Associations of total sedentary time, screen time and non-screen sedentary time with adiposity and physical fitness in youth: the mediating effect of physical activity

Exploring the Factors Behind Regional Differences in Physical Fitness of Geological University Students

The intention of this study is to investigate the distribution of physical fitness of the geographical students. The indicators among freshmen at a Chinese geological university and compare their fitness levels with students from other types of institutions. The research revealed that students at higher latitudes exhibited greater physical strength but were less athletic than those at lower latitudes. Spatial dependence on physical fitness was more pronounced in males than in females, particularly for indicators characterizing athletic capacity. Influencing factors such as PM10, air temperature, rainfall, eggs consumption, grain consumption, and GDP which were identified as the major climate, dietary structure, and economic level were examined. Revised：PM10, air temperature and eggs consumption, factors influencing the spatial distribution of male physical fitness across the country. Rainfall, grains consumption and GDP, factors influencing the spatial distribution of female physical fitness across the country. respectively. These factors were found to affect males (42.43%) more than females (25.33%). These findings highlight the significance of regional differences in students' physical fitness levels, with students in geological universities demonstrating better overall physical fitness compared to their counterparts at other schools. Consequently, it is essential to develop tailored physical education strategies for students in various regions, taking into account local economic, climatic, and dietary factors. This study offers a greater explanation of physical fitness disparities between the Chinese university students as well as provides insights for designing effective physical education programs.

Working Memory in Overweight Boys during Physical Education Classes

This study examined the effect of small-sided football games (SSFG) and small-sided Ultimate Frisbee games (SSUFG) on working memory, response times, and feeling mood of boys with overweight. Twenty-eight boys (age 12.23 ± 1.58 years) participated in two trials during physical education lessons (20-min SSFG and 20-min SSUFG) in a counterbalanced, randomized crossover design. The response times and feeling mood were measured for all participants post-exercise through the Sternberg paradigm and feeling scale. For the response times, the paired samples t-test revealed a significantly better reaction time after SSUFG at the "One item level" of the Sternberg paradigm (p = 0.014, Hedges' g = 0.27, small effect) and (p = 0.010, Hedges' g = 0.74, medium effect), at "Three item level" (p = 0.000106, Hedges' g = 1.88, very large effect). The SSFG also showed vigor at the "Five item level" (p = 0.047, Hedges' g = 0.61, medium effect). For the feeling mood, the feeling score was significantly higher after the SSUFG session than the SSFG session and the increase in feeling scores observed after switching from SSFG to SSUFG was significantly different (p < 0.001) from the decrease observed in feeling scores after switching from SSUFG to SSFG. Therefore, the results of the study allow the teacher to introduce new sports and reflect on the motor tasks he or she proposes for boys with overweight during physical education classes.

Influence of Volume and Bouts of Sedentary Time and Physical Activity on School-Aged Youth's Physical Fitness: The UP & DOWN Longitudinal Study

BACKGROUND

The aim of this study was to examine associations of total volume and bouts of sedentary time (ST) and moderate to vigorous physical activity (MVPA) with physical fitness (PF) in youth.

METHODS

This was a 2-year follow-up study with 1418 children and adolescents (51.7% boys). Accelerometers were used to assess ST and MVPA. Cardiorespiratory and muscular fitness values were objectively measured and combined in a global PF variable. Weight status was objectively obtained. Linear regression analyses were used to examine the cross-sectional (using scores at baseline) and longitudinal associations (using the change in the variables) of total volume and bouts of ST and MVPA with PF.

RESULTS

Total ST was negatively associated with global PF (β = -0.488, P < .001 in cross-sectional analysis; β = -0.234, P = .003 in longitudinal analysis). However, this association was not independent of MVPA. Total volume of MVPA showed a positive association with global PF independently of ST and weight status (β = 0.285, P < .001 in cross-sectional analysis; β = 0.119, P = .001 in longitudinal analysis). Longitudinal associations found between ST and MVPA accumulated in bouts of various lengths and global PF became nonsignificant when their respective total volumes are included in the model.

CONCLUSIONS

These results underline the need to accumulate minutes of MVPA, regardless of the bout duration, to increase PF levels in youth.

How are children coping with COVID-19 health crisis? Analysing their representations of lockdown through drawings

Spain is one of the European countries most affected of COVID-19, and also the one with the most stringent restrictions for children. This study aims to explore how COVID-19 lockdown affects children by analysing 151 drawings from children in lockdown. Findings were represented in four main categories: (1) Activities; (2) Emotions; (3) Socialization; and (4) Academic. The results indicate the need to manage the lockdown situation taking into account also children's voices and by placing greater emphasis on social and inclusive policies to help alleviate the possible effects of the pandemic and the lockdown on them.

Associations between Sedentary Time and Sedentary Patterns and Cardiorespiratory Fitness in Chinese Children and Adolescents

The increase in sedentary behavior in children and adolescents has become a worldwide public health problem. This study aimed to explore the associations between sedentary time (ST) and sedentary patterns (SP) and the cardiorespiratory fitness (CRF) of Chinese children and adolescents. The CRF of 535 participants was determined using a 20-m shuttle run test. ST and SP were measured with accelerometers. Questionnaires were used to investigate the different types of ST. Multiple linear regression models were used to test the associations between ST and SP and CRF. In this study, only some ST and SP indicators were found to be significantly associated with CRF in girls. With each additional 10 min of screen time or passive traffic time, VO2max decreases by 0.06 mL/kg/min (B = −0.006, 95% CI: −0.010~−0.001) and 0.31 mL/kg/min (B = −0.031, 95% CI: −0.061~−0.002), respectively, with MVPA control. With each additional 10 min of breaks in ST or duration of breaks in ST, VO2max increases by 0.41 mL/kg/min (B = 0.041, 95% CI: 0.007~0.076) and 0.21 mL/kg/min (B = 0.021, 95% CI: 0.007~0.035), respectively, with control total ST. Breaks in ST (B = 0.075, 95% CI: 0.027~0.123) and the duration of breaks in ST (B = 0.021, 95% CI: 0.012~0.146) were positively correlated with CRF when controlling for LPA, but these associations were not significant when controlling for MVPA (B = 0.003, 95% CI: −0.042~0.048; B = 0.001, 95% CI: −0.024~0.025). The total ST of children and adolescents was found to not be correlated with CRF, but when ST was divided into different types, the screen time and passive traffic time of girls were negatively correlated with CRF. More breaks in ST and the duration of breaks in ST were positively associated with higher CRF in girls. MVPA performed during breaks in ST may be the key factor affecting CRF. Schools and public health departments should take all feasible means to actively intervene with CRF in children and adolescents.

The Combinations of Physical Activity, Screen Time, and Sleep, and Their Associations with Self-Reported Physical Fitness in Children and Adolescents

Much evidence has indicated that adherence to the 24 h movement guidelines (physical activity, screen time and sleep) is associated with physical health, while little is known about the adherence to the 24 h movement guidelines and self-reported physical fitness in adolescents. This study, therefore, aims to explore the association between the 24 h movement guidelines (in isolation or combination) and self-reported physical fitness in a sample of Chinese adolescents in an age range of 10-17.

METHODS

A convenient sample of 3807 children and adolescents from 12 schools was adopted in the present study. A questionnaire based on the Health Behaviour in School-aged Children was used to assess physical activity and screen time, and the Pittsburgh Sleep Scale was utilized to measure sleep duration. The International Fitness Scale was used to assess physical fitness in study participants. Ordinal logistic regression was performed to estimate the association between adherence to the 24 h movement guidelines and self-reported physical fitness.

RESULTS

Of all study participants, 0.9% of them met the 24 h movement guidelines, and meeting the guidelines was significantly associated with higher levels of self-reported physical fitness. The analysis for the association between specific combinations of 24 h movement guidelines and self-reported physical fitness underscored the importance of meeting the physical activity recommendations.

CONCLUSION

Adherence to more recommendations contained in the 24 h movement guidelines was associated with higher self-reported physical fitness, especially cardiorespiratory fitness and muscular strength. Our study also stressed the importance of promoting moderate to vigorous physical activity in children and adolescents. Further works should focus on the association of a recommendation of adherence with other health indicators and replicate this study on larger samples among Chinese children and adolescents. Additionally, longitudinal or interventional studies that include more socio-demographic factors are needed to explore the association between 24 h movement guidelines and self-reported physical fitness, and the 24 h movement guidelines also should be promoted on a large scale in Chinese children and adolescents. Moreover, it is also needed to gain better insights into the directionality of the relationship between compliance with 24 h movement guidelines and self-reported physical fitness, as well as the mechanisms underlying the associations in Chinese children and adolescents.

Associations between Physical Activity Patterns, Screen Time and Cardiovascular Fitness Levels in Swedish Adolescents

Cardiovascular fitness (CVF) has been associated with cardiovascular risk factors in adolescents. CVF levels are determined by non-modifiable and modifiable factors; one modifiable factor is physical activity (PA). There is a lack of studies investigating the associations between PA patterns and CVF and how gender, parental education, BMI status and country of birth are associated with CVF. The aim of this study was to explore the cross-sectional associations between PA patterns and CVF in Swedish 13–14-year-old adolescents. CVF was estimated using the Ekblom-Bak submaximal test, data on PA patterns were collected using hip-worn accelerometers and a questionnaire. The mean CVF was 44.8 mL/kg/min in girls (n = 569) and 55.5 mL/kg/min in boys (n = 451) p < 0.01. The results showed a significant association between participation in organised sports (β = 3.32 CI: 2.14, 4.51, β = 4.38, CI: 2.80, 5.96), MVPA (β = 0.07, CI: 0.04, 0.11, β = 0.07, CI: 0.03, 0.11), a high proportion of SED (β = −0.47, CI: −0.70, −0.25, β = −0.41, CI: −0.64, −0.18) and CVF in girls and boys, respectively. More than five hours of screen time on weekdays was associated with lower CVF (β = −2.32 CI: −3.92, −0.71 in girls and boys β = −2.82, CI: −5.14, −0.50). While causal relations remain unknown, these findings could be relevant when designing future interventions with the aim to improve CVF.

The Impact of Scholastic Factors on Physical Activity Levels during the COVID-19 Lockdown: A Prospective Study on Adolescents from Bosnia and Herzegovina

Scholastic factors (academic achievement) are hypothesized to be important determinants of health-related behaviors in adolescents, but there is a lack of knowledge on their influence on physical activity levels (PAL), especially considering the COVID-19 pandemic and the imposed lockdown. This study aimed to investigate the associations between scholastic factors and PAL before and during the pandemic lockdown. The participants were adolescents form Bosnia and Herzegovina (n = 525, 46% females), who were observed prospectively at the baseline (before the pandemic lockdown) and during the lockdown in 2020 (follow-up). The scholastic factors (grade point average, behavioral grade, school absences, unexcused absences) were evidenced at the baseline (predictors). The outcome (PAL) was evaluated using the Physical Activity Questionnaire for Adolescents at the baseline and the follow-up. Gender, age, parental/familial conflict, and sport participation were observed as confounders. No significant influence of the predictors on PAL were evidenced at the baseline or at the follow-up. The scholastic variables were significantly associated with the changes of PAL which occurred due to pandemic lockdown, with a lower risk for negative changes in PAL among adolescents who were better in school (OR = 0.56, 95%CI: 0.34–0.81, and OR = 0.66, 95%CI: 0.34–0.97, for the grade point average and behavioral grade, respectively). Students who do well in school are probably more aware of the health benefits of proper PAL, and therefore are devoted to the maintenance of their PAL even during the home-confinement of lockdown. Public health authorities should focus more on helping adolescents to understand the importance and benefits of proper PAL throughout the school system.

Mediating effect of fitness and fatness on the association between lifestyle and body dissatisfaction in Spanish youth

BACKGROUND

Previous studies have identified sedentary behaviour, physical activity and eating habits as variables that define a healthy lifestyle. The aims of this investigation were to determine the association between lifestyle and body dissatisfaction, as well as to test the mediating effect of fatness and fitness in this relationship in adolescents.

METHODS

The sample comprised 2216 adolescents aged 13.1 ± 0.90 years, of whom 980 were girls (age 13.1 ± 0.86) and 1236 were boys (age 13.1 ± 0.92). Body composition was measured by body mass index, neck circumference, waist to height ratio and body fat percentage, whereas physical activity, sedentary time, body dissatisfaction and eating habits were self-reported. Physical fitness was evaluated through the ALPHA-Fitness Battery.

RESULTS

The results showed that lifestyle was negatively related with body dissatisfaction. Moreover, physical fitness (β = -0.062; SE = 0.022; 95% IC [-0.106, -0.017]) and fatness (β = -0.052; SE = 0.011; 95% IC [-0.075, -0.032]) showed a significant mediation effect on the relationship between lifestyle and body dissatisfaction. The bootstrapped confidence intervals for the indirect effect were statistically significant, suggesting the mediation effect of fatness (percentage of the total effect of 51.0%) and fitness (percentage of the total effect of 21.3%) on the relationship between healthy lifestyle and body dissatisfaction.

CONCLUSION

The study suggests that adolescents with a healthy lifestyle may have less body dissatisfaction. Fatness and physical fitness can positively affect this relationship, decreasing young people's body dissatisfaction. Therefore, this study highlights the importance of a healthy lifestyle on physical and psychological health in adolescence.

Physical Activity, Screen-Based Sedentary Behavior and Physical Fitness in Chinese Adolescents: A Cross-Sectional Study

Purpose: The aim of this study is to explore the relationship between screen-based sedentary behavior, physical activity and physical fitness among Chinese adolescents. Methods: This study randomly selected adolescents from 10 administrative districts in Shandong, China. The data gathering tools for demographic and other characteristics (gender, age, body mass index and socioeconomic status), PA (PAQ-A) and screen-based sedentary behavior (YRBSS) and physical fitness (NSPFH 2014) were utilized in this study. Statistical analysis was performed by T-test, chi-square test and multiple linear regression. Results: 10,002 adolescents (14.39 years ± 1.79) participated in the study. The results demonstrated that BMI and high TV viewing time had a significant negative correlation with physical fitness, but there was no association between the amount of time spent playing computer/video games and physical fitness among adolescents. High SES and physical activity in leisure time five or more times per week were significantly associated with most dimensions of physical fitness. Conclusions: the results suggest that we not only need to focus on adolescent risk behavior associated with low socioeconomic status and obesity, but also enforce physical activity and reduce sedentary television-watching behavior, which will be crucial pathways and strategies to improve the physical fitness of Chinese adolescents.

From secondary school to university: associations between sport participation and total and domain-specific sedentary behaviours in Spanish students

Effective ways to reduce sedentary behaviour in adolescents are needed to mitigate the risk of chronic disease and poor mental health. Organised sport participation is the most practiced physical activity during adolescence. However, the influence sport participation has on sedentary behaviours remains unclear. This study investigated the associations between sport participation, total and domain-specific sedentary behaviour and physical activity during the transition from secondary school to university. A 3-year longitudinal survey followed Spanish secondary school students (n = 113) to their first year of university. Generalized linear models, adjusted by gender and year, assessed the relationships between sport participation, total and domain-specific sedentary behaviour and physical activity. Compared with non-sport participants, teenagers who played individual sports from baseline during secondary school spent significantly less total time sitting (- 110.5 min/day at weekends), watching television (- 18.7 min/day at weekends) or using the computer for leisure (- 37.4 min/day weekdays). Those who played team sports from baseline at secondary school spent less time sitting (- 126.4 min/day at weekends) or socialising (- 37 min/day at weekends)Conclusion: From secondary school to university, sport participation-based interventions might be an effective strategy to reduce sitting time spent on some domain-specific behaviours. Promoting sports could reduce the rise of sedentary behaviour during adolescence, a stage where sedentary behaviour evolves. What is Known: • Sitting too much and for too long is an important risk factor during adolescence. • Replacing adolescent's sedentary time with moderate-to-vigorous physical activity has been associated with a better quality of life. What is New: • Playing sport is associated with spending less time in total SB on the transition from high school to college. • Not all SB domains are linked to sport participation with associations differing from whether participants played individual or team sports.

Associations of leisure screen time with cardiometabolic biomarkers in college-aged adults

We examined whether screen time was associated with cardiometabolic disease (CMD) risk factors in young adults. Ninety-five adults (19.9 ± 11.4 years) self-reported medical and health behavior history, screen time (television viewing, video games and computer games), and dietary intake. Waist circumference, blood pressure, fasting glucose and lipid levels, cardiorespiratory fitness (VO₂peak), and body composition were measured. Total sedentary behavior and moderate-to-vigorous physical activity (MVPA) were measured by accelerometer. On average, leisure screen time (2.0 ± 1.6 h day^-1) accounted for 24% of total sedentary time (8.4 ± 1.5 h day^-1). After adjustment for demographics, smoking, sleep duration, total energy intake, total sedentary time and MVPA, a 1-standard deviation increase in leisure screen time was associated with a 26% higher BMI, 29% higher waist circumference, 25% higher fat mass, 23% higher triglyceride, and 24% lower VO₂peak (p < 0.05). Our findings suggest that screen time may contribute to the risk of obesity and CMD in young adults.

Changes in the school and non-school sedentary time in youth: The UP&DOWN longitudinal study

The aims of this study were (i) to examine the sedentary time (ST) during different time periods [i.e., weekend, out-of-school weekdays hours, school hours, recess, physical education classes (PEC)] in children and adolescents; (ii) to identify 2-year longitudinal changes in the ST for these periods; and (iii) to examine if ST at baseline is associated with ST 2 years later. This was a 2-year follow-up study with 826 (51.9% boys) children and 678 (50.7% boys) adolescents. Accelerometers were used to assess ST. Students spent more than 60% of their weekend, out-of-school hours and school hours in ST. During these periods, girls and adolescents were more sedentary than boys and children, respectively (p < 0.05). Over 2-year follow-up, ST increased during the weekend, out-of-school hours, school hours and recess in all subgroups studied (p < 0.001). ST during PEC declined 2% per year in children (p < 0.001) but it increased in adolescents (p < 0.05). ST during the periods analysed at baseline was lowly associated with ST during these periods 2 years later (intraclass correlations from <0.001 to 0.364). Interventions in these settings may be adequate if the intention is to avoid ST increase in students.