Social-Cognitive Correlates of Physical Activity in a Multi-Ethnic Cohort of Middle-School Girls: Two-year Prospective Study

Insufficient physical activity among adolescent girls is a public health concern in the United States. Large declines in girls’ leisure time physical activity have been reported between ages 9 and 18 (Caspersen, Pereira, Curran, 2000; Kimm et al., 2002), and the rate of decline during high school is nearly twice as great in girls than boys (Grunbaum et al., 2004). It is important to identify mediators and moderators of change in physical activity that can guide successful interventions to increase and maintain physical activity levels as girls develop (Lewis, Marcus, Pate, & Dunn, 2002; Luban, Foster, & Biddle, 2008). Social-cognitive variables (i.e., beliefs that are formed by social learning and reinforcement history) are putative influences on self-initiated change in health behaviors such as physical activity (Bandura, 2004). They may be especially important during early adolescence, when physical activity increasingly becomes a leisure choice. According to self-efficacy theory (Bandura, 1997), a belief in personal capabilities to plan and execute the courses of action required to attain a behavioral goal is the proximal influence on physical activity. Self-regulatory efficacy beliefs about the ease or difficulty of overcoming personal (e.g., sedentary choices or lack of skill) and environmental (e.g., bad weather or securing social support) barriers to participating in physical activity have been related to physical activity among adolescent girls, regardless of outcome-expectancy values (Beets, Pitetti, & Forlaw, 2007; Dishman et al., 2004; Hagger, Chatzisarantis, & Biddle, 2001; Motl et al., 2002; Neumark-Sztainer, Story, Hannan, & Rex, 2003). However, those studies used subjective self-reports (which can be biased by inaccurate recall and socially desirable responses) to assess physical activity, rather than an objective measure, and most used a cross-sectional design or assessed self-efficacy at a single time. Recent reports of longitudinal, cohort studies of adolescent girls suggest that declines in physical activity during the period from late middle-school through high school are mitigated by self-efficacy for overcoming barriers to physical activity and by perceived social support (Dishman, Saunders, Motl, Dowda, & Pate, 2009), especially from family (Dowda, Dishman, Pfeiffer, & Pate, 2007) and friends (Duncan, Duncan, Strycker, & Chaumeton et al., 2007). According to self-efficacy theory (Bandura, 1989; 1997), efficacy beliefs can affect physical activity both directly and indirectly by influencing self-management (e.g., goal setting, self-persuasion, planning, and problem solving) and perceptions about socio-cultural environments that present barriers or, conversely, provide support for physical activity (Bandura 2004). In these ways, beliefs in personal capability to overcome barriers to physical activity would sustain physical activity despite the perception of such barriers or low support of physical activity from family or friends. Similarly, perceptions of social support can have reciprocal relations with self-efficacy and might influence physical activity indirectly through perceived barriers and self-management (Dishman et al., 2002; 2005). Whether self-efficacy and perceived social support act as moderators (e.g., Dishman, Saunders, et al., 2009) or mediators (e.g., Dishman et al., 2004) of change in girls’ physical activity has received little study (Luban et al., 2008) and is as yet unknown. Other evidence indicates that activity levels are lowest among girls of African American or Hispanic/Latino ancestry or who have high body mass index (BMI) (Gordon-Larsen, Adair, & Popkin 2002; Kimm et al., 2002; Sulemana, Smolensky, & Lai, 2006). It is not known whether these potential moderators are related to change in physical activity independently of social-cognitive variables. For example, girls having less social capital or different cultural values about body weight and physical activity might have lower self-efficacy while perceiving more barriers and less social support. Or, they might be less likely to use self-management strategies such as goal setting. We previously found that physical activity and self-efficacy for overcoming barriers to physical activity were each higher among White girls than Black or Hispanic/Latino girls in the 8th grade (Dishman, Saunders, et al., 2009). While declines in those girls’ physical activity and their perceptions of social support during high school were related to each other regardless of race, self-efficacy did not change and was not directly related to the physical activity change. Rather, self-efficacy moderated the activity–social support relation. The stability of these variables and their relations during middle school are not known. Here, we report a longitudinal, observational study of relations of objectively measured physical activity with social-cognitive variables derived from self-efficacy theory among an ethnically diverse cohort of girls who were participants in the control and intervention arms of the Trial of Activity for Adolescent Girls (TAAG) during their 6th through 8th grade school years. The design and primary outcomes of the intervention have been described elsewhere (Stevens et al., 2005; Webber et al., 2008). Although the intervention did not result in an increase in the primary outcome measures among the study cohort, secondary aims of TAAG were to examine whether variations in physical activity would be related to social support of physical activity, self-efficacy for overcoming barriers to physical activity, the use of self-management strategies, and perceived barriers to physical activity (Elder et al., 2007). Our primary goal here was to test hypothesized direct and indirect (i.e., mediated by self-management and perceived barriers) relations of barriers of self-efficacy and perceived social support with physical activity, consistent with self-efficacy theory and previous cross-sectional findings in other 6th and 8th grade girls (Dishman et al., 2005); see Figure 1. We also tested whether barriers self-efficacy moderated the relations of perceived social support with perceived barriers and self-management strategies, and we examined whether the relations were similar in White, Black, and Hispanic/Latino girls. Secondary goals were to determine the stability of the variables between the 6th and 8th grade assessments and whether initial status and change in the variables were related to race/ethnicity. Novel features of the TAAG study were the opportunities to examine putative mediators of objectively measured physical activity in a longitudinal, multi-ethnic cohort of girls from six regions of the United States. Figure 1. Results of the hypothesized model. Variables at the 8th grade were adjusted for initial status in the 6th grade, relations among the variables in the 6th grade, and the change between the 6th and 8th grade. Dotted lines indicate paths that were tested ...