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Purpose: Examine in preschool-aged children: (1) the associations between parental-reported and device-measured outdoor play (OP) and health indicators of physical, cognitive, and social–emotional development and (2) whether associations were independent of outdoor moderate- to vigorous-intensity physical activity (MVPA). Methods: This cross-sectional study included 107 participants. Children’s OP was measured via a parental questionnaire and the lux feature of accelerometers. Children’s growth, adiposity, and motor skills were assessed as physical development indicators. Visual–spatial working memory, response inhibition, and expressive language were assessed as cognitive development indicators. Sociability, prosocial behavior, internalizing, externalizing, and self-regulation were assessed as social–emotional development indicators. Regression models were conducted that adjusted for relevant covariates. Additional models further adjusted for outdoor MVPA. Results: Parental-reported total OP, OP in summer/fall months, and OP on weekdays were negatively associated (small effect sizes) with response inhibition and working memory. After adjusting for outdoor MVPA, these associations were no longer statistically significant. OP on weekdays was negatively associated with externalizing (B = −0.04; 95% confidence interval, −0.08 to −0.00; P = .03) after adjusting for outdoor MVPA. A similar pattern was observed for device-based measured total OP (B = −0.49; 95% confidence interval, −1.05 to 0.07; P = .09). Conclusions: Future research in preschool-aged children should take into account MVPA and contextual factors when examining the association between OP and health-related indicators.

Purpose: To describe serum irisin and fibroblast growth factor-21 (FGF-21) concentrations in healthy female adolescents with different training activity patterns and their associations with bone mineral properties and metabolic markers. Methods: A total of 62 adolescent girls aged 14–18 years were recruited: 22 rhythmic gymnasts, 20 swimmers, and 20 untrained controls. Bone mineral characteristics by dual-energy X-ray absorptiometry, daily energy intake by dietary recall, serum irisin, FGF-21, undercarboxylated osteocalcin, and C-terminal telopeptide of type I collagen were measured in all girls. Results: Whole body and lumbar spine areal bone mineral density and lumbar spine bone mineral content were higher in the rhythmic gymnasts group compared with swimmers and untrained controls groups (P < .05). Serum irisin, FGF-21, undercarboxylated osteocalcin, and C-terminal telopeptide of type I collagen levels were not significantly different between the groups. In the rhythmic gymnasts group, serum FGF-21 concentration was positively correlated with lumbar spine areal bone mineral density independently of confounding factors (r = .51; P = .027). Conclusions: Serum irisin and FGF-21 levels were not different between adolescent eumenorrheic girls with different training activity patterns. FGF-21 was positively associated with lumbar spine areal bone mineral density, which predominantly consists of trabecular bone in adolescent rhythmic gymnasts.

Purpose: Anecdotal evidence suggests that children with epilepsy (CWE) are limited in the frequency of their daily physical activity (PA). However, there is limited research utilizing device-based measures of PA. We compared levels of PA and sedentary behavior in CWE (11–15 y) and age- and gender-matched healthy controls. Method: Participants (n = 60 CWE [25 males, 35 females] and n = 49 controls [25 males, 24 females]) wore a Actigraph accelerometer (GT3X or GT3X+) for 7 consecutive days during waking hours and self-reported their PA and sedentary behaviors. CWE were compared with control children on time spent in different intensities of PA and on self-reported PA and sedentary behavior. Factors associated with PA were analyzed using linear regression. Results: CWE spent less time in accelerometer assessed light (189.15 vs 215.01 min/d, P < .05) and vigorous PA (35.14 vs 44.28 min/d, P < .05) on weekdays compared with controls. There were no significant differences between CWE and control participants in accelerometer assessed time spent sedentary or time spent in PA on weekends. Among CWE, older children engaged in more reported sedentary behavior and younger children spent more time in most domains of PA (P < .05). Furthermore, CWE reported less PA than controls (P = .006). Sixteen percent of controls met World Health Organization PA guidelines compared with 10% of CWE. There was a positive relationship between accelerometer assessed PA and quality of life for CWE. Conclusion: CWE spent less time in light and moderate to vigorous PA on weekdays. Further research is needed to understand reasons for these differences.

Purpose: To compute reference centiles for 5- and 30-m sprint times relative to chronological and skeletal age in youth soccer players. Subsequently, to compare individual’s sprint performance scores derived from the chronological and skeletal age reference centiles. Methods : Sprint times were collected for a sample of male U11 to U19 soccer players (n = 1745 data points). Skeletal age data were available for a subsample (n = 776 data points). Reference centiles were fitted using generalized additive models for location, scale, and shape. Individual z scores relative to chronological and skeletal age reference centiles were computed and compared for each maturity group (late, on-time, early, and very early) using standardized mean differences (SMD). Results : Reference centiles for chronological age increased more rapidly between 10.5 and 15.5 years, while reference centiles for skeletal age increased more rapidly between 13.0 and 16.5 years. Differences in chronological and skeletal z scores for very early (SMD: −0.73 to −0.43) and late (SMD: 0.58 to 1.29) maturing players were small to large, while differences for early (SMD: −0.30 to −0.19) and on-time (SMD: 0.16 to 0.28) were trivial to small. Conclusion : Reference centiles provide a valuable tool to assist the evaluation of sprint performance in relation to chronological and skeletal age for talent identification purposes in youth soccer players.

Purpose: The purpose of this study was to compare the gross motor skills of children with a chronic physical illness with those of their healthy peers. Methods: Data for children with a chronic physical illness come from the Multimorbidity in Children and Youth Across the Life Course study, and data from children without a physical illness come from the Health Outcomes and Physical Activity in Preschoolers study. Multimorbidity in Children and Youth Across the Life Course and Health Outcomes and Physical Activity in Preschoolers included children ages 3–5 years and administered the Peabody Development Motor Scales-second edition. Participants were sex and age matched (20 male and 15 female pairs; M _age = 54.03 [9.5] mo). Results : Gross motor skills scores were “below average” for 47% of children with a physical illness compared with 9% of children without a physical illness (P = .003). Matched-paired t tests detected significant differences in total gross motor scores (d _z  = −0.35), locomotor (d _z  = −0.31), and object control (d _z  = −0.39) scores, with healthy children exhibiting better motor skills, and no significant difference in stationary scores (d _z  = −0.19). Conclusions : This skill gap may increase burden on children with physical illness and future research should assess gross motor skills longitudinally to establish whether the gap widens with age.

Purpose: Associations between health-related parameters and lung function remain unclear in childhood. The study aims to evaluate the relationship between physical fitness and anthropometric parameters with the lung function of healthy scholar-aged children. Method : A total of 418 children aged 7 years old participated in this study. The associations of physical fitness (handgrip strength, standing broad jump, and 800-m run) and anthropometric (waist circumference and body mass index) parameters with lung function (forced vital capacity and forced expiratory volume in 1 s) were analyzed using a mixed-linear regression model. Results: Girls had significantly lower forced vital capacity values (P = .006) and physical fitness (P < .030) compared to boys. On mixed-linear regression analyses, waist circumference (P = .003) was independently associated with forced vital capacity, explaining 34.6% of its variance, while handgrip strength (P = .042) and waist circumference (P = .010) were independently associated with forced expiratory volume in 1 second, accounting together for 26.5% of its variance in 7-year-old healthy children. Conclusions : Handgrip strength and waist circumference were associated with lung function in healthy children highlighting the influence of upper body muscular strength and trunk dimension on lung function. Our results corroborate the need to promote physical fitness during childhood to protect against lung complications in later on in life.

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

Purpose: Physical inactivity and sugar-sweetened beverage (SSB) consumption are associated with obesity. Gamification and self-monitoring to promote physical activity in youth is unknown, but evidence of effectiveness is present in adults. This study examined the effects of a gamification intervention on increased steps per day among parent–adolescent dyads with obesity compared with digital self-monitoring and if self-monitored SSB intake differed between these arms. Methods: Youth ages 10–16 years and their mothers (N = 39 pairs), both with obesity, were randomized to a self-monitoring (N = 18) or a self-monitoring plus gamification arm (N = 21) for 9 weeks. The step goal was set and incrementally increased each week and was measured with Fitbit devices. Mixed effects linear regression examined changes in steps and SSB consumption per day, per week by study arm. Results: During run-in, mothers averaged 8317 and youth 7508 steps per day. Compared with self-monitoring alone, gamification did not increase daily steps in mothers or youth beyond baseline levels. On average, SSB intake decreased in mothers by approximately 0.5 servings per day; occurred in both arms and persisted throughout the intervention. Conclusion: Gamification did not promote physical activity levels in mother–youth dyads with obesity. SSB intake declined in mothers with obesity in both study arms.