, studies suggest promise for using a transitional stage shift approach to better understand exercise behavior change mechanisms; however, methodological...
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