© 2014 American Psychological Association 0893-3200/15/$ 12.00 http://dx.doi.org/10.1037/fam0000049
Journal of Family Psychology 2015, Vol. 29, No. 1, 100-107
Developmental Patterns and Parental Correlates of Youth Leisure-Time Physical Activity Chun Bun Lam
Susan M. McHale
The Hong Kong Institute of Education
The Pennsylvania State University
This study examined the developmental patterns and parental correlates of youth leisure-time physical activity from middle childhood through adolescence. On 5 occasions across 7 years, fathers, mothers, and children who were first- and second born from 201 European American, working- and middle-class families participated in home and multiple nightly phone interviews. Multilevel modeling revealed that, controlling for family socioeconomic status, neighborhood characteristics, and youth overweight status and physical health, leisure-time physical activity increased during middle childhood and declined across adolescence, and the decline was more pronounced for girls than for boys. Moreover, controlling for time-varying, parental work hours and youth interest in sports and outdoor activities, on occasions when fathers and mothers spent proportionally more time on these activities with youth than usual, youth also spent more total time on these activities than usual. The within-person association between mother-youth joint involvement and youth’s total involvement in leisure-time physical activity reached statistical significance at the transition to adolescence, and became stronger over time. Findings highlight the importance of maintaining adolescents’, especially girls’, physical activity levels and targeting both fathers’ and mothers’ involvement to promote youth’s physical activity. Keywords: adolescence, longitudinal changes, parental involvement, physical activity, within-person associations
Previous research has highlighted physical activity (PA) as an effective means to prevent and reduce overweight and obesity (Penedo & Dahn, 2005; Warburton, Nicol, & Bredin, 2006). To promote youth’s PA, however, requires understanding its devel opmental patterns as well as identifying factors that support youth’s continued engagement (Brownson, Boehmer, & Luke, 2005; van Sluijs, McMinn, & Griffin, 2007). Although evidence suggests that middle childhood and adolescence are critical periods when dramatic changes in PA occur (Dumith, Gigante, Domingues, & Kohl, 2011), and that parents are important social ization agents who shape youth’s PA involvement (Simpkins, Fredricks, & Eccles, 2012), significant gaps in our knowledge remain. First, previous studies on changes in youth PA have mostly relied on questionnaires, and their results may be subject to memory and response biases (Adams et al., 2005; Ferrari, Friedenreich, & Matthews, 2007). Furthermore, prior investigations of parental influences on youth PA have focused on between-person associations, an approach that constrains the causal inferences that can be drawn, because alternative explanations involving stable selection factors cannot be ruled out (Bauman et al., 2012; Curran & Bauer, 2011). Finally, few researchers have used a developmen tal framework to study parental influences on youth PA, and discrepancies exist as to whether and how parental influences may vary as youth mature over time (Beets, Cardinal, & Alderman, 2010; Edwardson & Gorely, 2010; Pugliese & Tinsley, 2007). Accordingly, using multiple-wave, phone-diary data and testing paternal and maternal involvement as time-varying covariates, this study was designed to address two goals: (a) to chart how leisure time PA changed from middle childhood through adolescence and (b) to test whether—at a within-person level, using each individual
Rates of childhood and adolescent overweight and obesity are rising around the world (World Health Organization, 2014). In the United States, for example, the percentage of obese children has more than doubled over the past 30 years, growing from 7% in 1980% to 18% in 2012, and the percentage of obese adolescents has quadrupled in the same period of time, growing from 5% in 1980% to 21% in 2012 (Ogden, Carroll, Kit, & Regal, 2014). Individuals who are overweight or obese have a higher risk for a wide range of medical conditions, including heart disease, diabe tes, cancers, and stroke (Centers for Disease Control & Prevention, 2014). Youth overweight and obesity, therefore, are becoming an increasingly important issue for parents, practitioners, and policy makers.
This article was published Online First December 8, 2014. Chun Bun Lam, Department of Early Childhood Education, The Hong Kong Institute of Education; Susan M. McHale, Department of Human Development and Family Studies, The Pennsylvania State University. Portions of this article were presented at the Society for Research on Child Development Biennial Meeting, Montreal, Canada, April 2011. The authors wish to express gratitude to the undergraduate and graduate assis tants, staff, and faculty collaborators for their help in conducting this study, and to the participating families for their time and cooperation. This work was funded by grants from the United States Department of Health and Human Services, National Institutes of Health, National Institute of Child Health and Human Development (R01-HD32336 and R01-HD29409) to Ann C. Crouter and Susan M. McHale, coprincipal investigators. Correspondence concerning this article should be addressed to Chun Bun Lam, Department of Early Childhood Education, The Hong Kong Institute of Education, 10 Lo Ping Road, Tai Po, New Territories, Hong Kong. E-mail: [email protected]
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as his or her own control—the proportions of time that fathers and mothers spent on leisure-time PA with youth were linked to youth’s total time spent on leisure-time PA, and whether these linkages were moderated by youth’s age.
Developmental Patterns of Leisure-Time PA Dumith et al. (2011) conducted a pooled analysis of 26 studies on longitudinal changes in PA across adolescence, and found that PA declined linearly over time. A consistent gender difference in the rate of change was not evident, however, possibly due to the use of different measures across studies. Indeed, most of these 26 studies used questionnaires to measure PA, and methodological research shows that, compared to physiological sensors and daily diaries, questionnaires are particularly susceptible to memory dis tortion (Ferrari, Friedenreich, & Matthews, 2007) and social de sirability biases (Adams et al., 2005). The results of the few longitudinal studies that used physiological sensors or daily diaries to measure adolescent PA were yet mixed, with some indicating that PA did not change over time (Garcia, Pender, Antonakos, & Ronis, 1998; Morgan, Graser, & Pangrazi, 2008), some suggesting that it declined for both boys and girls (Nader, Bradley, Houts, McRitchie, & O’Brien, 2008; Pate et al., 2009), and some docu menting that it declined for boys, but not for girls (Raustorp, Svenson, & Perlinger, 2007). Fewer studies have used nonques tionnaire methods to examine changes in PA across middle child hood, and their results are equally inconclusive. There is evidence, for example, that PA remains stable over time (Telford, Cunning ham, & Telford, 2009), that PA decreases for both boys and girls (Basterfield et al., 2011; Cleland et al., 2008), and that PA in creases for boys, but not for girls (Janz et al., 2009). In the face of these inconsistent findings, theories of youth time use (Larson & Verma, 1999) posit that active leisure should follow a curvilinear pattern of change, increasing during middle childhood (when play is thought to be the “work” of youth) and decreasing across adolescence (when youth spend more time on other competing activities, such as homework, paid work, and socializing with peers). Gender theories (Cockburn & Clarke, 2002; Galambos, Berenbaum, & McHale, 2009) further predict that, because many qualities emphasized in sport, such as strength, competitiveness, and assertiveness, run contrary to the ideal of femininity, girls’ declines in PA may reflect intensified social pressures for youth to conform to traditional gender roles during adolescence. The first goal of this study was to examine the pattern of change in leisure-time PA using five waves of longitudinal data collected over 7 years via multiple nightly phone interviews. We focused on leisure-time PA, because in industrialized countries where manual labor and self-powered transportation are minimal, voluntary in volvement in PA represents a ripe target for intervention (Brownson et al., 2005; van Sluijs et al., 2007). Based on some previous findings (Dumith et al., 2011; Janz et al., 2009) and theories of time use and gender development (Cockburn & Clarke, 2002; Galambos et al., 2009; Larson & Verma, 1999), we expected that leisure-time PA would increase during middle childhood and de cline across adolescence, and that the decline would be more pronounced for girls than for boys. We controlled for family socioeconomic status, neighborhood characteristics, and youth overweight status and physical health, because these factors may have a direct impact on youth levels of PA. Specifically, they may
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reflect financial (socioeconomically disadvantaged families may not be able to afford youth involvement in certain PA), environ mental (youth may find it less convenient to get to the venues for PA by themselves in rural/suburban communities than in small cities/towns), and individual (overweight or obese and physically unhealthy youth may find PA more demanding and thus less attractive as a leisure activity) constraints on youth PA (Bauman et al., 2012; Ding, Sallis, Kerr, Lee, & Rosenberg, 2011).
Parental Correlates of Leisure-Time PA According to Eccles’s (Fredricks & Eccles, 2004; Simpkins et al., 2012) parental socialization model, parents influence their offspring’s PA through modeling (i.e., being physically active themselves), encouragement and reinforcement (e.g., praising their offspring for being physically active), provision of opportunities (e.g., enrolling their offspring in sports and outdoor activities), and joint involvement (e.g., engaging in sports and outdoor activities with their offspring). Studies in support of this view have amassed, and their findings indicate that parents’ own involvement in PA, as well as their socialization efforts, are linked to their offspring’s involvement in PA (Beets et al., 2010; Edwardson & Gorely, 2010; Pugliese & Tinsley, 2007). Nearly all of these studies, however, have focused on between-person associations—why some youth are more involved in PA than others (Bauman et al., 2012) - which can easily be confounded with stable selection factors, ranging from parent-youth shared genetic dispositions to their shared phys ical environment, that are not controlled for in the analyses (Curran & Bauer, 2011). A focus on within-person associations extends prior research, because it examines whether within-person varia tion (i.e., deviations from an individual’s own norm) in parental influences is linked to within-person variation in youth PA. By treating each individual as his or her own control, within-person associations rule out stable, third variables as alternative explana tions, and thus provide for stronger inferences (Raudenbush & Bryk, 2002). Fredricks and Eccles (2004) advocated using a developmental framework to study parental influences on youth PA. From their perspective, the magnitude of parental influences may differ de pending on youth developmental stage. Based on the number of significant associations among prior studies, qualitative reviews (Beets et al., 2010; Edwardson & Gorely, 2010) suggested that the impact of parent-youth joint involvement waned across adoles cence. Using quantitative methods of data synthesis, however, a meta-analytic review (Pugliese & Tinsley, 2007) showed that the association between parental modeling/parent-youth joint involve ment and youth PA was significantly stronger in studies conducted with children (< age 10) and middle and older adolescents (> age 12) than those conducted with young adolescents (age 10-12). These findings are consistent with theories of parent-youth rela tionships (Laursen & Collins, 2009), which hold that— contrary to a popular belief that adolescence invariably entails willful disobe dience toward parents and distancing from the family—increased parent-youth conflict is often limited to early adolescence, and such temporary perturbations have little impact on the subsequent quality of parent-youth relationships. The second goal of this study was to examine the within-person associations between the proportions of father- and mother-youth joint involvement in leisure-time PA and youth’s total involvement
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in leisure-time PA, and the role of youth’s age in these associa tions. We focused on parent-youth joint involvement as a potential influence highlighted in Eccles’s socialization model (Fredricks & Eccles, 2004; Simpkins et al., 2012), because it has been less often studied compared to other forms of parental influences (Beets et al., 2010; Edwardson & Gorely, 2010; Pugliese & Tinsley, 2007). Moreover, relative to questionnaires and physiological sensors, daily diaries are particularly effective for assessing the social contexts of time use (Kohl, Fulton, & Caspersen, 2000). In this study, parents were counted as involved in their offspring’s PA when they engaged in such activities with their offspring as play mates or coaches (Fredricks & Eccles, 2004; Simpkins et al., 2012). Further, given that the involvement of spectators is an integral part of many sports (Beets et al., 2010) and that parents often monitor/supervise their offspring’s activities in outdoor places out of safety concerns (Ding et al., 2011), parents were also counted as involved when they were physically present, and watching their offspring play or practice and not doing anything else at the same time: Even when they are not actively involved, parents’ presence may be seen as an expression of interest in their offspring’s activities. Youth may also experience these activities as shared when parents cheer from the sidelines and congratulate or commiserate about what they have observed during the course of a particular activity. On the basis on some prior findings (Pugliese & Tinsley, 2007) and theories of parental socialization and parentyouth relationships (Fredricks & Eccles, 2004; Laursen & Collins, 2009; Simpkins et al., 2012), we expected that the proportions of both father- and mother-youth joint involvement would be posi tively linked to youth’s total involvement, but that the magnitude of such associations would be temporarily reduced in early ado lescence. We included both paternal and maternal involvement in the same analytic model, because we were interested in examining the independent contribution of each parent (Pleck, 2010). Albeit with a control for stable individual differences, withinperson variation may still be affected by other time-varying factors (Raudenbush & Bryk, 2002). For example, on occasions when parents are more heavily engaged in paid work than usual, they may also spend less time with their offspring (Milkie, Mattingly, Nomaguchi, Bianchi, & Robinson, 2004) and be less able to help their offspring maintain active lifestyles than usual (Phipps, Leth bridge, & Burton, 2006). Moreover, on occasions when youth are more interested in PA than usual, they may also participate more in these activities and motivate their parents to become more active with them than usual— a child effects interpretation (Fredricks & Eccles, 2004). Thus, we included parental paid work hours and youth interest in PA as time-varying controls to further eliminate two important alternative explanations of the within-person asso ciations linking the proportions of father- and mother-youth joint involvement to youth’s total involvement in leisure-time PA.
Method Participants Data were drawn from the 1st, 2nd, 3rd, 6th, and 7th years (referred to as Times 1 through 5 hereafter) of a longitudinal study on family relationships, the years in which the data of interest were collected. Recruitment letters were sent home from all schools within 16 school districts of a northeastern state to families with
4th and 5th grade students. Because of the goal of the larger study, families were eligible if the parents were married, both parents were employed, the firstborn was in the 4th or 5th grade, and the second bom was 1 -4 years younger than the firstborn. The number of families that fulfilled our recruitment criteria but failed to respond was unknown, but over 90% of families who returned postcards participated in the study. Two families that dropped out after Time 1 were deleted, and the analyses were based on the remaining 201 families. Attrition was low: At Time 5, 95% of parents and youth still remained in the study. Reflecting the ethnic composition of the state where the study was conducted (85% European American; U.S. Census Bureau, 2000), the sample included almost exclusively biologically related, European American families (there were one stepfather and two youth adopted from Asia) living in small cities, towns, and rural and suburban communities. Moreover, reflecting the educational (>80% of adults completed high school) and financial (median income = $55,714 for married-couple families) backgrounds of the targeted population (U.S. Census Bureau, 2000), at Time 1, the average educational level was 14.57 years (SD = 2.15) for mothers and 14.67 years (SD = 2.43) for fathers (where a score of 12 indicated a high school graduate) and the median family income of the sample was $55,000 (SD = 28,613). At Time 1, the average age was 10.87 years (SD = 0.54) for firstborns and 8.26 years (SD = 0.93) for second boms. Because of the age differences between siblings and multiple waves of data collection, between 40 and 270 youth provided data at each chronological age from 7 (i.e., 6.5—7.5) to 18 (i.e., 17.5-18.5) years, allowing us to chart the development of leisure-time PA from middle childhood through adolescence. Sibling dyads were divided almost equally among the four possible gender constellations, meaning that we had roughly equal and sufficient numbers of girls (n = 203) and boys (n = 199) to test for potential gender differences.
Procedure and Measures Data were collected from fathers, mothers, and the two siblings via two methods. First, trained interviewers visited families to conduct annual home interviews. Families gave informed consent and received a monetary honorarium ($100 at Times 1 through 3; $200 at Times 4 and 5) at the beginning of the home interviews, and family members completed questionnaires independently. Sec ond, in the 2 to 3 weeks following the home interviews, trained interviewers called siblings individually to conduct seven (5 week days, 2 weekend days) nightly phone interviews. Each sibling was guided through a list of 70 activities and probed for the duration and social contexts of any activities completed outside of school. Measures. Background information collected in the home in terviews with parents at Time 1 included parents’ levels of edu cation and income, and family members’ age, gender, and ethnic ity. At Time 2, mothers also reported in the home interviews whether their neighborhoods were best characterized as small cities/towns, or rural/suburban communities. An index of family socioeconomic status was created by averaging fathers’ and moth ers’ levels of education (Hauser, 1994). The reference group (coded 0) for gender was boys and for neighborhood type was rural/suburban communities. Youth’s leisure-time PA was measured in the phone interviews at Times 1- 5. Youth reported how much time (in minutes) they
LEISURE-TIME PHYSICAL ACTIVITY spent on eight sports and outdoor activities, including sport, water activities, gymnastics, dancing, hiking and camping, biking and skating, hunting and fishing, and outdoor play. Leisure-time PA was measured as the total duration of time across the seven phone interviews. To correct for skewness, square-root transformations were used in the analyses. The proportions o f father- and motheryouth joint involvement were calculated by dividing the duration of time youth spent on sports and outdoor activities with their fathers and with their mothers, respectively, by the total duration of time youth spent on these activities. As noted, parents were counted as involved by engaging in the activities with their offspring, coach ing their offspring, or simply watching their offspring participate. Parents ’ work hours were measured in the home interviews at Times 1-5. Fathers and mothers reported how many hours they spent “at work,” “driving to and from work,” and “on work-related activities at home” in an average week. Items were summed, and higher scores indicated more work hours. Youth’s interest in PA was measured in the home interviews at Times 1-5. Youth used a scale ranging from 1 (not at all inter ested) to 4 (very interested) to rate their interest in seven sports and outdoor activities, including sport, water activities, gymnastics, dancing, hiking and camping, biking and skating, and hunting and fishing. Items were summed, and higher scores indicated higher interest. Youth's height and weight were reported in the home interviews by mothers at Times 2-4. Youth’s height and weight were first converted into body mass indices (BMIs), which were then con verted into binary variables that indicated whether youth were overweight, or ranked above the 85th percentiles of the age and gender specific BMI estimates issued by Centers for Disease Control and Prevention (2000). Youth’s overweight status showed moderate to strong cross-time stability (average rs = .60 for firstborns and .34 for second boms), and thus a general binary index was created to indicate whether youth were overweight at any of the three time points. The reference group was nonover weight youth. Youth’s physical health was measured in the home interviews with mothers at Times 2-4. Mothers used a scale ranging from 1 (very poor) to 5 (very good) to rate their firstborns’ and second borns’ physical health. Youth’s physical health showed moderate cross-time stability (average rs = .46 for firstborns and .45 for second boms), and thus a general index was created by averaging the ratings across the three time points. Analytic Strategy. Given the clustered nature of our data (i.e., time within individual, individuals within family), we used multi level modeling to take into account the correlations between the error residuals (Raudenbush & Bryk, 2002). Multilevel modeling also accommodates missing data and effectively reduces biases in parameter estimation (Schafer & Graham, 2002), although only about 5% of our data were missing. A series of three-level models was estimated using the MIXED procedure in SAS Version 9.1 (SAS Institute Inc., Cary, NC). At Level 1 (within-individual), we included time-varying variables. We used youth age as the metric of time, and included the linear and quadratic terms to describe the development of leisure-time PA. Youth age was centered at 13 years (i.e., the approximate mean age across youth and time points). We also included the time-varying covariates (i.e., the proportions of father- and mother-youth joint involvement in leisure-time PA) and the time-varying controls (i.e., fathers’ and
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mothers’ work hours and youth’s interest in PA) at this level. To separate within- from between-person variation, each time-varying covariate was indicated by two variables: At Level 1, the covariate was indicated by a time-varying, group-mean centered (at each individual’s own cross-time average) variable; at Level 2 (between-individual), the covariate was indicated by the grandmean centered (at the overall sample mean), cross-time average. Because the cross-time average of the covariate captured all the between-person variation, the Level 1 version of the covariate was limited to explaining within-person variation beyond stable inter individual differences. The time-varying controls were grandmean centered without including the cross-time averages, how ever, as the within- versus between-person effects of these factors were not of substantive interest in this study. At Level 2, we also included other time-invariant variables that were different for the two siblings, including youth’s gender, overweight status, and physical health. Physical health was grand-mean centered. Level 3 (between-family) included time-invariant variables that were the same for siblings from the same family, including family socio economic status and neighborhood type. Family socioeconomic status was grand-mean centered. We conducted the analyses in three steps: First, we tested a general change model (Model 1) to examine the overall pattern of change in leisure-time PA from middle childhood through adoles cence. Second, we tested a gender-specific change model (Model 2) to examine whether the pattern of change in leisure-time PA varied by youth gender, controlling for family socioeconomic status, neighborhood type, and youth overweight status and phys ical health, which may have a direct impact on the levels of youth PA (Bauman et al., 2012; Ding et al., 2011). Third, we tested a parental influence model (Model 3) to examine whether withinperson variation in the proportions of father- and mother-youth joint involvement in leisure-time PA was linked to within-person variation in youth’s total involvement in leisure-time PA, control ling for time-varying, paternal and maternal work hours and youth interest in PA, which may confound the linkages between parental involvement and youth PA (Milkie et al., 2004; Phipps et al., 2006). We also included the interactions between parent-youth joint involvement and youth age to test whether the magnitude of parental influences varied by youth’s age. For all analyses, we only included significant interactions in the final models, because re taining nonsignificant interactions would increase standard errors (Aiken & West, 1991).
Results Multilevel Models Coefficients for fixed effects can be found in Table 1. Model 1 revealed a significant quadratic effect of youth age. Overall, leisure-time PA increased steadily from age 7 to about age 12 and then declined. Model 2 revealed a significant main effect of gender, indicating that, at age 13 (the age at which our age variable was centered), the difference in leisure-time PA between boys (M = 411.42; SD = 321.73) and girls (M = 343.74; SD = 273.16) was significant. A significant Gender X Linear Time interaction further indicated that, at age 13, the negative linear effect was stronger for girls, y = -0 .6 2 , t = -6 .0 0 , p < .01, than for boys, y = —0.32, t = —3.03, p < .01. As Figure 1 shows, boys were
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Table 1 Multilevel Models o f Youth Leisure-Time Physical Activity Model 2
Model 1
Model 3
Variable
7
t ratio
7
t ratio
7
t ratio
Intercept Linear time Quadratic time Gender (0 = boys) Gender X Linear Time Family socioeconomic status Neighborhood type (0 = rural/suburban communities) Youth’s overweight status (0 = non-overweight youth) Youth’s physical health WP fathers’ involvement WP mothers’ involvement WP mothers’ involvement X Linear Time BP fathers’ involvement BP mothers’ involvement TV fathers’ work hours TV mothers’ work hours TV youth’s interest
17.67 -0.48 -0.17
44.18” -5 .6 4 ” -8 .5 6 ”
19.46 -0.32 -0.16 -2.79 -0.30 -0.11 0.33 -0.72 0.90
26.15" -3 .0 3 ” -8 .4 5 “ -5 .7 6 “ -2.35* -0.61 0.46 -1.32 1.80
19.20 0.11 -0.14 -2.56 -0.38 -0.05 0.16 -0.38 1.14 2.67 4.72 0.55 7.78 -0.44 0.03 -0.02 0.41
27.62” 1.01 -7 .1 5 “ -5.24** -3.11“ -0.30 0.25 -0.77 2.51* 3.49“ 5.55** 2.01* 4.24** -0.20 1.87 -1.74 7.32”
Note. BP = between-person; WP = within-person; TV = time-varying. Parents’ involvement was calculated by dividing the duration of time youth spent on physical activity with their parents by the total duration of time youth spent on physical activity. *p < .05. “ > < . 0 1 .
generally more involved in leisure-time PA than girls, and girls’ declines in leisure-time PA were more pronounced than boys’. The interaction between Gender X Quadratic Time was not significant, and thus was dropped from the model. Model 3 revealed a signif icant within-person effect of father-youth joint involvement, indi cating that, on occasions when fathers spent proportionally more time with youth in leisure-time PA than usual, youth also spent more total time on these activities than usual. A significant WithinPerson Mother-Youth Joint Involvement X Linear Time interac tion, together with follow-up tests, indicated that a significant within-person association between mother-youth joint involve ment and youth’s total involvement in leisure-time PA emerged at about age 9, y = 2.54, SE = 1.10,/? < .05, and became stronger over time. In other words, starting around age 9, on occasions when mothers spent proportionally more time with youth in leisure-time PA than usual, youth also spent more total time on these activities than usual. Other interactions involving youth’s
...e ... boys (observed) —* — boys (predicted) girls (observed) — • — girls (predicted)
7
8
9 10 11 12 13 14 15 16 17 18 Age (years)
Figure 1. Predicted (solid lines) and observed (dotted lines) means of youth leisure-time physical activity by gender.
age were not significant, and thus were dropped from the model. Exploratory analyses testing for interactions between parent-youth joint involvement and youth gender revealed no differences in parental influences on boys’ versus girls’ leisure time PA.
Discussion Childhood and adolescent overweight and obesity are on the rise in many countries (World Health Organization, 2014), including in the U.S. (Centers for Disease Control & Prevention, 2014; Ogden et al., 2014). Because PA is an effective means to preempt and reduce overweight and obesity, it is important to understand how PA involvement changes across childhood and adolescence and to identify factors that support youth’s continued involvement (Brownson et al., 2005; Penedo & Dahn, 2005; van Sluijs et al., 2007; Warburton et al., 2006). Using multiple-wave, phone-diary data and testing paternal and maternal involvement as timevarying covariates, this study tested the developmental patterns and parental correlates of youth leisure-time PA. Our results indicated that leisure-time PA increased during middle child hood and declined across adolescence, and that the decline was more pronounced for girls than for boys, highlighting the im portance of maintaining youth’s, especially girls’, PA at the transition to adolescence. Moreover, on a within-person level, the proportions of father- and mother-youth joint involvement were positively and independently linked to youth’s total in volvement in leisure-time PA, a finding that points to the importance of promoting both paternal and maternal involve ment in youth PA. Below, we elaborate on these conclusions and, taking into account the limitations of our study, discuss the implications of our findings for understanding youth PA as a developmental phenomenon and for parents, practitioners, and policymakers.
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Developmental Patterns of Leisure-Time PA Our study showed that changes in leisure-time PA were char acterized by a quadratic trend, increasing during middle childhood and declining across adolescence; also, the decline in adolescent PA was more pronounced for girls than for boys. These findings, though consistent with theories of youth time use and gender development (Cockbum & Clarke, 2002; Galambos et al., 2009; Larson & Verma, 1999), both support (Dumith et al., 2011; Janz et al., 2009) and contrast with (Basterfield et al., 2011; Cleland et al., 2008; Garcia et al., 1998; Morgan et al., 2008; Telford et al., 2009) those of previous studies. Due to differences in sample sizes, measures of PA, and data analytic strategies (especially how developmental time was operationalized), direct comparisons be tween previous studies and ours are difficult. Long-term, longitu dinal investigations that use multiple methods (i.e., physiological sensors, daily diaries, and questionnaires) to measure youth PA are needed to reconcile accumulated findings. However, given that most prior research (Dumith et al., 2011), as well as our work, documented a decline in adolescent PA, programs designed to maintain youth’s earlier levels of PA at the transition to adolescence should be given a high priority. In ado lescence, many youth activities move toward specialization and require increasingly more expertise, as tryouts, auditions, and other forms of adult screening set limits on who can be involved (WieseBjomstal, LaVoi, & Omli, 2009). At the same time, a growing orientation to peer relationships may mean that youth will become less inclined to spend time on activities that do not include their circles of friends (Larson & Verma, 1999). Programs that involve the peer group in more informal kinds of leisure activities (e.g., Frisbee, group workouts) may be useful for maintaining adoles cents’ levels of PA. Such efforts may be especially important for girls, who showed lower levels of and more pronounced declines in leisure-time PA compared to boys in our study. It is worth noting that these gender differences remained significant even when time-varying, youth interest in PA was included in the model (Model 3), suggesting that they were not attributable to girls being less interested in PA than boys. An important direction for future research is to examine how gender socialization processes, such as social expectations for adolescent girls to conform to the ideal of femininity, may limit their opportunities for PA participation (Cockbum & Clarke, 2002; Galambos et al., 2009).
Parental Correlates of Leisure-Time PA Our results were consistent with theories of parental socializa tion (Fredricks & Eccles, 2004; Simpkins et al., 2012) and findings pertaining to more commonly studied between-person associations (Beets et al., 2010; Edwardson & Gorely, 2010; Pugliese & Tin sley, 2007). Controlling for stable individual differences and timevarying, parental work hours and youth interest in PA, we found that, on occasions when fathers and mothers spent proportionally more time on PA with youth than usual, youth also spent more total time on these activities than usual. By considering multiple alternative explanations, including stable selection factors (Raudenbush & Bryk, 2002) and certain time-varying, contextual (Milkie et al., 2004; Phipps et al., 2006) and dispositional (Fredricks & Eccles, 2004) influences, we were able to make stronger inferences about the relation between parent-youth joint involvement and youth leisure-time PA than prior research. By
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distinguishing within- from between-person variation, we also avoided misattributing an aggregate relation to the level of the individual and reduced the risk of the ecological fallacy (Curran & Bauer, 2011). Contrary to our expectations, the magnitude of the withinperson association between the proportion of parent-youth joint involvement and youth’s total involvement in leisure-time PA did not show a temporary decline in early adolescence: The impact of paternal involvement remained consistent from middle childhood through adolescence, and the impact of maternal involvement reached statistical significance at the transition to adolescence and became stronger over time. Although parental influences on youth PA may change over time (Fredricks & Eccles, 2004), such changes are likely to be domain-specific and dependent on partic ular mechanisms of parental influences (Laursen & Collins, 2009). In fact, in Pugliese and Tinsley’s (2007) meta-analysis, parental modeling and parent-youth joint involvement— aggregated into one single category due to a lack of studies—were the only forms of parental influence that showed systematic variation across age groups. One possible explanation for the discrepancy between Pugliese and Tinsley’s and our findings, therefore, is that the influences of parental modeling versus parent-youth joint involve ment change in different ways as youth mature, a topic awaiting longitudinal investigations. The difference between paternal versus maternal influences may be related to both social expectations about gender and adolescent cognitive development. As many qualities emphasized in sport, including strength, competitiveness, and assertiveness, are re garded as masculine (Cockbum & Clarke, 2002; Galambos et a l, 2009), youth active leisure provides convenient sites where men reaffirm traditional masculine roles and simultaneously meet ex pectations for paternal involvement (Pleck, 2010). In contrast, traditional feminine roles do not highlight active leisure, and thus high levels of mother-youth joint involvement in PA may be of particular salience to youth, especially during adolescence, when youth become increasingly able to incorporate social comparative information to interpret the behaviors of their parents (Fredricks & Eccles, 2004). Because few researchers have used a developmental framework to study parental influences on youth PA, our results should be treated as a first step in understanding these processes: The future challenge is to test not only whether, but also why, the influence of maternal involvement in youth PA may vary across child and adolescent development. On a practical level, however, strategies that encourage both paternal and maternal involvement may constitute an important focus of intervention. More generally, our findings also indicate that, in the face of adolescents’ increas ing interest in the world beyond the family, fathers and mothers continue to make important (Laursen & Collins, 2009), and inde pendent (Pleck, 2010), contributions to their offspring’s well being, including by shaping their offspring’s involvement in PA (Penedo & Dahn, 2005; Warburton et al., 2006).
Limitations and Conclusion This study is not without limitations. First, although our sample reflected some population characteristics of married-couple fami lies from the state where the study was conducted (U.S. Census Bureau, 2000), it was not representative of the diversity of families in the U.S. Given that how youth spend their time is dependent on
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the embedding cultural, social, and economic contexts (Larson & Verma, 1999) and that overweight and obesity are more pro nounced for more socioeconomically disadvantaged populations (Ogden et al., 2014; Warburton et al., 2006), our findings need to be replicated with samples that are more diverse with respect to culture, family structure, and parental employment. Second, our use of time-varying covariates and inclusion of multiple, timevarying controls allowed us to examine relatively unconfounded associations, but conclusions about causal relations cannot be made based on correlational data. Intervention studies that use randomized designs to manipulate parent-youth joint involvement are needed to disentangle the underlying causal paths of the associations documented here. Third, our emphasis on whether parents were physically present when their youth’s sports and outdoor activities took place (Beets et al., 2010; Ding et al., 2011; Fredricks & Eccles, 2004) directed us to focus on the most generic form of parent-youth joint involvement, which combined, for example, more active forms of involvement (e.g., parents partici pating in PA with their offspring as playmates or coaches) with more passive ones (e.g., parents watching their offspring play or practice). A more differentiated measurement approach may illu minate the potentially unique influences of different forms of parent-youth joint involvement, such as those characterized by different structural (e.g., whether the involvement is organized in a progressive way to achieve a predetermined goal) and emotional (e.g., how close youth feel toward their parents) qualities, and whether and how these may interact with parent and youth gender to shape youth PA. Finally, daily diaries are sufficiently sensitive to detect the duration and social contexts, but not the intensities, of PA (Kohl et al., 2000). Considering that PA of different intensities may have different trajectories (Dumith et al., 2011) and correlates (Edwardson & Gorely, 2010), future researchers should combine both physiological sensors and daily diaries to capture the tempo ral, contextual, and intensity dimensions of PA. Despite these limitations, our study’s use of multiple-wave, phone-diary data and focus on within-person associations provided new insights about the development of and influences on leisure time PA. From the perspectives of parents and program providers, our findings highlight the importance of maintaining adolescents’, particularly girls’, PA by promoting both fathers’ and mothers’ involvement.
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LEISURE-TIME PHYSICAL ACTIVITY Laursen, B., & Collins, W. A. (2009). Parent-youth relationships during adolescence. In R. M. Lerner & L. Steinberg, Handbook o f adolescent psychology: Vol. 2. Contextual influences on adolescent development'. (3rd ed., pp. 3-42). Hoboken, NJ: Wiley. Milkie, M. A., Mattingly, M. J., Nomaguchi, K. M., Bianchi, S. M., & Robinson, J. P. (2004). The time squeeze: Parental statuses and feelings about time with children. Journal o f Marriage and Family, 66, 739—761. http://dx.doi.Org/10.l 11 l/j.0022-2445.2004.00050.x Morgan, C. F., Graser, S. V., & Pangrazi, R. P. (2008). A prospective study of pedometer-determined physical activity and physical self-perceptions in children. Research Quarterly fo r Exercise and Sport, 79, 133-140. http://dx.doi.org/10.1080/02701367.2008.10599476 Nader, P. R., Bradley, R. H., Houts, R. M., McRitchie, S. L., & O’Brien, M. (2008). Moderate-to-vigorous physical activity from ages 9 to 15 years. Journal o f the American Medical Association, 300, 295-305. http://dx.doi.Org/10.1001/jama.300.3.295 Ogden, C. L„ Carroll, M. D„ Kit, B. K„ & Flegal, K. M. (2014). Preva lence of childhood and adult obesity in the United States, 2011-2012. Journal o f the American Medical Association, 311, 806-814. http://dx .doi.org/10.1001/jama.2014.732 Pate, R. R., Stevens, J., Webber, L. S., Dowda, M., Murray, D. M., Young, D. R., & Going, S. (2009). Age-related change in physical activity in adolescent girls. Journal o f Adolescent Health, 44, 275-282. http://dx .doi.org/10.1016/j .jadohealth.2008.07.003 Penedo, F. J., & Dahn, J. R. (2005). Exercise and well-being: A review of mental and physical health benefits associated with physical activity. Current Opinion in Psychiatry, 18, 189-193. http://dx.doi.org/10.1097/ 00001504-200503000-00013 Phipps, S. A., Lethbridge, L., & Burton, P. (2006). Long-run consequences of parental paid work hours for child overweight status in Canada. Social Science & Medicine, 62, 977-986. http://dx.doi.Org/10.1016/j.socscimed .2005.06.054 Pleck, J. H. (2010). Fatherhood and masculinity. In M. E. Lamb (Ed.), The role o f the father in child development (5th ed., pp. 27-57). Hoboken, NJ: Wiley. Pugliese, J., & Tinsley, B. (2007). Parental socialization of child and adolescent physical activity: A meta-analysis. Journal o f Family Psy chology, 21, 331-343. http://dx.doi.org/10.1037/0893-3200.2L3.331 Raudenbush, S. W., & Bryk, A. S. (2002). Hierarchical linear models. Thousand Oaks, CA: Sage. Raustorp, A., Svenson, K., & Perlinger, T. (2007). Tracking of pedometerdetermined physical activity: A 5-year follow-up study of adolescents in Sweden. Pediatric Exercise Science, 19, 228-238.
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Schafer, J. L., & Graham, J. W. (2002). Missing data: Our view of the state of the art. Psychological Methods, 7, 147-177. doi:10.1037/1082-989X .7.2.147 Simpkins, S. D., Fredricks, J. A., & Eccles, J. S. (2012). Charting the Eccles’ expectancy-value model from mothers’ beliefs in childhood to youths’ activities in adolescence. Developmental Psychology, 48, 1019— 1032. http://dx.d0i.0rg/l 0.1037/a0027468 Telford, R. D., Cunningham, R. B., & Telford, R. M. (2009). Daydependent step-count patterns and their persistence over 3 years in 8—10-year-old children: The LOOK project. Annals o f Human Biology, 36, 669 - 679. http://dx.doi.org/10.3109/03014460902960271 United States Census Bureau. (2000). Census 2000 profiles fo r Pennsyl vania. Health, 26, 421-443. Retrieved from http://censtats.census.gov/ data/PA/04042.pdf http://dx.doi. 0rg/lO .l 146/annurev.publhealth.26 .021304.144437 United States Department of Health and Human Services, Centers for Disease Control and Prevention. (2000). CDC growth charts fo r the U.S., 2000. Retrieved from http://www.cdc.gov/nchs/data/series/sr_ll/ srll_246.pdf United States Department of Health and Human Services, Centers for Disease Control and Prevention. (2014). Overweight and obesity: Causes and consequences. Retrieved from http://www.cdc.gov/obesity/ adult/causes/index.html van Sluijs, E. M., McMinn, A. M., & Griffin, S. J. (2007). Effectiveness of interventions to promote physical activity in children and adolescents: Systematic review of controlled trials. BMJ: British Medical Journal, 335, 703-707. http://dx.doi.org/10.1136/bmj.39320.843947.BE Warburton, D. E. R., Nicol, C. W„ & Bredin, S. S. D. (2006). Health benefits of physical activity: The evidence. Canadian Medical Associ ation Journal, 174, 801-809. http://dx.doi.org/10.1503/cmaj.051351 Wiese-Bjomstal, D. M., LaVoi, N. M., & Omli, J. (2009). Child and adolescent development and sport participation. In B. Brewer (Ed.), Handbook o f sports medicine and science: Sport psychology (pp. 97112). Oxford, UK: W iley-Blackw ell. http://dx.doi.org/10.1002/ 9781444303650.chl0 World Health Organization. (2014, August). Obesity and overweight. Factsheet, 311. Retrieved from http://www.who.int/mediacentre/ factsheets/fs311/en/
Received March 4, 2014 Revision received October 28, 2014 Accepted November 2, 2014 ■
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Journal of Family Psychology 2015, Vol. 29, No. 1, 100-107
Developmental Patterns and Parental Correlates of Youth Leisure-Time Physical Activity Chun Bun Lam
Susan M. McHale
The Hong Kong Institute of Education
The Pennsylvania State University
This study examined the developmental patterns and parental correlates of youth leisure-time physical activity from middle childhood through adolescence. On 5 occasions across 7 years, fathers, mothers, and children who were first- and second born from 201 European American, working- and middle-class families participated in home and multiple nightly phone interviews. Multilevel modeling revealed that, controlling for family socioeconomic status, neighborhood characteristics, and youth overweight status and physical health, leisure-time physical activity increased during middle childhood and declined across adolescence, and the decline was more pronounced for girls than for boys. Moreover, controlling for time-varying, parental work hours and youth interest in sports and outdoor activities, on occasions when fathers and mothers spent proportionally more time on these activities with youth than usual, youth also spent more total time on these activities than usual. The within-person association between mother-youth joint involvement and youth’s total involvement in leisure-time physical activity reached statistical significance at the transition to adolescence, and became stronger over time. Findings highlight the importance of maintaining adolescents’, especially girls’, physical activity levels and targeting both fathers’ and mothers’ involvement to promote youth’s physical activity. Keywords: adolescence, longitudinal changes, parental involvement, physical activity, within-person associations
Previous research has highlighted physical activity (PA) as an effective means to prevent and reduce overweight and obesity (Penedo & Dahn, 2005; Warburton, Nicol, & Bredin, 2006). To promote youth’s PA, however, requires understanding its devel opmental patterns as well as identifying factors that support youth’s continued engagement (Brownson, Boehmer, & Luke, 2005; van Sluijs, McMinn, & Griffin, 2007). Although evidence suggests that middle childhood and adolescence are critical periods when dramatic changes in PA occur (Dumith, Gigante, Domingues, & Kohl, 2011), and that parents are important social ization agents who shape youth’s PA involvement (Simpkins, Fredricks, & Eccles, 2012), significant gaps in our knowledge remain. First, previous studies on changes in youth PA have mostly relied on questionnaires, and their results may be subject to memory and response biases (Adams et al., 2005; Ferrari, Friedenreich, & Matthews, 2007). Furthermore, prior investigations of parental influences on youth PA have focused on between-person associations, an approach that constrains the causal inferences that can be drawn, because alternative explanations involving stable selection factors cannot be ruled out (Bauman et al., 2012; Curran & Bauer, 2011). Finally, few researchers have used a developmen tal framework to study parental influences on youth PA, and discrepancies exist as to whether and how parental influences may vary as youth mature over time (Beets, Cardinal, & Alderman, 2010; Edwardson & Gorely, 2010; Pugliese & Tinsley, 2007). Accordingly, using multiple-wave, phone-diary data and testing paternal and maternal involvement as time-varying covariates, this study was designed to address two goals: (a) to chart how leisure time PA changed from middle childhood through adolescence and (b) to test whether—at a within-person level, using each individual
Rates of childhood and adolescent overweight and obesity are rising around the world (World Health Organization, 2014). In the United States, for example, the percentage of obese children has more than doubled over the past 30 years, growing from 7% in 1980% to 18% in 2012, and the percentage of obese adolescents has quadrupled in the same period of time, growing from 5% in 1980% to 21% in 2012 (Ogden, Carroll, Kit, & Regal, 2014). Individuals who are overweight or obese have a higher risk for a wide range of medical conditions, including heart disease, diabe tes, cancers, and stroke (Centers for Disease Control & Prevention, 2014). Youth overweight and obesity, therefore, are becoming an increasingly important issue for parents, practitioners, and policy makers.
This article was published Online First December 8, 2014. Chun Bun Lam, Department of Early Childhood Education, The Hong Kong Institute of Education; Susan M. McHale, Department of Human Development and Family Studies, The Pennsylvania State University. Portions of this article were presented at the Society for Research on Child Development Biennial Meeting, Montreal, Canada, April 2011. The authors wish to express gratitude to the undergraduate and graduate assis tants, staff, and faculty collaborators for their help in conducting this study, and to the participating families for their time and cooperation. This work was funded by grants from the United States Department of Health and Human Services, National Institutes of Health, National Institute of Child Health and Human Development (R01-HD32336 and R01-HD29409) to Ann C. Crouter and Susan M. McHale, coprincipal investigators. Correspondence concerning this article should be addressed to Chun Bun Lam, Department of Early Childhood Education, The Hong Kong Institute of Education, 10 Lo Ping Road, Tai Po, New Territories, Hong Kong. E-mail: [email protected]
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as his or her own control—the proportions of time that fathers and mothers spent on leisure-time PA with youth were linked to youth’s total time spent on leisure-time PA, and whether these linkages were moderated by youth’s age.
Developmental Patterns of Leisure-Time PA Dumith et al. (2011) conducted a pooled analysis of 26 studies on longitudinal changes in PA across adolescence, and found that PA declined linearly over time. A consistent gender difference in the rate of change was not evident, however, possibly due to the use of different measures across studies. Indeed, most of these 26 studies used questionnaires to measure PA, and methodological research shows that, compared to physiological sensors and daily diaries, questionnaires are particularly susceptible to memory dis tortion (Ferrari, Friedenreich, & Matthews, 2007) and social de sirability biases (Adams et al., 2005). The results of the few longitudinal studies that used physiological sensors or daily diaries to measure adolescent PA were yet mixed, with some indicating that PA did not change over time (Garcia, Pender, Antonakos, & Ronis, 1998; Morgan, Graser, & Pangrazi, 2008), some suggesting that it declined for both boys and girls (Nader, Bradley, Houts, McRitchie, & O’Brien, 2008; Pate et al., 2009), and some docu menting that it declined for boys, but not for girls (Raustorp, Svenson, & Perlinger, 2007). Fewer studies have used nonques tionnaire methods to examine changes in PA across middle child hood, and their results are equally inconclusive. There is evidence, for example, that PA remains stable over time (Telford, Cunning ham, & Telford, 2009), that PA decreases for both boys and girls (Basterfield et al., 2011; Cleland et al., 2008), and that PA in creases for boys, but not for girls (Janz et al., 2009). In the face of these inconsistent findings, theories of youth time use (Larson & Verma, 1999) posit that active leisure should follow a curvilinear pattern of change, increasing during middle childhood (when play is thought to be the “work” of youth) and decreasing across adolescence (when youth spend more time on other competing activities, such as homework, paid work, and socializing with peers). Gender theories (Cockburn & Clarke, 2002; Galambos, Berenbaum, & McHale, 2009) further predict that, because many qualities emphasized in sport, such as strength, competitiveness, and assertiveness, run contrary to the ideal of femininity, girls’ declines in PA may reflect intensified social pressures for youth to conform to traditional gender roles during adolescence. The first goal of this study was to examine the pattern of change in leisure-time PA using five waves of longitudinal data collected over 7 years via multiple nightly phone interviews. We focused on leisure-time PA, because in industrialized countries where manual labor and self-powered transportation are minimal, voluntary in volvement in PA represents a ripe target for intervention (Brownson et al., 2005; van Sluijs et al., 2007). Based on some previous findings (Dumith et al., 2011; Janz et al., 2009) and theories of time use and gender development (Cockburn & Clarke, 2002; Galambos et al., 2009; Larson & Verma, 1999), we expected that leisure-time PA would increase during middle childhood and de cline across adolescence, and that the decline would be more pronounced for girls than for boys. We controlled for family socioeconomic status, neighborhood characteristics, and youth overweight status and physical health, because these factors may have a direct impact on youth levels of PA. Specifically, they may
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reflect financial (socioeconomically disadvantaged families may not be able to afford youth involvement in certain PA), environ mental (youth may find it less convenient to get to the venues for PA by themselves in rural/suburban communities than in small cities/towns), and individual (overweight or obese and physically unhealthy youth may find PA more demanding and thus less attractive as a leisure activity) constraints on youth PA (Bauman et al., 2012; Ding, Sallis, Kerr, Lee, & Rosenberg, 2011).
Parental Correlates of Leisure-Time PA According to Eccles’s (Fredricks & Eccles, 2004; Simpkins et al., 2012) parental socialization model, parents influence their offspring’s PA through modeling (i.e., being physically active themselves), encouragement and reinforcement (e.g., praising their offspring for being physically active), provision of opportunities (e.g., enrolling their offspring in sports and outdoor activities), and joint involvement (e.g., engaging in sports and outdoor activities with their offspring). Studies in support of this view have amassed, and their findings indicate that parents’ own involvement in PA, as well as their socialization efforts, are linked to their offspring’s involvement in PA (Beets et al., 2010; Edwardson & Gorely, 2010; Pugliese & Tinsley, 2007). Nearly all of these studies, however, have focused on between-person associations—why some youth are more involved in PA than others (Bauman et al., 2012) - which can easily be confounded with stable selection factors, ranging from parent-youth shared genetic dispositions to their shared phys ical environment, that are not controlled for in the analyses (Curran & Bauer, 2011). A focus on within-person associations extends prior research, because it examines whether within-person varia tion (i.e., deviations from an individual’s own norm) in parental influences is linked to within-person variation in youth PA. By treating each individual as his or her own control, within-person associations rule out stable, third variables as alternative explana tions, and thus provide for stronger inferences (Raudenbush & Bryk, 2002). Fredricks and Eccles (2004) advocated using a developmental framework to study parental influences on youth PA. From their perspective, the magnitude of parental influences may differ de pending on youth developmental stage. Based on the number of significant associations among prior studies, qualitative reviews (Beets et al., 2010; Edwardson & Gorely, 2010) suggested that the impact of parent-youth joint involvement waned across adoles cence. Using quantitative methods of data synthesis, however, a meta-analytic review (Pugliese & Tinsley, 2007) showed that the association between parental modeling/parent-youth joint involve ment and youth PA was significantly stronger in studies conducted with children (< age 10) and middle and older adolescents (> age 12) than those conducted with young adolescents (age 10-12). These findings are consistent with theories of parent-youth rela tionships (Laursen & Collins, 2009), which hold that— contrary to a popular belief that adolescence invariably entails willful disobe dience toward parents and distancing from the family—increased parent-youth conflict is often limited to early adolescence, and such temporary perturbations have little impact on the subsequent quality of parent-youth relationships. The second goal of this study was to examine the within-person associations between the proportions of father- and mother-youth joint involvement in leisure-time PA and youth’s total involvement
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in leisure-time PA, and the role of youth’s age in these associa tions. We focused on parent-youth joint involvement as a potential influence highlighted in Eccles’s socialization model (Fredricks & Eccles, 2004; Simpkins et al., 2012), because it has been less often studied compared to other forms of parental influences (Beets et al., 2010; Edwardson & Gorely, 2010; Pugliese & Tinsley, 2007). Moreover, relative to questionnaires and physiological sensors, daily diaries are particularly effective for assessing the social contexts of time use (Kohl, Fulton, & Caspersen, 2000). In this study, parents were counted as involved in their offspring’s PA when they engaged in such activities with their offspring as play mates or coaches (Fredricks & Eccles, 2004; Simpkins et al., 2012). Further, given that the involvement of spectators is an integral part of many sports (Beets et al., 2010) and that parents often monitor/supervise their offspring’s activities in outdoor places out of safety concerns (Ding et al., 2011), parents were also counted as involved when they were physically present, and watching their offspring play or practice and not doing anything else at the same time: Even when they are not actively involved, parents’ presence may be seen as an expression of interest in their offspring’s activities. Youth may also experience these activities as shared when parents cheer from the sidelines and congratulate or commiserate about what they have observed during the course of a particular activity. On the basis on some prior findings (Pugliese & Tinsley, 2007) and theories of parental socialization and parentyouth relationships (Fredricks & Eccles, 2004; Laursen & Collins, 2009; Simpkins et al., 2012), we expected that the proportions of both father- and mother-youth joint involvement would be posi tively linked to youth’s total involvement, but that the magnitude of such associations would be temporarily reduced in early ado lescence. We included both paternal and maternal involvement in the same analytic model, because we were interested in examining the independent contribution of each parent (Pleck, 2010). Albeit with a control for stable individual differences, withinperson variation may still be affected by other time-varying factors (Raudenbush & Bryk, 2002). For example, on occasions when parents are more heavily engaged in paid work than usual, they may also spend less time with their offspring (Milkie, Mattingly, Nomaguchi, Bianchi, & Robinson, 2004) and be less able to help their offspring maintain active lifestyles than usual (Phipps, Leth bridge, & Burton, 2006). Moreover, on occasions when youth are more interested in PA than usual, they may also participate more in these activities and motivate their parents to become more active with them than usual— a child effects interpretation (Fredricks & Eccles, 2004). Thus, we included parental paid work hours and youth interest in PA as time-varying controls to further eliminate two important alternative explanations of the within-person asso ciations linking the proportions of father- and mother-youth joint involvement to youth’s total involvement in leisure-time PA.
Method Participants Data were drawn from the 1st, 2nd, 3rd, 6th, and 7th years (referred to as Times 1 through 5 hereafter) of a longitudinal study on family relationships, the years in which the data of interest were collected. Recruitment letters were sent home from all schools within 16 school districts of a northeastern state to families with
4th and 5th grade students. Because of the goal of the larger study, families were eligible if the parents were married, both parents were employed, the firstborn was in the 4th or 5th grade, and the second bom was 1 -4 years younger than the firstborn. The number of families that fulfilled our recruitment criteria but failed to respond was unknown, but over 90% of families who returned postcards participated in the study. Two families that dropped out after Time 1 were deleted, and the analyses were based on the remaining 201 families. Attrition was low: At Time 5, 95% of parents and youth still remained in the study. Reflecting the ethnic composition of the state where the study was conducted (85% European American; U.S. Census Bureau, 2000), the sample included almost exclusively biologically related, European American families (there were one stepfather and two youth adopted from Asia) living in small cities, towns, and rural and suburban communities. Moreover, reflecting the educational (>80% of adults completed high school) and financial (median income = $55,714 for married-couple families) backgrounds of the targeted population (U.S. Census Bureau, 2000), at Time 1, the average educational level was 14.57 years (SD = 2.15) for mothers and 14.67 years (SD = 2.43) for fathers (where a score of 12 indicated a high school graduate) and the median family income of the sample was $55,000 (SD = 28,613). At Time 1, the average age was 10.87 years (SD = 0.54) for firstborns and 8.26 years (SD = 0.93) for second boms. Because of the age differences between siblings and multiple waves of data collection, between 40 and 270 youth provided data at each chronological age from 7 (i.e., 6.5—7.5) to 18 (i.e., 17.5-18.5) years, allowing us to chart the development of leisure-time PA from middle childhood through adolescence. Sibling dyads were divided almost equally among the four possible gender constellations, meaning that we had roughly equal and sufficient numbers of girls (n = 203) and boys (n = 199) to test for potential gender differences.
Procedure and Measures Data were collected from fathers, mothers, and the two siblings via two methods. First, trained interviewers visited families to conduct annual home interviews. Families gave informed consent and received a monetary honorarium ($100 at Times 1 through 3; $200 at Times 4 and 5) at the beginning of the home interviews, and family members completed questionnaires independently. Sec ond, in the 2 to 3 weeks following the home interviews, trained interviewers called siblings individually to conduct seven (5 week days, 2 weekend days) nightly phone interviews. Each sibling was guided through a list of 70 activities and probed for the duration and social contexts of any activities completed outside of school. Measures. Background information collected in the home in terviews with parents at Time 1 included parents’ levels of edu cation and income, and family members’ age, gender, and ethnic ity. At Time 2, mothers also reported in the home interviews whether their neighborhoods were best characterized as small cities/towns, or rural/suburban communities. An index of family socioeconomic status was created by averaging fathers’ and moth ers’ levels of education (Hauser, 1994). The reference group (coded 0) for gender was boys and for neighborhood type was rural/suburban communities. Youth’s leisure-time PA was measured in the phone interviews at Times 1- 5. Youth reported how much time (in minutes) they
LEISURE-TIME PHYSICAL ACTIVITY spent on eight sports and outdoor activities, including sport, water activities, gymnastics, dancing, hiking and camping, biking and skating, hunting and fishing, and outdoor play. Leisure-time PA was measured as the total duration of time across the seven phone interviews. To correct for skewness, square-root transformations were used in the analyses. The proportions o f father- and motheryouth joint involvement were calculated by dividing the duration of time youth spent on sports and outdoor activities with their fathers and with their mothers, respectively, by the total duration of time youth spent on these activities. As noted, parents were counted as involved by engaging in the activities with their offspring, coach ing their offspring, or simply watching their offspring participate. Parents ’ work hours were measured in the home interviews at Times 1-5. Fathers and mothers reported how many hours they spent “at work,” “driving to and from work,” and “on work-related activities at home” in an average week. Items were summed, and higher scores indicated more work hours. Youth’s interest in PA was measured in the home interviews at Times 1-5. Youth used a scale ranging from 1 (not at all inter ested) to 4 (very interested) to rate their interest in seven sports and outdoor activities, including sport, water activities, gymnastics, dancing, hiking and camping, biking and skating, and hunting and fishing. Items were summed, and higher scores indicated higher interest. Youth's height and weight were reported in the home interviews by mothers at Times 2-4. Youth’s height and weight were first converted into body mass indices (BMIs), which were then con verted into binary variables that indicated whether youth were overweight, or ranked above the 85th percentiles of the age and gender specific BMI estimates issued by Centers for Disease Control and Prevention (2000). Youth’s overweight status showed moderate to strong cross-time stability (average rs = .60 for firstborns and .34 for second boms), and thus a general binary index was created to indicate whether youth were overweight at any of the three time points. The reference group was nonover weight youth. Youth’s physical health was measured in the home interviews with mothers at Times 2-4. Mothers used a scale ranging from 1 (very poor) to 5 (very good) to rate their firstborns’ and second borns’ physical health. Youth’s physical health showed moderate cross-time stability (average rs = .46 for firstborns and .45 for second boms), and thus a general index was created by averaging the ratings across the three time points. Analytic Strategy. Given the clustered nature of our data (i.e., time within individual, individuals within family), we used multi level modeling to take into account the correlations between the error residuals (Raudenbush & Bryk, 2002). Multilevel modeling also accommodates missing data and effectively reduces biases in parameter estimation (Schafer & Graham, 2002), although only about 5% of our data were missing. A series of three-level models was estimated using the MIXED procedure in SAS Version 9.1 (SAS Institute Inc., Cary, NC). At Level 1 (within-individual), we included time-varying variables. We used youth age as the metric of time, and included the linear and quadratic terms to describe the development of leisure-time PA. Youth age was centered at 13 years (i.e., the approximate mean age across youth and time points). We also included the time-varying covariates (i.e., the proportions of father- and mother-youth joint involvement in leisure-time PA) and the time-varying controls (i.e., fathers’ and
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mothers’ work hours and youth’s interest in PA) at this level. To separate within- from between-person variation, each time-varying covariate was indicated by two variables: At Level 1, the covariate was indicated by a time-varying, group-mean centered (at each individual’s own cross-time average) variable; at Level 2 (between-individual), the covariate was indicated by the grandmean centered (at the overall sample mean), cross-time average. Because the cross-time average of the covariate captured all the between-person variation, the Level 1 version of the covariate was limited to explaining within-person variation beyond stable inter individual differences. The time-varying controls were grandmean centered without including the cross-time averages, how ever, as the within- versus between-person effects of these factors were not of substantive interest in this study. At Level 2, we also included other time-invariant variables that were different for the two siblings, including youth’s gender, overweight status, and physical health. Physical health was grand-mean centered. Level 3 (between-family) included time-invariant variables that were the same for siblings from the same family, including family socio economic status and neighborhood type. Family socioeconomic status was grand-mean centered. We conducted the analyses in three steps: First, we tested a general change model (Model 1) to examine the overall pattern of change in leisure-time PA from middle childhood through adoles cence. Second, we tested a gender-specific change model (Model 2) to examine whether the pattern of change in leisure-time PA varied by youth gender, controlling for family socioeconomic status, neighborhood type, and youth overweight status and phys ical health, which may have a direct impact on the levels of youth PA (Bauman et al., 2012; Ding et al., 2011). Third, we tested a parental influence model (Model 3) to examine whether withinperson variation in the proportions of father- and mother-youth joint involvement in leisure-time PA was linked to within-person variation in youth’s total involvement in leisure-time PA, control ling for time-varying, paternal and maternal work hours and youth interest in PA, which may confound the linkages between parental involvement and youth PA (Milkie et al., 2004; Phipps et al., 2006). We also included the interactions between parent-youth joint involvement and youth age to test whether the magnitude of parental influences varied by youth’s age. For all analyses, we only included significant interactions in the final models, because re taining nonsignificant interactions would increase standard errors (Aiken & West, 1991).
Results Multilevel Models Coefficients for fixed effects can be found in Table 1. Model 1 revealed a significant quadratic effect of youth age. Overall, leisure-time PA increased steadily from age 7 to about age 12 and then declined. Model 2 revealed a significant main effect of gender, indicating that, at age 13 (the age at which our age variable was centered), the difference in leisure-time PA between boys (M = 411.42; SD = 321.73) and girls (M = 343.74; SD = 273.16) was significant. A significant Gender X Linear Time interaction further indicated that, at age 13, the negative linear effect was stronger for girls, y = -0 .6 2 , t = -6 .0 0 , p < .01, than for boys, y = —0.32, t = —3.03, p < .01. As Figure 1 shows, boys were
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Table 1 Multilevel Models o f Youth Leisure-Time Physical Activity Model 2
Model 1
Model 3
Variable
7
t ratio
7
t ratio
7
t ratio
Intercept Linear time Quadratic time Gender (0 = boys) Gender X Linear Time Family socioeconomic status Neighborhood type (0 = rural/suburban communities) Youth’s overweight status (0 = non-overweight youth) Youth’s physical health WP fathers’ involvement WP mothers’ involvement WP mothers’ involvement X Linear Time BP fathers’ involvement BP mothers’ involvement TV fathers’ work hours TV mothers’ work hours TV youth’s interest
17.67 -0.48 -0.17
44.18” -5 .6 4 ” -8 .5 6 ”
19.46 -0.32 -0.16 -2.79 -0.30 -0.11 0.33 -0.72 0.90
26.15" -3 .0 3 ” -8 .4 5 “ -5 .7 6 “ -2.35* -0.61 0.46 -1.32 1.80
19.20 0.11 -0.14 -2.56 -0.38 -0.05 0.16 -0.38 1.14 2.67 4.72 0.55 7.78 -0.44 0.03 -0.02 0.41
27.62” 1.01 -7 .1 5 “ -5.24** -3.11“ -0.30 0.25 -0.77 2.51* 3.49“ 5.55** 2.01* 4.24** -0.20 1.87 -1.74 7.32”
Note. BP = between-person; WP = within-person; TV = time-varying. Parents’ involvement was calculated by dividing the duration of time youth spent on physical activity with their parents by the total duration of time youth spent on physical activity. *p < .05. “ > < . 0 1 .
generally more involved in leisure-time PA than girls, and girls’ declines in leisure-time PA were more pronounced than boys’. The interaction between Gender X Quadratic Time was not significant, and thus was dropped from the model. Model 3 revealed a signif icant within-person effect of father-youth joint involvement, indi cating that, on occasions when fathers spent proportionally more time with youth in leisure-time PA than usual, youth also spent more total time on these activities than usual. A significant WithinPerson Mother-Youth Joint Involvement X Linear Time interac tion, together with follow-up tests, indicated that a significant within-person association between mother-youth joint involve ment and youth’s total involvement in leisure-time PA emerged at about age 9, y = 2.54, SE = 1.10,/? < .05, and became stronger over time. In other words, starting around age 9, on occasions when mothers spent proportionally more time with youth in leisure-time PA than usual, youth also spent more total time on these activities than usual. Other interactions involving youth’s
...e ... boys (observed) —* — boys (predicted) girls (observed) — • — girls (predicted)
7
8
9 10 11 12 13 14 15 16 17 18 Age (years)
Figure 1. Predicted (solid lines) and observed (dotted lines) means of youth leisure-time physical activity by gender.
age were not significant, and thus were dropped from the model. Exploratory analyses testing for interactions between parent-youth joint involvement and youth gender revealed no differences in parental influences on boys’ versus girls’ leisure time PA.
Discussion Childhood and adolescent overweight and obesity are on the rise in many countries (World Health Organization, 2014), including in the U.S. (Centers for Disease Control & Prevention, 2014; Ogden et al., 2014). Because PA is an effective means to preempt and reduce overweight and obesity, it is important to understand how PA involvement changes across childhood and adolescence and to identify factors that support youth’s continued involvement (Brownson et al., 2005; Penedo & Dahn, 2005; van Sluijs et al., 2007; Warburton et al., 2006). Using multiple-wave, phone-diary data and testing paternal and maternal involvement as timevarying covariates, this study tested the developmental patterns and parental correlates of youth leisure-time PA. Our results indicated that leisure-time PA increased during middle child hood and declined across adolescence, and that the decline was more pronounced for girls than for boys, highlighting the im portance of maintaining youth’s, especially girls’, PA at the transition to adolescence. Moreover, on a within-person level, the proportions of father- and mother-youth joint involvement were positively and independently linked to youth’s total in volvement in leisure-time PA, a finding that points to the importance of promoting both paternal and maternal involve ment in youth PA. Below, we elaborate on these conclusions and, taking into account the limitations of our study, discuss the implications of our findings for understanding youth PA as a developmental phenomenon and for parents, practitioners, and policymakers.
LEISURE-TIME PHYSICAL ACTIVITY
Developmental Patterns of Leisure-Time PA Our study showed that changes in leisure-time PA were char acterized by a quadratic trend, increasing during middle childhood and declining across adolescence; also, the decline in adolescent PA was more pronounced for girls than for boys. These findings, though consistent with theories of youth time use and gender development (Cockbum & Clarke, 2002; Galambos et al., 2009; Larson & Verma, 1999), both support (Dumith et al., 2011; Janz et al., 2009) and contrast with (Basterfield et al., 2011; Cleland et al., 2008; Garcia et al., 1998; Morgan et al., 2008; Telford et al., 2009) those of previous studies. Due to differences in sample sizes, measures of PA, and data analytic strategies (especially how developmental time was operationalized), direct comparisons be tween previous studies and ours are difficult. Long-term, longitu dinal investigations that use multiple methods (i.e., physiological sensors, daily diaries, and questionnaires) to measure youth PA are needed to reconcile accumulated findings. However, given that most prior research (Dumith et al., 2011), as well as our work, documented a decline in adolescent PA, programs designed to maintain youth’s earlier levels of PA at the transition to adolescence should be given a high priority. In ado lescence, many youth activities move toward specialization and require increasingly more expertise, as tryouts, auditions, and other forms of adult screening set limits on who can be involved (WieseBjomstal, LaVoi, & Omli, 2009). At the same time, a growing orientation to peer relationships may mean that youth will become less inclined to spend time on activities that do not include their circles of friends (Larson & Verma, 1999). Programs that involve the peer group in more informal kinds of leisure activities (e.g., Frisbee, group workouts) may be useful for maintaining adoles cents’ levels of PA. Such efforts may be especially important for girls, who showed lower levels of and more pronounced declines in leisure-time PA compared to boys in our study. It is worth noting that these gender differences remained significant even when time-varying, youth interest in PA was included in the model (Model 3), suggesting that they were not attributable to girls being less interested in PA than boys. An important direction for future research is to examine how gender socialization processes, such as social expectations for adolescent girls to conform to the ideal of femininity, may limit their opportunities for PA participation (Cockbum & Clarke, 2002; Galambos et al., 2009).
Parental Correlates of Leisure-Time PA Our results were consistent with theories of parental socializa tion (Fredricks & Eccles, 2004; Simpkins et al., 2012) and findings pertaining to more commonly studied between-person associations (Beets et al., 2010; Edwardson & Gorely, 2010; Pugliese & Tin sley, 2007). Controlling for stable individual differences and timevarying, parental work hours and youth interest in PA, we found that, on occasions when fathers and mothers spent proportionally more time on PA with youth than usual, youth also spent more total time on these activities than usual. By considering multiple alternative explanations, including stable selection factors (Raudenbush & Bryk, 2002) and certain time-varying, contextual (Milkie et al., 2004; Phipps et al., 2006) and dispositional (Fredricks & Eccles, 2004) influences, we were able to make stronger inferences about the relation between parent-youth joint involvement and youth leisure-time PA than prior research. By
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distinguishing within- from between-person variation, we also avoided misattributing an aggregate relation to the level of the individual and reduced the risk of the ecological fallacy (Curran & Bauer, 2011). Contrary to our expectations, the magnitude of the withinperson association between the proportion of parent-youth joint involvement and youth’s total involvement in leisure-time PA did not show a temporary decline in early adolescence: The impact of paternal involvement remained consistent from middle childhood through adolescence, and the impact of maternal involvement reached statistical significance at the transition to adolescence and became stronger over time. Although parental influences on youth PA may change over time (Fredricks & Eccles, 2004), such changes are likely to be domain-specific and dependent on partic ular mechanisms of parental influences (Laursen & Collins, 2009). In fact, in Pugliese and Tinsley’s (2007) meta-analysis, parental modeling and parent-youth joint involvement— aggregated into one single category due to a lack of studies—were the only forms of parental influence that showed systematic variation across age groups. One possible explanation for the discrepancy between Pugliese and Tinsley’s and our findings, therefore, is that the influences of parental modeling versus parent-youth joint involve ment change in different ways as youth mature, a topic awaiting longitudinal investigations. The difference between paternal versus maternal influences may be related to both social expectations about gender and adolescent cognitive development. As many qualities emphasized in sport, including strength, competitiveness, and assertiveness, are re garded as masculine (Cockbum & Clarke, 2002; Galambos et a l, 2009), youth active leisure provides convenient sites where men reaffirm traditional masculine roles and simultaneously meet ex pectations for paternal involvement (Pleck, 2010). In contrast, traditional feminine roles do not highlight active leisure, and thus high levels of mother-youth joint involvement in PA may be of particular salience to youth, especially during adolescence, when youth become increasingly able to incorporate social comparative information to interpret the behaviors of their parents (Fredricks & Eccles, 2004). Because few researchers have used a developmental framework to study parental influences on youth PA, our results should be treated as a first step in understanding these processes: The future challenge is to test not only whether, but also why, the influence of maternal involvement in youth PA may vary across child and adolescent development. On a practical level, however, strategies that encourage both paternal and maternal involvement may constitute an important focus of intervention. More generally, our findings also indicate that, in the face of adolescents’ increas ing interest in the world beyond the family, fathers and mothers continue to make important (Laursen & Collins, 2009), and inde pendent (Pleck, 2010), contributions to their offspring’s well being, including by shaping their offspring’s involvement in PA (Penedo & Dahn, 2005; Warburton et al., 2006).
Limitations and Conclusion This study is not without limitations. First, although our sample reflected some population characteristics of married-couple fami lies from the state where the study was conducted (U.S. Census Bureau, 2000), it was not representative of the diversity of families in the U.S. Given that how youth spend their time is dependent on
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the embedding cultural, social, and economic contexts (Larson & Verma, 1999) and that overweight and obesity are more pro nounced for more socioeconomically disadvantaged populations (Ogden et al., 2014; Warburton et al., 2006), our findings need to be replicated with samples that are more diverse with respect to culture, family structure, and parental employment. Second, our use of time-varying covariates and inclusion of multiple, timevarying controls allowed us to examine relatively unconfounded associations, but conclusions about causal relations cannot be made based on correlational data. Intervention studies that use randomized designs to manipulate parent-youth joint involvement are needed to disentangle the underlying causal paths of the associations documented here. Third, our emphasis on whether parents were physically present when their youth’s sports and outdoor activities took place (Beets et al., 2010; Ding et al., 2011; Fredricks & Eccles, 2004) directed us to focus on the most generic form of parent-youth joint involvement, which combined, for example, more active forms of involvement (e.g., parents partici pating in PA with their offspring as playmates or coaches) with more passive ones (e.g., parents watching their offspring play or practice). A more differentiated measurement approach may illu minate the potentially unique influences of different forms of parent-youth joint involvement, such as those characterized by different structural (e.g., whether the involvement is organized in a progressive way to achieve a predetermined goal) and emotional (e.g., how close youth feel toward their parents) qualities, and whether and how these may interact with parent and youth gender to shape youth PA. Finally, daily diaries are sufficiently sensitive to detect the duration and social contexts, but not the intensities, of PA (Kohl et al., 2000). Considering that PA of different intensities may have different trajectories (Dumith et al., 2011) and correlates (Edwardson & Gorely, 2010), future researchers should combine both physiological sensors and daily diaries to capture the tempo ral, contextual, and intensity dimensions of PA. Despite these limitations, our study’s use of multiple-wave, phone-diary data and focus on within-person associations provided new insights about the development of and influences on leisure time PA. From the perspectives of parents and program providers, our findings highlight the importance of maintaining adolescents’, particularly girls’, PA by promoting both fathers’ and mothers’ involvement.
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Received March 4, 2014 Revision received October 28, 2014 Accepted November 2, 2014 ■
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