Family support for physical activity in girls from 8th to 12th grade in South Carolina
Introduction
The prevalence of obesity in children and adolescents is increasing in the United States (Jolliffe, 2004, Ogden et al., 1999) and in other countries (Frye and Heinrich, 2003, Booth et al., 2003, Reilly and Dorosty, 1999). In girls, a decline in physical activity (PA) in adolescence may contribute to this increase. Kimm et al. (2002) reported the decline in PA that occurred in girls followed from age 9 or 10 to age 18 or 19 in the NHLBI Growth and Health Study. Over the 10-year period of the study median PA scores declined 64% in White girls and 100% in Black girls. Further, each decline in activity of 10 metabolic equivalent (MET)-times per week was associated with an increase in BMI of 0.14 kg/m2 (Kimm et al., 2005).
Family support has been a consistently reported correlate of PA in adolescents (Kohl and Hobbs, 1998; Sallis et al., 2001). Parents and siblings may support PA by providing transportation and encouragement (Hoefer et al., 2001, Biddle and Goudas, 2002, McGuire et al., 2002, Felton et al., 2002), as well as by participating in PA with adolescents (Felton et al., 2002). Family support was a strong predictor of team sport participation and a modest predictor of moderate-to-vigorous PA in 8th grade girls in one study (Saunders et al., 2004), and a significant predictor of vigorous PA outside of school in 9th and 11th grade girls in another study (Zakarian et al., 1994). But, studies have also shown a decline in perceived social support in girls followed from 5th or 6th grade to 6th or 7th grade (Garcia et al., 1998), and little is known about changes in perceptions of family support during the transition to high school.
Although family support has been shown to be associated with PA in cross-sectional studies (Saunders et al., 2004, Zakarian et al., 1994), little is known about changes in the perception of family support over time and its effects on physical activity over time in girls. As pointed out in a recent review, longitudinal studies can help to better understand the relationship between parental support and child PA (Gustafson and Rhodes, 2006). In addition little is known about the association of family support with psychosocial factors that have been shown to influence PA in girls, such as perceived behavioral control (Motl et al., 2002, Motl et al., 2005), self-efficacy (Motl et al., 2002), attitudes (Dishman et al., 2004) and equipment accessibility (Motl et al., 2005). Therefore, the purpose of this study was to use growth curve analyses to understand how the influence of demographic variables, self-efficacy, perceived behavioral control, attitudes, availability of equipment, and perceived family support affect changes in PA over time in adolescent girls. PA and other variables were measured at 8th, 9th and 12th grades.
Section snippets
Participants
Participants were adolescent girls who completed a measurement protocol during 8th, 9th and 12th grades (1998–2003), as part of a large PA intervention study (Pate et al., 2005) which was based on social cognitive theory (Bandura, 1986). Overall, 2744 girls ([mean (SD)]: 13.6 years (0.6 years); 49.0% Black) completed the measurement protocol in 8th grade (Table 1). The same girls were invited to complete the protocol again in 9th and 12th grades. The study reported in this paper is based on the
Results
About 60% of the 421 girls followed from 8th to 12th grade had a parent with greater than a high school education, 44% were from control schools and 58% were Black. Means (SE) for the study variables are shown in Table 3 for 8th, 9th, and 12th grades. Total METs and perceived family support, self-efficacy, reported sport equipment, and BMI percentile declined, while BMI increased, from 8th to 12th grade. There were significant correlations between family support and the other study variables,
Discussion
This study was unique because longitudinal data from 8th through 12th grades were used to study the relationship between perceived parental support and decline in PA in girls. A unit change in family support was associated with an estimated 1/3 of a standard deviation change in PA (total METs). Perceived family support was independently related to total METs. Girls with higher values of perceived family support at the 8th grade measure had higher total MET scores at 12th grade regardless of
Acknowledgments
This study was funded by a grant from the National Institutes of Health (RO1HL057775). The authors thank LaVerne Shuler for capably administering the study and Gaye Groover Christmus, MPH for editing the manuscript.
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