Children change their body size, shape, and gross motor coordination (GMC) as they grow. Further,GMCis expected to link to changes in children's body size, physical activity (PA), and physical fitness (PF). The objective was to modelGMCchanges in children followed longitudinally and to investigate associations between these changes andPAandPFlevels. A total of 245 children (122 girls) were observed at 6 years of age and followed annually until 9 years. A sequence of allometric models was fitted, that is, 1. body mass, stature, andPA; 2. addition of fourPFtests; 3. addition of four morePFtests. In Model 1, changes inGMCare nonlinear, and body mass (−0.60 ± 0.07,P < .001) and stature (2.91 ± 0.35,P < .001) parameter estimates were significant suggesting children with a more linear body size/shape showed higherGMCperformances. Girls tend to outperform boys across time, andPAwas not associated withGMCchanges. Model 2 fitted the data better, and thePFtests (handgrip, standing long jump, 50‐yard dash, and shuttle run) were significantly linked toGMCchange. In Model 3, adding the remainingPFtests did not change the order of any factors importance. The greatestGMCchanges were achieved by children whose body size/shape has an ectomorphic dominance across the years. Considering that leaner and physically fitter children tended to be more coordinated, physical education should also focus onPFdevelopment in components related to muscular strength, speed, agility, and aerobic capacity, along with nutritional education to reduce fat mass.

This study modelled children’s gross motor coordination, investigated sex-differences and identified the effects of fixed and dynamic correlates on motor coordination development. A total of 344 Portuguese children (170 girls), from 6 age cohorts (5 to 9 years of age), were followed consecutively for three years (age range 5 to 11 years) using a mixed-longitudinal cohort design. Birth weight, hand dominance and socioeconomic status (SES) were identified. Gross motor coordination, body mass index, physical fitness (PF) and physical activity (PA) were assessed annually. A sequence of multilevel hierarchical linear models were developed. Model 1 found that age, age², sex, sex-by-age and sex-by-age² were significant predictors (p < 0.05) of gross motor coordination. Boys outperformed girls from 6 years of age onwards. Model 2 found a cohort effect (p < 0.05). Model 3 found that right handers were more coordinated (p < 0.05). When the confounders of body mass index, PF and PA were added to the model (Model 4) it was found that boys and girls had parallel trajectories in their gross motor coordination development. In conclusion children with increasing body mass index were less coordinated, while those who were stronger and more agile had steeper trajectories of gross motor coordination with age.

Children's differences in moderate-to-vigorous physical activity levels are not at random. This study investigates the relevance of individual- and school-level characteristics in explaining these differences. In total, 307 children (154 girls) aged 5-10 years, from 19 Portuguese schools, were sampled. Height and weight were measured, and body mass index was calculated. Time spent in moderate-to-vigorous physical activity was measured by accelerometry. Gross motor coordination was assessed with the KörperkoordinationsTest für Kinder battery and socio-economic status was obtained via the school social support system. School characteristics were obtained with an objective school audit. A multilevel analysis was used as implemented in Stata 15. Schools explained 18.2% of the total variance in moderate-to-vigorous physical activity, with the remainder being ascribed to children's distinct characteristics. Boys were more active (β=29.59±11.52, p<0.05), and having higher gross motor coordination levels (β=0.11±0.04, p<0.05) was positively associated with daily moderate-to-vigorous physical activity, whereas being older (β=-5.00±1.57, p<0.05) and having higher socio-economic status (β=-7.89±3.12, p<0.05) were negatively related with moderate-to-vigorous physical activity. From the school-level correlates, only playground dimension was significantly associated with moderate-to-vigorous physical activity levels. Children from schools with medium (40m² to 69m²) and large playground dimensions (≥70m²) were less active than children with smaller playground dimensions (10m² to 39m²). Variation in school children's moderate-to-vigorous physical activity is mostly explained by their individual characteristics; school characteristics also play a role but to a smaller degree. Future intervention programs to change this behavior should be more personalized, emphasizing mostly individual-level characteristics.

Background: Children’s physical fitness is potentially influenced by biological, behavioural and environmental factors. Aim: To investigate the importance of individual-level and school-level characteristics in explaining variation in children’s physical fitness. Subjects and methods: The sample comprised 354 Portuguese children, aged 5-10 years. Physical fitness [(handgrip (HG) strength, standing long jump (SLJ), shuttle-run (SR), total physical fitness score (PFz)], gross motor coordination (GMC), and body mass index (BMI) were assessed. Moderate-to-vigorous physical activity (MVPA) was objectively monitored; birth weight and socio-economic status (SES) were obtained by questionnaire. School contexts were assessed via an objective audit. Multilevel models using the Bayesian approach were used. Results: Age was positively associated with HG, SLJ, and PFz (p < 0.05); BMI was positively associated with HG (p < 0.05), and GMC with all physical fitness components (p < 0.05); MVPA was only associated with PFz (p < 0.05); children with level A SES outperformed those with level C SES in HG (p < 0.05), but those with level B SES outperformed their level A SES peers in SR (p < 0.05). Within the school context, no equipment for physical education was negatively associated to HG (p < 0.05). Conclusions: In the primary school years, individual-level characteristics were more important than the school context in explaining variation in physical fitness.

Background: There is a renewed interest in longitudinal studies which link children’s growth, motor and cognition development. This is important for both educational outcomes and identification of children who are at risk. Aim: To identify cross-sectional sex-differences. Subjects and methods: In total, 1166 Portuguese children, aged 4–11 years, were recruited into the Growth, Motor Development and Cognition Study (GMDC-Vouzela study). Measures included: anthropometry, gestational development, motor coordination, cognitive performance, laterality, physical fitness, metabolic syndrome risk, lifestyle characteristics and environmental exposures. Analysis of covariance was used to compare outcomes between boys and girls, adjusting for chronological age. Results: Most variables did not show significant differences between the sexes (p > 0.05). However, girls had more body fat mass than boys (p < 0.05) and boys were significantly heavier at birth (p < 0.05); furthermore, boys outperformed girls in a hopping high coordination test (p < 0.001) and were more physically fit (p < 0.05). Conclusions: Baseline results from the GMDC-Vouzela study indicate the dynamic relationships between children's biological and environmental characteristics. They also highlight lifestyle traits that will most likely effect subsequent growth, motor and cognitive development.

(1) Background: The popularity of motion-sensing computer-based games, like virtual reality (VR) exergames, is increasing among adolescents. However, their efficacy compared to conventional physical training methods remains unclear. This study investigated whether VR exergames produce effects on reaction time (RT) comparable to traditional tennis training in school-aged adolescents. (2) Methods: In total, 130 adolescents (mean age: 15.6 ± 2.0 years; 67 boys: 15.5 ± 2.2 years; 63 girls: 15.7 ± 1.8 years) were recruited in schools and assigned to one of three groups: VR exergame (G1, n = 39), tennis training (G2, n = 25), or control (G3, n = 66). Participants’ RTs were evaluated before and after the interventions. G1 engaged in VR exergames for 8 min, G2 underwent traditional tennis training for 30 min, and G3 did not participate in any physical activity. (3) Results: Our results indicated that in G3, girls exhibited slower RTs compared to boys (p < 0.0). No differences were observed in RTs when comparing G1 and G2. (4) Conclusions: Sex appeared to influence RT, with girls showing slower RTs than boys in G3. The findings suggest that VR exergames and traditional tennis training have similar impacts on RT. This indicates the potential of VR exergames as an alternative to conventional physical training for improving RT in adolescents.