The aim of this study was to identify child and school-level characteristics that explained inter-individual differences in gross motor coordination (GMC). Participants (n = 390), recruited from 18 Portuguese primary schools, were aged 6 to 10 years of age. Birth weight, body fat (BF), physical activity (PA), physical fitness (PF) and GMC were assessed. School size, setting, infrastructure and physical education classes were considered as school context markers. A multilevel modeling approach was used to identify hierarchical effects (child and school levels). It was found that children-level variables (sex, PF, and BF) significantly explained 63% of the 90% variance fraction at the individual level; boys outperformed girls (p < 0.05), individuals with higher BF were less coordinated (p < 0.05), and those with higher PF were more coordinated (p < 0.05). School-variables (e.g. school size and playing surface) explained 84% of the 10% variation fraction. These findings confirm the roles of sex, PFS and BF. Interestingly they also suggest that the school environment plays a minor but significant role in GMC development. However, it is important to stress that the school context and conditions can also play an important role in a child’s motor development, providing adequate and enriching motor opportunities.

The objective of this study is to present a model to estimate sex-specific genetic effects on physical activity (PA) levels and sedentary behaviour (SB) using three generation families. The sample consisted of 100 families covering three generations from Portugal. PA and SB were assessed via the International Physical Activity Questionnaire short form (IPAQ-SF). Sex-specific effects were assessed by genotype-by-sex interaction (GSI) models and sex-specific heritabilities. GSI effects and heterogeneity were tested in the residual environmental variance. SPSS 17 and SOLAR v. 4.1 were used in all computations. The genetic component for PA and SB domains varied from low to moderate (11 % to 46 %), when analyzing both genders combined. We found GSI effects for vigorous PA (p = 0.02) and time spent watching television (WT) (p < 0.001) that showed significantly higher additive genetic variance estimates in males. The heterogeneity in the residual environmental variance was significant for moderate PA (p = 0.02), vigorous PA (p = 0.006) and total PA (p = 0.001). Sex-specific heritability estimates were significantly higher in males only for WT, with a male-to-female difference in heritability of 42.5 (95 % confidence interval: 6.4, 70.4). Low to moderate genetic effects on PA and SB traits were found. Results from the GSI model show that there are sex-specific effects in two phenotypes, VPA and WT with a stronger genetic influence in males.

This study models children’s musculoskeletal fitness (MSF) developmental trajectories and identifies individual differences related to effects of time-invariant, as well as time-varying covariates. A total of 348 Portuguese children (177 girls) from six age cohorts were followed for three years. MSF tests (handgrip strength, standing long jump and shuttle run), age, body mass index (BMI), socioeconomic status (SES), gross motor coordination (GMC) and physical activity (PA) were assessed. Data were analyzed using multilevel models. Between 5 and 11 years of age, boys outperformed girls in all three MSF tests (p < 0.05). Birth weight was positively associated with shuttle run performance (β = −0.18 ± 0.09, p < 0.05). BMI was positively associated with handgrip strength (β = 0.35 ± 0.04, p < 0.001) and shuttle run performance (β = 0.06 ± 0.01, p < 0.001), but negatively associated with standing long jump performance (β = −0.93 ± 0.23, p < 0.001). GMC was positively associated (p < 0.001) with all three MSF tests, while PA was associated with standing long jump (β = 0.08 ± 0.02, p < 0.05) and shuttle run (β = −0.003 ± 0.002, p < 0.05) performance only. No school environment effects were found, and SES was not related to any MSF tests. Children’s MSF development showed a curvilinear shape with increasing age, with boys outperforming girls. Weight status and physical behavior characteristics predicted MSF development, while environmental variables did not. Examining potential longitudinal predictors of MSF across multiple dimensions is important to gain a more holistic understanding of children’s physical development as well as to future interventions.

O propósito principal deste estudo foi construir valores de referência percentílica para provas de aptidão física (AptF), ao mesmo tempo que contrasta, graficamente, os níveis de AptF de crianças e adolescentes vouzelenses com os de outras pesquisas nacionais e internacionais. Foi avaliada uma amostra de 1920 crianças e adolescentes, com idades entre os 7 e os 17 anos em cinco testes motores: dinamometria manual, impulsão horizontal, corrida vaivém, corrida de 50 jardas e corrida/marcha da milha. As cartas percentílicas foram construídas com base no método LMS, implementado no software LMSchartmarker Pro versão 2.54. Os resultados sugerem forte variabilidade interindividual no desempenho motor. Em todas as provas, os rapazes apresentaram valores médios mais elevados do que as raparigas, sobretudo durante o período circum-pubertário. Na comparação do percentil 50 da prova de força manual, crianças e jovens vouzelenses tiveram desempenho similar aos de outros estudos, enquanto nas provas de impulsão horizontal, corrida vaivém e de 50 jardas constatou-se superioridade da amostra norte-americana. Na corrida/marcha da milha, a performance dos vouzelenses foi superior às amostras açoriana e americana.