Gymnastik- och idrottshögskolan, GIH

Aim

To investigate physical activity (PA), sedentary time, and screen time by age, sex, and parental education in a national sample of young children.

Method

This cross-sectional study, conducted 2021–2024, of Swedish children recruited via their parents, included 1078 children aged 18 months, mean 1.5 ± 0.1 years, and 750 aged four, mean 4.1 ± 0.1 years. PA, sedentary time, and screen time were measured with accelerometry and questionnaire.

Results

PA guidelines were met by 94% of the 18-month-old children and 51% of those 4 years old. Among 18-month-old children, 22% met screen time guidelines on weekdays and 17% on weekends; corresponding percentages among children 4 years old were 60% and 28%. Device-measured PA levels were consistently lower for girls than boys at age four, but sex differences were small among 18-month-old children. More children whose parents were highly educated participated in organised activities and used active transport modes; they also had lower screen time than children whose parents had low education.

Conclusion

Nearly all 18-month-old children met PA guidelines, versus only half of those aged 4 years. Many children in both age groups exceeded screen time guidelines. Age, sex, and parental education were associated with children's PA and screen time, suggesting targeted interventions.

Background Attention-deficit/hyperactivity disorder (ADHD) symptoms are associated with adverse health outcomes; this may be partially due to unhealthy lifestyle factors such as low physical activity (PA) and high sedentary behavior (SED). However, this association remains unclear. ADHD and PA have a medium-to-high heritability; therefore, genetically informed studies are warranted. This study aimed to increase the understanding of the association between ADHD symptoms and time spent in PA and SED in children. Additionally, we aimed to determine whether sex, symptom type, and genetics influence this association. This could guide the design of health promotion and preventive interventions.Methods This cross-sectional twin study included 9-year-old children from the Swedish Twin Registry born from 2011 to 2015 who had complete data on ADHD symptoms and accelerometry. ADHD symptoms were assessed through a parental-report questionnaire. Inattention and hyperactivity/impulsivity symptoms were analyzed together and separately. Triaxial accelerometry measured the average time (minutes) spent in SED, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Linear generalized estimating equations regression models were used to assess the association in the full cohort and stratified by sex. Within-twin pair analyses were performed separately for dizygotic and monozygotic twins. Regression coefficients and 95% confidence intervals (CI) were calculated.Results 1966 children (52.8% girls) were included. In the full cohort, ADHD symptoms were significantly associated with less time in SED (beta = -0.32; 95% CI -0.59, -0.06) and more time in MVPA (beta = 0.30; 95% CI 0.12, 0.47). These associations were primarily driven by hyperactivity/impulsivity symptoms and were significant only in girls. The associations remained in dizygotic twins but became non-significant among monozygotic twins.Conclusion Our findings suggest that in girls, higher hyperactivity/impulsivity symptoms are associated with higher PA levels. Associations were largely explained by shared familial factors, including genetics. Longitudinal studies are needed to corroborate these results.

Background: Adolescence is a crucial phase for the development of cognitive abilities linked to academic performance. Factors such as physical activity (PA) and fitness have been hypothesized to be linked to these outcomes, although the evidence is inconclusive. This study aimed to examine the associations between PA, fitness, academic, and cognitive performance in the same sample of adolescents.

Methods: In this cross-sectional study, 1139 Swedish adolescents (mean age 13.4 years) participated. We assessed PA (accelerometry), cardiovascular fitness (submaximal ergometer test), cognitive performance (computer-based test assessing episodic and working memory with 3 tests per domain), and academic performance (grades in math and language, Swedish). We utilized multilevel mixed models to explore associations and structural equation modeling to perform mediation analyses.

Results: We found a weak positive association between cardiovascular fitness and math grades (b: 0.18, 95% CI: 0.09, 0.26 β: 0.18), language grades (b: 0.16, 95% CI: 0.07, 0.25 β: 0.13), and cognitive performance (b: 0.01, 95% CI: 0.00, 0.02 β: 0.11). Further, cognitive performance scores mediated 40% of the associations between fitness and math, and language grades. Adolescents with parents with short education (≤12 years of education) or foreign-born had lower fitness levels and grades in math and language (all p < 0.05).

Conclusion: Fitness was the only significant factor associated with cognitive and academic performance, although the association was weak. Given our findings of low fitness and academic performance among adolescents with parents with short education or parents born abroad, future studies should tailor their interventions to ensure the inclusion of these groups.

Physical activity (PA) plays a key role in children's health, yet it remains unclear why girls are often less active and more sedentary than boys. This study examined genetic and environmental (shared and non-shared) influences on device-measured PA and sedentary time (SED) across girls and boys. This cross-sectional study contained data on zygosity, sex, PA, and SED for 2046 9-year-old twins in Sweden. The accelerometer-measured PA was expressed as the proportion of time in SED, light (LPA), moderate (MPA) or vigorous PA (VPA). Structural equation modelling within a twin framework estimated the heritability of PA and SED, decomposing variance into additive genetic (A), shared environment (C), and non-shared environment (E). Quantitative sex differences were examined by allowing the variance components (A, C, E) to differ across sexes. In the total cohort, genetic contribution was highest in VPA (Atotal: 0.64) but lower in SED, LPA and MPA (Atotal: 0.50-0.55). Boys and girls had differing patterns of genetic contributions, with the largest contributions among girls found for LPA (Agirl: 0.44; Aboy: 0.37) while the genetic contribution in VPA was larger in boys (Agirl: 0.15; Aboy: 0.57), and the difference was statistically significant for VPA (p = 0.001). While the non-shared environment was similar in all models, the shared environment showed the opposite pattern to the genetic contributions. This twin study shows that genetic influences on PA and SED differ by sex, highlighting the importance of considering how biological mechanisms that drive activity patterns might differ across sex, especially in vigorous physical activity.

BACKGROUND: A majority of adolescents do not meet the recommended levels of physical activity, while reported levels of mental health problems are increasing, and socioeconomic disparities in academic performance are widening. Many schools are implementing physical activity in different forms, but there is inconclusive evidence on what types of interventions improve mental health, cognitive functions, and academic performance and how to implement such interventions. There is a critical need for integrated, feasible, and equitable interventions. The objective of this study is to develop an effective multi-component school-based intervention that will target both physical activity and homework support during an extended school day and evaluate its effects on mental health, cognitive function and academic performance.

METHODS: The study is designed as a cluster-randomised controlled trial with 54 schools and approximately 2,700 students in grade 8 (age 14-15). The intervention includes three weekly 60-minute sessions: (1) Different types of physical activities (2), Homework support with short activity breaks, and (3) Walking and listening to audiobooks. This study will evaluate both outcome effects and implementation process. The primary outcome is anxiety, assessed using the Spence Children's Anxiety Scale (SCAS-S). Secondary outcomes include physical activity, sedentary time and behaviours measured by accelerometry and questionnaire, cognitive functions assessed by a computer-based test battery, mental health and sleep with questionnaires, and academic performance by grades. Process evaluation will include fidelity, dose, feasibility, acceptability and context, using structured documentation, interviews, focus groups, and observations. The effectiveness of outcomes between groups will be assessed using mixed-effects regression analysis, adjusting for relevant covariates. Process data will be analysed using descriptive statistics and content, and thematic analysis.

DISCUSSION: This study addresses key knowledge gaps in school-based health promotion by integrating physical activity and homework support within the school structure. The results will yield insights into both effectiveness and implementation, informing future policy and practice in schools to promote health and facilitate students' learning. The intervention targets youth in diverse socioeconomic contexts and is expected to contribute to reducing health and education inequalities.

TRIAL REGISTRATION: The trial was retrospectively registered on April 27, 2021. ISRCTN78666212.

AIM: Evidence on physical activity (PA), sedentary time, and fitness in adolescents with impairments has been limited. We aimed to compare outcomes in Swedish adolescents with and without impairments and between impairment types.

METHODS: This cross-sectional study, from September to December 2019, comprised of adolescents from 34 mainstream schools within 3 h' drive of Stockholm, Sweden. Parents reported impairment status. PA and sedentary time were measured with accelerometers during school and leisure time on weekdays and weekends. Fitness was estimated using the Ekblom-Bak submaximal cycle test, sports participation was self-reported and multilevel mixed models were used for analyses.

RESULTS: We enrolled 972 adolescents (51% girls), with a mean age of 13.4 ± 0.3 years. Just under a third (31%) had impairments. Adolescents with impairments showed lower PA levels, less adherence to recommendations, lower fitness and less participation in organised sports than those without impairments. Those with learning or visual impairments engaged in less vigorous activity and the former had lower fitness levels.

CONCLUSION: Adolescents with impairments were less physically active, more sedentary and had lower fitness than peers without impairments. This emphasises the need for equitable opportunities for PA, to support long-term health and well-being in adolescents with impairments.

PURPOSE: Mental health problems are increasingly prevalent during adolescence. Nutritional factors, particularly antioxidants, are of interest due to their potential to reduce oxidative stress and inflammation linked to mental health issues. However, the relationship between dietary antioxidants and adolescent mental health remains unclear. This study aimed to investigate this association in Swedish adolescents and explore potential gender differences.

METHODS: Cross-sectional data were gathered among Swedish boys and girls aged 13-14 years (n = 1139). Participants reported their dietary intake using a detailed web-based method and mental health outcomes, including anxiety, psychosomatic symptoms, and health-related quality of life (HRQoL) using self-report scales. Multiple linear regression analysis, adjusted for confounders, was used to investigate the associations between mental health outcomes and tertiles of dietary intake of vitamin C, E and β-carotene.

RESULTS: Adolescents in the highest tertile of β-carotene intake reported lower anxiety (β=-1.23, 95% CI=-2.34, -0.12), fewer psychosomatic symptoms (β=-0.91, 95% CI=-1.69, -0.13), and better HRQoL (β = 0.89, 95% CI = 0.11, 1.68). Similarly, higher vitamin C intake was associated with fewer psychosomatic problems (β=-1.00, 95% CI=-1.79, -0.21). Vitamin E intake showed no associations. Significant gender interactions were observed on the multiplicative scale analysis and limited to the middle tertiles of β-carotene and vitamin C for anxiety and psychosomatic symptoms, respectively.

CONCLUSION: Our findings underscore the potential role of dietary antioxidants, particularly β-carotene and vitamin C, in adolescent mental health. Further research including diverse populations and employing prospective designs could deepen the understanding and inform public health interventions.

AIM: Investigate the longitudinal relationship between physical activity, organised physical activity, fitness, screen time and academic performance among Swedish adolescents.

METHODS: Data from 1139 adolescents at age 13, included vigorous physical activity (accelerometry), fitness (submaximal ergometer test), screen time and organised physical activity participation (self-reported) and academic performance (math and Swedish grades at ages 13 and 16 from registry). Academic performance at age 16 was categorised as A-D (higher grades or pass) or E, F (fail or at-risk of failing). Multilevel logistic regression models were used to examine the relationships while adjusting for gender, parental education, parental country of birth and academic performance at age 13.

RESULTS: Higher fitness at age 13 was associated with increased odds of receiving A-D at age 16 (OR: 1.04 per mL, 99% CI 1.00, 1.07, p = 0.003). High screen time during weekdays was associated with reduced odds (OR: 0.40, 99% CI 0.20, 0.81, p = 0.001) compared to low screen time.

CONCLUSION: Academic performance at the end of compulsory school (age 16) was related to fitness and screen time 3 years earlier. These findings create a paradigm for future randomised controlled trials to explore how influencing these factors might affect academic performance.

Tackling inequities and inequalities related to adolescents' engagement in physical activity and sport is highlighted in recent research. However, rarely addressed are the issues of intersecting hierarchal systems of power that interlocks on both micro and macro levels, affecting how physical activity patterns express social memberships across several contexts. Therefore, this study aimed to explore how adolescents' physical activity during leisure and school hours expressed intersecting social positions and institutional school segregation, using a critical intersectionality approach. Nested in a larger study, a cross-sectional design was applied, including a total of 1139 adolescents in grade 7 (age 13-14) from Swedish school settings. Data was retrieved from surveys, accelerometers, and national registries. Descriptive statistics and stratified analyses were performed to examine levels of moderate-to-vigorous physical activity (MVPA) during school and leisure hours connected to intersecting social positions and school segregation contexts. The statistical analysis indicated that MVPA, to varying extents, expressed both individual social position and school segregation across the sub-groups explored. Inequalities in MVPA were closer connected to intercategorical gendered social positions in school contexts, rather than during leisure hours. However, there were significant intracategorical differences among girls during leisure hours across segregated contexts. Our results suggest that the power structures of school segregation together with educational and sport logics intertwined seem to 'disadvantage' especially girls with a non-ethnically Swedish background. Yet, it also highlights a need to problematize 'the absent minority girl' in equity focused physical activity research. This study emphasizes how an intersectionality approach can shed light on social (dis)advantages connected to adolescents' MVPA from two poles of power, contributing to a more comprehensive and critical understanding of social inequities in physical activity and health research.

Aim: Insufficient physical activity among adolescents, combined with poorer well-being and mental health, are worrying societal problems. Adolescents with ADHD encounter daily challenges and are more prone to experiencing mental and physical health issues compared to their peers. The aim was to investigate associations between moderate-to-vigorous physical activity, sedentary time, screen-time, psychosomatic problems, and ADHD symptoms in adolescents. Method: Data came from a cross-sectional study. Participants (N = 1139) were seventh-grade students who answered questionnaires on screen-time, psychosomatic problems, hyperactivity, and ADHD and were assigned an accelerometer, worn for seven consecutive days. Data were analyzed using linear regression. Results: A negative association was found between moderate to vigorous physical activity and psychosomatic problems in the entire sample. Moderate-to-vigorous physical activity was more strongly associated with psychosomatic problems for adolescents with self-reported ADHD symptoms (B = -0.14 (-0.24, -0.04)) than adolescents without ADHD symptoms (B: -0.03 (-0.05, -0.01)). Conclusions: Moderate-to-vigorous physical activity, sedentary time, and screen-time were all significantly associated with psychosomatic problems among all participants. Moderate-to-vigorous physical activity showed a stronger association with psychosomatic problems among participants with ADHD. This indicates that this group may be particularly responsive to interventions attempting to promote mental health through physical activity.