Comparison of raw accelerometry data from ActiGraph, Apple Watch, Garmin, and Fitbit using a mechanical shaker table.

The purpose of this study was to evaluate the reliability and validity of the raw accelerometry output from research-grade and consumer wearable devices compared to accelerations produced by a mechanical shaker table. Raw accelerometry data from a total of 40 devices (i.e., n = 10 ActiGraph wGT3X-BT, n = 10 Apple Watch Series 7, n = 10 Garmin Vivoactive 4S, and n = 10 Fitbit Sense) were compared to reference accelerations produced by an orbital shaker table at speeds ranging from 0.6 Hz (4.4 milligravity-mg) to 3.2 Hz (124.7mg). Two-way random effects absolute intraclass correlation coefficients (ICC) tested inter-device reliability. Pearson product moment, Lin's concordance correlation coefficient (CCC), absolute error, mean bias, and equivalence testing were calculated to assess the validity between the raw estimates from the devices and the reference metric. Estimates from Apple, ActiGraph, Garmin, and Fitbit were reliable, with ICCs = 0.99, 0.97, 0.88, and 0.88, respectively. Estimates from ActiGraph, Apple, and Fitbit devices exhibited excellent concordance with the reference CCCs = 0.88, 0.83, and 0.85, respectively, while estimates from Garmin exhibited moderate concordance CCC = 0.59 based on the mean aggregation method. ActiGraph, Apple, and Fitbit produced similar absolute errors = 16.9mg, 21.6mg, and 22.0mg, respectively, while Garmin produced higher absolute error = 32.5mg compared to the reference. ActiGraph produced the lowest mean bias 0.0mg (95%CI = -40.0, 41.0). Equivalence testing revealed raw accelerometry data from all devices were not statistically significantly within the equivalence bounds of the shaker speed. Findings from this study provide evidence that raw accelerometry data from Apple, Garmin, and Fitbit devices can be used to reliably estimate movement; however, no estimates were statistically significantly equivalent to the reference. Future studies could explore device-agnostic and harmonization methods for estimating physical activity using the raw accelerometry signals from the consumer wearables studied herein.

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.

Development and Calibration of a PATCH Device for Monitoring Children's Heart Rate and Acceleration.

INTRODUCTION: Current wearables that collect heart rate and acceleration were not designed for children and/or do not allow access to raw signals, making them fundamentally unverifiable. This study describes the creation and calibration of an open-source multichannel platform (PATCH) designed to measure heart rate and acceleration in children ages 3-8 yr. METHODS: Children (N = 63; mean age, 6.3 yr) participated in a 45-min protocol ranging in intensities from sedentary to vigorous activity. Actiheart-5 was used as a comparison measure. We calculated mean bias, mean absolute error (MAE) mean absolute percent error (MA%E), Pearson correlations, and Lin's concordance correlation coefficient (CCC). RESULTS: Mean bias between PATCH and Actiheart heart rate was 2.26 bpm, MAE was 6.67 bpm, and M%E was 5.99%. The correlation between PATCH and Actiheart heart rate was 0.89, and CCC was 0.88. For acceleration, mean bias was 1.16 mg and MAE was 12.24 mg. The correlation between PATCH and Actiheart was 0.96, and CCC was 0.95. CONCLUSIONS: The PATCH demonstrated clinically acceptable accuracies to measure heart rate and acceleration compared with a research-grade device.

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.

Policies, Practices, and Environmental Characteristics Among Family Child Care Homes in South Carolina.

Background: Child care program requirements have adopted nutrition and physical activity standards to address childhood obesity, but few studies have examined the effects of these standards in family child care homes (FCCHs). Methods: In a cross-sectional study (2017-2019), the Childcare Home Eating and Exercise study examined self-reported provider characteristics and observed policies and practices related to physical activity and nutrition in FCCHs in South Carolina. Two-sample t-tests were used to compare observed nutrition and physical activity policy, practice, and environment scores in child care homes that participated in versus did not participate in the state's ABC Quality program, which is designed to improve child care and includes policies and practices intended to increase physical activity levels and improve diet quality. Results: Environment and Policy Assessment and Observation results for nutrition and physical activity were 7.5 out of 21 and 11.8 out of 30, respectively, indicating much room for improvement in nutrition and physical activity policies, practices, and environment in South Carolina FCCHs. The study found one difference between FCCHs that did and did not participate in the ABC Quality program; non-ABC homes provided more time for physical activity. Conclusions: Future research should develop ways to strengthen the guidelines and improve the implementation of obesity prevention standards in FCCHs.

Household Food Insecurity Is Associated With Physical Activity in Youth and Young Adults With Diabetes: A Cross-Sectional Study.

BACKGROUND: Physical activity (PA) is essential for optimal diabetes management. Household food insecurity (HFI) may negatively affect diabetes management behaviors. The purpose of this study was to cross-sectionally examine the association between HFI and PA in youth and young adults (YYA) with type 1 (N = 1998) and type 2 (N = 391) diabetes from the SEARCH for Diabetes in Youth Study. METHODS: HFI was measured with the US Household Food Security Survey Module. PA was measured with the International Physical Activity Questionnaire Short Form. Walking, moderate-intensity PA (excluding walking), vigorous-intensity PA, moderate- to vigorous-intensity PA, and total PA were estimated as minutes per week, while time spent sitting was assessed in minutes per day. All were modeled with median regression. Meeting PA guidelines or not was modeled using logistic regression. RESULTS: YYA with type 1 diabetes who experienced HFI spent more time walking than those who were food secure. YYA with type 2 diabetes who experienced HFI spent more time sitting than those who were food secure. CONCLUSIONS: Future research should examine walking for leisure versus other domains of walking in relation to HFI and use objective PA measures to corroborate associations between HFI and PA in YYA with diabetes.

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.

Factors Associated with Children's Physical Activity During Youth Soccer Practices.

Purpose: To identify practice and social contextual factors that associate with physical activity (PA) levels of children during their participation in a youth soccer program. Methods: Twenty-seven youth soccer teams serving children ages 6-11 years participated. Research staff directly observed and recorded PA intensity and practice and social contextual factors using momentary time-sampling procedures. Each team was observed for 1 practice, during which approximately 6 children were each observed for twenty 30-s observation blocks (10-s observation, 20-s recording). In total, children were observed for 3,102 intervals. Multilevel logistic regression analyses were conducted to describe associations between PA intensity and practice and social contexts. Interaction terms were introduced into the models to determine if the associations differed across girls-only, boys-only, and coed teams. Results: A total of 158 children were observed across the 27 teams. Children were more likely to engage in moderate or vigorous PA while performing fitness (Odds Ratio [OR], 9.9, 95% CI = 5.34-18.04), game (OR, 4.0, 95% CI = 2.88-5.66), warm-up (OR, 2.8, 95% CI = 1.85-4.11), and drill (OR, 1.9, 95% CI = 1.41-2.67) activities compared to tactic/instructional activities. The associations between PA intensity levels and practice and social contexts did not differ across girls-only, boys-only, and coed teams. Conclusions: Fitness activities and full-team game play were associated with higher PA intensity levels during children's participation in youth soccer practices. Youth sport practice protocols can be modified to increase children's physical activity.

Young Children's Dietary Quality in Family Child Care and in Their Own Home.

BACKGROUND: Some evidence suggests that children may have higher quality dietary intake in early care and education settings, compared with their respective homes, but no studies have explored these differences among children in less formal family child care. OBJECTIVE: The purpose of this study was to compare dietary quality via the Healthy Eating Index 2015 among children in family child care and in their own home. DESIGN: This was a cross-sectional analysis of baseline dietary intake data from the Childcare Home Eating and Exercise Research study, a natural experiment, using directly observed dietary data in child care and 24-hour recall data in homes among children in South Carolina. PARTICIPANTS/SETTING: Participants were 123 children in 52 family child-care homes between 2018 and 2019. MAIN OUTCOME MEASURE: The main outcome was total and component Healthy Eating Index 2015 scores. STATISTICAL ANALYSIS: The analysis was a hierarchical linear regression of children nested within family child care homes adjusting for child, provider, facility, and parent characteristics, including sex, age, race, ethnicity, and income, with parameters and SEs estimated via bootstrap sampling. RESULTS: Children had a mean ± SD Healthy Eating Index 2015 score of 60.3 ± 12.1 in family child-care homes and 54.3 ± 12.9 in their own home (P < 0.001). In adjusted analysis and after accounting for clustering of children in family child care homes, total HEI-2015 scores were lower at home than in care (ß = -5.18 ± 1.47; 95% CI -8.05 to -2.30; P = 0.003). CONCLUSIONS: Children had healthier dietary intake in family child-care homes vs their respective homes.

Physical activity in infancy and early childhood: a narrative review of interventions for prevention of obesity and associated health outcomes.

In the context of the childhood obesity epidemic, this narrative review aims to explore opportunities to promote physical activity (PA) between birth and age 5 years as well as the health outcomes associated with PA in early childhood. Although early childhood is an ideal time to promote healthy habits, guidelines for PA have often ignored early childhood given the limited evidence for children <5 years old. Herein we discuss and highlight infant, toddler and preschool age interventions to promote PA and prevent obesity both in the short and long-term. We describe novel and modified interventions to promote improved early childhood health outcomes, encompassing cardiorespiratory, muscle, and bone strengthening components necessary for short-term motor development and long-term health. We call for new research aimed at developing and testing innovative early childhood interventions that may be performed in home or childcare settings, monitored by parents or caregivers.

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.

An Assessment of State-Level Planning for Physical Activity Promotion in the United States.

The prevalence and attributable risk of disease due to physical inactivity require it to be made a public health priority. Public health planning allows for prioritization and resource allocation, particularly at the state and local levels. The extent to which state planning efforts for physical activity exist in the United States is unknown. The purpose of this paper is to describe the scope in which physical activity is incorporated in state-level public health plans in the United States, with an emphasis on alignment with the national guidelines and the National Physical Activity Plan. A standardized internet search audit was developed and conducted for each of 50 US states and the District of Columbia between May 2017 and January 2018 to determine the prevalence and characteristics of health planning documents that include physical activity. Data abstracted for analysis used a standardized search protocol that included the components of the Physical Activity Guidelines for Americans and the US National Physical Activity Plan. Results found that most states had between 4 and 6 chronic disease prevention and control plans that mention physical activity; however, it was inconsistently aligned with recommendations from both the Guidelines and the National Plan. Only 2 states had stand-alone public health planning documents explicitly dedicated to physical activity promotion. No state planning documents addressed children and adolescents, adults, and older adults simultaneously. To be maximally effective, state public health planning for physical activity should be made a priority and these efforts should align as much as possible with current guidance from the Physical Activity Guidelines for Americans and the US National Physical Activity Plan.

Longitudinal associations between sleep and weight status in infants and toddlers.

BACKGROUND: The limited research assessing relationships between sleep duration and weight status in infants and toddlers relies primarily on parent-reported sleep and cross-sectional studies. OBJECTIVES: Examine whether average sleep duration and changes in sleep duration among 6-24-month-old children were associated with weight-for-length z-scores, and whether these associations varied by race/ethnicity, socioeconomic status and sex. METHODS: Data were collected when children were approximately 6, 12, 18 and 24 months old (N = 116). Sleep duration was measured using actigraphy. Weight-for-length z-scores were calculated using children's height and weight. Physical activity was assessed using accelerometry. Diet was assessed using a feeding frequency questionnaire. Demographic characteristics included sex, race/ethnicity and socioeconomic status. Separate associations of between- and within-person changes in sleep duration were estimated with weight-for-length z-score treated as the outcome variable in linear mixed model analyses. Additional models were assessed that included interactions between sleep and demographic characteristics. RESULTS: At time points where children slept longer at night compared to their own average, their weight-for-length z-score was lower. This relationship was attenuated by physical activity levels. CONCLUSIONS: Increasing sleep duration can improve weight status outcomes in very young children who have low physical activity levels.

Buffering effects of protective factors on light and moderate-to-vigorous physical activity among african american women.

Physical activity (PA) plays an integral role in reducing risk for the leading causes of death and has also been shown to buffer stress. Based on the stress-buffering hypothesis, the present study examined whether protective factors (self-efficacy and informal social control) buffered the effects of perceived stress on PA over time. Secondary data analyses of female African American caregivers (N = 143) were conducted using data from the Families Improving Together (FIT) trial. Validated measures of stressors and protective factors were assessed at baseline. Light PA and moderate-to-vigorous PA were assessed using seven-day accelerometry estimates over sixteen weeks. Multilevel growth modeling was used to assess whether protective factors moderated the effects of perceived stress on PA outcomes across 16 weeks. There was a significant two-way interaction between informal social control and time (B = 0.40, SE = 0.17, p = .019) such that higher informal social control was positively associated with MVPA over time. There was a marginal three-way interaction (B = -18.90, SE = 10.31, p = .067) such that stress was associated with greater LPA at baseline under conditions of high but not low self-efficacy. This study provides preliminary support that social factors may be important for maintaining MVPA regardless of stress levels, while cognitive resources may be more important to target for influencing LPA engagement under conditions of high stress.

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.

Exercise and Cardiovascular Disease Risk Factors in Children and Adolescents With Obesity: A Systematic Review With Meta-Analysis of Randomized Controlled Trials.

The purpose of this study was to examine the effects of exercise on cardiovascular disease (CVD) risk factors in children and adolescents with obesity. Randomized controlled trials (RCTs) of exercise ≥4 weeks in children and adolescents with obesity were included if one or more CVD risk factors were included as an outcome. Studies were retrieved by searching 7 electronic databases, cross-referencing, and expert review. Data were pooled using the inverse-variance heterogeneity (IVhet) model and strength of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) instrument. Thirty-nine studies representing 1548 participants (847 exercise, 701 control) met the inclusion criteria. Aerobic exercise improved 10 of 12 (83.3%) outcomes (P < .05 for all) while combined aerobic and strength training improved 5 of 8 (62.5%) outcomes (P < .05 for all). The strength of evidence ranged from "very low" to "moderate." It was concluded that aerobic exercise, as well as combined aerobic and strength training, is associated with improvements in multiple CVD risk factors among children and adolescents with obesity. However, the generally low strength of evidence suggests a need for future well-designed and conducted RCTs on the effects of exercise, especially strength training, in children and adolescents with obesity.