Determinants of Change in Physical Activity in Children During the Transition from Elementary to High School.

INTRODUCTION: Effective public health interventions targeting factors that influence physical activity are urgently needed to reduce the age-related decline in physical activity in youth. The purpose of this study was to identify associations between physical activity and a set of potential influences on physical activity in children as they transition from elementary to high school. METHODS: Participants were 951 children from South Carolina school districts who completed outcome and independent variable measures on at least two time points from the 5th through 11th grades in 2010 - 2017. The primary outcome variable was physical activity, measured by accelerometry. Independent variables included a comprehensive set of variables in the child, parent/home, school, and community domains. Children, parents and school administrators, and staff completed questionnaires to assess psychosocial and home, school, and neighborhood environmental influences. Growth curve analyses identified independent variables associated with physical activity over time, either as a main effect or as an interaction with age. RESULTS: As main effects, self-efficacy, self-schema, sport participation, weekday outdoor hours, importance of child participating in sports and physical activity, safe to play outside, and Physical Activity Resource Assessment weighted score were positively associated with physical activity. The associations between physical activity and enjoyment motivation, appearance motivation, weekend outdoor time, and home equipment exhibited significant interactions with age. Enjoyment motivation influenced physical activity during the earlier years, whereas the remaining three variables influenced physical activity in the later years. CONCLUSIONS: Interventions should target multiple domains of influences that may vary by age.

Clustering Patterns of 24-Hour Physical Activity in Children 6-36 Months Old.

PURPOSE: To determine 24-hour physical activity (PA) clusters in children 6-36 months of age, factors associated with the clusters, and their agreement across time. METHOD: A longitudinal study followed 150 infants from South Carolina up to 36 months of age. Measures included 24-hour PA and demographic data. Functional clustering was used to obtain the clusters. The association between cluster membership and infant/parent characteristics was examined by Kruskal-Wallis and chi-squared tests. Concordance was measured with the kappa coefficient and percent agreement. RESULTS: At each follow-up, 3 clusters were optimal, identified as late activity (cluster 1), high activity (cluster 2), and medium activity (cluster 3). The defining feature of the late activity cluster was that their physical activity (PA) activity was shifted to later in the day versus children in clusters 2 and 3. At 6 months, the clusters were associated with race (<0.001), crawling (0.043), other children in the household (0.043), and mother's education (0.004); at 12 months with race (0.029), childcare (<0.001), and education (<0.001); and at 36 months with other children in the household (0.019). Clusters showed moderate agreement (kappa = .41 [.25 to .57], agreement = 61% [49% to 72%]) between 6 and 12 months and, at 36 months, showed no agreement with either 6 or 12 months. CONCLUSION: Twenty-four-hour PA can be clustered into medium, high, and late PA. Further research is needed into the consequences of late sleeping in children at this age. Clusters are associated with household and childcare factors, and cluster membership is dynamic across time.

Association of physical activity, sedentary behavior, diet quality with adiposity: a longitudinal analysis in children categorized by baseline weight status.

BACKGROUND/OBJECTIVES: Childhood obesity rates have increased in recent years. The effectiveness of future public health interventions to reduce childhood obesity will be enhanced by a better understanding of behavioral factors that influence adiposity in children as they transition from childhood to adolescence. The purpose of this study was to examine whether initial weight status modifies the longitudinal associations of physical activity, sedentary behavior, and diet quality with changes in adiposity over time. SUBJECTS/METHODS: A total of 658 children (45% boys) were stratified into 3 groups based on 5th grade BMI percentiles ( < 85th, 85-95th, > 95th) and followed from 5th grade to 6th and/or 7th grade. Study variables, including fat-mass-index (FMI), moderate-to-vigorous physical activity (MVPA), diet quality, and sedentary behavior, were measured at 5th, 6th, and/or 7th grades. Separate growth curve models were conducted within each weight status group to examine the associations between MVPA, sedentary behavior, diet quality and adiposity, operationalized as FMI. All models controlled for sex, maturity offset, race, and parent education. RESULTS: Of the 658 children, 53% were classified with normal weight at baseline, 18% with overweight, and 29% with obesity. Associations between MVPA, sedentary behavior, diet quality and FMI varied within each weight status group. MVPA was negatively associated with adiposity (FMI) for all weight status groups. Diet quality and sedentary behavior were associated with adiposity only in children with obesity at baseline; neither diet quality nor sedentary behavior was associated with FMI for those with overweight. CONCLUSIONS: MVPA was negatively associated with adiposity (FMI) in all weight status groups, suggesting that MVPA may protect against higher adiposity. Sedentary behavior and diet quality were associated with adiposity only in children with obesity at baseline; neither sedentary behavior nor diet quality was associated with FMI for children with overweight.

Longitudinal changes in domains of physical activity during the transition from elementary school to high school in the U.S.

OBJECTIVES: To describe patterns of age-related change in self-reported physical activity domains within a heterogeneous sample of boys and girls in the U.S. transitioning from elementary to high school. DESIGN: Prospective cohort study. METHODS: Participants included n = 644 children recruited in 5th grade (10.5 ±â€¯0.5 years old, 45 % female) who completed the Physical Activity Choices survey at least twice over 5 time points (5th, 6th, 7th, 9th and 11th grade). Participants' self-reported physical activities were categorized into organized and non-organized activities, and a comprehensive variable was created as the product of the total number of physical activities reported in the past 5 days, the number of days spent in each activity, and the total time spent in each activity. Descriptive statistics and growth curve models (controlling for covariates) for the total sample and by sex were examined for total, organized, and non-organized physical activities from ages 10 to 17. RESULTS: There was a significant age by gender interaction (p < 0.05) for time spent in non-organized physical activities. Specifically, both sexes had similar patterns of decline before age 13, while boys increased after age 13 and girls declined and then maintained. In contrast, boys and girls declined in organized physical activities from ages 10 to 17 (p < 0.001). CONCLUSIONS: We observed stark differences in the age-related change between organized and non-organized physical activities and marked differences in the patterns of non-organized physical activities between boys and girls. Future research should examine physical activity interventions that consider age-, sex-, and domain-specific physical activity options for youth.

Longitudinal Associations of Cardiorespiratory Fitness and Poverty With Academic Performance Among Youth.

BACKGROUND: Cardiorespiratory fitness (CRF) plays a significant role in health and academic performance in youth. The purpose of this study was to examine the longitudinal relationship between CRF and academic performance from fifth to eighth grade among a large, diverse, and state-wide cohort of students, and to determine the extent to which the relationship between change in CRF and academic performance is moderated by poverty status. METHODS: CRF and academic performance data were obtained for a retrospective state-wide cohort of 11,013 students with baseline (fifth grade, school year 2015-2016) and follow-up (eighth grade, school year 2018-2019) data. Analysis of covariance was used to examine the association between changes in CRF over a 3-year follow-up period and eighth grade academic performance. RESULTS: After adjusting for covariates, change in CRF and poverty status were positively and significantly associated with eighth grade academic performance. Poverty status did not significantly moderate the association between changes in CRF and academic performance. CONCLUSIONS: Schools should prioritize evidence-based policies and programs that optimize students' access to high quantity and quality physical activity throughout the school day. Such efforts can improve and maintain student CRF and thus academic performance outcomes.

A Summary of One Research Team's Contributions to Understanding Physical Activity Behavior in Children and Youth.

Schools are well-positioned to provide physical activity opportunities to help youth achieve the recommended 60 or more daily minutes of moderate-to-vigorous physical activity. The Children's Physical Activity Research Group (CPARG) at the University of South Carolina has focused on understanding physical activity in school-aged youth for 30+ years. The purpose of this article was to critically review (CPARG) contributions to the field in school settings and school-age youth. We reviewed 127 published CPARG articles from six research projects conducted between 1993-2019. The review was guided by questions in five categories: measurement of physical activity and its determinants, characteristics of physical activity behavior, correlates/determinants of physical activity, physical activity interventions, and race/ethnicity and physical activity. Results were summarized by question and synthesized across categories. CPARG contributions included assessing physical activity levels, patterns, forms, and contexts; identifying and measuring physical activity correlates/determinants; and conducting school-based physical activity interventions. Identifying multiple domains of physical activity determinants enables researchers and practitioners to select/design age-appropriate, valid, and reliable instruments to assess determinants. Focusing on determinants enables them to create effective physical activity interventions, environments, programs, and policies in schools. These efforts must address race/ethnicity differences, ensuring that measurement instruments and intervention strategies are culturally appropriate.

Longitudinal association of biological maturation with physical activity behaviors in girls transitioning from 5th to 7th grade.

INTRODUCTION: This longitudinal study determined if social cognitive variables influence physical activity in girls stratified on the basis of maturity status. METHODS: Participants attended South Carolina public schools (Mage in 5th grade = 11.1 years) and included a cohort of 529 girls who provided physical activity data in the 5th grade and in 6th and/or 7th grade. The measure of maturity status was age at peak height velocity (APHV) estimated from maturity offset when the children were in the 5th grade. The Earlier Maturity (EM) group included girls whose APHV was one standard deviation or more below the mean APHV for the full sample. All other girls were placed in the Later Maturity (LM) group. Physical activity was assessed at each time point via accelerometry. Social-cognitive variables were assessed at each time point by a questionnaire measuring self-efficacy, enjoyment, competence, appearance, fitness, and social motives for physical activity. Growth curves for the total, Earlier Maturing, and Later Maturing groups assessed relationships between physical activity over time and time-varying social cognitive variables. RESULTS: Physical activity was lower in the Earlier Maturing group and was positively associated with self-efficacy and enjoyment motivation in the total group. These relationships were observed in the 5th grade and maintained through 7th grade. In the Later Maturing group, we observed positive relationships between physical activity and self-efficacy, enjoyment and competence motivation. CONCLUSIONS: Strategies to increase confidence, skills, and enjoyment of physical activity may only be effective for promoting activity among later maturing girls.

Patterns of age-related change in physical activity during the transition from elementary to high school.

This study was designed: 1) to describe patterns of age-related change in total and moderate-to-vigorous physical activity (MVPA) in children as they transitioned from elementary school to high school, and 2) to determine if those patterns differed across demographic sub-groups formed on the basis of gender, race/ethnicity, parent education (socioeconomic status), and urbanicity. A cohort of children (analysis sample, N = 951) was comprised of students drawn from two public school districts in South Carolina. Physical activity was measured by accelerometry on at least two and up to five occasions between 2010 and 2017. Growth curve analyses were performed to describe the pattern of age-related change in the physical activity variables for the full sample and for demographic sub-groups. A relatively steep age-related decline in total physical activity was observed in children before age 14, with a slower rate after that age. Physical activity was lower in girls than boys, and the age-related rate of decline was steeper in girls. Physical activity patterns did not differ across race/ethnicity groups, but children of parents with less education were more active than children of parents with more education. Children living in rural areas participated in less MVPA than children living in urban settings, and this difference increased with increasing age. These findings indicate that children experience a particularly steep decrease in physical activity as they transition from elementary to middle school, and this trend is particularly prominent in girls, children living in rural areas, and children of parents with college education.

Behavioral, Environmental, and Demographic Factors Associated with Objectively Measured Physical Activity in Infants.

Background: To describe objectively measured physical activity (PA) in infants, and to identify demographic, behavioral, and environmental factors associated with infants' PA. Methods: Participants were 6-7-month-old infants and their mothers (N = 143 dyads) from two Southeastern US counties. Infant measures included PA assessed by accelerometers at ankle and waist sites, motor developmental status (i.e., stationary and locomotion), and anthropometric characteristics (i.e., height and weight). Mothers provided information on home environment, child care settings, and family demographic factors. PA levels were compared across demographic subgroups. Correlation coefficients described associations between PA and continuous variables, including motor developmental status and anthropometric characteristics. Multiple linear regression analyses examined factors found to be independently associated with PA. Results: Infants' PA counts were greater at the ankle (77,700 counts/hr) vs. the waist site (32,500 counts/hr). In univariate analyses, a diverse set of environmental, behavioral, and infant-level demographic factors were found to be significantly associated with PA at the ankle site. Multivariate analyses indicated that more advanced motor development status (B = 666.3 ± 329.8, p < 0.05), attendance at home child care settings (B = -13,724.4 ± 5083.9, p < 0.05), greater exposure to tummy time (B = 213.5 ± 79.9, p < 0.05), and white racial/ethnic composition (B = -19,953.4 ± 5888.5, p < 0.01) were independently, associated with infants' PA. Conclusions: In 6-7-month-old infants, objectively measured PA was found to be associated with motor developmental status and physical and social environmental factors, including both demographic moderators and factors that are influenced by parents and caregivers. Longitudinal studies are needed to determine if these relationships persist or change as infants develop.

Walkability indices and children's walking behavior in rural vs. urban areas.

PURPOSE: This study described associations between selected walk indices (WI) and walking and physical activity behaviors in rural and urban children. FINDINGS: WI were higher in urban environments, yet children from rural areas walked for transportation more than children from urban areas. There was a negative correlation between National WI scores and walking for transportation in urban areas, and between the Frank WI scores and walking for exercise in rural areas. CONCLUSIONS: Indices of walkability are not associated with objectively measured physical activity or self-reported walking behavior in children living in rural and urban settings.

Nighttime sleep and physical activity in 6-7 month-old infants.

This study examined associations between objectively-measured nighttime sleep duration and physical activity in a sample of 6-7 month-old infants (N=93). The study also investigated relationships between infant sleep and demographic and environmental characteristics. Cross-sectional relationships were assessed using linear regression analyses. Nighttime sleep duration was positively associated with physical activity levels. Nighttime sleep duration was greater when infants had a consistent bedtime, slept in a separate room, were male, and had mothers who reported having a college education or greater. These findings can inform the development of interventions that aim to improve infant sleep.

The role of parental support for youth physical activity transportation and community-level poverty in the healthy communities study.

This study evaluates whether parental provision of transportation for physical activity is associated with child/adolescent moderate-to-vigorous physical activity, while also evaluating community-level poverty. Self- and parental-reported surveys were administered with parents/caregivers and children in the Healthy Communities Study (N = 5138). Associations between individual-level demographics, community-level poverty, parental provision of transportation for physical activity, and moderate-to-vigorous physical activity were examined in multi-level models. Even when accounting for community-level poverty, which was significantly associated with lower moderate-to-vigorous physical activity, parental provision of transportation for physical activity was positively associated with greater moderate-to-vigorous physical activity. This study provides evidence for the importance of considering multiple systems of influence (e.g., community and individual factors) and considering how gaps in physical activity transportation for youth can be addressed in future health policies.

Operationalizing and Testing the Concept of a Physical Activity Desert.

BACKGROUND: The prevalence of childhood obesity is higher in economically and socially deprived areas. Higher levels of physical activity reduce the risk of excessive weight gain in youth, and research has focused on environmental factors associated with children's physical activity, though the term "physical activity desert" has not come into wide use. METHODS: This exploratory study operationalized the term "physical activity desert" and tested the hypothesis that children living in physical activity deserts would be less physically active than children who do not. A cross-sectional study design was applied with 992 fifth-grade students who had provided objectively measured physical activity data. Five of 12 possible elements of the built environment were selected as descriptors of physical activity deserts, including no commercial facilities, no parks, low play spaces, no cohesion, and the presence of incivilities. RESULTS: Univariate and multivariate analyses showed that only the absence of parks was associated with less physical activity in children. CONCLUSION: Children living in a "no park" zone were less active than their counterparts who lived near a park. This study contributes preliminary conceptual and operational definitions of "physical activity desert." Future studies of physical activity deserts should be undertaken in larger and more diverse samples.

Associations between three measures of physical activity and selected influences on physical activity in youth transitioning from elementary to middle school.

Measurement of physical activity is challenging, and objective and subjective methods can be used. The purposes of this study were to apply structural equation modeling in: 1) examining the associations between three distinct measures of physical activity and three factors that are often found to be correlated to physical activity in children, and 2) examining the associations of the combination of three measures with the same correlates in a cohort of youth followed from 5th to 7th grade. A total of 409 children (45% boys) had complete physical activity data derived from accelerometers, self-report by youth, and proxy-report by parents. The potential correlates of physical activity included self-efficacy, physical activity support, and facilities for physical activity. Structural equation models were used to assess the relationship between physical activity and the correlates. The structural equation models examining associations between individual measures of physical activity and selected correlates showed that parent-reported and child self-reported physical activity were associated with parental support for physical activity and self-efficacy. Objectively measured physical activity was associated only with facilities for physical activity. A structural equation model showed that a composite expression of physical activity, based on the inclusion of all three individual measures, was associated with all three correlates of physical activity. In conclusion, combining measures of physical activity from different sources may improve the identification of correlates of physical activity. This information could be used to plan more effective physical activity interventions in children and youth.

Neighborhood Socioeconomic Deprivation Associated with Fat Mass and Weight Status in Youth.

(1) Background: Few studies have examined the relationship between neighborhood socioeconomic deprivation (SED) and weight-related outcomes in youth, controlling for weight-related behaviors. Hence, the purpose of this study was to examine the association between neighborhood SED, weight status, and fat mass in a diverse sample of youth, before and after controlling for physical activity and diet. (2) Methods: The sample included 828 youth from the Transitions and Activity Changes in Kids study. Neighborhood SED was expressed as an index score at the census tract of residence. Height, weight, and body composition were measured and used to calculate fat mass index (FMI) and weight status. Moderate-to-vigorous physical activity (MVPA) and sedentary behavior (min/h) were measured via accelerometry. Diet quality was assessed via the Block Food Screener for Kids. Multilevel regression models were employed to examine these relationships. (3) Results: Neighborhood SED was significantly associated with FMI and weight status before and after controlling for MVPA, sedentary behavior, and diet. Notably, youth residing in the most deprived neighborhoods had significantly higher FMI and were 30% more likely to be overweight/obese (OR = 1.30; 95% CI = 1.03-1.65). (4) Conclusions: Greater neighborhood SED was consistently and significantly associated with higher fat mass index and increased likelihood of overweight/obesity among youth.

Personal, Social, and Environmental Influences on Physical Activity in Groups of Children As Defined by Different Physical Activity Patterns.

BACKGROUND: Interventions promoting physical activity (PA) in youth have had limited success, in part because studies with methodological challenges have yielded an incomplete understanding of personal, social, and environmental influences on PA. This study described changes in these factors for subgroups of youth with initially high PA that decreased (Active-Decline) compared with children with initially low PA that decreased (Inactive-Decline) from fifth to ninth grades. METHODS: Observational, prospective cohort design. Participants (n = 625) were fifth-grade children recruited in 2 school districts and followed from elementary to high school. Students and their parents responded to questionnaires to assess personal, social, and perceived physical environmental factors in the fifth (mean age = 10.5 [.5] y) and ninth (mean age = 14.7 [.6] y) grades. Analyses included a mixed-model 2-way repeated analysis of variances. RESULTS: Children in the Active-Decline compared with those in the Inactive-Decline group showed a more favorable profile in 6 of 8 personal variables (perceived barriers, self-efficacy, self-schema, enjoyment, competence, and fitness motives) and 4 of 6 social variables (friend support, parent encouragement, parent support, and parent-reported support). CONCLUSIONS: The results suggest efforts to promote PA should target selected personal, social, and perceived environmental factors beginning before age 10 and continuing through adolescence.

Cross-Country Comparisons of Physical Activity and Sedentary Behavior among 5-Year-Old Children.

PURPOSE: Previous studies have observed that physical activity (PA) levels tend to be lower in the U.S. population than in many other countries. Within the U.S., PA levels in children are lower in the South than in other regions. Cross-country and interregional differences in PA have not been studied in young children. METHODS: In an ongoing study of children at genetic risk for Type 1 diabetes, PA was measured by accelerometry in samples of 5-year-old children (n = 2008) from Finland (n = 370), Germany (n = 85), Sweden (n = 706), and the U.S. (n = 847). The U.S. sample was drawn from centers in Washington State, Colorado, and Georgia/Florida. Children wore accelerometers for 7 days, and the data were reduced to daily minutes of light-, moderate- (MPA), vigorous- (VPA), and moderate-to-vigorous- (MVPA) intensity PA and sedentary behavior. Multiple regression was used to compare children across countries and across regions in the U.S, adjusting for wear time, body mass index, and demographic characteristics. RESULTS: After adjusting for previously mentioned factors, MVPA and MPA were lower in U.S. children than those in Finland and Sweden. Estimates of physical activity were higher in Finland than in other countries, although not all comparisons were significantly different. U.S children spent significantly more time in sedentary behavior than children in Finland (p < 0.0001). Within the U.S., children's PA was consistently lowest in Georgia/Florida and highest in Washington. CONCLUSIONS: Cross-country differences in PA, previously reported for adults and adolescents, are evident in 5-year-old children. In general, PA levels are lower in U.S. children than their European counterparts, and within the U.S., are lower in Georgia/Florida and Colorado than in Washington. Future studies should be designed to identify the factors that explain these differences.

Poverty Status Moderates the Relationship between Cardiorespiratory Fitness and Academic Achievement.

BACKGROUND: The purpose of the study was to examine the associations among cardiorespiratory fitness (CRF), weight status and academic achievement in youth, and to determine if these relationships are moderated by poverty status. METHODS: The sample included 5th (N = 27,791) and 8th grade (N = 16,047) South Carolina students. Academic achievement was assessed using a state-wide assessment and classified into 2 categories (ie, does not meet/approaches standards vs meets/exceeds standards). CRF was assessed and expressed as Healthy Fitness Zone (HFZ) or Needs Improvement/Needs-Improvement-Health Risk. Students' demographics and poverty status were reported. Multilevel logistic regression analyses were used to examine the association between CRF, weight status and academic achievement. Interaction terms were introduced into the final models. Analyses were performed separately by grade level and academic subject. RESULTS: The CRF was significantly associated with the odds of meeting/exceeding academic standards after controlling for covariates and adjusting for weight status. The relationship between CRF and academic achievement varied significantly by poverty status. After adjustment for CRF, weight status was not significantly associated with academic achievement. CONCLUSIONS: The odds of achieving academic standards were significantly higher among students achieving CRF HFZ regardless of poverty status. CRF may partially mitigate the adverse effect of poverty on academic achievement.

Linking Activity, Nutrition, and Child Health (LAUNCH): protocol for a longitudinal cohort study of children as they develop from infancy to preschool age.

BACKGROUND: Physical activity is known to provide important health benefits in children ages 3 years and above, but little is known about the effects of physical activity on health in very young children under age 3. LAUNCH (Linking Activity, Nutrition, and Child Health) is a study designed to expand the body of knowledge on development of physical activity behavior and associations between physical activity and other health characteristics as children transition from infancy to preschool age. METHODS: Physical activity and sedentary behavior will be measured objectively in young children over a period of 30 months. Each child will complete a measurement protocol at 6, 12, 18, 24, 30 and 36 months of age. The following factors will be measured at each time point: physical activity, sedentary behavior, anthropometric characteristics, and motor developmental status. Objectively-measured sleep behavior will be included as an optional component of the protocol. Parents will provide information on demographic factors, parenting behaviors, home and childcare characteristics, and the child's dietary and sleep behaviors. DISCUSSION: LAUNCH will employ a longitudinal study design and objective measures of physical activity, sedentary behavior and sleep in examining developmental trends for those characteristics in children between the ages of 6 and 36 months. Associations among physical activity, sedentary behavior, sleep, and weight status will be examined. Findings will inform public health guidance and intervention strategies for very young children.

Changes in Diet Quality in Youth Living in South Carolina From Fifth to 11th Grade.

OBJECTIVE: To examine diet quality levels and changes in a diverse sample of youth from fifth to 11th grade, and interactions by race/ethnicity and socioeconomic status. DESIGN: Transitions and Activity Changes in Kids prospective cohort study. SETTING: Elementary, middle, and high schools in South Carolina. PARTICIPANTS: A sample of 260 fifth-graders (106 boys and 154 girls) with complete data at baseline and at least 1 time point each in middle school and in high school. MAIN OUTCOME MEASURE: Dietary intake assessed with the Block Food Screener for Kids (last week). Diet quality was assessed using energy-adjusted intakes of 5 food groups. ANALYSIS: Descriptive statistics and growth curve models for the total group and by gender for diet quality from fifth to 11th grade (P < 0.05). RESULTS: Both boys and girls had low levels of diet quality, which continued to decline through 11th grade. Significant main effects by race and poverty as well as a race by poverty interaction were observed. CONCLUSIONS AND IMPLICATIONS: Programs and policies that support healthy dietary patterns in children transitioning from elementary to middle and high school are needed. Specific efforts that focus on nutrition disparities in children from low-income and minority backgrounds are warranted.