BACKGROUND: Physical activity (PA) during the school day is crucial for the health and well-being of adolescents. This study examines the impact of the COVID-19 pandemic on youth PA patterns to better understand these changes and to provide guidelines for school programming. METHODS: Differences in PA within specific segments of the school day were examined before and after the pandemic using the Youth Activity Profile questionnaire. Participants included 956 boys and 1,317 girls from 21 high schools. The study involved 12 Czech and 9 Polish high schools before the pandemic and 9 Czech and 8 Polish high schools after the pandemic. RESULTS: Both Czech and Polish boys and girls exhibited significantly less transportation PA to and from school and reduced PA during the school day after the pandemic compared to before. Additionally, Czech and Polish boys were significantly less physically active during school breaks, and Czech boys and girls had notably less PA during physical education lessons. The pandemic disrupted the habit of regular PA on school days, particularly evident in the decline of PA to and from school. CONCLUSION: The study confirms a significant difference in PA of Czech and Polish adolescents in various segments of the school day after students return to school following pandemic restrictions. Promoting achievement of the recommendations in the segments of the school day and in comprehensive school PA programs should be an important part of school health and education policy and public health promotion for adolescents.

• Keywords
• COVID-19, active transport, education policy, physical activity recommendation, school day,
• MeSH
• COVID-19 * epidemiology   prevention & control   MeSH
• Exercise * MeSH
• Humans MeSH
• Adolescent MeSH
• Pandemics MeSH
• Surveys and Questionnaires MeSH
• SARS-CoV-2 MeSH
• Schools * MeSH
• Students * statistics & numerical data   MeSH
• Check Tag
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Poland epidemiology   MeSH

OBJECTIVES: The aim of this study was to developed sex- and age-specific normative-referenced percentile values for health-related fitness among 12 to 18 years old Czech youth. METHODS: This study included cross-sectional data from 1,173 participants (50.7% boys) collected between 2013 and 2016. Participants were recruited from 32 elementary or secondary schools across eight cities located in the Czech Republic. Health-related fitness was objectively measured using both anthropometric (height, body mass, and sum of skinfolds) and performance (20-m shuttle run for cardiorespiratory endurance, modified push-ups for muscular strength/endurance, and V sit-and-reach for flexibility) tests. Sex- and age-specific normative values were calculated using the Lambda Mu Sigma method. Sex- and age-related differences in means were expressed as standardized effect sizes. RESULTS: Normative percentiles were tabulated and displayed as smoothed curves. Among boys, measures of health-related fitness generally increased with age, except for an age-related decline in the sum of skinfolds and a plateau in V sit-and-reach. Among girls, most measures of health-related fitness increased from age 12 to 16 years before stabilizing, except for the sum of skinfolds, which remained stable from age 12 to 18 years. The sex-related differences were large with boys having higher cardiorespiratory endurance and muscular strength/endurance than girls. Girls compared to boys had higher flexibility. CONCLUSIONS: This study presents the most up-to-date sex- and age-specific normative-referenced percentile values for health-related fitness among Czech youth. Normative values may be useful for fitness and public health screening and surveillance, for example, by helping to identify youth with low fitness who might benefit from a fitness-enhancing intervention.

• Keywords
• anthropometry, normative data, percentiles, performance, physical fitness, youth,
• MeSH
• Exercise MeSH
• Child MeSH
• Body Mass Index MeSH
• Humans MeSH
• Adolescent MeSH
• Cross-Sectional Studies MeSH
• Physical Fitness * MeSH
• Exercise Test * MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH

School physical activity (PA) is an indispensable part of daily PA, the foundation for developing lifelong PA and fitness, and an easy way to gain physical and health literacy. School PA is equally important for understanding the continuity of physical and mental health, even in broader psychosocial aspects. Regarding long-term outcomes, significant attention has been paid to the determination of daily and weekly recommendations for adolescent PA. However, comprehensive approaches suggesting recommendations for PA in segments of the school day are rare. This study aimed to (a) provide a rationale for PA recommendations in segments of school days and incorporate it into generally accepted PA recommendations, and (b) promote radical changes in the educational process toward a healthy school lifestyle through PA recommendations in segments of school days. The results of research conducted in 98 secondary schools in the Czech Republic and 104 secondary schools in Poland from 2009 to 2017 were used in this study. In total, 3,860 boys and 5,237 girls from the Czech Republic and 3,052 boys and 3,329 girls from Poland, all aged 15-19, participated. We recommended at least 2,000 steps (or 10 min of moderate-to-vigorous PA) for the before school segment and at least 6,000 steps (or 30 min of moderate-to-vigorous PA) for the after-school segment. For the time spent at school, we further recommended at least 500 steps/h (alternatively, at least 3,000 steps/school time), 20 min of moderate-to-vigorous PA (≥3METs or 60% HRmax), and at least one HRsubmax/max response to significant stress during PA to mitigate educational stress and high levels of sedentary behavior in schools. PA should account for at least 25% of school time, even on days with no scheduled physical education lessons. We propose using PA recommendations in segments of school days to achieve positive changes in the educational process and school lifestyle. Acceptance of PA recommendations in segments of school days theories on physical education could help refine and concretize demands for changes in PA and lifestyle in secondary schools. In practice, it could support the creation of innovative and comprehensive school PA programs. Future research should focus on obtaining evidence in support for adolescent PA by applying PA recommendations in segments of school days.

• Keywords
• comprehensive school physical activity program, physical education, physical literacy, school lifestyle, steps,
• MeSH
• Exercise * MeSH
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Schools * MeSH
• Health Behavior MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH
• Poland MeSH