NHANES National Youth Fitness Survey Research Articles

Have the Fundamental Movement Skills of U.S. Children Changed?

ABSTRACT Purpose: By using four national data sets, this study aimed to examine the changes in U.S. children’s fundamental movement skills (FMS) from 1985 to 2019. Method: Three Tests Gross of Motor Development (TGMD) normative studies, i.e. TGMD-1 (N = 909, male% = 50), TGMD-2 (N = 1143, male% = 50) and TGMD-3 (N = 864, male% = 51), and the TGMD-2 data of the 2012 NHANES National Youth Fitness Survey (NNYFS-2012; raw N = 352, national represented population = 12,509,706, male% = 51) were used for analyses. Each item in TGMD-2/NNYFS and TGMD-3 was carefully examined, and these that did not match to TGMD-1 were deleted. Cohen’s D effect size (ES) was utilized for the difference among year-to-year comparisons. Result: From 1985 to 2000, FMS in US children of 3–7 years old (90% increase & 10% no change) increased temporarily, but remained stable (17% increase & 83% no change) among 8–10 years old. Between 2000 and 2019, however, U.S. children began to demonstrate a slight/stable drop in FMS among 3–5 years old (22% decrease & 78% no change), and a distinct decline among 6–10 years old (80% decrease & 20% no change). While children with normal BMI showed the highest FMS score, the direct cause of reduction in FMS is still unknown. Conclusion: An overall up-and-down change was observed in U.S. children’s FMS between 1985 and 2019, and more longitudinal studies with FMS-related variables are needed.

Site And Unit: Two Flaws Of Physical Activity Assessment In NHANES National Youth Fitness Survey

PURPOSE: To explore possible flaws in physical activity (PA) assessment in the 2012 NHANES National Youth Fitness Survey (NNYFS 2012) that led to a very high PA passing rate. METHOD: The weighted physical activity data (N = 11,223,647, 51% boys, for 3-5 yr. old) collected using ActiGraph in NNYFS 2012 were analyzed to determine the prevalence of meeting the recommendation of the PA guidelines. Specifically, after the released data in Monitor-Independent Movement Summary (MIMS) unit were converted to the MIMS-EQ-Count, an equivalent of ActiGraph count, based on the results of a test equating study by Qin et al. (2021), the prevalence was computed using the cutoff scores by Johansson et al. (2016) for 3-5 yr. old. RESULTS: Unexpected, very high pass rates (%) were observed based on the daily 120 min (SHAPE America, 2020) moderate and vigorous PA (MVPA) and 180 min PA, including 60 min MVPA (WHO, 2019) cutoffs (Boys, Girls, Total):The higher passing rates observed were likely caused by the wrist site, where ActiGraph was worn, employed in NNYFS 2012 and the noise movements by hands (e.g., playing the computer games) that were mistakenly classified as MVPA. Using MIMS, rather than ActiGraph counts, as the unit of the data was another problem since MIMS’ PA intensity cutoff scores have not been established and validated. Together, due to failing to create trustful MVPA data, these two flaws made PA data from NNYFS 2012 less meaningful and useful. CONCLUSION: The very high prevalence of US children meeting PA recommendations was likely caused by two major flaws when collecting PA by wearing ActiGraph on wrist and releasing the data in MIMS unit.

Ultraprocessed Food Intake Is Associated With Poor Cardiovascular Fitness in US Children and Adolescents

ObjectivesUltraprocessed food intake is an established risk factor for cardiovascular disease in adults, however few studies have examined the association between intake of ultraproecssed foods during childhood and risk for cardiovascular disease. The objective of this study was to determine the association between eating patterns, specifically consumption of ultraprocessed foods, and markers of physical fitness in a nationally representative sample of children and youth. MethodsUsing data from NHANES National Youth Fitness Survey, the association between ultraprocessed food consumption and cardiovascular fitness level was evaluated. During the NNYFS, cardiovascular fitness was assessed in adolescents aged 12–15 y and locomotor development was assessed in children age 3–5. Dietary intake information was collected using 24-hour recall; recalled foods were classified using the NOVA classification system and NOVA Category 4 (ultraprocessed) were identified. Cardiovascular fitness level was categorized based on gender-age specific cut-points of estimated VO2max. All data were analyzed using SAS 9.4 survey procedures to account for the unequal sampling probability and complex survey design of the. ResultsIn older children, we observed a significant positive association between consumption of ultraprocessed foods and cardiovascular fitness level after controlling for age, sex, race, and household income. Children with cardiovascular fitness levels categorized as “high risk” consumed approximately 200kcal more/day of ultraprocessed foods than children in the “healthy fitness zone”, p = 0.002. In younger children, greater intake of ultraprocessed foods was associated with lower locomotor development score; children with the lowest locomotor development scores consumed 273kcal/more day of ultraprocessed foods than children with the highest locomotor development scores, p = 0.0006. ConclusionsThese findings expand on previous work from our group evaluating the association between childhood eating behaviors and fitness indicators. Interventions that aim to educate families about cost-effective methods of reducing ultraprocessed food intake may assist in decreasing risk for cardiovascular health problems in adulthood. Funding SourcesNone.

Cross-sectional association of light sensor-measured time outdoors with physical activity and gross motor competency among U.S. preschool-aged children: the 2012 NHANES National Youth Fitness Survey

BackgroundTime spent outdoors (outdoor time) has been suggested to be beneficial for physical activity (PA) and healthy development among preschool-aged children. The aim of this study was to quantify PA level and gross motor competency associated with light sensor-measured daily outdoor time in a representative sample of U.S. children aged 3 to 5 years.MethodsThe study sample included 301 participants (149 girls) aged 3 to 5 years from the 2012 U.S. National Health and Examination Survey National Youth Fitness Survey. ActiGraph GT3X+ accelerometers with a built-in ambient light sensor were used to measure PA (expressed in monitor-independent movement summary [MIMS]) and outdoor time. The Test of Gross Motor Development-Second Edition (TGMD-2) was used to assess gross motor skills. Multivariable linear regression models were fit to predict daily and gross motor scores by daily outdoor time.ResultsAverage daily outdoor time was 95 min (median of 84 min; interquartile range of 52 to 123 min). Means of daily outdoor time and daily MIMS were not significantly different between boys and girls. Among girls, every additional 10 min of daily outdoor time was associated with an additional 540 daily total MIMS (95% CI = 372, 708). Among boys, every additional 10 min of daily outdoor time was associated with an additional 296 daily total MIMS (95% CI = 131, 460). Every additional 10 min of daily outdoor time was associated with a 0.1-point (95% CI = 0.001, 0.130) higher object control standard score. Daily outdoor time was not associated with a locomotor standard score.ConclusionsIn a representative sample of U.S. preschool-aged children, daily outdoor time was positively associated with daily PA. The contribution of outdoor time to PA was greater among girls than boys, suggesting that providing outdoor opportunities is critical for promoting PA, particularly among girls.

Cardiovascular Fitness and Muscle Strength in Asthmatic Children

The aim of this retrospective study is to evaluate the cardiovascular fitness and muscle strength performance of children with asthma versus without. Participants include patients who were involved in the 2012 NHANES National Youth Fitness Survey (NNYFS) as published by the Centers for Disease Control and Prevention. The average cardiovascular fitness and muscle strength scores will be appreciated by analyzing the averages of time spent on treadmill, maximal heart rate, heart rate at end of exam, recovery time, maximal endurance time, cardiovascular fitness report, upper body strength and lower body strength using two-tailed T-tests between patients with asthma versus without. Children with asthma have a statistically lower total time spent on treadmill and maximal endurance time (p = 0.006, p = 0.006, respectively). Children with asthma do not have statistically different maximal heart rate, heart rate at end of exam, recovery time, cardiovascular fitness, upper body strength, or lower body strength compared to children without asthma. History of asthma should not be considered a direct, baseline cause of decreased cardiovascular fitness or muscle strength performance in children. The anxiety of breathlessness in an asthma attack or lack of proper medical management may encourage asthmatics to have a sedentary lifestyle without engaging in regular physical activity. Our findings support the growing research that encourages the individuals with asthma to pursue a healthy, active lifestyle alongside proper medical management in order to achieve optimal cardiovascular and musculoskeletal health.

U.S. Children and Youth's Physical Activities Inside and Outside of School PE: 1985 vs. 2012.

The purpose of this study was, by taking advantage of the rich data from two U.S. national fitness surveys, to examine the physical activity (PA) students engaged in, both inside and outside school physical education (PE), determine if there are differences by grade, sex, and weight status, and if there was a change between 1985 and 2012. The data from the 1985 National Children and Youth Fitness Study (NCYFS) and the 2012 NHANES National Youth Fitness Survey (NNYFS) were matched, merged (N = 6178, 3107 boys and 3071 girls), and analyzed. It was found that basketball remained the most popular PA inside school PE across both surveys. Swimming was the most popular PA outside of school PE in 1985, but was replaced by running in 2012. Although PA taught and promoted inside of school PE and that such PA practiced outside were moderately correlated across the surveys, some disconnections were noticed. The impact of grade, sex, and weight status on PA preference and participation was also confirmed. What is needed is to the design and integration of more lifelong and individual PAs in future school PE curricula and school and community children and youth sport and PA programs.

Movement behaviors and health-related fitness among peripubertal adolescents: 2012 NHANES national youth fitness survey data.

Less than half of adolescents in the United States meet the recommended levels of moderate-to-vigorous physical activity (MVPA) and health-related fitness (HRF). Using the 2012 NHANES National Youth Fitness Survey data, this study aimed to examine the associations of movement behaviors (i.e., MVPA and screen-based sedentary behaviors) with HRF (i.e., cardiovascular and muscular fitness) among 11-16- year-old peripubertal boys and girls, respectively. A total of 470 adolescents (227 boys, 243 girls; age: 13.59±1.12 years old) from the 2012 NHANES dataset were included. The study variables included movement behaviors (i.e., MVPA and screen-based sedentary behavior), anthropometric indices (i.e., waist circumference, Body Mass Index [BMI]), and HRF (i.e., cardiovascular fitness and muscular fitness). Correlational and hierarchical regression analyses were conducted for boys and girls, respectively. MVPA significantly predicted cardiovascular fitness for boys (β=0.16, P<0.05) and girls (β=0.15, P<0.05) regardless of weight status; screen-based sedentary behavior and waist circumference in girls significantly predicted muscular fitness (β=-0.13 and β=-0.42, P<0.05). To increase overall HRF in peripubertal girls and boys, it is important to help them maintain healthy weight status and to promote MVPA and limit screen-based sedentary behavior, especially in adolescent girls.

Health Insurance Moderates the Waist Circumference and Cardiorespiratory Fitness Relationship in U.S. Adolescents

Background: Abdominal obesity is a cardiometabolic risk factor and shown to be related to cardiorespiratory fitness (CRF). The purpose of this study was to examine the moderating effects of health insurance (HI) on the waist circumference (WC) and CRF relationship in U.S. adolescents. Methods: Data from youths 12 to 15 years of age participating in the 2012 NHANES National Youth Fitness Survey (NNYFS) were used. Both WC (cm) and CRF (ml/kg/min) were measured by trained medical personnel with HI status assessed via questionnaire by proxy. Binary variables were created at the median for WC and CRF. Multivariate logistic regression was used to examine the relationship between WC, HI and CRF while controlling for confounding variables. Results: The overall prevalence of no HI was 6.5% (95% CI: 2.78 - 10.20). Findings from the fully adjusted model predicting low CRF showed a significant (p = .020) WC-by-HI interaction. Slicing the model by HI status showed a significant decreased risk of low CRF for adolescents with HI and low WC (OR = 0.25, 95% CI: 0.19 - 0.33). Additionally, a significant decreased risk of low CRF was seen among those with no HI and low WC (OR = 0.50, 95% CI: 0.28 - 0.88). Slicing the model by WC status showed a significant increased risk of low CRF for adolescents with low WC and no HI (OR = 2.44, 95% CI: 1.22 - 5.32). However, no significant HI and CRF relationship was observed among adolescents with high WC. Conclusion: This study showed that HI moderates the WC and CRF relationship in U.S. adolescents. Specifically, having low WC appears to protect adolescents against low CRF. Whereas having HI looks as if to protect against low CRF only for those with low WC.

Relationship between fitness performance and a newly developed continuous body composition score in U.S. adolescent boys.

Body composition (BC) assessment typically requires the administration of a single test and can have different evaluation outcomes depending on the selected test and the specific population. The purpose of this study was twofold. Firstly, to develop and validate a novel continuous body composition (CBC) score using the continuous response model (CRM). Secondly, to examine the relationship between CBC scores and fitness performance. Data from the 2012 NHANES National Youth Fitness Survey (NNYFS) were used and consisted of n=212 adolescent boys 12-15 years of age. CBC scale variables included body mass (BM), body mass index (BMI), arm circumference (AC), waist circumference (WC), calf circumference (CC), calf skinfold (CSF), triceps skinfold (TSF), and subscapular skinfold (SSF). Fitness performance variables included cardiorespiratory fitness (CRF, mL/kg/min), leg strength (LS, lb), modified pull-ups (MPU, #), grip strength (GS, kg), and plank (PL, sec). Samejima's CRM, factor analysis, convergent validity coefficients and score reliability were used to validate the CBC scale. Multinomial logistic regression and multiple linear regression were used to examine the relationship between CBC scores and fitness performance variables. Factor analysis of the CBC scale variables retained a single factor (loadings >0.81, 88% explained variance) with strong internal consistency (α=0.96). The CRM analysis indicated all CBC scale variables fit a unidimensional construct with adequate discrimination (as: 0.71-2.16) and difficulty (bs:-0.04-1.44). CBC scores (Mean=0, SD=1.00) displayed strong reliability (SEE.θ=0.22, r.θ=0.95) with lower values representing smaller-more-lean individuals and higher values representing larger-less-lean individuals. All fully adjusted regression models showed significant (ps<0.05) negative relationships between CBC scores and CRF, MPU, and PL and positive relationships between CBC scores and LS and GS. The CRM-derived CBC score is a novel measure of BC and found to be positively associated with strength performance and negatively associated with endurance performance in U.S. adolescent boys.

Disparities in physical fitness of 6\u201311-year-old children: the 2012 NHANES National Youth Fitness Survey

BackgroundChildren’s physical fitness is an important predictor of metabolic health, physical function, and academic achievement. Although fitness is determined partially by heritable factors, it can be maintained and improved through regular physical activity. Because physical activity is known to vary by socioeconomic status, physical fitness may be expected to vary similarly. With this in mind, the purpose of this study was to examine disparities in physical fitness performance among a nationally-representative sample of 6–11 year-old children living in the United States.MethodsWe conducted secondary analysis of physical fitness data of children ages 6–11 years (n = 686) from the nationally representative National Health and Nutrition Survey (NHANES) Youth Fitness Survey (NNYFS) 2012. We estimated sex-stratified weighted means of four fitness performance tests: cardiorespiratory endurance, upper-, lower-, and core-muscular strength. The weighted mean for each fitness assessment was compared by income groups (federal income to poverty ratio – FIPR) accounting for complex sampling design and adjusting for age.ResultsIncome disparities in physical fitness performance were evident among girls but not among boys. Girls from lower income groups (< 130% FIPR and 130–349% FIPR groups) showed significantly lower cardiorespiratory endurance and core muscle strength compared to those from the highest income group (≥ 350% FIPR).ConclusionThese findings highlight the need to support health-promoting physical activity among girls from disadvantaged backgrounds prior to the adolescent period.

Predicting Gross Motor Skills In Children: Data From The 2012 NHANES National Youth Fitness Survey

Predicting Gross Motor Skills In Children: Data From The 2012 NHANES National Youth Fitness Survey

Socioeconomic and Familial Factors Associated with Gross Motor Skills among US Children Aged 3-5 Years: The 2012 NHANES National Youth Fitness Survey.

The first aim of this study was to examine the prevalence of below average gross motor skills in a representative sample of US children aged 3 to 5 years. The second aim was to identify socioeconomic and familial characteristics that are associated with below average gross motor skills. Secondary analysis was conducted using the datasets from the 2012 National Health and Examination Survey National Youth Fitness Survey (NNYFS). The NNYFS assessed gross motor skills among 329 children aged 3–5 years, using the Test of Gross Motor Development-Second Edition (TGMD-2). Socioeconomic and familial characteristics of interest, such as family income and family structure, were asked in an in-person interview. This study estimated that one in three US children age 3 to 5 years old (33.9%) scored below average for gross motor quotient. In the gross motor subsets, one in four (24.4%) scored below average for locomotion and two in five (39.9%) scored below average for object control. Children living below the poverty threshold were more likely to have a higher gross motor quotient (odds ratio, OR = 2.76; 95% confidence interval, CI = 1.09–7.00). Girls were more likely to have a higher locomotor score (OR = 2.17; 95% CI = 1.10–4.25). Those living with other child(ren) aged ≤5 years were more likely to have a higher locomotor score (OR = 2.36; 95% CI = 1.01–5.54), while those living with child(ren) aged 6–17 years were more likely to have a higher object control score (OR = 1.83; 95% CI = 1.24–2.69). This study revealed risk factors associated with poor gross motor development, furthering our understanding of gross motor development in early childhood.

Socioeconomic status and physical fitness in youth: Findings from the NHANES National Youth Fitness Survey

ABSTRACTThis study examined the associations between socioeconomic status (SES) and musculoskeletal (MSF) and cardiorespiratory fitness (CRF) in youth. The sample consisted of boys and girls between 3-15 years. SES was categorized utilizing family-income-to-poverty ratio (FIPR). All analyses were standardized for age and sex. For each test of physical fitness, SES was used to estimate mean fitness test percentile and 95% confidence intervals, controlling for race/ethnicity and physical activity. Odds ratios were calculated for the likelihood of having low fitness by SES category. In general, the high SES group had a better composite MSF, body composition, and CRF profiles than low and moderate SES groups. Statistically significant differences were identified for relative grip strength, plank, body mass index, and cardiovascular endurance time (all p < 0.05). Additionally, the odds of low/poor MSF fitness were 1.7 and 1.6 times higher in the low and moderate SES groups (respectively) compared to the children from high SES families. The moderate SES group had an odds of poor CRF 1.6 times higher than the high SES group as well. Children and adolescents from high SES families tend to have higher mean fitness and were less likely to have low/poor fitness.

Eat Better, Run Longer? Dietary Energy Density Is Associated with Cardiovascular Fitness Level in a Nationally Representative Sample of Adolescents (P16-030-19)

ObjectivesObesity during childhood and adolescence is a risk factor for several types of chronic disease in adulthood. Researchers have identified dietary energy density (ED, kcal/g) and sedentary behavior as risk factors for obesity during adulthood, but little is known about the relationship between diet and measured cardiovascular fitness levels. The 2012 National Health and Nutrition Examination Survey National Youth Fitness Survey (NNYFS) collected data on dietary intake, physical activity and fitness levels in a nationally representative sample of US adolescents. The objective of this study was to determine the association between eating patterns, specifically dietary energy density, and physical fitness in a nationally representative sample of youth. MethodsUsing data from NHANES National Youth Fitness Survey, the association between dietary energy density (ED, kcal/g) and cardiovascular fitness level was evaluated. During the NNYFS, cardiovascular fitness was assessed in adolescents aged 12–15y. Dietary intake information was collected using 24-hour recall, and assessment of diet quality involved calculation of dietary energy density. Cardiovascular fitness level was categorized based on gender-age specific cut-points of estimated VO2max. All data were analyzed using SAS 9.4 survey procedures to account for the unequal sampling probability and complex survey design of the NHANES. ResultsWe observed a significant positive association between dietary energy density and cardiovascular fitness level after controlling for age, sex, race, and household income. Children with cardiovascular fitness levels categorized as “high risk” had significantly higher dietary energy density than children in the “healthy fitness zone” (1.82 vs 1.97, P = 0.04). ConclusionsThese findings expand on previous work from our group indicating that dietary energy density is associated with obesity in children and that diet in early childhood corresponds with development of physical characteristics that are associated with fitness ability. Interventions that aim to lower dietary energy density in adolescence may aid in the reduction of chronic disease risk during adulthood. Funding SourcesNone. Supporting Tables, Images and/or Graphs▪

The Influence of Acculturation on Physical Activity Behavior of Hispanic Adolescents

Objective: Participation in physical activity (PA) among adolescents lowers the risk for various chronic diseases. Yet, few adolescents in the U.S., particularly minority adolescents, meet guidelines of recommended PA (60 minutes daily). Acculturation has been shown to affect PA among adults but is less investigated among Hispanic adolescents. Thus, the objective of this study was to examine the association between acculturation and PA utilizing a nationally representative sample from the 2012 NHANES National Youth Fitness Survey. Methods: A final sample of 119 (weighted sample 3.3 million) adolescents (12-15 years) completed validated acculturation (language as a proxy measure) and PA questionnaires (# of days engaging in 60 min/day). Results: After adjustments, and compared to speaking only Spanish/little English, those who spoke equal English/Spanish (β=-.92, p=.05) and more English than Spanish (β=-.99, p=.04) engaged in fewer days of PA. Conclusion: These findings are, generally, in contrast to adult studies, which show that greater acculturation is associated with more PA. Tailored PA and sedentary interventions among Hispanic adolescents should consider their degree of acculturation.

Physical Activity Guideline Adherence and Physical Fitness

Encouraging regular physical activity (PA) is a major public health objective in the United States for several reasons, including the promotion of physical fitness. As such, the first edition of federal Physical Activity Guidelines for Americans (PAG) was released in 2008. For youth, these PAG include recommendations for aerobic and muscle- strengthening (MS) activity. PURPOSE: To examine the association between adherence to PAG and physical fitness in a nationally-representative sample of children and adolescents. METHODS: The NHANES National Youth Fitness Survey (NNYFS) collected fitness test and PA questionnaire data on children and adolescents (ages 3-15 years, n = 1,576). Fitness testing was completed for the plank (3-15 years), modified pull-up (5-15 years), handgrip strength (6-15 years), and aerobic fitness (12-15 years) by trained test administrators. Fitness test results were converted into age-specific percentile scores. All subjects reported the number of previous days of the week that included 60 minutes of PA, while 12-15 year olds also reported the number of previous days that included MS activities. Independent t-tests were used to compare the mean physical fitness percentile of youth reporting 7 days of 60 minutes of PA to those reporting ≤ 6 days and adolescents reporting 2 or more days of muscle-strengthening activity to those reporting ≤ 1 day. RESULTS: Youth reporting 7 days/week of PA had a higher mean relative grip strength (53.8 vs. 46.8 percentile), modified pull-up (53.7 vs. 47.1 percentile), and VO2max (48.9 vs. 40.8 percentile) compared to those with ≤ 6 days/week (all p < 0.05). Those participating in MS activity 2 days/week had a higher relative grip strength (54.7 vs. 45.3 percentile), modified pull-up (54.2 vs. 46.8 percentile), plank (54.5 vs. 44.4 percentile), and VO2max (45.7 vs. 39.8 percentile) compared to the ≤ 1 day/week group (all p < 0.05). CONCLUSION: In this nationally-representative sample, meeting PAG’s were associated with measures of aerobic capacity, muscular strength, and muscular endurance. Future prospective research is needed to investigate the impact of changing PA level to meet (or not meet) the PAG on physical fitness.

Reference Curves for Field Tests of Musculoskeletal Fitness in U.S. Children and Adolescents: The 2012 NHANES National Youth Fitness Survey.

Laurson, KR, Saint-Maurice, PF, Welk, GJ, and Eisenmann, JC. Reference curves for field tests of musculoskeletal fitness in U.S. children and adolescents: The 2012 NHANES National Youth Fitness Survey. J Strength Cond Res 31(8): 2075-2082, 2017-The purpose of the study was to describe current levels of musculoskeletal fitness (MSF) in U.S. youth by creating nationally representative age-specific and sex-specific growth curves for handgrip strength (including relative and allometrically scaled handgrip), modified pull-ups, and the plank test. Participants in the National Youth Fitness Survey (n = 1,453) were tested on MSF, aerobic capacity (via submaximal treadmill test), and body composition (body mass index [BMI], waist circumference, and skinfolds). Using LMS regression, age-specific and sex-specific smoothed percentile curves of MSF were created and existing percentiles were used to assign age-specific and sex-specific z-scores for aerobic capacity and body composition. Correlation matrices were created to assess the relationships between z-scores on MSF, aerobic capacity, and body composition. At younger ages (3-10 years), boys scored higher than girls for handgrip strength and modified pull-ups, but not for the plank. By ages 13-15, differences between the boys and girls curves were more pronounced, with boys scoring higher on all tests. Correlations between tests of MSF and aerobic capacity were positive and low-to-moderate in strength. Correlations between tests of MSF and body composition were negative, excluding absolute handgrip strength, which was inversely related to other MSF tests and aerobic capacity but positively associated with body composition. The growth curves herein can be used as normative reference values or a starting point for creating health-related criterion reference standards for these tests. Comparisons with prior national surveys of physical fitness indicate that some components of MSF have likely decreased in the United States over time.

Validity of a Sedentary Behavior Guideline for Youth

Sedentary behavior (SB) has been identified as an independent risk factor for many health outcomes such as metabolism, cardiovascular and obesity. The Canada research group provided SB guideline that is no more than 2 hours of SB per day. The SB guideline also indicated lower levels of SB are associated with higher level of fitness. Little is known about the validity of the SB guideline. PURPOSE: The purpose of this study is to examine the validity of Canada sedentary behavior guideline for Youth. METHODS: Data from NHANES National Youth Fitness Survey (NNYFS) 2012 were analyzed for this study. A total of 432 participants (221 males) aged 12-15 years completed the survey and a physical fitness examination. The NNYFS questionnaire included two questions regarding recreational SB; in the past 30 days how many hours of TV or videos were watched and how many hours of computer use. Recreation SB was categorized in two levels: (1) 2 hours and less per day; (2) more than 2 hours per day. Health related fitness consisted of body composition, muscular strength and cardiorespiratory fitness. Body composition was measured by BMI, muscular strength was measured by plank, and cardiorespiratory was measured by VO2max in NNYFS examination. To validate SB guideline, the general linear model was used to examine the association between the recreational SB and health related fitness after controlling the covariates (i.e., age, gender, and physical activity). RESULTS: After adjusting the covariates, recreational SB was related to plank, F (1, 427) = 4.14, p = .043. Recreational SB, however, was not related to VO2max and BMI, F (1, 427) = 1.62, p = .20 and F (1, 427) = 0.67, p = .413, respectively. CONCLUSIONS: Recreational SB was only associated with muscular strength. The lack of validity for the SB guideline may be due to surrogate measure of SB used in the current study. Further validity research is needed using more accurate measures of SB.

Mother’s Smoking Status during Pregnancy on Child’s Motor Development

PURPOSE: To determinate the impact of a mother’s smoking status during pregnancy on a child’s motor development using a propensity score (PS) analysis, a statistical method for evaluating treatment effects when using nonexperimental or observational data. METHODS: Five NHANES National Youth Fitness Survey 2012 data sets, “Demographic Variables,” “Physical Functioning,” “Early Childhood,” in which mother’s smoking status during pregnancy was asked, “Physical Activity,” and “Test of Gross Motor Development (TGMD-2)”were merged. By matching 10 variables, including “Sex of the child,” “At least one adult aged 60 years or older living in the participant’s household,” “the household reference person’s sex,” “Weight at birth, pounds,” “Your child was overweight,” “Crawl, walk, run, play limitations,” “Impairment requiring special equipment,” “Receive Special Ed or Early Intervention,” “Days physically activity least 60 min,” and “Hours watch TV or video past 30 days,” a regression model was employed for the PS analysis (with inverse probability weighting adjustment and greedy algorithms with 1:1 matching; the covariate adjustment were used to estimate the effect of “Did biological mother smoke at any time while she was pregnant” on a child’s gross motor development). The full sample weights were used for the analysis. RESULTS: The negative impacts of a mother smoking while pregnant on their child’s motor development, with and without the PS analysis, are summarized below:Table: No title available.CONCLUSION: By applying the PS analysis, the negative impact of mothers smoking status during pregnancy on children’s gross motor development was further confirmed.

A National Survey of Popular Physical Activities among U.S. Children and Youth

PURPOSE: Understanding what children and youth enjoy to play is beneficial in helping design intervention and other physical activity (PA) related programs to help improve children’s fitness levels. The aim of this study was to determine the popularity of different PA among children and youth aged from 3 to 15 yr. old. METHODS: The national representative data (N = 53,669,505; 51.12% male; 3-15 yr.) from the 2012 NHANES National Youth Fitness Survey were employed for the analysis. Descriptive analysis was applied to examine the popularity of different type of PA and t-tests were used to determine the sex difference and ANOVAs were applied to examine the age difference on total PA participation. RESULTS: Among the 30 types of PA listed, including running, football, basketball, soccer, swimming, dance, and walking, etc., the most popular PA for children and youth in all age groups is running (33.30%), followed by bike riding (27.86%), and backyard games (21.71%). The 3 most popular PA for boys are running (35.18%), basketball (30.31%), and bike riding (29.90%), and for girls are running (31.33%), bike riding (25.73%), and walking (21.55%). About 16.9% of children/youth participated in no activity, but about 18.7% took part in at least one activity and about 64.4% took part in more than one activities; on average, children/youth took part in 2.59 ±2.18 (M±SD) activities and boys (2.81±2.31) participated in more activities than girls (2.36±2.02; t=758.544, p<0.00, effect size = .10). From 3 to11 yr., as the children got older, they participated in more PA, but the PA participation decreased after 12yr. CONCLUSIONS: Running is the most popular PA for the US children and youth, and some gender and age impact on PA participation was found.Table: No title available.