RESUMO
Background: A new Danish school policy with a requirement for 45 min physical activity daily during school hours was introduced in 2014. The objective of this natural experiment was to evaluate the effect of this nationwide school policy on physical activity in Danish children and adolescents. Methods: Four historical studies completed between 2009 and 2012 comprised the pre-policy study population. Post-policy data were collected in 2017/18. All post-policy schools were represented in the four pre-policy studies. Age-groups and seasons were matched. In total, 4816 children and adolescents aged 6-17 were included in the analyses (2346 pre-policy and 2470 post-policy). Children and adolescents were eligible if they had accelerometer measurements and did not have any physical disabilities preventing activity. Physical activity was measured by accelerometry. Main outcome was any bodily movement. Secondary outcomes were moderate to vigorous physical activity and overall movement volume (mean counts per minute). Findings: The school policy interrupted a linear decreasing pre-policy trend in physical activity during school hours. All activity outcomes increased post-policy during a standardized school day (8:10 am-1 pm). Increases were more pronounced in the youngest children. Specifically, we observed a daily increase during a standardized school day in 2017/2018 of 14.2 min of movement (95% CI: 11.4-17.0, p < 0.001), 6.5 min of moderate to vigorous physical activity (95% CI: 4.7-8.3, P < 0.001), and 141.8 counts per minute (95% CI: 108.5-175.2, P < 0.001). Interpretation: A national school policy may be an important strategy to increase physical activity during school hours among children and adolescents. Funding: The Danish Foundation TrygFonden has funded the PHASAR project (ID 115606).
RESUMO
Background Overweight adults have low circulating concentrations of ANP (atrial natriuretic peptide) and proANP fragments. We tested the hypothesis that an intensive lifestyle intervention with an intended weight loss would increase plasma concentrations of a proANP fragment in overweight children. Methods and Results We measured MR-proANP (midregional proANP) concentrations in plasma from overweight children who participated in the OOIS (Odense Overweight Intervention Study). OOIS randomized 115 overweight children (11-13 years, 55% girls) to an intensive day-camp intervention arm with increased physical activity and healthy diet or to a less intensive standard intervention arm for 6 weeks. We used linear mixed-effects modeling for repeated measures to estimate the difference in the mean change with 95% CIs in fasting plasma MR-proANP concentrations between the 2 arms, and we used partial least squares regression analysis to identify candidate mediators. Differences in weight, fitness, and metabolic factors were also analyzed. At baseline, fasting plasma MR-proANP concentrations were (median [interquartile range]) 35.0 pmol/L (26.8-42.0) in the day-camp intervention arm and 37.2 pmol/L (31.7-44.7) in standard intervention arm participants, respectively. After 6 weeks intervention, children in the day-camp intervention arm had increased their MR-proANP (5.4 pmol/L [0.8-10.0], P=0.022) and their fitness (2.33 mL O2/min per kg [0.52-4.14], P=0.012) and they had deceased their body mass index (-2.12 kg/m2 [-2.59 to -1.65], P<0.001) as compared with children in standard intervention arm. In the partial least squares analysis, decreases in fasting insulin and in estimated insulin resistance were associated with the observed increase in MR-proANP concentrations. Conclusions An intensive lifestyle intervention increases plasma MR-proANP among overweight children. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01574352.
