BACKGROUND: Interventions to improve physical activity (PA) among adolescents continue to be a public health priority. To promote PA more effectively, we need to identify the main factors contributing to (not) engagement in PA in the perspective of adolescents themselves. Thus, we explored the barriers and enablers for sufficient moderate-to-vigorous physical activity (MVPA) in adolescents from their point of view. METHODS: We used qualitative data collected as part of the international Health Behaviour in School-Aged Children study. We obtained data from 14-17 years old adolescents from the first year of Slovak high school. We conducted 11 online, semi-structured individual and group interviews with 24 participants in total (7 boys; mean age = 15.17, SD = 0.87) in Slovakia. We analysed the data using consensual qualitative research and thematic analysis. RESULTS: In the statements of adolescents, four main themes were identified regarding factors contributing to (not) engagement in PA among adolescents. 'Myself as a source' represents the importance of adolescents' own efforts, knowledge, physical predispositions and PA experience. 'How PA can be done' represents school as an opportunity for PA, and PA teachers and sports coaches as specialists who can create an enabling environment for sports. 'Others as a source' represents the social circle that can set a positive sports example and can encourage adolescent's efforts in PA. 'Factors outside' represents other factors that can inspire adolescents, e.g. by giving them a comfortable space and time to exercise, or can be a barrier to PA. CONCLUSION: The potential factors that include adolescents' perspectives can be more leveraged in designing supportive, inclusive, enjoyable, and skills-appropriate PA programmes.

• MeSH
• cvičení * MeSH
• dítě MeSH
• kvalitativní výzkum MeSH
• lidé MeSH
• mladiství MeSH
• sedavý životní styl MeSH
• sporty * MeSH
• veřejné zdravotnictví MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE: The aim of this article is to systematically review articles and annual reports concerning young peoples' physical activity (PA) and linking this to considerations of the state and national defense. METHOD: A systematic search of the literature included an analysis of publications accessible in global databases and other available books, student papers, and projects. The articles and reports were categorized based on year of publication, methods used, age of respondents, sample size, country, and digital object identifier (DOI). RESULTS: The result of this search is an overview of the extent and manner in which the worldwide scientific community is addressing the current situation and the long-term development of the physical fitness of adolescents. This publication also maps to what extent professional publications and articles are addressing PA from the perspective of the needs of armies and armed forces of various countries around the world. CONCLUSIONS: The article provides a systematic overview of methods used to measure PA, and an overview of articles dealing with assessing PA. The examined articles indicate that from the perspective of not only national defense, but also health and overall quality of life, in particular, we need initiatives to encourage and motivate young people to increase their everyday PA. The research therefore also includes an overview of factors that may considerably influence PA. The results ascertained in this publication will be used, i.a. for investigating a longitudinal defense research project of the Ministry of Defense of the Czech Republic in which the authors are participating.

• Klíčová slova
• adolescents, fitness tests, military, physical activity, state defense,
• Publikační typ
• časopisecké články MeSH
• systematický přehled MeSH

Adolescence is a critical stage in the development of an individual's physical activity (PA) habits and preferences. Adolescents' perceptions of PA can influence their motivation to engage in PA and, consequently, their overall level of PA. Thus, our primary aim was to investigate whether Czech adolescents misperceive their peers' PA. Our dataset comprised cross-sectional data on 1289 adolescents aged 11-15 years. PA was measured using self-reported items used in the HBSC study. To describe the gender and school grade differences in VPA, independent samples T, ANOVA, Mann-Whitney U, and Kruskal-Wallis H tests were performed. To analyze the effect of gender, school grade, school, and participants' own PA on the underestimation of PA, binomial regression models were used. Our study points out that there is a discrepancy between self-perceived levels of PA and the perceived descriptive norms of peers' PA. Adolescents underestimate the prevalence of sufficient PA, and thus perceived descriptive norms in PA as being worse than levels of own PA. These findings indicate room for targeted interventions based on social-norms-based approaches to increase the PA of adolescents or at least strengthen their actual positive behavior.

• Klíčová slova
• MVPA, VPA, adolescents, perception, social norms,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: This study aimed to map the available evidence related to physical activity (PA) and sedentary behaviour (SB) in Czech children and adolescents and suggest future directions and improvements to strengthen the surveillance of PA and SB in the Czech Republic. METHODS: The search of articles published between January 2000 and December 2020 included the Medline and Medvik databases and a manual search in eight Czech journals related to the topic. This review followed the "Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews". RESULTS: Out of 350 identified articles, 79 articles met the criteria for selection and referred to 27 studies. The majority of the articles were cross-sectional (89%), approximately two-thirds of the articles (61%) examined only PA, and half of the articles (51%) employed device-based assessments. Approximately 47% of the articles reported the prevalence of physical inactivity on the basis of inconsistently defined recommendations. Approximately 14%, 23%, and 10% of the articles focused on active transportation, organized PA (including physical education or leisure-time PA), and parent-child PA, respectively. CONCLUSIONS: Future studies need to focus on longitudinal design and interventions, randomly selected samples, a mix of device-based and self-reported methods, and the recognition of health-related 24-hour time use patterns. This review advocates the government-supported development of a national surveillance system that will help to reduce insufficient PA and excessive SB.

• Klíčová slova
• Health, Insufficient physical activity, Prevalence, Youth,
• MeSH
• cvičení * MeSH
• lidé MeSH
• mladiství MeSH
• pohybová aktivita MeSH
• prevalence MeSH
• sedavý životní styl * MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• scoping review MeSH
• Geografické názvy
• Česká republika MeSH

BACKGROUND: To date, no longitudinal study using a compositional approach has examined sedentary behavior (SB) patterns in relation to adiposity in the pediatric population. Therefore, our aims were to (1) investigate the changes in SB patterns and adiposity from childhood to adolescence, (2) analyze the prospective compositional associations between changes in SB patterns and adiposity, and (3) estimate the changes in adiposity associated with substituting SB with physical activity (PA) of different intensities. METHODS: The study presents a longitudinal design with a 5-year follow-up. A total of 88 participants (61% girls) were included in the analysis. PA and SB were monitored for seven consecutive days using a hip-worn accelerometer. Adiposity markers (fat mass percentage [FM%], fat mass index [FMI], and visceral adiposity tissue [VAT]) were assessed using the multi-frequency bioimpedance analysis. The prospective associations were examined using compositional data analysis. RESULTS: Over the follow-up period, the proportion of time spent in total SB increased by 154.8 min/day (p < 0.001). The increase in total SB was caused mainly by an increase in middle and long sedentary bouts, as these SB periods increased by 79.8 min/day and 62.0 min/day (p < 0.001 for both), respectively. FM%, FMI, and VAT increased by 2.4% points, 1.0 kg/m2, and 31.5 cm2 (p < 0.001 for all), respectively. Relative to the remaining movement behaviors, the increase in time spent in middle sedentary bouts was significantly associated with higher FM% (βilr1 = 0.27, 95% confidence interval [CI]: 0.02 to 0.53) at follow-up. Lower VAT by 3.3% (95% CI: 0.8 to 5.7), 3.8% (95% CI: 0.03 to 7.4), 3.9% (95% CI: 0.8 to 6.9), and 3.8% (95% CI: 0.7 to 6.9) was associated with substituting 15 min/week spent in total SB and in short, middle, and long sedentary bouts, respectively, with an equivalent amount of time spent in vigorous PA. CONCLUSIONS: This study showed unfavorable changes in SB patterns and adiposity status in the transition from childhood to adolescence. Incorporating high-intensity PA at the expense of SB appears to be an appropriate approach to reduce the risk of excess adiposity in the pediatric population.

• Klíčová slova
• Adolescent, Child, Fat mass, Fat mass index, Movement behaviors, Physical activity, Prolonged sitting, Sedentary lifestyle, Visceral adipose tissue,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Between-person differences in sedentary patterns should be considered to understand the role of sedentary behavior (SB) in the development of childhood obesity. This study took a novel approach based on compositional data analysis to examine associations between SB patterns and adiposity and investigate differences in adiposity associated with time reallocation between time spent in sedentary bouts of different duration and physical activity. METHODS: An analysis of cross-sectional data was performed in 425 children aged 7-12 years (58% girls). Waking behaviors were assessed using ActiGraph GT3X accelerometer for seven consecutive days. Multi-frequency bioimpedance measurement was used to determine adiposity. Compositional regression models with robust estimators were used to analyze associations between sedentary patterns and adiposity markers. To examine differences in adiposity associated with time reallocation, we used the compositional isotemporal substitution model. RESULTS: Significantly higher fat mass percentage (FM%; βilr1 = 0.18; 95% CI: 0.01, 0.34; p = 0.040) and visceral adipose tissue (VAT; βilr1 = 0.37; 95% CI: 0.03, 0.71; p = 0.034) were associated with time spent in middle sedentary bouts in duration of 10-29 min (relative to remaining behaviors). No significant associations were found for short (< 10 min) and long sedentary bouts (≥30 min). Substituting the time spent in total SB with moderate-to-vigorous physical activity (MVPA) was associated with a decrease in VAT. Substituting 1 h/week of the time spent in middle sedentary bouts with MVPA was associated with 2.9% (95% CI: 1.2, 4.6), 3.4% (95% CI: 1.2, 5.5), and 6.1% (95% CI: 2.9, 9.2) lower FM%, fat mass index, and VAT, respectively. Moreover, substituting 2 h/week of time spent in middle sedentary bouts with short sedentary bouts was associated with 3.5% (95% CI: 0.02, 6.9) lower FM%. CONCLUSIONS: Our findings suggest that adiposity status could be improved by increasing MVPA at the expense of time spent in middle sedentary bouts. Some benefits to adiposity may also be expected from replacing middle sedentary bouts with short sedentary bouts, that is, by taking standing or activity breaks more often. These findings may help design more effective interventions to prevent and control childhood obesity.

• Klíčová slova
• Accelerometry, Body mass index, Child behavior, Pediatric obesity, Sedentary behavior,
• MeSH
• adipozita * MeSH
• akcelerometrie MeSH
• analýza dat MeSH
• dítě MeSH
• index tělesné hmotnosti MeSH
• lidé MeSH
• průřezové studie MeSH
• sedavý životní styl * MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Although there is an increasing awareness of the suitability of using compositional data methodology in public health research, classical methods of statistical analysis have been primarily used so far. The present study aims to illustrate the potential of robust statistics to model movement behaviour using Czech adolescent data. We investigated: (1) the inter-relationship between various physical activity (PA) intensities, extended to model relationships by age; and (2) the associations between adolescents' PA and sedentary behavior (SB) structure and obesity. These research questions were addressed using three different types of compositional regression analysis-compositional covariates, compositional response, and regression between compositional parts. Robust counterparts of classical regression methods were used to lessen the influence of possible outliers. We outlined the differences in both classical and robust methods of compositional data analysis. There was a pattern in Czech adolescents' movement/non-movement behavior-extensive SB was related to higher amounts of light-intensity PA, and vigorous PA ratios formed the main source of potential aberrant observations; aging is associated with more SB and vigorous PA at the expense of light-intensity PA and moderate-intensity PA. The robust counterparts indicated that they might provide more stable estimates in the presence of outlying observations. The findings suggested that replacing time spent in SB with vigorous PA may be a powerful tool against adolescents' obesity.

• Klíčová slova
• compositional data, compositional linear regression, log-ratio methodology, physical activity, pivot coordinates,
• MeSH
• chování mladistvých * MeSH
• cvičení * MeSH
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• obezita dětí a dospívajících etiologie   MeSH
• regresní analýza * MeSH
• sedavý životní styl * MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH