I.

with both lower current perceived anxiety and lower current perceived worse mood among a sample of Spanish adults.

Long periods of free-movement restrictions may negatively affect cardiorespiratory fitness and health. The present study investigated changes after the COVID-19 confinement in maximal oxygen intake (VO 2 max) levels in a sample of 89 Spanish school children aged 12 and 14 years at baseline (49.8% girls). The 20-m shuttle run test served to estimate VO 2 max before and after the COVID-19 confinement. Paired t -tests estimated an overall difference of − 0.5 ml.kg −1 .min −1 (SD 0.3) ( p = 0.12), whereas the highest significant reductions were observed for girls aged 14 years (− 1.5 ml.kg −1 .min −1 (SD 0.6) ( p < 0.05)). Boys aged 14 years showed a slight increase (0.4 ml.kg −1 .min −1 (SD 0.5) ( p = 0.44)), whereas boys aged 12 years presented an important decrease (− 1.2 ml.kg −1 .min −1 (SD 0.7) ( p = 0.14)). Healthy Fitness Zone (HFZ) levels also experienced a decrease of − 3.4% as regards baseline levels over the examined period. All the examined subgroups showed lower levels in relation to a normal VO 2 max rate development, although girls aged 14 and boys aged 12 years accounted for the highest part. Conclusion : The results indicate that COVID-19 confinement might delay the normal development of VO 2 max in adolescents. Strategies to tackle this concerning decline are warranted. What is Known: • First study analyzing cardiorespiratory fitness levels in teenagers after COVID-19 confinement. What is New: • Important delay in maximal oxygen intake identified in a sample of Spanish teenagers. • These results should be considered to develop strategies of a more active lifestyle in teenagers during and after confinements.

ObjectiveTo quantify the association between physical activity and risk of SARS-CoV-2 infection, COVID-19-associated hospitalisation, severe illness and death due to COVID-19 in adults.DesignA systematic review and meta-analysis.Data sourcesThree databases were systematically searched through March 2022.Eligibility criteria for selecting studiesPeer-reviewed articles reporting the association between regular physical activity and at least one COVID-19 outcome in adults were included. Risk estimates (ORs, relative risk (RR) ratios or HRs) were extracted and pooled using a random-effects inverse-variance model.ResultsSixteen studies were included (n=1 853 610). Overall, those who engaged in regular physical activity had a lower risk of infection (RR=0.89; 95% CI 0.84 to 0.95; I2=0%), hospitalisation (RR=0.64; 95% CI 0.54 to 0.76; I2=48.01%), severe COVID-19 illness (RR=0.66; 95% CI 0.58 to 0.77; I2=50.93%) and COVID-19-related death (RR=0.57; 95% CI 0.46 to 0.71; I2=26.63%) as compared with their inactive peers. The results indicated a non-linear dose–response relationship between physical activity presented in metabolic equivalent of task (MET)-min per week and severe COVID-19 illness and death (p for non-linearity <0.001) with a flattening of the dose–response curve at around 500 MET-min per week.ConclusionsRegular physical activity seems to be related to a lower likelihood of adverse COVID-19 outcomes. Our findings highlight the protective effects of engaging in sufficient physical activity as a public health strategy, with potential benefits to reduce the risk of severe COVID-19. Given the heterogeneity and risk of publication bias, further studies with standardised methodology and outcome reporting are now needed.PROSPERO registration numberCRD42022313629.

Highlights Higher vigorous-intensity physical activity seems to be negatively related to adiposity and cardiometabolic risk score among children and adolescents later in life. Higher vigorous-intensity physical activity is positively related to cardiorespiratory fitness and total body bone mineral density among children and adolescents later in life. The present results support the need to further strengthen vigorous-intensity physical activity recommendations for children and adolescents.