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.

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.

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.

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.

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.

Raising an Active and Healthy Generation: A Comprehensive Public Health Initiative.

Physical activity (PA) provides important health benefits to youth, but most U.S. children and adolescents fail to meet federal PA guidelines. The purpose of this article is to present a plan for a large-scale public health initiative aimed at producing population-level increases in PA among U.S. youth.

Group-based physical activity trajectories in children transitioning from elementary to high school.

BACKGROUND: Physical activity has been observed repeatedly to decline as children transition into adolescence; however, few studies have explored the possibility that sub-groups of children experience unique patterns of change during this transition. The purpose of this longitudinal study was to examine the physical activity trajectories in clusters of youth transitioning from 5th to 11th grade. METHODS: Participants (n = 652) were recruited as 5th graders (ages 10-12 years) from elementary schools (n = 21) in two school districts. Demographic, anthropometric, and physical activity data were collected once per year when children were in 5th, 6th, 7th, 9th, and 11th grades. Children wore accelerometers for 7 consecutive days. Group-based trajectory modeling statistical techniques were applied to identify patterns of physical activity trajectories. Posterior probabilities confirmed participants' membership in their respective group. RESULTS: Three distinct physical activity trajectories were identified. Group 1 (n = 27) remained highly active over time, and physical activity increased from ages 14 to 16 years. Group 2 (n = 365) was active at baseline, but activity declined and remained low as group members aged. Group 3 (n = 260) had the lowest levels of physical activity at all ages, and activity declined from ages 10 to 16 years. CONCLUSIONS: While most children experienced a decline in physical activity as they transitioned into high school, some remained highly active and increased their level of physical activity. Future studies should test physical activity interventions for youth that are tailored for age-related trajectory groups.

Role of Organizational Support on Implementation of an Environmental Change Intervention to Improve Child Fruit and Vegetable Intake: a Randomized Cross-Over Design.

Little is known about the role of organizational or administrative support in implementation of health promotion interventions, particularly outside of school settings. The purpose was to determine the change in fruit and vegetable (FV) intake among children living in residential children's homes (RCHs) and assess the relationships among change in organizational support, intervention implementation, and child nutrition outcomes. Data were collected from 29 RCHs and 614 children living in RCHs, as part of a group randomized design with delayed intervention, at three cross-sectional waves: 2004, 2006, and 2008. RCH staff made environmental changes to increase intake of FV. Implementation and organizational support data were collected from staff at the RCHs. Child FV intake were measured via 24-h dietary recalls. A two-way (condition by time) repeated measures ANOVA was conducted to test whether FV intake increased in response to the intervention. A two-level path analysis with a robust maximum likelihood estimator was used to explore the relationships among organizational support, intervention implementation fidelity, and child FV intake. There was a significant increase in FV intake within all RCHs from 2004 to 2006 (P = 0.022 for the intervention group, P = 0.015 for the control group). This increase was maintained in both groups from 2006 to 2008 (post-intervention mean servings: intervention = 3.2 vs control = 3.4). Increases in organizational support resulted in greater overall implementation fidelity. When RCH staff, supervisors, and the RCH CEO were perceived to be supportive of the intervention, more environmental changes were made to encourage eating FV. Fostering organizational support may improve implementation of interventions.

How Does the Relationship Between Motor Skill Performance and Body Mass Index Impact Physical Activity in Preschool Children?

PURPOSE: To determine if weight status modifies the relationship between motor skill (MS) performance and physical activity (PA) in preschoolers. METHODS: Preschoolers (N = 227, age 3-5 y) were recruited from 22 preschools. Preschoolers' MS (locomotor, object control, and total MS) were assessed with the Children's Activity and Movement in Preschool Study MS protocol. PA was measured by accelerometry. Mixed linear models were used to examine the relationship of MS performance and body mass index (BMI) z score to PA. Models were adjusted for age, race, sex, and parent education, with preschool as a random effect. RESULTS: There was a significant correlation between MS performance and PA (r = .14-.17, P < .05). A significant interaction was observed between BMI z score and object control, and between BMI z score and total MS score on PA (P = .03). Preschoolers with higher BMI z scores and high object control scores engaged in significantly (P = .03) more PA than preschoolers with lower BMI z scores and high object control scores (PA = 15.04 min/h and 13.54 min/h, respectively). Similarly, preschoolers with higher BMI z scores and high total MS scores spent significantly (P = .01) more time in PA compared with those with lower BMI z scores and high total MS scores (PA = 15.65 min/h and 13.91 min/h, respectively). CONCLUSION: Preschool children's MS performance is positively correlated with PA, and BMI z score modified the relationship between MS performance and PA.

Effects of a New State Policy on Physical Activity Practices in Child Care Centers in South Carolina.

OBJECTIVES: We sought to determine the extent to which child care centers in South Carolina improved physical activity practices after a new policy took effect. METHODS: In 2012, South Carolina adopted new mandatory physical activity standards within its child care quality enhancement program. This quasi-experimental study used North Carolina, a state not making policy changes, as the comparison. Participants were 34 child care centers in South Carolina and 30 centers in North Carolina. Researchers used the Environment and Policy Assessment and Observation (EPAO) tool to conduct center observations before and after policy implementation and then conducted repeated-measures linear regression with interaction between state and time for the Physical Activity Environment Total Score and the 8 subscale scores. RESULTS: Compared with centers in North Carolina, EPAO subscale scores in South Carolina centers increased significantly for the Fixed Play Environment (P < .001) and Physical Activity Training and Education (P = .015). The state-by-time interaction of Physical Activity Environment Total Score approached statistical significance (P = .06). CONCLUSIONS: Adoption of new physical activity standards in South Carolina child care centers was associated with improvements in practices aimed at increasing children's physical activity.

Associations Between Maternal Support and Physical Activity Among 5th Grade Students.

BACKGROUND: A large body of research has established an association between parental support for children's physical activity (PA) and children's PA. However, there has been little attention to the relative influences of parent and child perceptions of that parental support. PURPOSE: To examine agreement among parent and child perceptions of parent support for PA and whether these perceptions are associated with objectively-measured moderate-to-vigorous physical activity (MVPA) among those children. METHODS: Cross-sectional associations between PA of children measured via accelerometers and child-reported and mother-reported perceptions of parental support for children's PA were assessed via mixed-model regression analyses in a cohort of 693 5th graders. Results Children's perceptions of parental support for PA were consistent with those of their mothers. Nonetheless, in models that included both children's and mothers' perceptions of parental support for PA, mothers' perceptions, but not children's perceptions, were significantly associated with children's PA. Associations were consistent for Total MVPA, After School MVPA, and Evening MVPA, with stronger associations among males than among females. CONCLUSION: Maternal support may influence children's PA. Studies which consider only children's accounts of parental support may overlook important mechanisms.

Creating a Physical Activity Self-Report Form for Youth Using Rasch Methodology.

Measurement of youth's physical activity levels is recommended to ensure that children are meeting recommended activity guidelines. This article describes the creation of an instrument to measure youth's levels of physical activity, where a strong test validation perspective (Benson, 1998) was followed to create the scale. The development process involved a mixed-method (qualitative followed by quantitative) framework. First, focus groups were conducted, where results informed item creation. Next, three alternative forms were created with different response formats to measure childrens' frequency of participation in various physical activities and intensity of participation. Lastly, a sample of over 500 middle school children was obtained, where three different response scales were investigated. The optimal scale considered measurement of physical activity using a three-point Likert frequency; intensity of activity participation did not strongly contribute to the measurement of children's activity levels. The final version form is thought to be acceptable for use with children in surveillance and large-group studies, as well as in smaller sample applications.

Policies for promotion of physical activity and prevention of obesity in adolescence.

Obesity rates among children and adolescents in developed countries have increased dramatically since the 1970s. During that same period, numerous secular changes have combined to reduce the demand for physical activity in day-to-day life, and many barriers to physical activity are now evident. As a consequence, most children and adolescents do not meet the accepted public health guidelines for physical activity. Accordingly, public health interventions are needed to increase physical activity in adolescence. Such interventions, if successfully implemented, can be expected to improve fitness and health as well as reduce the prevalence of overweight and obesity in young people. Promotion of physical activity in populations of children and adolescents will require comprehensive strategic planning and adoption of new policies in multiple societal sectors. This paper highlights nine initiatives that can address the problem of physical activity in children. The initiatives are to: establish comprehensive school physical activity programming; demand high quality physical education; require physical activity in early child care and education; require physical activity in afterschool programs; create equity in community resources; activate youth sports programs; re-normalize active transport to school; institutionalize clinic-based physical activity assessment and counseling; and build activity-friendly homes. A case will be made for comprehensive national and international strategic planning aimed at effective and large-scale implementation of these initiatives and tactics.

Associations Between Home Environment and After-School Physical Activity and Sedentary Time Among 6th Grade Children.

This study examined associations of various elements of the home environment with after-school physical activity and sedentary time in 671 6th-grade children (Mage = 11.49 ± 0.5 years). Children's after-school total physical activity, moderate-to-vigorous physical activity, and sedentary time were measured by accelerometry. Parents completed surveys assessing elements of the home social and physical environment. Mixed-model regression analyses were used to examine the associations between each element of the home environment and children's after-school physical activity and sedentary time. Availability of home physical activity resources was associated positively with after-school total physical activity and negatively with after-school sedentary time in boys. Parental support was associated positively with after-school total physical activity and MVPA and negatively with after-school sedentary time in girls. The home physical environment was associated with boys' after-school physical activity and sedentary time, whereas the home social environment was associated with girls' after-school physical activity and sedentary time.

Perceptions of the Neighborhood Environment and Children's Afterschool Moderate-to-Vigorous Physical Activity.

Previous research suggests the neighborhood environment may be an important influence on children's physical activity (PA) behaviors; however, findings are inconsistent. The purpose of this study was to further understand the relationship between perceptions of the neighborhood environment and children's afterschool moderate-to-vigorous PA. Utilizing a structural equation modeling technique, we tested a conceptual model linking parent and child perceptions of the neighborhood environment, parent support for PA, and child outdoor PA with children's afterschool moderate-to vigorous PA. We found that child perception of the neighborhood environment and outdoor PA were positively associated with afterschool moderate-to-vigorous PA. In addition, parent support for PA positively influenced children's outdoor PA. The neighborhood environment and outdoor activity appear to play an influential role on children's afterschool PA behaviors.

Assessing preschool children's physical activity: how many days of accelerometry measurement.

The purpose of this study was to determine the minimum number of days of accelerometry required to estimate accurately MVPA and total PA in 3- to 5-year-old children. The study examined these metrics for all days, weekdays, and in-school activities. Study participants were 204 children attending 22 preschools who wore accelerometers for at least 6 hr per day for up to 12 days during most waking hours. The primary analysis considered the intraclass correlation coefficient (ICC) for each metric to estimate the number of days required to attain a specified reliability. The ICC estimates are 0.81 for MVPA-all days, 0.78 for total PA-all days, 0.83 for MVPA weekdays, 0.80 for total PA-weekdays, 0.81 for in-school MVPA, and 0.84 for in-school total PA. We recommend a full seven days of measurement whenever possible, but researchers can achieve acceptable reliability with fewer days, as indicated by the Spearman-Brown prophecy: 3-4 days for any weekday measure and 5-6 days for the all-days measures.

Child and mother characteristics associated with 6-month weight gain for infants and toddlers during 6 to 36 months.

BACKGROUND: The prevalence of childhood obesity in the U.S. has increased, likely due to decreased physical activity, increased sedentary behaviour and unhealthy diets. Little is known about the relationships between these factors and weight gain in those under the age of three. OBJECTIVES: This study aimed to understand the longitudinal associations of weight gain over 6-month intervals with child and parent characteristics as children develop from 6 to 36 months. METHODS: Mother and infant data were collected at 6-month intervals from 6 to 36 months. Weight (kg) was the primary outcome variable, and potential explanatory variables included child and parent characteristics, physical activity, motor development, diet and sleep. Structural equation modelling was used to assess associations between explanatory variables and 6-month weight gain. RESULTS: Weight increased ~1 kg per 6-month interval (p < 0.001) from 6 to 36 months. Childcare outside of the home at 12 months was associated with 0.272 kg (p = 0.002) greater weight gain at 18 months, while children's physical activity was associated with 0.228 kg (per 2 SD, p = 0.051) less weight gain during the same time period. Mother's TV and screen media use (0.102 kg per hour/day, p = 0.046) and child's intake of high-energy beverages at 18 months (0.387 kg, p = 0.037) were both associated with greater weight gain at 24 months. CONCLUSION: Childcare, physical activity, screen media use and high-energy beverage consumption might affect weight gain at different time points in early childhood. These insights can inform efforts to prevent excessive weight gain and childhood obesity effectively.

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 to 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.

Construct validity of selected measures of physical activity beliefs and motives in fifth and sixth grade boys and girls.

OBJECTIVE: Scales used to measure selected social-cognitive beliefs and motives for physical activity were tested among boys and girls. METHODS: Covariance modeling was applied to responses obtained from large multi-ethnic samples of students in the fifth and sixth grades. RESULTS: Theoretically and statistically sound models were developed, supporting the factorial validity of the scales in all groups. Multi-group longitudinal invariance was confirmed between boys and girls, overweight and normal weight students, and non-Hispanic black and white children. The construct validity of the scales was supported by hypothesized convergent and discriminant relationships within a measurement model that included correlations with physical activity (MET • min/day) measured by an accelerometer. CONCLUSIONS: Scores from the scales provide valid assessments of selected beliefs and motives that are putative mediators of change in physical activity among boys and girls, as they begin the understudied transition from the fifth grade into middle school, when physical activity naturally declines.

Study of Health and Activity in Preschool Environments (SHAPES): study protocol for a randomized trial evaluating a multi-component physical activity intervention in preschool children.

BACKGROUND: Physical inactivity is a recognized public health concern. Inadequate proportions of children in the U.S, including those of preschool age, are meeting physical activity recommendations. In response to low numbers of preschool children attaining appropriate physical activity levels, combined with the large number of young children who attend preschool, researchers have identified the need to devise interventions to increase physical activity at preschools. However, few multi-component interventions to increase physical activity in preschool children exist. The aims of this study were to observe the effects of a multi-component intervention on physical activity, sedentary behavior, and physical activity energy expenditure in 3-5 year-old children; identify factors that associate with change in those variables; and evaluate the process of implementing the multi-component intervention. The purpose of this manuscript is to describe the study design and intervention protocol. METHODS/DESIGN: The overall design of the Study of Health and Activity in Preschool Environments (SHAPES) was a two-year randomized trial (nested cohort design), with two conditions, two measurement occasions, and preschool serving as the unit of analysis. Sixteen schools (eight intervention and eight control) were enrolled. The intervention protocol was based on the social ecological model and included four main components: (a) indoor physical activity ("move inside"), (b) recess ("move outside"), (c) daily lessons ("move to learn"), and (d) social environment. Components were implemented using teacher and administrator trainings and workshops, site support visits, newsletters, and self-monitoring methods. Outcomes included accelerometer assessment of physical activity, sedentary behavior, and physical activity energy expenditure; weight status; and demographic factors; family/home social and physical environment; and parental characteristics. An extensive process evaluation battery was also used to monitor dose delivered by interventionists, completeness of intervention component delivery by teachers, and fidelity of teachers' implementation. DISCUSSION: The study will address important gaps relative to increasing physical activity in preschool children. Few studies to date have incorporated a multi-component approach, rigorous measurement protocol, and thorough evaluation of intervention implementation.