The association of self-efficacy and parent social support on physical activity in male and female adolescents.

The lack of sufficient physical activity among youth is a major health concern nationally (Miller & Silverstein, 2007). Only 8% of adolescents are meeting the national guidelines of engaging in 60 minutes a day of moderate-to-vigorous physical activity (PA; Troiano et al., 2008). Youth of low socioeconomic status (SES) and African-Americans in particular, engage in less physical activity than their non-minority counterparts (Wilson et al., 2011) and there is a scarce amount of studies that have tested mediation to understand PA in these populations (Wilson & Kitzman-Ulrich, 2008). Previous research also shows that girls engage in fewer minutes of PA daily than boys (Trost et al., 2002). Interventions to increase PA are therefore crucial, and continuing to research possible underlying mechanisms could advance the field. Mediation models may help investigators specify mechanisms that are effective in the delivery of PA interventions (Wilson, 2009). Social Cognitive Theory (Bandura, 1989) suggests that strong social support networks increase an individual’s self-efficacy (SE) to overcome barriers to being physically active. Parent influence especially constitutes a major source of social support throughout a child’s lifespan. According to socialization theory, parent influence has an effect on a youth’s competency to engage in a specific behavior such as increasing PA (Bois, Sarrazin, Brustad, Trouilloud, & Cury, 2005; Eccles & Harold, 1991). Empirical research (van Suijs, McMinn, & Griffin, 2007) also supports the important role of parents and family on increasing PA in youth. In an intervention for mothers with young children that emphasized social support and overcoming barriers to PA, SE mediated PA behavior change (Miller, Trost, & Brown, 2002). An intervention emphasizing parent support also mediated the relationship on adolescent PA through SE (Haerens et al., 2008). Taken together, these studies support investigating further how parent socialization of adolescent PA may be mediated through SE. Parents can provide emotional social support for engaging in PA through providing encouragement and they can provide instrumental social support through offering tangible support such as transportation to PA events (Barrera, 1986). Previous research has shown that parent emotional and instrumental social support are positively associated with PA in youth (Duncan, Duncan, & Strycker, 2005; Heitzler, Martin, Duke, & Huhman, 2006). In a recent review by Beets and colleagues (2010) parent social support was also shown to be consistently positively associated with adolescent PA. However, further research is needed to understand what mechanisms may explain how parent social support influences PA in youth specifically. SE for overcoming barriers to PA has been shown to be a significant mediator between PA interventions and adolescent PA engagement (Haerens et al., 2008). Past cross-sectional (Motl, Dishman, Saunders, Dowda, & Pate, 2007) and longitudinal studies (Shields et al., 2008) support the role of SE as a mediator between family social influences (including support) and adolescent PA, though some researchers have shown inconsistent effects (Wu & Pender, 2002). Given the inconsistent evidence further research is needed to expand understanding of mechanisms, especially among underserved youth who are at high risk for inactivity. Few studies have examined sex differences in understanding the role of SE and different types of social support in relation to PA. Wu and colleagues (2003) examined SE as a mediator between social influences (parent and peer emotional support, modeling, norms) and adolescent PA, and found the pathway between peer social influences and adolescent SE to be stronger for boys than girls, whereas the pathway between SE and PA was similar for boys and girls. Parent social influences were not related to PA directly or indirectly through SE. Other research shows that SE relates stronger to boys’ PA than girls’ PA (DiLorenzo, Stucky-Ropp, Vander Wal, & Gotham, 1998) and that girls report more barriers to being physically active than boys (Cardon et al., 2005). Given these sex difference in SE and PA, it is important to better understand how boys and girls may differ in the types of social support that may influence their daily regulation and self-efficacy for engaging in PA. Boys and girls also may demonstrate different preferences for certain types of social support. For example, Belle (1987) reports that social relationships of females are more dyadic, exclusive, intimate and self-disclosing than those of males. This preference for verbal discussion and support may be indicative of emotional social support having a more important role for girls than boys, due to the differences in socialization of sex roles. Choquet and colleagues (2008) found that a lack of general parent emotional support was associated with a high risk for drug use among girls but not boys. Another study demonstrated that under stress, boys showed less physiological arousal with instrumental social support compared to emotional social support, but not for girls (Wilson, Kliewer, Bayer et al, 1999). This suggests that boys tend to react more negatively to emotional social support than girls. Findings from past studies have been mixed regarding which type of social support is more strongly related to adolescent PA in boys as compared to girls. One study showed that family emotional social support was positively associated with PA for boys, but not for girls (McGuire et al., 2002). This contradicts a study among adolescent females, showing that family encouragement was significantly related to girls’ PA (Springer et al., 2006). Clearly, more studies are needed that investigate how specific types of social support may influence PA differentially in boys versus girls. Results from another study demonstrated that mothers’ logistical support (e.g. transportation) and fathers’ explicit modeling were positively associated with girls’ PA (Davison, Cutting, & Birch, 2003). Other investigators found that parent transportation to sports activities was significantly related to girls’ and boys’ PA, but this relationship was stronger in girls (Hoefer, McKenzie, Sallis, Marshall, & Conway, 2001). Taken together these studies suggest that there may be sex differences in the relation between parent social support and adolescent PA, though there are inconsistencies. Examining the role of indirect effects may help clarify these discrepancies. The present study expands on past research by investigating the unique contribution of instrumental and emotional social support on adolescent PA. In particular, this study examined boys and girls separately to clarify potential differences in direct and indirect relationships between social support, SE and adolescent PA. A recent review (Gustafson & Rhodes, 2006) noted that few previous studies have used objective measures of PA, therefore the present study’s use of accelerometry is a major strength. Furthermore, little is known about minority populations and PA (Van der Host, Paw, Twisk, & Van Mechelen, 2007). De Bourdeaudhuij and Sallis (2002) suggested that more studies are necessary to gain a consensus on the role that different types of social support have on promoting PA among minority groups. Based on previous research, it was hypothesized that adolescent SE for overcoming barriers would account for the relationship between parent social support (emotional and instrumental) and adolescent PA across boys and girls. In addition, given that boys and girls are socialized to seek out and respond differentially to emotional and instrumental support, it was hypothesized that emotional social support would have stronger direct and indirect effects on PA for girls than boys and that instrumental social support would have stronger direct and indirect effects on PA for boys than girls. Furthermore, given previous empirical findings it was hypothesized that the relationship between SE and PA would be stronger in boys than girls.