Associations between accelerometer-measured physical activity and body fatness in school-aged children

Moderate to Vigorous Physical Activity Patterns and Cardiometabolic Risk Factors in Urban Indian Children

OBJECTIVE

To determine the duration of moderate to vigorous physical activity (MVPA), perceived barriers to physicaly activity and examine its association with cardiometabolic risk factors in Indian children.

METHODS

Sociodemographic data, physical activity patterns and the barriers to physical activity were collected using questionnaires, from urban children aged 6-19 years residing in Bengaluru, Karnataka. Anthropometry, body composition, blood pressure, glycated hemoglobin, and lipid profile were measured.

RESULTS

The mean (SD) age of a total of 4004 enrolled children was 13.1 (2.5) years; 17.8% were overweight/obese. The median (IQR) duration of MVPA was 7.7 (0.0, 44.1) minutes/day, with 81% (n = 3252) not meeting the MVPA recommendation, particularly girls (88.6%; n = 1980/2234). In adjusted analysis, children who did not engage in MVPA had elevated systolic blood pressure (mm Hg) [1.07 (95% CI 0.40, 1.35)] and diastolic blood pressure (mm Hg) [1.09 (95% CI 0.40, 1.77)]. Significant barriers to engaging in physical activity included time constraints due to academic work and lack of space/facilities.

CONCLUSION

Indian children do not meet the required daily MVPA recommendations; academic demands and limited access to space/facilities were significant barriers to physical activity. Children who did not engage in any form of MVPA had significantly higher blood pressure.

Differences in physical activity, sedentary time, and anthropometric variables among children and adolescents: The TUBON project

BACKGROUND

Although physical inactivity may lead to increasing obesity prevalence, research on anthropometric variables changes based on physical activity (PA) in children and adolescents is limited. PA decreases with age, while sedentary behavior increases. The study aimed to examine differences in objectively measured sedentary time, light-intensity physical activity (LPA), and moderate-to-vigorous intensity physical activity (MVPA) between children and adolescents, and the differences in the percentiles of anthropometric variables between physically active and inactive groups according to World Health Organization PA recommendations.

METHODS

A total of 759 participants aged 6-17 years (boys, n=358; girls, n=401) were included in the study. The ActiGraph wGT3x-BT accelerometer was used to measure sedentary time, LPA, and MVPA. Height, weight, waist circumference (WC), triceps skinfold thickness (T-SFT), and medial-calf skinfold thickness (M-SFT) were measured. Body fat percentage (BF%) and body mass index (BMI) were calculated, and the percentiles of anthropometric variables were categorized.

RESULTS

The findings showed that children had less sedentary time and a higher LPA than adolescents for both genders (p<0.05). Children had a higher MVPA than adolescents in girls (p<0.05), but the difference was insignificant in boys (p>0.05). In boys, physically active children were in lower percentiles for T-SFT and BF% than those who did not (p<0.05). In boys, adolescents who were physically inactive were in higher percentiles for BMI, T-SFT, M-SFT, and BF% (p<0.05). In addition, in girls, adolescents who were physically active were in lower percentiles of BMI, M-SFT, and BF%, whereas children who were physically active were in lower percentiles of M-SFT and BF% (p<0.05).

CONCLUSION

Sedentary time increases while PA decreases with age. Children and adolescents who met the WHO PA recommendation had lower percentiles of anthropometric variables, indicating the importance of PA in preventing obesity in these age groups.

Data Analytics in Physical Activity Studies With Accelerometers: Scoping Review

BACKGROUND

Monitoring free-living physical activity (PA) through wearable devices enables the real-time assessment of activity features associated with health outcomes and provision of treatment recommendations and adjustments. The conclusions of studies on PA and health depend crucially on reliable statistical analyses of digital data. Data analytics, however, are challenging due to the various metrics adopted for measuring PA, different aims of studies, and complex temporal variations within variables. The application, interpretation, and appropriateness of these analytical tools have yet to be summarized.

OBJECTIVE

This research aimed to review studies that used analytical methods for analyzing PA monitored by accelerometers. Specifically, this review addressed three questions: (1) What metrics are used to describe an individual's free-living daily PA? (2) What are the current analytical tools for analyzing PA data, particularly under the aims of classification, association with health outcomes, and prediction of health events? and (3) What challenges exist in the analyses, and what recommendations for future research are suggested regarding the use of statistical methods in various research tasks?

METHODS

This scoping review was conducted following an existing framework to map research studies by exploring the information about PA. Three databases, PubMed, IEEE Xplore, and the ACM Digital Library, were searched in February 2024 to identify related publications. Eligible articles were classification, association, or prediction studies involving human PA monitored through wearable accelerometers.

RESULTS

After screening 1312 articles, 428 (32.62%) eligible studies were identified and categorized into at least 1 of the following 3 thematic categories: classification (75/428, 17.5%), association (342/428, 79.9%), and prediction (32/428, 7.5%). Most articles (414/428, 96.7%) derived PA variables from 3D acceleration, rather than 1D acceleration. All eligible articles (428/428, 100%) considered PA metrics represented in the time domain, while a small fraction (16/428, 3.7%) also considered PA metrics in the frequency domain. The number of studies evaluating the influence of PA on health conditions has increased greatly. Among the studies in our review, regression-type models were the most prevalent (373/428, 87.1%). The machine learning approach for classification research is also gaining popularity (32/75, 43%). In addition to summary statistics of PA, several recent studies used tools to incorporate PA trajectories and account for temporal patterns, including longitudinal data analysis with repeated PA measurements and functional data analysis with PA as a continuum for time-varying association (68/428, 15.9%).

CONCLUSIONS

Summary metrics can quickly provide descriptions of the strength, frequency, and duration of individuals' overall PA. When the distribution and profile of PA need to be evaluated or detected, considering PA metrics as longitudinal or functional data can provide detailed information and improve the understanding of the role PA plays in health. Depending on the research goal, appropriate analytical tools can ensure the reliability of the scientific findings.

Barriers and enablers for sufficient moderate-to-vigorous physical activity: The perspective of adolescents

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.

Effect of a Multifaceted Intervention on Children's Body Image and the Mediating Role of Body Image in Changes in Adiposity Indicators

Besides genetic factors and energy-related behaviors, psycho-cultural factors are also important in obesity etiology. Previous studies have suggested that improving body image might be an effective method for managing body weight. Thus, this study aimed to evaluate the effects of a multifaceted intervention on the body image of children and explore whether body image played a mediating role in changes in adiposity indicators. This study was embedded in a cluster randomized controlled trial, involving 1287 children from 24 primary schools in three cities in China (Beijing, Changzhi and Urumqi). The 9-month multifaceted intervention on childhood obesity included five components (three targeted children and two targeted environments), and randomization was performed by an independent person who was blinded to the schools. Two indicators (body size perception and body size expectation) were chosen to characterize body image and were measured by Ma figural stimuli at baseline and the end of the trial. Changes in body image indicators were classified as conducive to weight loss or not. Other anthropometric measures and self-reported behaviors were also collected at both time points. Generalized linear mixed models were used in the analyses. Compared to the controls (n = 648), the proportion of body size perception conducive to weight loss increased in the intervention group (n = 639), with an odds ratio of 2.42 (95%CI: 1.70~3.45, p < 0.001). The proportion of body size expectation conducive to weight loss also increased more in the intervention group than in the controls (OR = 1.74, 95%CI: 1.14~2.66, p = 0.010). In children whose baseline nutritional status was "normal weight with higher BMI" or "overweight/obese", the improvements in body size perception and body size expectation partly mediated the association between the intervention and changes in BMI, BMI Z score, waist circumference and body fat percentage (p < 0.05). This multifaceted study effectively improved the body image of children, which, in turn, led to beneficial changes in adiposity indicators. For the first time, body size perception and body size expectation have been confirmed to be important factors associated with the beneficial effect of a childhood obesity intervention, suggesting that body image components should be generalized in the future.

Assessment of physical activity among adolescents: a guide to the literature

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.

How Czech Adolescents Perceive Their Physical Activity

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.

Relationship of 24-Hour Movement Behaviors with Weight Status and Body Composition in Chinese Primary School Children: A Cross-Sectional Study

24 h movement behaviors, specifically physical activity (PA), sedentary behavior, and sleep, play a crucial role in the prevention and intervention of childhood obesity. This study aimed to examine the association of 24 h movement behaviors with weight status and body composition among Chinese primary school children. Using a random stratified sampling, 978 eligible participants (9.1 ± 1.4 years, 53.2% boys) were recruited from 1 May to 15 July 2021. Demographics included children's age, gender, grade, parents' education level, and household income. Movement behaviors were measured by validated self-reported scales. Weight status and body composition (percent of body fat, PBF; fat-free mass, FFM; skeletal muscle mass, SMM) were measured objectively. Results indicated that participants who were younger, boys, and at lower grade showed higher guidelines adherence. PA was inversely associated with PBF, while screen time (ST) was positively associated with overweight/obesity risk and FFM. Sleep showed no association with any health indicators. Meeting the behavioral guidelines was associated with better weight status and lower PBF, yet not with FFM and SMM. Interventions to improve the Children's weight status and PBF should involve enhancing their overall movement behaviors and considering their demographic differences. More research on examining the association of movement guidelines adherence with body composition indicators is needed.

Surveillance of physical activity and sedentary behaviour in czech children and adolescents: a scoping review of the literature from the past two decades

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.

Changes in sedentary behavior patterns during the transition from childhood to adolescence and their association with adiposity: a prospective study based on compositional data analysis

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% (β_ilr1 = 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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-021-00755-5.

Influence of Physical Self-Concept and Motivational Processes on Moderate-to-Vigorous Physical Activity of Adolescents

There is a growing concern about the increasing decline in physical activity among adolescents. In the search for variables that may be related to physical activity, this study examined the influence of physical self-concept on objectively measured moderate-to-vigorous physical activity (MVPA) of adolescents through the mediation of the needs satisfaction and two types of autonomous motivation, for academics and for physical education. Data were collected from 618 students (301 boys and 317 girls) aged 10–14 years from 24 secondary schools in Spain. The path analysis results showed that physical self-concept positively predicted needs satisfaction and this, in turn, was positively and significantly related to the two types of autonomous motivation. Finally, only the autonomous motivation for physical education significantly and positively predicted the adolescents’ MVPA. Our findings showed that there was no evidence of an indirect effect of physical self-concept on MVPA. The results are discussed along the lines of the self-determination theory, through the analysis of the role of physical self-concept in increasing adolescents’ physical activity.

Association between Objectively Determined Physical Activity Levels and Body Composition in 6-8-Year-Old Children from a Black South African Population: BC-IT Study

Physical inactivity in children is a global pandemic in parallel with increasing obesity prevalence. However, studies assessing the association between physical activity (PA) and body composition (BC) report conflicting findings, possibly because of the different methodologies across studies, with objective methods promising reliable results. This study determines the association between objectively determined PA levels and BC in 6–8-year-old children from a black South African population. Ninety-three children aged 6–8 years, who formed part of a larger study on BC using the deuterium dilution method (DDM), were included. Height and weight were measured according to the standard procedures, and body mass index z-score was calculated. Fatness was determined by DDM. An accelerometer was used to measure PA levels. Regression models were performed to determine the relationship between PA and BC. Approximately 23% of the children did not meet the recommended PA guidelines and 27% were overfat. After adjustments were made, more time spent in vigorous PA was significantly associated with lower fat mass (β = −0.25, p = 0.01, 95%CI: −11.08; −1.20) and fat mass % (β = −0.20, p = 0.04, 95%CI: −12.63; −0.18). Participation in high PA, especially of high intensity, was associated with reduced adiposity in children. Behavioural changes such as increasing high intensity PA is strongly recommended for reducing adiposity.

Sex-specific differences in somatic investment and strategies of physical activity among Portuguese schoolchildren

OBJECTIVES

Physical activity (PA) is required for healthy growth, development, and maturation and plays an important role in the prevention of overweight and obesity in childhood and adolescence. Sex-differences in PA levels are well documented, with boys spending more time in PA, especially in moderate-to-vigorous activities. Following the Life History Theory, our aim is to study if PA affects the fat tissues increases during childhood and juvenile phases in both sexes.

METHODS

Time spent in sedentary, light, and moderate-to-vigorous PA levels were measured in a sample of 415 Portuguese children and juveniles (207 females/208 males; aged 6-11 years), using an accelerometer for 7 days. Skinfolds related with body fat were objectively collected and socioeconomic status factors were reported using a parental questionnaire.

RESULTS

The outcomes show that girls' and boys' fat variables increased during the end of the childhood and the juvenile phase. However, these variables were differently affected by PA. Girls increased fat variables with the sedentary activity while boys decreased fat variables with moderate-to-vigorous PA. Alike, active boys but not girls reduced the fat increase tendency with age.

CONCLUSIONS

Although both sexes displayed a general fat increment with age, moderate-to-vigorous PA dampens the increase only in boys. In fact, active girls increased body fat in the same manner as non-active girls. From an evolutionary perspective, it could explain sex-specific somatic strategies related to future reproduction or, with future mating and intrasexual competition.

Associations of Physical Activity and Sedentary Behaviour Assessed by Accelerometer with Body Composition among Children and Adolescents: A Scoping Review

The possible adverse health effects of reduced physical activity (PA) on children and adolescents have been extensively documented as a result of the global obesity epidemic. However, the research has sometimes led to controversial results, due to the different methods used for the assessment of PA. The main aim of this review was to evaluate the association between PA and body composition parameters based on quantitative PA studies using the same equipment (Actigraph accelerometer) and cutoffs (Evenson’s). A literature review was undertaken using PUBMED and Scopus databases. Subjects aged 6–15 were considered separately by sex. Weighted multiple regression analyses were conducted. From the analysis of fourteen selected articles, it emerged that 35.7% did not evaluate the association of sedentary time (ST) and moderate-to-vigorous physical activity (MVPA) with body composition, while the remaining 64.3% found a negative association of MVPA with BMI and fat mass with different trends according to sex. Furthermore, only 7.1% of these studies identified a positive association between ST and fat percentage. Based on the regression analyses conducted on the literature data, ST and MVPA were found to be significant predictors of body composition parameters, in addition to age and sex. Further studies using standardized methodologies to assess PA and body composition are needed. The inclusion of sex-disaggregated data may also be crucial to understand this phenomenon and to provide stronger evidence of the determinants of body composition in order to prevent the risk of obesity.

Sedentary behavior patterns and adiposity in children: a study based on compositional data analysis

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%; β_ilr1 = 0.18; 95% CI: 0.01, 0.34; p = 0.040) and visceral adipose tissue (VAT; β_ilr1 = 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.

Associations Among Physical Education, Activity-Related Healthy Lifestyle Practices, and Cardiorespiratory Fitness of Chinese Youth

PURPOSE

Physical education (PE) in school provides opportunities for physical activity (PA) engagement and reportedly results in improved health-related fitness. This study explored the underlying correlations between PE and activity-related healthy lifestyle practices with current level of cardiorespiratory fitness.

METHODS

A total of 13,138 students age 14 (boys = 7,094, 54.0%) in Grade 8 from the China National Assessment of Educational Quality - Physical Education & Health 2015 were included in this study. Two independent structural equation modeling (SEM) analyses were conducted to obtained sex-specific results. Data included the results of the 15-m progressive aerobic cardiovascular endurance run (PACER) and questionnaire data regarding PE curriculum implementation, learning and practice, perceived support from PE teachers, PE facilities, PE equipment, activity-related healthy lifestyle practices, habitual physical fitness, appropriate method of physical fitness, and breakfast eating habits. Structural equation modeling was applied to examine the associations between variables, controlling for socioeconomic status, the location of schools, and Body Mass Index.

RESULTS

There was a statistically significant relationship between cardiorespiratory fitness and activity-related healthy lifestyle practices, which was somewhat positively impacted by skill learning and practice and perceived support from PE teachers. Together, the boy's model explained 21.8% of the variance in cardiorespiratory fitness, whereas the girl's model explained 15.9%.

CONCLUSIONS

A well-organized PE program is related to students' activity-related healthy lifestyle practices, and consequently provides an improvement to cardiorespiratory fitness.

Perspectives of adolescents, parents, and teachers on barriers and facilitators of physical activity among school-age adolescents: a qualitative analysis

Background

Physical activity levels are low among adolescents in Morocco; however, the influences on physical activity behavior of adolescents have not yet been explored in a qualitative study. Here, we explored potential social-ecological barriers and facilitators of physical activity in Moroccan adolescents with the goal of developing a successful intervention program aimed at improving their physical activity level.

Methods

For this study, we conducted 17 focus group discussions (100 participants, composed of 56 adolescents, 26 parents, and 18 teachers from two middle schools in Taza city, Morocco). Discussions during focus groups were facilitated by a semi-structured interview guide. Guide questions were underpinned by the social-ecological model as a theoretical framework. Data analysis was carried out by two coders using thematic analysis.

Results

We found that barriers and facilitators of physical activity in adolescents are organized into six themes that belong to different levels of the social-ecological model. Three themes belonged to the intrapersonal level (perceived motivating and limiting factors, physical activity awareness, and time constraints), two themes were classified into the interpersonal/cultural level (social support and gender and cultural norms), and one theme belonged to the environmental level (access to opportunities). Most of the themes were at the individual level, with each theme including both barriers and facilitators.

Conclusions

Adolescent participation in physical activity can be facilitated or hampered by many factors. Results from the focus group discussions showed that these factors belonged to different levels of the social-ecological model, but most were at the individual level. Our findings have several implications. First, they may offer suggestions for a tailored intervention program aimed at improving adolescent physical activity. Second, they can improve quantitative research by enriching the battery of questions of physical activity instruments (e.g., a question related to physical disability). Third, the proposed thematic map can contribute to understanding interactions and causal pathways in the social-ecological model.

Robust Compositional Analysis of Physical Activity and Sedentary Behaviour Data

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.