In the wake of the COVID-19 pandemic, social restrictions to contain the spread of the virus have disrupted behaviors across the 24-h day including physical activity, sedentary behavior, and sleep among children (5–12 years old) and adolescents (13–17 years old). Preliminary evidence reports significant decreases in physical activity, increases in sedentary behavior, and disrupted sleep schedules/sleep quality in children and adolescents. This commentary discusses the impact of COVID-19-related restrictions on behaviors across the 24-h day in children and adolescents. Furthermore, we suggest recommendations through the lens of a socio-ecological model to provide strategies for lasting behavior change to insure the health and well-being of children and adolescents during the COVID-19 pandemic.

Objectives To assess physical activity (PA), mental health and well-being of adults in the UK, Ireland, New Zealand and Australia during the initial stages of National governments’ Coronavirus disease (COVID-19) containment responses. Design Observational, cross-sectional. Methods An online survey was disseminated to adults (n = 8,425; 44.5 ± 14.8y) residing in the UK, Ireland, New Zealand and Australia within the first 2-6 weeks of government-mandated COVID-19 restrictions. Main outcome measures included: Stages of Change scale for exercise behaviour change; International Physical Activity Questionnaire (short-form); World Health Organisation-5 Well-being Index; and the Depression Anxiety and Stress Scale-9. Results Participants who reported a negative change in exercise behaviour between pre-initial COVID-19 restrictions and during initial COVID-19 restrictions demonstrated poorer mental health and well-being compared to those demonstrating either a positive-or no change in their exercise behaviour ( p < 0.001). Whilst women reported more positive changes in exercise behaviour, young people (18-29y) reported more negative changes (both p < 0.001). Individuals who had more positive exercise behaviours reported better mental health and well-being ( p < 0.001). Although there were no differences in PA between countries, individuals in New Zealand reported better mental health and well-being ( p < 0.001). Conclusion The initial COVID-19 restrictions have differentially impacted upon PA habits of individuals based upon their age and sex, and therefore have important implications for international policy and guideline recommendations. Public health interventions that encourage PA should target specific groups (e.g., men, young adults) who are most vulnerable to the negative effects of physical distancing and/or self-isolation.

Prolonged, uninterrupted sitting negatively impacts markers of peripheral vascular health, particularly, vasodilatory function of leg arteries. Whether sitting can similarly impact measures of central vascular health, as well as overall leg vasoreactivity (i.e., vaso-dilatory and vasoconstrictor function) remains unknown. To address this, measurements were made in relatively healthy participants (i.e., free of overt disease; n = 20, age = 26 § 7; body mass index = 30 § 7 kg/m2; 7 female) pre, during and post 3 hours of uninterrupted sitting. Measures of central vascular health included arterial wave reflection (augmentation index and Reflection Magnitude-RM%) and aortic vascular stiffness (aortic pulse wavevelocity). Local vasoreactivity of the distal, posterior tibialartery was measured using flow-mediated dilation-FMD, coupled with low-flow mediated constriction, and microvascular function was assessed through the total hyperemic blood velocity (area-under-curve) response during FMD. After sitting, there was a significant increase in aortic pulse wave velocity (pre sit = 5.7 § 0.3 vs post sit = 6.1 § 0.3 m/s; p=0.009, d = 0.36), whereas, augmentation index decreased (pre sit=13 § 3 vs post sit=3 § 1%; p < 0.001, d = 0.71). Albeit a moderate effect for decrease, RM % was not significantly altered during sitting (p = 0.13, d = 0.3). Vasodilatory (i.e., FMD pre sit = 0.5 § 0.04 vs post sit =0.3 § 0.04 mm; p = 0.014, d = 0.29) and micro vascular function (i.e., Microvascular area-under-curve: pre sit = 2,196 § 333 vs1, 157 §172 AU; p = 0.003, d = 0.31) decreased, but vasoconstrictor function (low-flow mediated constriction; p = 0.85, d = 0.005) was unaffected by sitting. In conclusion, these data demonstrate that a prolonged bout of uninterrupted sitting negatively impacts markers of peripheral and central vascular health in relatively healthy adults.

The current evidence suggests that exercise intervention in overweight and obese adolescents improves body composition, particularly by lowering body fat. The limited available evidence further indicates that exercise intervention may improve some cardiometabolic risk factors.