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 (β = -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.

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.

The association of physical activity to oral glucose tolerance test outcomes in multiple autoantibody positive children: The TEDDY Study

OBJECTIVE

To examine the association of physical activity (PA), measured by accelerometry, to hemoglobin AIC (HbA1c) and oral glucose tolerance test (OGTT) outcomes in children who were multiple persistent confirmed autoantibody positive for type 1 diabetes (T1D).

METHODS

The Environmental Determinants of Diabetes in the Young (TEDDY) multinational study followed children from birth. Children ≥3 years of age who were multiple persistent confirmed autoantibody positive were monitored by OGTTs every 6 months. TEDDY children's PA was measured by accelerometry beginning at 5 years of age. We examined the relationship between moderate plus vigorous (mod + vig) PA, HbA1c, and OGTT in 209 multiple autoantibody children who had both OGTT and PA measurements.

RESULTS

Mod + vig PA was associated with both glucose and C-peptide measures (fasting, 120-min, and AUC); higher mod + vig PA was associated with a better OGTT response primarily in children with longer duration of multiple autoantibody positivity. Mod + vig PA also interacted with child age; lower mod + vig PA was associated with a greater increase in C-peptide response across age. Mod + vig PA was not related to fasting insulin, HOMA-IR or HbA1c.

CONCLUSIONS

The OGTT is the gold standard for diabetes diagnosis and is used to monitor those at high risk for T1D. We found higher levels of mod + vig PA were associated with better OGTT outcomes in children ≥5 years of age who have been multiple autoantibody positive for longer periods of time. Physical activity should be the focus of future efforts to better understand the determinants of disease progression in high-risk children.

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.

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.

An observation system to assess physical activity of children with developmental disabilities and delays in preschool

BACKGROUND

Physical activity (PA) behaviors during preschool settings can influence the health and development of children with developmental disabilities (DD). There is a need for a direct observation system that simultaneously assesses PA and preschool environmental contexts.

OBJECTIVE

The purpose of this study was to develop an observation instrument for measuring PA and related contextual factors of preschoolers with DD, and to establish content validity and reliability.

METHODS

Content validity was established through consultation with experts, informal observations in inclusive and special education preschools, and literature reviews. Categories and codes were identified and modified from existing observational systems for young children. Reliability was assessed in a convenience sample of preschool children with DD using a cross-sectional design. Data were collected using a momentary time sampling system (5-sec observe, 25-sec record) following a focal child. Inter-rater reliability was assessed during 20% of the observation sessions.

RESULTS

The instrument development process resulted in ten coding categories that accounted for PA levels, types, and social and physical environmental contexts relevant to preschoolers with disabilities. Observers completed 137.5 observation sessions, yielding 5498 30-s observation intervals. Interval-by-interval percent agreement was excellent (91%-100%) and kappa values were high (0.82-0.99).

CONCLUSIONS

The instrument was found to be a reliable measure of PA of preschoolers with DD and provided important contextual information about PA behaviors in early childhood special education settings. Additionally, it allowed for the simultaneous measurement of specific types and contexts of PA behaviors of preschoolers with DD and will be useful for describing PA and informing future interventions.

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.

Self-efficacy, beliefs, and goals: Moderation of declining physical activity during adolescence

OBJECTIVE

To examine whether the decline in physical activity observed from childhood through adolescence is explained by moderating effects of self-efficacy on concurrent changes in children's goals and beliefs about their physical activity environments.

METHOD

Latent growth modeling was used in longitudinal tests in a cohort of 79 boys and 108 girls assessed in 5th, 6th, 7th, 9th, and 11th grades.

RESULTS

Physical activity measured objectively by an accelerometer declined most in students who had bigger declines in self-efficacy and (1) maintained higher perceptions of barriers to physical activity, (2) had bigger declines in enjoyment and fitness goals, or (3) had smaller declines in appearance and social goals.

CONCLUSIONS

Trials of physical activity interventions based on social-cognitive theory should consider that the influence of changing goals on physical activity may differ according to whether students maintain high efficacy beliefs about overcoming barriers to physical activity coincident with perceptions of their physical activity environment. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Moderating effect of the neighbourhood physical activity environment on the relation between psychosocial factors and physical activity in children: a longitudinal study

Background

Few studies have examined the moderating role of neighbourhood environments on the relation between psychosocial factors and physical activity, and results of these studies are mixed. This study examined this relationship in 636 fifth to seventh graders from South Carolina, USA.

Methods

From 2010 to 2013, children and their parent/guardian completed annual self-reported surveys assessing psychosocial factors, and children wore accelerometers for 1 week each year. Neighbourhood environments were classified as supportive or non-supportive for physical activity (PA) based on in-person audits of facilities near children’s homes and windshield surveys of children’s streets. Growth curve analyses were completed to assess the moderating effect of the neighbourhood physical activity environment (NPAE) on the relation between psychosocial factors and total physical activity (TPA) over time.

Results

Significant interactions on TPA were found for (1) time, NPAE and parent-reported parent support for PA; (2) time, NPAE and child-reported equipment in the home; (3) child-reported parental support for PA and time; (4) child-reported parental support for PA and NPAE; (5) PA self-schema and time and (6) child-reported parental encouragement and time. Parental support and a supportive NPAE were important for TPA, especially as children transitioned to middle school, whereas home equipment and a supportive NPAE were important for fifth graders’ TPA.

Conclusion

Consistent with the socioecological model, PA behaviour was dependent on interacting effects across levels of influence. Generally, both a supportive NPAE and positive psychosocial factors were needed to support TPA. Factors influencing PA across multiple levels should be addressed in PA interventions.

EASY-An Instrument for Surveillance of Physical Activity in Youth

PURPOSE

Physical activity (PA) promotion among youth is a public health priority, and there is a need for robust surveillance systems to help support such initiatives. Existing youth PA self-report instruments that are used for surveillance lack information regarding the types and contexts of activity. Further, these instruments have limited validity with accelerometry. The purpose of the present study was to develop a self-report instrument, with sound psychometric properties, for monitoring compliance with PA guidelines in youth.

METHODS

In focus groups, 162 middle school students identified 30 forms of PA that are highly prevalent in that age-group. We incorporated these activities into three preliminary forms of a self-report instrument. An independent sample of middle school students (n = 537) was randomly assigned to complete one of the three preliminary versions of the instrument. Rasch analysis was applied to the responses to the three formats, and a yes/no plus frequency format emerged as the preferred method. A third sample of 342 middle school students then completed the yes/no plus frequency instrument twice after a 7-d period during which they wore an accelerometer. Using both Rasch analysis and traditional correlational methods, validity and reliability of a 14-item instrument were established. Data were collected during 2012-2015.

RESULTS

Spearman correlation coefficient for the association between the cumulative score for the 14 items and minutes per day of accelerometry-derived moderate-to-vigorous physical activity was 0.33 (95% confidence interval = 0.22-0.43, P < 0.001). The sensitivity and specificity values of the 14-item instrument were 0.90 and 0.44, respectively.

CONCLUSIONS

The study produced a PA self-report instrument for youth that was found to be reliable (r = 0.91), valid versus accelerometry (r = 0.33), and with acceptable specificity and sensitivity in detecting compliance with PA guidelines.

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.

Change in Children's Physical Activity: Predictors in the Transition From Elementary to Middle School

INTRODUCTION

Interventions to promote physical activity in children should be informed by knowledge of the factors that influence physical activity behavior during critical developmental transitions. The purpose of this study is to identify, from a comprehensive, multidomain set of factors, those that are associated with change in objectively measured physical activity in children as they transition from elementary to middle school.

METHODS

The study used a prospective cohort design, with children observed in fifth, sixth, and seventh grades. Growth curve analyses were used to examine associations between exposure variables measured at baseline and children's physical activity across three observations. A total of 828 children, aged 10.6 (SD=0.5) years at baseline provided physical activity data in fifth grade and at one or both follow-ups. Exposure variables assessed child characteristics, parent characteristics, home characteristics, social factors, school environment, and community characteristics. Physical activity was measured via accelerometry. Data were collected in two school districts in South Carolina in 2010-2013 and analyzed in 2017.

RESULTS

Variables measured within the child, parent/home, and community domains were positively associated with children's physical activity as they transitioned from fifth to seventh grade. These included parent encouragement of physical activity, parental support for physical activity, child sports participation, parent's report of the child's physical activity level, the child's time spent outdoors, social spaces for physical activity in the community, and the number of physical activity facilities that were proximal to the child's home.

CONCLUSIONS

Interventions designed to increase children's physical activity should include strategies that target multiple domains of influence.

Associations between community programmes and policies and children's physical activity: the Healthy Communities Study

BACKGROUND

Community initiatives to promote physical activity in children are common, but evidence supporting their effectiveness is limited.

OBJECTIVES

The objective of this study is to examine the relationships between community programmes and policies and children's physical activity in a large and diverse sample of US communities.

METHODS

Programmes and policies to promote children's physical activity were assessed in 130 communities by key informant interviews, and physical activity behaviours were measured by self-report and parental report in samples of children in each community (total n = 5138). Associations between composite indices of community programmes and policies and indicators of total and moderate-to-vigorous physical activity were examined without and with adjustment for demographic factors.

RESULTS

An index reflecting the 6-year history of the number of behaviour change strategies used in community programmes and policies was positively associated with children's moderate-to-vigorous physical activity. This association was attenuated with adjustment for demographic factors. Effect modification analyses found that the association was positive among non-Hispanic children but was negative for Hispanic children.

CONCLUSIONS

Community initiatives to promote physical activity in children were positively associated with children's physical activity in non-Hispanic children. Such initiatives were negatively associated with physical activity in Hispanic children, suggesting that future research should consider unique cultural factors when designing community initiatives to promote activity in this population sub-group.

Association between community characteristics and implementation of community programmes and policies addressing childhood obesity: the Healthy Communities Study

BACKGROUND

Little is known about whether characteristics of communities are associated with differential implementation of community programmes and policies to promote physical activity and healthy eating. This study examines associations between community characteristics (e.g. region and race/ethnicity) and the intensity of community programmes and policies implemented to prevent childhood obesity. It explores whether community characteristics moderate the intensity of community efforts to prevent childhood obesity.

OBJECTIVE

The objective of this study is to investigate associations between community characteristics and the intensity of community policies and programmes to prevent childhood obesity documented in the Healthy Communities Study that engaged a diverse sample of US communities.

METHOD

Programmes and policies were documented in 130 communities across the USA, reporting over 9000 different community programmes and policies to prevent obesity among children ages 4-15. We examined associations between community characteristics and the intensity of community programmes and policies implemented (i.e. their amount and reach, duration and strength of change strategy).

CONCLUSION

Community characteristics explain 25% of the variability in the intensity of community programmes and policies implemented in communities. Particular characteristics - urbanicity, region, being a large county and the per cent of African-Americans in a community - contributed to more (over 18% of the 25%) of the observed variability.

The longitudinal relationship between community programmes and policies to prevent childhood obesity and BMI in children: the Healthy Communities Study

BACKGROUND

Although a national epidemic of childhood obesity is apparent, how community-based programmes and policies (CPPs) affect this outcome is not well understood.

OBJECTIVES

This study examined the longitudinal relationship between the intensity of CPPs in 130 communities over 10 years and body mass index (BMI) of resident children. We also examined whether these relationships differ by key family or community characteristics.

METHODS

Five thousand one hundred thirty-eight children in grades K-8 were recruited through 436 schools located within 130 diverse US communities. Measures of height, weight, nutrition, physical activity and behavioural and demographic family characteristics were obtained during in-home visits. A subsample of families consented to medical record review; these weight and height measures were used to calculate BMI over time for 3227 children. A total of 9681 CPPs were reported during structured interviews of 1421 community key informants, and used to calculate a time series of CPP intensity scores within each community over the previous decade. Linear mixed effect models were used to assess longitudinal relationships between childhood BMI and CPP intensity.

RESULTS

An average BMI difference of 1.4 kg/m² (p-value < 0.01) was observed between communities with the highest and lowest observed CPP intensity scores, after adjusting for community and child level covariates. BMI/CPP relationships differed significantly by child grade, race/ethnicity, family income and parental education; as well as community-level race/ethnicity.

CONCLUSIONS

These results indicate that, over time, more intense CPP interventions are related to lower childhood BMI, and that there are disparities in this association by sociodemographic characteristics of families and communities.

Relationship of objective street quality attributes with youth physical activity: findings from the Healthy Communities Study

BACKGROUND

Residential environments may significantly influence youth physical activity (PA). However, few studies have examined detailed street quality attributes via observational audits in relation to context-specific PA among youth.

OBJECTIVES

The objective of this study was to explore whether the overall quality of street environments, as well as specific attributes, was associated with neighbourhood-based and street-based PA within a national sample of youth in the Healthy Communities Study.

METHODS

Data were collected from 4616 youth from 130 communities across the USA. Youth PA in the neighbourhood and on the participant's street was captured using 7-d recall interviews. Windshield survey observational audits documented five street quality variables: burned, boarded up or abandoned residential units, litter, overall condition of residences, street type and presence of sidewalks in good condition.

RESULTS

Youth with no litter on their street reported significantly lower neighbourhood-based PA and youth living on a side street, cul-de-sac, dead-end or one-way street reported greater neighbourhood-based PA. No significant associations were detected for the overall street quality index or with street-based PA.

CONCLUSIONS

Specific street quality attributes may be associated with youth PA. Further research and collaboration between diverse disciplines and agencies should focus on understanding and improving street quality to promote youth PA and health.

Declining Physical Activity and Motivation from Middle School to High School

PURPOSE

The purpose of this study was to determine whether naturally occurring changes in intrinsic motivation, behavioral regulation, and goals mitigate declining physical activity among adolescents.

METHODS

Latent growth modeling was applied in tests of change in intrinsic motivation, facets of behavioral regulation, and their interactions with goals on change in physical activity measured by accelerometer in a cohort of 260 boys and girls evaluated longitudinally from sixth through ninth grades.

RESULTS

Physical activity declined less in youths who maintained higher intrinsic motivation or integrated regulation, but only when they maintained higher enjoyment goal compared with other students. Physical activity also declined less in students who maintained higher intrinsic motivation or integrated motivation and had bigger declines in appearance goal (or social and competence goals with intrinsic motivation) compared with students who maintained higher levels of those goals. The interactions correspond to 1 to 2 min·h less decrease in physical activity.

CONCLUSIONS

Consistent with Self-Determination Theory, the findings encourage interventions that target autonomous motivation among youths. The results extend prior evidence in three ways. First, the cohort was tracked for 3 yr using an objective measure of physical activity. Second, influences of intrinsic motivation and integrated regulation on changing physical activity were not direct. They interacted with changing goals, indicating that interventions should also focus on specific goals for physical activity as effect modifiers. Third, interventions focused on autonomous motivation should consider that controlled, introjected motivation may also interact with goals to influence physical activity during the transition between middle school and high school.

Changes in Physical Activity in the School, Afterschool, and Evening Periods During the Transition From Elementary to Middle School

BACKGROUND

We examined longitudinal changes in children's physical activity during the school day, afterschool, and evening across fifth, sixth, and seventh grades.

METHODS

The analytical sample included children who had valid accelerometer data in fifth grade and at least one other time-point, and provided complete sociodemographic information (N = 768, 751, and 612 for the 3 time-periods studied). Accelerometer-derived total physical activity (TPA) and moderate-to-vigorous physical activity (MVPA) were expressed in minutes per hour for the school day (∼7:45 am to 3:30 pm), afterschool (∼2:25 to 6:00 pm), and evening (6:00 to 10:00 pm) periods. We used growth curve analyses to examine changes in TPA and MVPA.

RESULTS

School day TPA and MVPA declined significantly; we observed a greater decrease from fifth to sixth grades than from sixth to seventh grades. Afterschool TPA declined significantly, but MVPA increased significantly among girls and remained stable for boys. Evening TPA decreased significantly and MVPA declined significantly in girls and remained stable among boys.

CONCLUSIONS

To inform the development of effective intervention strategies, research should focus on examining factors associated with the decline in physical activity during the transition from elementary to middle school, particularly during the hours when children are in school.

Naturally-occurring changes in social-cognitive factors modify change in physical activity during early adolescence

PURPOSE

To determine whether naturally-occurring changes in children's motives and beliefs are associated with the steep decline in physical activity observed from childhood to early adolescence.

METHODS

Latent growth modeling was applied in longitudinal tests of social-cognitive influences, and their interactions, on physical activity in a large cohort of boys and girls evaluated annually between 5th and 7th grades.

RESULTS

Measurement equivalence of motives and beliefs was confirmed between boys and girls. After adjustment for gender and maturity differences, physical activity declined less in children who reported the least decreases in self-efficacy for overcoming barriers to activity and perceived parental support. Physical activity also declined less in students who persistently felt they had more parental and friend support for activity compared to those who reported the largest decrease in support from friends. After further adjustment for race, the decline in physical activity was less in those who had the largest decrease in perceived barriers and maintained a favorable perception of their neighborhood environment. Changes in enjoyment and social motives were unrelated to change in physical activity.

CONCLUSION

Using an objective measure of physical activity, we confirm that naturally-occurring changes in children's beliefs about barriers to physical activity and their ability to overcome them, as well as perceptions of their neighborhood environment and social support, are concurrent with age-related declines in children's physical activity. The longitudinal findings confirm these putative social-cognitive mediators as plausible, interacting targets of interventions designed to mitigate the marked decline in physical activity that occurs during the transition between elementary and middle schools.

Physical Activity and Changes in Adiposity in the Transition from Elementary to Middle School

OBJECTIVES

This study examined the longitudinal associations of objectively measured physical activity, sedentary behavior, and diet quality with two measures of adiposity and a measure of weight status.

METHODS

A total of 658 children from 21 elementary schools (45.1% boys; 40% white, 33% black, 9% Hispanic, and 18% other race/ethnicity) were assessed at least twice in fifth, sixth, and/or seventh grade. Fat mass index (FMI), percent body fat (PBF), and BMI were calculated from body weight, standing and seated heights, and bioelectrical impedance (BIA) measured each year.

RESULTS

At follow-up, both FMI and PBF decreased among boys and increased among girls, while BMI increased in both boys and girls. After controlling for race/ethnicity, parent education, and maturity offset at baseline, growth curve analyses showed that moderate-to-vigorous physical activity (MVPA) was significantly and negatively associated with FMI, PBF, and BMI for both boys and girls. After forming tertiles of fifth grade MVPA, least-square means for FMI, PBF, and BMI were examined by grade and gender. For both boys and girls, higher MVPA was associated with lower FMI, PBF, and BMI at all three grade levels. The relationships between sedentary behavior and diet quality and FMI, PBF, and BMI were not consistent for boys or girls.

CONCLUSIONS

As boys and girls transitioned from elementary to middle school, children who participated in higher levels of MVPA maintained more favorable levels of two indicators of adiposity and a measure of weight status. These findings support the need for interventions to help children meet current public health guidelines for physical activity.

Motivation and Behavioral Regulation of Physical Activity in Middle School Students

PURPOSE

This study aimed to examine whether intrinsic motivation and behavioral self-regulation are related to physical activity during middle school.

METHOD

Structural equation modeling was applied in cross-sectional and longitudinal tests of self-determination theory.

RESULTS

Consistent with theory, hypothesized relations among variables were supported. Integrated regulation and intrinsic motivation were most strongly correlated with moderate-to-vigorous physical activity measured by an accelerometer. Results were independent of a measure of biological maturity. Construct validity and equivalence of measures were confirmed longitudinally between the sixth and seventh grades and between boys and girls, non-Hispanic Black and White children and overweight and normal-weight students.

CONCLUSIONS

Measures of autonomous motivation (identified, integrated, and intrinsic) were more strongly related to physical activity in the seventh grade than measures of controlled motivation (external and introjected), implying that physical activity became more intrinsically motivating for some girls and boys as they moved through middle school. Nonetheless, change in introjected regulation was related to change in physical activity in the seventh grade, suggesting that internalized social pressures, which can be detrimental to sustained activity and well-being, also became motivating. These results encourage longer prospective studies during childhood and adolescence to clarify how controlled and autonomous motivations for physical activity develop and whether they respond to interventions designed to increase physical activity.

Validation of Interviewer-Assisted Recall for Measuring Minutes of Moderate to Vigorous Physical Activity in Elementary School Children, Grades 3 and 5

OBJECTIVE

To test the validity of interviewer-administered recall for measuring moderate to vigorous physical activity (MVPA) in third- and fifth-grade children who reported physical activity (PA) only or both PA and diet, using a short (same-day recall in the afternoon) or long (previous-day recall in the morning) retention interval.

METHODS

Randomly selected children (n = 95) wore an accelerometer 1 day in school. Interviews occurred in the afternoon of the day on which the accelerometer was worn or on the next morning. Assignment to interview content was random. Spearman correlations were calculated between MVPA interview and MVPA accelerometer minutes.

RESULTS

The MVPA interview minutes were positively associated with the MVPA accelerometer minutes when the interview focused on PA only (r = .34; P = .02) but not when children recalled PA and diet (r = .12; P = .40). The MVPA interview minutes for the previous day was associated with the MVPA accelerometer minutes (r = .33; P = .02), but not for the same day (r = .17; P = .26).

CONCLUSIONS

A recall interview method that focuses solely on PA is a promising approach to assessing children's school-day PA.

A Tale of 2 Teachers: A Preschool Physical Activity Intervention Case Study

BACKGROUND

Preschool settings vary greatly, and research has shown that interventions are more successful when they can be adapted to individual settings. This is a descriptive case study of how 2 teachers successfully adapted and implemented a preschool physical activity intervention.

METHODS

The Study of Health and Activity in Preschool Environments (SHAPES) was a 3-year physical activity intervention. A detailed case study of 2 high-implementing teachers was conducted. Multiple data sources included accelerometry, direct observation, teacher surveys, and intervention staff field notes.

RESULTS

Teacher A focused on integrating physical activity into a wide range of activities, including parent and community events. Teacher B focused on high-intensity, structured activities. Both teachers supported the intervention, worked closely with intervention staff, and operated their classroom as an autonomous unit with support from their directors. Teacher A provided an average of 31.5, 78.0, and 67.5 min of physical activity opportunity per day of observation during years 1, 2, and 3. Teacher B provided an average of 2.7, 33.5, and 73.3 minutes of physical activity opportunity per day of observation.

CONCLUSION

Successful implementation of physical activity interventions may look different in different contexts; thus, interventions should allow for flexible implementation.

Development and Testing of the Observational System for Recording Physical Activity in Children: Elementary School

PURPOSE

This study describes the development and pilot testing of the Observational System for Recording Physical Activity-Elementary School (OSRAC-E) Version.

METHOD

This system was developed to observe and document the levels and types of physical activity and physical and social contexts of physical activity in elementary school students during the school day. Interobserver agreement scores and summary data were calculated.

RESULTS

All categories had Kappa statistics greater than .80, with the exception of the activity initiator category. Interobserver agreement scores were 96% or greater. The OSRAC-E was shown to be a reliable observation system that allows researchers to assess physical activity behaviors, the contexts of those behaviors, and the effectiveness of physical activity interventions in the school environment.

CONCLUSION

The OSRAC-E can yield data with high interobserver reliability and provide relatively extensive contextual information about the physical activity of students in elementary schools.

Physical Activity Measures in the Healthy Communities Study

The risk of obesity is reduced when youth engage in recommended levels of physical activity (PA). For that reason, public health organizations in the U.S. have encouraged communities to implement programs and policies designed to increase PA in youth, and many communities have taken on that challenge. However, the long-term effects of those programs and policies on obesity are largely unknown. The Healthy Communities Study is a large-scale observational study of U.S. communities that is examining the characteristics of programs and policies designed to promote healthy behaviors (e.g., increase PA and improve diet) and determining their association with obesity-related outcomes. The purpose of this paper is to describe the methods used to measure PA in children and the personal and community factors that may influence it. The study used both self-reported and objective measures of PA, and measured personal, family, and home influences on PA via three constructs: (1) PA self-schema; (2) parental support; and (3) parental rules regarding PA. Neighborhood and community factors related to PA were assessed using three measures: (1) child perceptions of the neighborhood environment; (2) availability of PA equipment; and (3) attributes of the child's street segment via direct observation. School influences on children's PA were assessed via three constructs: (1) school PA policies; (2) child perceptions of the school PA environment; and (3) school outdoor PA environment. These measures will enable examination of the associations between characteristics of community PA programs and policies and obesity-related outcomes in children and youth.

Weight Status Measures Collected in the Healthy Communities Study: Protocols and Analyses

The Healthy Communities Study is one of the largest studies to assess the relationship between characteristics of community programs and policies to prevent childhood obesity and obesity-related outcomes. The purpose of this paper is to describe the protocol that was developed for collecting the anthropometric data for the study and the procedures for analyzing the data. Data were collected from 2013 to 2015 and analyses will be completed by mid-2016. During in-home visits, Healthy Communities Study staff collected height, weight, and waist circumference measurements from child participants and height and weight measurements from adult participants. The protocol for obtaining these measurements was adapted from the protocol used by the National Health and Nutrition Examination Survey, with modifications to accommodate assessments conducted in homes rather than in a Mobile Examination Center. In addition to anthropometric data from in-home visits, the Healthy Communities Study collected retrospective height and weight measurements from the medical records of child participants. These data were used to calculate trajectories of BMI and BMI z-scores. The study implemented procedures for ensuring the accuracy of the in-home measurements and abstracted medical data. These procedures included automatically checking the ranges on entered data, reviewing data for end-digit patterns, and abstracting selected medical records using two independent abstractors to assess agreement. The collection of longitudinal height and weight measures will allow researchers to address several pressing questions related to how characteristics of community programs and policies are associated with obesity-related outcomes among children.

A validation study concerning the effects of interview content, retention interval, and grade on children's recall accuracy for dietary intake and/or physical activity

BACKGROUND

Practitioners and researchers are interested in assessing children's dietary intake and physical activity together to maximize resources and minimize subject burden.

OBJECTIVE

Our aim was to investigate differences in dietary and/or physical activity recall accuracy by content (diet only; physical activity only; diet and physical activity), retention interval (same-day recalls in the afternoon; previous-day recalls in the morning), and grade (third; fifth).

DESIGN

Children (n=144; 66% African American, 13% white, 12% Hispanic, 9% other; 50% girls) from four schools were randomly selected for interviews about one of three contents. Each content group was equally divided by retention interval, each equally divided by grade, each equally divided by sex. Information concerning diet and physical activity at school was validated with school-provided breakfast and lunch observations, and accelerometry, respectively. Dietary accuracy measures were food-item omission and intrusion rates, and kilocalorie correspondence rate and inflation ratio. Physical activity accuracy measures were absolute and arithmetic differences for moderate to vigorous physical activity minutes.

STATISTICAL ANALYSES PERFORMED

For each accuracy measure, linear models determined effects of content, retention interval, grade, and their two-way and three-way interactions; ethnicity and sex were control variables.

RESULTS

Content was significant within four interactions: intrusion rate (content×retention-interval×grade; P=0.0004), correspondence rate (content×grade; P=0.0004), inflation ratio (content×grade; P=0.0104), and arithmetic difference (content×retention-interval×grade; P=0.0070). Retention interval was significant for correspondence rate (P=0.0004), inflation ratio (P=0.0014), and three interactions: omission rate (retention-interval×grade; P=0.0095), intrusion rate, and arithmetic difference (both already mentioned). Grade was significant for absolute difference (P=0.0233) and five interactions mentioned. Content effects depended on other factors. Grade effects were mixed. Dietary accuracy was better with same-day than previous-day retention interval.

CONCLUSIONS

Results do not support integrating dietary intake and physical activity in children's recalls, but do support using shorter rather than longer retention intervals to yield more accurate dietary recalls. Additional validation studies need to clarify age effects and identify evidence-based practices to improve children's accuracy for recalling dietary intake and/or physical activity.

Young children's motor skill performance: relationships with activity types and parent perception of athletic competence

OBJECTIVES

The aims were to examine the relationship between children's motor skill levels and types of physical activities performed during preschool attendance, and to examine the relationship between motor skill performance and parent perception of athletic competence.

DESIGN

Cross-sectional.

METHODS

Participants were 264, 3-, 4-, and 5-year-old children from 22 preschools. Locomotor and object control skills were assessed with a standardized motor skill protocol. Direct observation (OSRAC-P) was used to record activity types: walk, run, jump/skip, dance, and throw. Parents rated their child's athletic competence. Children were categorized into tertiles for locomotor and object control scores. Mixed models were used to test for differences across motor skill tertiles for each aim. Models controlled for sex, age, race/ethnicity, body mass index, and parent education, with preschool as a random variable.

RESULTS

Children in the highest locomotor tertile engaged in more dancing than children in the lowest tertile (p = 0.04). Children in the highest object control tertile engaged in throwing more frequently than children in lower tertiles (p < 0.05). Parents of children in the highest locomotor tertile perceived their children's competence as higher than parents of children in lower tertiles (p < 0.05). Parents of children in the lowest object control tertile perceived their children's competence as significantly lower than parents of children in higher tertiles (p < 0.05).

CONCLUSIONS

These findings point to the need for policy and practice research to help parents and child care professionals provide opportunities for young children to learn and practice motor skills.

Physical activity in preschool children: comparison between Montessori and traditional preschools

BACKGROUND

Little is known about the influence of Montessori methods on children's physical activity (PA). This cross-sectional study compared PA of children attending Montessori and traditional preschools.

METHODS

We enrolled 301 children in 9 Montessori and 8 traditional preschools in Columbia, South Carolina. PA was measured by accelerometry on weekdays during preschool (In-School), non-school (Non-School), and all day (All Day). Minutes/hour of light, moderate-to-vigorous (MVPA), and total PA (light + MVPA) were calculated.

RESULTS

Children attending Montessori preschools accumulated more In-School light (7.7 vs. 6.5 minute/hour), MVPA (7.7 versus 6.5 minute/hour), and total PA (15.4 versus 13.0 minute/hour) than children attending traditional preschools, after adjusting for sex, race/ethnicity, body mass index, parent education and neighborhood poverty index. For Non-School (8.5 versus 6.2 minute/hour) and All Day (8.5 versus 7.6 minute/hour), children in Montessori preschools accumulated more MVPA than children in traditional preschools. In-School PA was higher for children in private Montessori than public Montessori preschools (8.1 versus 7.0 minute/hour; 8.1 versus 6.7 minute/hour; 16.1 versus 13.6 minute/hour, for light, MVPA, and total PA, respectively).

CONCLUSIONS

Children attending Montessori preschools were more active than children attending traditional preschools. Adopting the Montessori system may be an important strategy for promoting PA in children.

Maternal inactivity: 45-year trends in mothers' use of time

OBJECTIVE

To examine 45-year trends in time use and physical activity energy expenditure (PAEE) in a nationally representative sample of US mothers.

PARTICIPANTS AND METHODS

We quantified time allocation to physical activity (PA), sedentary behaviors (SED), and PAEE from 1965 to 2010 in mothers with older children (MOC) (>5 to ≤18 years) and mothers with younger children (MYC) (≤5 years). Physical activity was the sum of time allocated to housework, child care, laundry, food preparation, postmeal cleanup, and exercise. Sedentary behavior was the sum of time spent in a vehicle and using screen-based media. Physical activity energy expenditure was calculated using body weights from national surveys and metabolic equivalents.

RESULTS

From 1965 to 2010, the time allocated to PA decreased by 11.1 h/wk (from 32.0 to 20.9 h/wk) in MOC and by 13.9 h/wk (from 43.6 to 29.7 h/wk) in MYC. The time spent in SED increased by 7.0 h/wk in MOC (from 17.7 to 24.7 h/wk) and increased by 5.7 h/wk in MYC (from 17.0 to 22.7 h/wk). Physical activity energy expenditure decreased by 1237.6 kcal/wk (176.8 kcal/d) in MOC (from 5835.3 to 4597.7 kcal/wk), and in MYC, PAEE decreased by 1572.5 kcal/wk (224.6 kcal/d), from 7690.5 to 6118.0 kcal/wk.

CONCLUSION

There was a significant reallocation of time by mothers from PA (eg, housework) to SED (eg, watching television) between 1965 and 2010. Given the essential role of PA for health and the potential for the intergenerational transmission of obesity and obesogenic behaviors, these results suggest that maternal inactivity may be an important target for the primary prevention of chronic noncommunicable diseases and obesity.

Sedentary behaviors in fifth-grade boys and girls: where, with whom, and why?

BACKGROUND

An understanding of the context surrounding screen- and non-screen-based sedentary behavior would facilitate efforts to reduce children's overall sedentary behavior. This study examined the prevalence of specific types of sedentary behavior in children, the social and physical contexts surrounding these behaviors, and differences by gender.

METHODS

Participants included 686 fifth graders participating in the Transitions and Activity Changes in Kids Study (TRACK). The Physical Activity Choices instrument measured child participation in seven sedentary behaviors, the social (i.e., with whom) and physical (i.e., where) contexts, and perceptions (i.e., why) of those behaviors. Analysis included mixed-model regression adjusted for race/ethnicity, BMI, and socioeconomic status.

RESULTS

Children participated in both screen- and non-screen-based sedentary behaviors at very high frequencies. The most popular activities included watching television or videos, listening to music, playing video games (boys only), and talking on the phone or texting (girls only). Children engaged in sedentary behaviors most often at home, at school, or in their neighborhood. In general, the patterns of social context for the behaviors were similar for boys and girls, with the exception of video game playing. Girls perceived listening to music and talking on the phone or texting to be more fun than boys; children did not differ in their other perceptions (i.e., how much choice or how important) of the behaviors.

CONCLUSIONS

Multi-level interventions that target reducing sedentary behavior in the home, neighborhood, and school context may be most effective; however, the approach needed will likely differ by gender.

Top 10 research questions related to physical activity in preschool children

The purpose of this article was to highlight important research needs related to physical activity in 3- to 5-year-old children. We identified research needs in 3 major categories: health effects, patterns of physical activity, and interventions and policies. The top research needs include identifying the health effects of physical activity, the effects of physical activity on the development of healthy weight, the effects of physical activity on learning and behavior, and the health implications of sedentary behavior. Research questions concerning patterns of physical activity include determining the prevalence of 3- to 5-year-olds meeting the current physical activity guidelines; the social and environmental factors that influence physical activity in home, preschool, and community settings; and how physical activity tracks into later childhood, adolescence, and adulthood. Research questions about interventions and policies include identifying the most effective strategies to promote physical activity in home, child care, and community settings and to reach diverse populations of young children, identifying effective intervention implementation and dissemination strategies, and determining the effectiveness of national, state, local, and institutional policies for increasing physical activity. In conclusion, research is needed to establish a full understanding of the health implications of physical activity in 3- to 5-year-old children, to better understand the nature of physical activity behavior in this group, and to learn how to promote physical activity in young children.

A pilot study of the effects of interview content, retention interval, and grade on accuracy of dietary information from children

OBJECTIVE

Investigate differences in dietary recall accuracy by interview content (diet only or diet and physical activity), retention interval (same day or previous day), and grade (third or fifth).

METHODS

Thirty-two children observed eating school-provided meals and interviewed once each; interview content and retention interval randomly assigned. Multivariate analysis of variance on rates for omissions (foods observed but unreported) and intrusions (foods reported but unobserved); independent variables: interview content, retention interval, grade.

RESULTS

Accuracy differed by retention interval (P = .05; better for same day [omission rate, intrusion rate: 28%, 20%] than previous day [54%, 45%]) but not interview content (P > .48; diet only: 41%, 33%; diet and physical activity: 41%, 33%) or grade (P > .27; third: 48%, 42%; fifth: 34%, 24%).

CONCLUSIONS AND IMPLICATIONS

Although the small sample limits firm conclusions, results provide evidence-based direction to enhance accuracy: specifically, to shorten the retention interval. Larger validation studies need to investigate the combined effect of interview content, retention interval, and grade on accuracy.

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.

Physical activity behaviours of highly active preschoolers

BACKGROUND

Understanding the physical activity behaviour of young children who are highly active may provide important guidance for promoting physical activity in preschools.

OBJECTIVES

The objective of this study was to describe the movement characteristics of high-active (HA) children during attendance at preschools.

METHODS

Children in 20 preschools (n = 231) wore accelerometers and were classified into tertiles of moderate-to-vigorous physical activity. Children's movement characteristics were observed using the Observational System for Recording Physical Activity in Children-Preschool Version. Mixed-model analyses compared movement types between HA children and lower-active (LA) children during the total school day.

RESULTS

HA (n = 77) children were observed to be more active than LA children (n = 154) indoors (P < 0.001), but no differences were observed outdoors. HA children were more frequently observed running, crawling, climbing, jumping, skipping, swinging and throwing across the total school day than LA children. Outdoors, HA children participated in more swinging and throwing and less jumping or skipping than LA children. Indoors, HA children spent more time pulling, pushing and running, and less time walking than LA children.

CONCLUSIONS

HA children have unique activity patterns. Further interventions to increase physical activity of all preschoolers should increase the time spent outside and include varied activity types throughout the entire school day.

45-Year trends in women's use of time and household management energy expenditure

CONTEXT

Relationships between socio-environmental factors and obesity are poorly understood due to a dearth of longitudinal population-level research. The objective of this analysis was to examine 45-year trends in time-use, household management (HM) and energy expenditure in women.

DESIGN AND PARTICIPANTS

Using national time-use data from women 19-64 years of age, we quantified time allocation and household management energy expenditure (HMEE) from 1965 to 2010. HM was defined as the sum of time spent in food preparation, post-meal cleaning activities (e.g., dish-washing), clothing maintenance (e.g., laundry), and general housework. HMEE was calculated using body weights from national surveys and metabolic equivalents.

RESULTS

The time allocated to HM by women (19-64 yrs) decreased from 25.7 hr/week in 1965 to 13.3 hr/week in 2010 (P<0.001), with non-employed women decreasing by 16.6 hr/week and employed women by 6.7 hr/week (P<0.001). HMEE for non-employed women decreased 42% from 25.1 Mj/week (6004 kilocalories per week) in 1965 to 14.6 Mj/week (3486 kcal/week) in 2010, a decrement of 10.5 Mj/week or 1.5 Mj/day (2518 kcal/week; 360 kcal/day) (P<0.001), whereas employed women demonstrated a 30% decrement of 3.9 Mj/week, 0.55 Mj/day (923 kcal/week, 132 kcal/day) (P<0.001). The time women spent in screen-based media use increased from 8.3 hr/week in 1965 to 16.5 hr/week in 2010 (P<0.001), with non-employed women increasing 9.6 hr/week and employed women 7.5 hr/week (P<0.001).

CONCLUSIONS

From 1965 to 2010, there was a large and significant decrease in the time allocated to HM. By 2010, women allocated 25% more time to screen-based media use than HM (i.e., cooking, cleaning, and laundry combined). The reallocation of time from active pursuits (i.e., housework) to sedentary pastimes (e.g., watching TV) has important health consequences. These results suggest that the decrement in HMEE may have contributed to the increasing prevalence of obesity in women during the last five decades.

In vivo nitric oxide suppression of lipolysis in subcutaneous abdominal adipose tissue is greater in obese than lean women

Mounting evidence suggests there is a reduced mobilization of stored fat in obese compared to lean women. It has been suggested that this decreased lipid mobilization may lead to, or perpetuate, the obese state; however, there may be a beneficial effect of reduced lipolysis, either by allowing for a sink of excess fatty acids, or by limiting a potentially harmful rise in interstitial and circulating fatty acid concentration. Nitric oxide (NO) may be responsible for a portion of the reduced in vivo rates of lipolysis in obese women because NO reduces adipose tissue lipolysis and adipose tissue nitric oxide synthase (NOS) mRNA is higher in obese than lean individuals. The purpose of this study was to determine if the inhibition of NOS by L-N(g)-monomethyl-L-arginine (L-NMMA) in the absence and presence of lipolytic stimulation would result in a larger increase in lipolytic rate in obese (OB) than lean (LN) women. Microdialysis probes were inserted into the subcutaneous abdominal adipose tissue of seven obese and six lean women to monitor lipolysis. Dialysate glycerol concentration increased in response to L-NMMA in OB (basal 125 ± 26 µmol/l; L-NMMA 225 ± 35 µmol/l) to a greater extent than in LN (basal 70 ± 18 µmol/l; L-NMMA 84 ± 20 µmol/l) women (P < 0.05). Dialysate glycerol increased to a similar extent in OB and LN in response to adrenergic stimulation by isoprenaline or norepinephrine in the presence of L-NMMA. The differential glycerol responses to L-NMMA between obese and lean could not be explained by differential blood flow responses. It can be concluded that NO suppresses basal lipolysis in obese women to a greater extent than in lean women.

Assessing children's physical activity in their homes: the observational system for recording physical activity in children-home

The present study describes the development and pilot testing of the Observation System for Recording Physical Activity in Children-Home version. This system was developed to document physical activity and related physical and social contexts while children are at home. An analysis of interobserver agreement and a description of children's physical activity in various settings are presented. The system, which was shown to be reliable, provides a direct observation tool for researchers who are interested in assessing and intervening in physical activity in the home environment.

Social and environmental factors associated with preschoolers' nonsedentary physical activity

The twofold purposes of the investigation were (a) to describe with direct observation data the physical activity behaviors and the accompanying social and environmental events of those behaviors for children in preschools and (b) to determine which contextual conditions were predictors of moderate to vigorous physical activity (MVPA) and nonsedentary physical activity (i.e., light activity + MVPA) for 3-, 4-, and 5-year-old children during their outdoor play. The results indicate that preschoolers' physical activity is characterized as sedentary in nature throughout their preschool day (i.e., 89% sedentary, 8% light activity, and 3% MVPA). During outdoor play periods, when children are most likely to be physically active, some contextual and social circumstances better predict their physical activity. Implications for policy makers, practitioners, and researchers are discussed.

Policies and characteristics of the preschool environment and physical activity of young children

OBJECTIVE

The purpose of this study was to examine policies and characteristics of preschools and the extent to which they influence the physical activity of 3- to 5-year-old children during the preschool day.

METHODS

A total of 299 children from 20 preschools wore accelerometers for an average of 8.1 hours/day (SD: 1.5 hours/day), for 5.5 days (SD: 2.1 days). A researcher completed the Early Childhood Environment Rating Scale-Revised for each preschool to assess quality. Classrooms and playgrounds were measured, and the preschool director was interviewed about physical activity policies. For each policy or characteristic, preschools were divided into 2 groups on the basis of whether the characteristic/policy was presumed to promote or not promote physical activity.

RESULTS

Children spent fewer minutes per hour in sedentary activity and more minutes per hour in moderate/vigorous physical activity in preschools that had higher quality scores, less fixed playground equipment, more portable playground equipment, lower use of electronic media, and larger playgrounds. Five preschools had all 5 of these characteristics, and children in those preschools had significantly more moderate/vigorous physical activity minutes per hour and fewer sedentary minutes per hour compared with children in the other preschools.

CONCLUSION

Children in the top 5 physical activity-promoting preschools accumulated >60 minutes of moderate/vigorous physical activity per day, compared with the children in the other preschools, who accumulated <60 minutes of moderate/vigorous physical activity per day.

Motor skill performance and physical activity in preschool children

Children with better-developed motor skills may find it easier to be active and engage in more physical activity (PA) than those with less-developed motor skills. The purpose of this study was to examine the relationship between motor skill performance and PA in preschool children. Participants were 80 three- and 118 four-year-old children. The Children's Activity and Movement in Preschool Study (CHAMPS) Motor Skill Protocol was used to assess process characteristics of six locomotor and six object control skills; scores were categorized as locomotor, object control, and total. The actigraph accelerometer was used to measure PA; data were expressed as percent of time spent in sedentary, light, moderate-to-vigorous PA (MVPA), and vigorous PA (VPA). Children in the highest tertile for total score spent significantly more time in MVPA (13.4% vs. 12.8% vs. 11.4%) and VPA (5% vs. 4.6% vs. 3.8%) than children in middle and lowest tertiles. Children in the highest tertile of locomotor scores spent significantly less time in sedentary activity than children in other tertiles and significantly more time in MVPA (13.4% vs. 11.6%) and VPA (4.9% vs. 3.8%) than children in the lowest tertile. There were no differences among tertiles for object control scores. Children with poorer motor skill performance were less active than children with better-developed motor skills. This relationship between motor skill performance and PA could be important to the health of children, particularly in obesity prevention. Clinicians should work with parents to monitor motor skills and to encourage children to engage in activities that promote motor skill performance.

Validation and calibration of an accelerometer in preschool children

OBJECTIVE

Obesity rates in young children are increasing, and decreased physical activity is likely to be a major contributor to this trend. Studies of physical activity in young children are limited by the lack of valid and acceptable measures. The purpose of this study was to calibrate and validate the ActiGraph accelerometer for use with 3- to 5-year-old children.

RESEARCH METHODS AND PROCEDURES

Thirty preschool children wore an ActiGraph accelerometer (ActiGraph, Fort Walton Beach, FL) and a Cosmed portable metabolic system (Cosmed, Rome, Italy) during a period of rest and while performing three structured physical activities in a laboratory setting. Expired respiratory gases were collected, and oxygen consumption was measured on a breath-by-breath basis. Accelerometer data were collected at 15-second intervals. For cross-validation, the same children wore the same instruments while participating in unstructured indoor and outdoor activities for 20 minutes each at their preschool.

RESULTS

In calibrating the accelerometer, the correlation between Vo(2) (ml/kg per min) and counts was r = 0.82 across all activities. The only significant variable in the prediction equation was accelerometer counts (R(2) = 0.90, standard error of the estimate = 4.70). In the cross-validation, the intraclass correlation coefficient between measured and predicted Vo(2) was R = 0.57 and the Spearman correlation coefficient was R = 0.66 (p < 0.001). Cut-off points for moderate- and vigorous-intensity physical activity were identified at 420 counts/15 s (Vo(2) = 20 mL/kg per min) and 842 counts/15 s (Vo(2) = 30 mL/kg per min), respectively. When these cutpoints were applied to the cross-validation data, percentage agreement, kappa, and modified kappa for moderate activity were 0.69, 0.36, and 0.38, respectively. For vigorous activity, the same measures were 0.81, 0.13, and 0.62.

DISCUSSION

Accelerometer counts were highly correlated with Vo(2) in young children. Accelerometers can be appropriately used as a measure of physical activity in this population.

Relationship between body composition and skeletal muscle eNOS

OBJECTIVE

Owing to the relationship between nitric oxide related endothelial dysfunction, insulin resistance and cardiovascular disease in overweight individuals, we investigated if skeletal muscle endothelial nitric oxide synthase (eNOS) protein content and activity are lower in overweight than lean women.

DESIGN

A total of 19 women (age 26.0+/-1.7 years) underwent a resting muscle biopsy, body composition analysis by hydrostatic weighing and peak aerobic capacity determination using indirect calorimetry (Study 1). An additional separate set of six lean (< or = 25% fat) and six overweight (>25% fat) women were subsequently studied for the determination of eNOS activity, and to better control for absolute peak aerobic capacity between lean and overweight women (Study 2).

RESULTS

Skeletal muscle eNOS content was inversely related to percent body fat (r2 = 0.58, P < 0.01), and body mass index (r2 = 0.35, P < 0.05). Total eNOS activity was lower in overweight than lean women (2.09 +/- 0.22 vs 1.44 +/- 0.17 U, P < 0.05; n = 12), and was inversely related to percent body fat (r2 = 0.32, P = 0.05), and BMI (r 2 = 0.41, P < 0.05). Absolute and relative aerobic capacity were not independent predictors of skeletal muscle eNOS content (r2 = 0.11 and 0.26, respectively).

CONCLUSION

There is an inverse relationship between eNOS and percent body fat that may have implications for the previously reported reduced endothelial function and insulin sensitivity in overweight women.

Sport participation and physical activity in adolescent females across a four-year period

PURPOSE

To determine the odds of engaging in future moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) in adolescent female sport participants. A secondary purpose was to compare activity levels of three groups of girls, those who played sports at three time points, those who dropped out, and those who did not participate in sports.

METHODS

Data were collected at three time points, eighth, ninth, and 12th grades, in 429 adolescent girls across the state of South Carolina. Demographic, sport participation and physical activity (PA) data were collected using surveys. Odds ratios were calculated to determine the association between sport participation and future PA behavior. PA was also compared for three sport participation groups (nonparticipants, dropouts, or three-year participants) using analysis of variance.

RESULTS

For MVPA, ninth grade participants were more likely to be active in 12th grade (OR = 1.74 [1.13, 2.67]), and eighth and ninth grade participants more likely to be active in 12th grade than nonparticipants (OR = 1.54 [confidence interval 1.01, 2.35]). For VPA, sport participants had higher odds of being active at all future time points. Three-year participants were significantly more vigorously active than nonparticipants and dropouts at all three time points (p < .01).

CONCLUSIONS

Adolescent girls who participate in sports in eighth, ninth, and 12th grades are more likely to be vigorously active in 12th grade. These findings are novel in providing evidence that sport participation contributes to overall vigorous physical activity during late adolescence, when overall physical activity is known to decline precipitously.

Validation and calibration of the Actical accelerometer in preschool children

PURPOSE

Decreased physical activity (PA) is likely a contributor to the rising prevalence of obesity in children. Lack of valid and acceptable measures of PA has been an issue in studies involving young children. The Actical accelerometer is a promising tool for measurement of PA in young children. The purpose of this study was to calibrate and validate the Actical accelerometer for use with 3- to 5-yr-old children.

METHODS

Eighteen preschool children wore an Actical accelerometer and a Cosmed portable metabolic system during a period of rest, while performing three structured activities in a laboratory setting (used for calibration), and during 20 min each of unstructured indoor and outdoor activities at their preschool (used for cross-validation). Expired respiratory gases were collected, and oxygen consumption was measured on a breath-by-breath basis. Accelerometer data were collected in 15-s intervals.

RESULTS

For the accelerometer calibration, the correlation between VO2 and counts was r = 0.89 across all activities. The calibration equation established was VO2 = counts x 15 s(-1) (0.01437) + 9.73 (R2 = 0.96, SEE = 3.02). The cut-point for moderate activity (20 mL x kg(-1) x min(-1)) was 715 counts x 15 s(-1) (sensitivity 97.2%, specificity 91.7%), and the cut-point for vigorous activity (30 mL x kg(-1) x min(-1)) was 1411 counts x 15 s(-1) (sensitivity 98.2%, specificity 61.1%). For the cross-validation, the intraclass correlation coefficient was R = 0.59 and the Spearman correlation coefficient was R = 0.80 (P < 0.001) between measured and predicted VO2. Percentage of agreement, kappa, and modified kappa for moderate activity were 0.73, 0.40, and 0.46, respectively. For vigorous activity, the same measures were 0.85, 0.26, and 0.71, respectively.

CONCLUSION

The Actical accelerometer is a valid tool for measuring PA in young children.