Adherence to 24-hour movement guidelines in low-income Brazilian preschoolers and associations with demographic correlates.

BACKGROUND: The importance of movement behaviors for health is well known, although few studies have examined the adherence to movement guidelines in low-income preschoolers from a middle-income country, as Brazil. This study reports the proportion of preschoolers meeting the 24-hour movement guidelines and investigates its associations with demographic correlates in Brazilian low-income preschoolers. METHODS: Two hundred and seventy preschoolers (132 boys, means age = 3.97 ± 0.80) provided physical activity (PA) data (Actigraph wGT3X). Sleep duration, screen time, and social correlates were parent-reported. Preschoolers were classified as compliant/not compliant with the 24-hour movement guidelines. Relationships between compliance with movement behaviors guidelines and demographic correlates were calculated using a network analysis (Mplus 8.0; Rstudio). RESULTS: Preschoolers were active (273.52 ± 62.08 minutes/day of total PA), though moderate-to-vigorous physical activity (MVPA) time was below the guideline (58.68 ± 22.51 minutes/day); spent more than the recommended 60 minutes/day on screen time (169.91 ± 97.07 minutes/day); and slept less than 10 hours per night (9.44 ± 1.12 hours/day). Only 3% of the sample complied with the guidelines. PA showed the highest compliance (43%), compared to sleep duration (35%) and screen time (15%). Male sex was related to adherence to MVPA recommendations, while female sex, with adherence to total PA recommendations. Child's primary caregiver was the most important centrality indicator in the network. CONCLUSION: Only 3% of the assessed preschoolers are compliant with the 24-hour movement behaviors guidelines. Strategies to promote adherence to movement behaviors among low-income preschoolers should consider child's primary caregivers to support movement behaviors.

Physical activity, sedentary time and bone tissue: effects of an 8-months interdisciplinary program with overweight/obese children / Atividade física, tempo sedentário e tecido ósseo: efeitos de um programa interdisciplinar de oito meses com crianças com sobrepeso/obesidade

Moderate to vigorous physical activity plays a recognized osteogenic effect on bone. Moreover, sedentary time, and fat accumulation are unfavorable to bone health. Our study aimed (1) to examine changes in body composition, bone tissue, physical activity, and sedentary time; and (2) to explore whether changes in physical activity intensities and in sedentary time are associated with changes in bone outcomes after a school-based interdisciplinary intervention program. A total of 53 over-weight/obese students (10.6 ± 3.5 year-olds; 26 girls) participated in physical activity classes. Bone area, bone mass, and bone mineral density z-score, body composition (fat mass, fat lean mass), phys-ical activity, sedentary time and potential confounders (vitamin D and maturational status) were assessed at baseline, and 8 months later. General Linear Models were carried out and significance level was set at 5%. Changes in moderate to vigorous physical activity were positively correlated with changes in all bone mass indicators. We observed a significant overall effect of the intervention on bone mineral density z-score changes, however after adjustments for changes in sedentary time and moderate to vigorous physical activity, no effect was observed. Finally, variations in sedentary time and in moderate to vigorous physical activity play an important role in bone mass density in those participants of the interdisciplinary program

A atividade física moderada-vigorosa tem efeito osteogênico reconhecido no osso. Além disso, o tempo sedentário e o acúmulo de gordura são desfavoráveis à saúde óssea. Este estudo objetivou: (1) examinar mudanças na composição corporal, tecido ósseo, atividade física e tempo sedentário; e (2) explorar se as mudanças nas intensidades de atividade física e no tempo sedentário estão associadas a mudanças nos resultados ósseos após um programa de intervenção interdisciplinar de base escolar. 53 estudantes com sobrepeso/obesidade (10,6 ± 3,5 anos; 26 meninas) participaram de aulas com atividade física. Área óssea, massa óssea e escore z de densidade mineral óssea, composição corporal (massa gorda, massa magra de gordura), atividade física, tempo sedentário e potenciais confundidores (vitamina D e status maturacional) foram avaliados no início e após 8 meses. Modelos Lineares Generalizados foram realizados e o nível de significância foi estabelecido em 5%. Alterações na atividade física moderada-vigorosa foram positivamente correlacionadas com as mu-danças em todos os indicadores de massa óssea. Observou-se um efeito geral significativo da intervenção nas alterações do escore z de densidade mineral óssea, entretanto, após ajustes para mudanças no tempo sedentário e atividade física moderada-vigorosa, nenhum efeito foi observado. Por fim, variações no tempo sedentário e na atividade física moderada a vigorosa desempenham importante papel na densidade da massa óssea nos participantes do programa interdisciplinar