Association between Weight Status and Physical Fitness in Chinese Mainland Children and Adolescents: A Cross-Sectional Study

Sex Differences in Grip Strength From Birth to Age 16: A Meta-Analysis

In 1985, Thomas and French published results of a meta-analysis that examined sex differences in grip strength in children 5 years of age and older. Their analysis included results from only four studies, and no update has been published. The purpose of the current study was to use meta-analysis to examine sex differences in grip strength from birth to age 16. The analysis included 808 effects from 169 studies conducted in 45 countries between 1961 and 2023. The total sample was 353,676 (178,588 boys, 175,088 girls). From birth to 16 years of age, grip strength was consistently greater in boys than girls. Between 3 and 10 years old, the effect size was small-to-moderate, with female grip strength equaling 90% of male grip strength (Hedges g = 0.33-0.46). At age 11, the effect size decreased slightly, likely due to girls reaching puberty before boys (g = 0.29, 95% confidence intervals (CI) [0.22, 0.35]). At age 13, the effect size increased markedly likely due to male puberty (g = 0.63, 95% CIs [0.55, 0.70]). By age 16, the sex difference in grip strength was substantial, with female grip strength equaling 65% of male grip strength (g = 2.07, 95% CIs [1.86, 2.27]). Secondary analyses revealed that the sex difference in grip strength is broadly similar between countries and has been mostly stable since the 1960s, except for a narrowing of the difference among 5-10-year-olds after 2010. Various biological factors explain why, on average, boys are stronger than girls from birth onward.

Evaluating the impact of motor quotient physical fitness training on health-related fitness indicators and obesity risk in children aged 7-8 years in Tianjin, China

This study aimed to evaluate the impact of Motor Quotient (MQ) physical fitness training on health-related fitness indicators and obesity risk in children aged 7-8 years in Tianjin, China. A total of 60 obese participants were randomly divided into an experimental group (N = 30) and a control group (N = 30). The intervention program focused on improving children's physical, behavioral, and task-related capabilities through structured MQ training. Key results indicated that the experimental group demonstrated significant improvements in Body Mass Index (BMI), with a reduction from 21.28 ± 1.15 kg/m² to 18.86 ± 1.24 kg/m² for boys (p < 0.001) and from 21.04 ± 1.54 kg/m² to 17.47 ± 1.07 kg/m² for girls (p < 0.001). Physical performance metrics improved substantially, including enhanced 2 × 30 m Shuttle Run times (boys: +12.97%, girls: +13.96%, both p < 0.001) and increased Plank duration (boys: +41.36%, girls: +35.26%, both p < 0.01), reflecting improved cardiovascular endurance and core strength. Significant gains were also observed in task-related motor skills, such as Hand-eye Coordination, Behavior Imitation, and Reaction capability (all p < 0.001). Behavioral adaptations included higher scores in exercise behavior (p < 0.01), while strong correlations were found between BMI and cardiovascular fitness indicators, such as the 20 m Backward Run (r = 0.974, p < 0.001). These findings highlight the effectiveness of MQ training in reducing obesity risk and improving multidimensional fitness outcomes. The program demonstrates significant potential as a practical and evidence-based strategy to promote health-related fitness and motor development in children.

Is There a Curvilinear Trajectory of Motor Competence Across Different Weight Status? Exploring the Non-Linear Hypothesis in Adolescents

Background: Evidence supports that motor competence is inversely associated with weight status, yet less is known about this relationship among young people who are underweight. We hypothesized that there is a non-linear trajectory of motor competence across weight status categories (from underweight to obesity). Purpose: To check whether a non-liner relationship exists between motor competence and weight status in adolescents. Research Design: Cross-sectional study. Study sample: we assessed the motor competence of 310 participants (44.8% boys), aged 12-15 years. Data Collection: Motor competence was assessed the Korperkoordinationstest für Kinder (KTK). Weight status (underweight, normal weight, overweight and obesity) was determined using body mass index (BMI). Results: Motor competence was inversely associated with BMI in normal weight (rho = -.222, p = .001), overweight (rho = -.309, p = .028) and obesity (rho = -.663, p < .001), but not in underweight (rho = .193, p = .508). Adolescents with normal weight presented higher motor competence than those with overweight (mean difference = 17.198, p = .001) and obesity (mean difference = 31.686, p < .001). There was no significant difference in motor competence between normal weight and underweight categories. In addition, boys showed a curvilinear trajectory of motor competence, being ascendant from underweight to normal weight and then downward with increasing BMI. Polynomial regressions, fitting a non-linear model, confirmed a non-linear relationship between motor competence and BMI in boys (B = -3.534, p < .001). Conclusions: Our findings suggest that the inverse relationship between motor competence and BMI does not occur in adolescents who are underweight. Furthermore, our results supported the non-linear hypothesis about the relationship between motor competence and weight status in boys.

Prevalence and factors associated with overweight and obesity among adolescents in Nagarjun municipality: a cross-sectional study

Introduction

Overweight and obesity are a growing global public health threat increasingly prevalent among adolescents in low-income and middle-income countries such as Nepal. These conditions are influenced by multifaceted social, behavioural, and habitual factors. Adolescents are particularly at risk due to changing dietary and lifestyle patterns. Additionally, the current nutritional shift, economic progress and rapid urbanisation pose significant threats to nutrition-related health outcomes. This study aims to assess the prevalence and factors associated with overweight and obesity among adolescents in Nepal.

Methods

A school-based cross-sectional study was conducted from September 2022 to January 2023 among 768 randomly selected adolescents from 10 schools in the Nagarjun municipality of Nepal. Anthropometric measurements of height and weight were assessed using standard tools, and the corresponding body mass index (BMI) was calculated. Factors associated with overweight/obesity were examined using the χ2 tests, followed by logistic regression analyses. The statistical significance was set at p<0.05 and 95% Confidence Intervals (CIs).

Results

The overall prevalence of overweight/obesity among adolescents was 6.38% (95% CI 4.64% to 8.11%). The mean weight, height and BMI of the participants were 50.22±9.37 kg, 160.17±9.14 cm and 19.56±3.24 kg/m2, respectively. Adolescents studying in higher grades (AOR 3.61, 95% CI 1.26 to 10.30), uninvolved in any kind of physical activity (AOR 4.97, 95% CI 2.38 to 10.34) and various games and extracurricular activities at school (AOR 2.49, 95% CI 1.16 to 5.28) and consuming high-calorie sugar-rich foods as lunch (AOR 3.02, 95% CI 1.31 to 6.94) were more likely of being overweight/obese than their respective counterparts.

Conclusion

Overweight and obesity are significantly influenced by lifestyles that involve minimal to no physical activity and by the dietary habits of adolescents. The findings warrant interventions in educational and home settings aiming to improve the lifestyles of adolescents.

The Effects of a School-Based Physical Activity Program on Physical Fitness in Egyptian Children: A Pilot Study from the DELICIOUS Project

BACKGROUND

Ensuring the physical fitness of Egyptian children is of paramount importance to their overall well-being, given the unique socio-cultural and educational barriers they face that may hinder their active participation. As part of the DELICIOUS project, the "Be Fit Program" aims to increase the level of physical fitness among Egyptian school-aged children. This study explores the effectiveness of a structured, six-week physical activity (PA) program in improving various facets of physical fitness in children, including body composition, speed, coordination, muscular strength, and cardiovascular endurance. With the increasing prevalence of sedentary lifestyles, such efforts are imperative to improve overall health outcomes.

METHODS

A cohort of 125 children, aged 8.50 to 12.25 y (mean age 10.19 ± 1.03 y), participated in the study. Their body composition, speed, coordination, strength, and aerobic fitness were assessed before and after the Be Fit Program using the revised International Physical Performance Test Profile. Paired t-tests were used to detect changes between the pre- and post-tests.

RESULTS

Following the six-week intervention, statistical analyses revealed significant improvements in coordination and lower body strength (p < 0.01). Aerobic endurance showed marginal improvements, approaching statistical significance (p = 0.06). Conversely, there were no statistically significant changes in body composition, speed, or upper body strength (p > 0.05).

CONCLUSIONS

The study confirms that tailored, non-competitive physical activities can positively influence specific fitness components in Egyptian children. However, achieving holistic improvements across all targeted fitness domains may require further strategic adjustments or a longer program duration. This pilot study underscores the importance of culturally tailored, school-based PA programs and highlights the continued need for research and program refinement to comprehensively improve children's fitness in the Egyptian context.

[Investigation on the current situation and influencing factors of sitting time and health literacy among high school students in China]

OBJECTIVE

To investigate the current situation of sitting time and health literacy among high school students in China, in order to provide a basis for improving their physical and mental health levels.

METHODS

A stratified random cluster sampling method was used to investigate the length of sitting time and health literacy of first and second grade high school students from 31 provinces, cities, and autonomous regions in China(data did not include that of Hong Kong and Macao Special Administrative Region, and Taiwan Province of China). The Kruskal-Wallis H method, independent sample Mann-Whitney U test, and regression model were used to analyze the influencing factors of sitting time and total health literacy score.

RESULTS

(1) The total score of health literacy was statistically significant (P < 0.01) in different regions, urban and rural distribution, annual family income, parents' educational background, age, and gender. (2) The length of sitting was statistically significant (P < 0.01) among multiple groups in different regions, family annual income, parental education, and gender. However, there was no statistically significant difference between groups of different ages and urban-rural distribution (P>0.05). (3) The analysis of multiple linear regression model showed that the total score of health literacy was positively correlated with the family' s annual income and the mother' s education, and negatively correlated with the father' s education and the length of sitting. Standardized regression coefficient β comparison: Father' s education (-0.32) > family annual income (0.15) > mother' s education (0.09) > average daily sitting time (-0.02), with father' s education having the greatest impact, followed by family annual income. The length of sitting was positively related to the family' s annual income and the mother' s educational background, and negatively related to the total score of health literacy. Standardized regression coefficient β comparison: Annual family income (0.14) > education background of mother (0.13)> total score of health literacy (-0.02), with the impact of annual family income the largest, followed by education background of mother.

CONCLUSION

China' s first and second grade high school students generally spend a long time sitting every day, and the level of health literacy is generally low. The level of health literacy and sitting time are negatively correlated with each other, and are most influenced by the educational background of high school students' parents and their family economic levels.

Physical Fitness and Body Mass Index Status of Hong Kong Primary Schoolchildren across the COVID-19 Pandemic, before and after School Closure

OBJECTIVE

To determine whether health-related physical fitness and body mass index (BMI) status differed before and after school closure from the COVID-19 pandemic in a population-based cohort of Hong Kong primary schoolchildren.

STUDY DESIGN

We examined the BMI z score, BMI status, and physical fitness z scores including (i) upper limb muscle strength, (ii) 1-minute sit-up test, (iii) sit-and-reach test, and (iv) endurance run tests, among 3 epochs: prepandemic (September 2018-August 2019), before school closure (September 2019-January 2020), and partial school reopening (September 2021-August 2022), using a repeated cross-sectional approach.

RESULTS

A total of 137 752 primary schoolchildren aged 6-12 years were recruited over 3 academic years. Obesity increased significantly from 25.9% in 2018/19 to 31.0% in 2021/22, while underweight increased slightly from 6.1% to 6.5%. All tested parameters were adversely affected by the pandemic. The negative trend over time was far more pronounced in all 4 physical fitness scores in the underweight group, although performance in handgrip strength had no significance between 2018/19 and 2021/22.

CONCLUSIONS

Schoolchildren who are both underweight and overweight/obese are vulnerable to adverse changes in physical fitness during the COVID-19 pandemic. To eliminate the negative health and fitness outcomes, it is urgent to develop strategies for assisting schoolchildren in achieving a healthy weight, especially in the postpandemic era.

Effects of intervention integrating physical literacy into active school recesses on physical fitness and academic achievement in Chinese children

Background/Objective

The aim of this study was to examine the effects of school-based intervention integrating physical literacy (PL) into active school recesses (ASR) on physical fitness (i.e., body composition, 20-m shuttle run, 50-m run, rope skipping, sit and reach, handgrip) and academic achievement (i.e., academic result of Chinese and Mathematics) in Chinese children.

Methods

A total of 357 children (mean age: 7.8 ± 0.7 years; boys: 50.4%) were recruited from two schools and these two schools were randomly assigned as the intervention group (IG) and the control group (CG), respectively. The IG consisted of 155 children (mean age: 7.9 ± 0.7 years, boys: 51.0%), and 202 children (mean age: 7.8 ± 0.7 years; boys: 50%) were allocated to the CG. Children in the IG received a 10-week intervention integrating PL that was conducted during ASR. In the CG, children's regular school activity was remained during the intervention period. Generalized estimating equation was performed to compare the levels of physical fitness and academic achievement between the IG and the CG after intervention.

Results

Regarding physical fitness, there was a significant group × time interaction on 20-m shuttle run (β = -3.89, 95% CI [-5.08; -2.71], p < 0.001) and handgrip (β = -0.70, 95% CI [-1.20; -0.20], p = 0.006). After intervention, children in the IG had a greater increase than the CG (p < 0.001) in terms of 20-m shuttle run and handgrip. In addition, the post-test analysis indicated that performance of children in the IG was significantly greater than those in the CG (20-m shuttle run: p < 0.001, handgrip: p = 0.002). There was a significant group × time interaction on academic result of Chinese (β = -1.21, 95% CI [-1.91; -0.56], p = 0.001) and academic result of Mathematics (β = 16.71, 95% CI [15.14; 18.143], p < 0.001). Statistically significant positive difference in post-test was observed in academic result of Mathematics between the IG and the CG (p = 0.012).

Conclusion

The results of this intervention study indicate that intervention integrating PL into ASR could bring a promising effect on physical fitness and academic achievement in children. It is recommended that future studies are necessary to assess the effects of ASR-based PL intervention on physical and cognitive outcomes using a wide range of sample.

Body Mass Index and Physical Fitness among Chinese Adolescents Aged 15-18: A Cross-Sectional Study of Gender Differences

OBJECTIVE

The aim of this study is to examine the relationship between varying levels of obesity and physical fitness test scores among Chinese adolescents, while also investigating gender differences in physical fitness and overall health. Data on height, weight, 50 m sprints, 1000/800 m runs, standing long jumps, sit and reach exercises, pull-ups/bent-leg sit-ups, and additional variables were collected from the DYH health database. Physical fitness indicators were evaluated based on the revised 2014 National Physical Fitness Standards for Students, and scores were assigned accordingly. An ordinal logistic regression (ologit) model was employed to analyze the relationship between body mass index (BMI) and physical fitness.

RESULTS

(1) Normal-weight boys achieved significantly higher physical fitness test scores than boys in other weight categories. (2) Underweight and normal-weight girls obtained significantly higher physical fitness test scores compared to overweight and obese girls, with underweight girls scoring slightly higher than those with a normal weight.

CONCLUSIONS

(1) There is a significant non-linear relationship between BMI levels and physical fitness test scores. (2) Gender differences were observed in physical fitness and overall health outcome. (3) The findings indicate an inverted U-shaped association between BMI and physical fitness among boys, while girls displayed an inverse relationship. This could be attributed to the cultural association between thinness and beauty among girls in China.

Perceived Physical Literacy Is Associated with Cardiorespiratory Fitness, Body Composition and Physical Activity Levels in Secondary School Students

BACKGROUND

Overweight and obese adolescents are often associated with lower Physical Activity (PA) levels and low Cardiorespiratory Fitness (CRF). Recently, the concept of Physical Literacy (PL), has been suggested to be associated with higher levels of active behavior and better health in adolescents. The purpose of this study is to investigate the relationships between PL, body composition, cardiorespiratory fitness and physical activity levels in French secondary school students.

METHODS

The level of PL was assessed in 85 French adolescents using a French version of the Perceived Physical Literacy Instrument (F-PPLI). Cardiorespiratory fitness was measured by the "20 m adapted walk/shuttle run test". The PA level was assessed by the Youth Risk Behavior Surveillance System questionnaire. Weight status was measured by the Body Mass Index (BMI) and the body composition data.

RESULTS

We find a significant association between the PL and the percentage Fat Mass (%FM) (r = -0.43; p ≤ 0.01), between the PL and moderate to vigorous PA (MVPA) per week (r = 0.38; p ≤ 0.01). The PL was associated (r = 0.36; p ≤ 0.01) with the percentage of Skeletal Muscle Mass (%SMM) and cardiorespiratory fitness (r = 0.40; p ≤ 0.05).

CONCLUSIONS

Developing the PL for the most disadvantaged secondary school students in a PA program could be a suitable strategy to increase their PA level, reduce their adiposity, and promote better long-term health.

Secular Trends in Physical Fitness of Peruvian Children Living at High-Altitude

The physical fitness of children is an important marker of health, and monitoring its temporal changes provides important information for developing interventions. We aimed to: (1) describe secular trends in physical fitness across age, within each sex, in Peruvian schoolchildren; and (2) verify if these trends are also present when adjusted for changes in height and weight. We sampled 1590 children (707 in 2009; 883 in 2019), aged 6-11 years. Physical fitness was assessed with four tests from the EUROFIT battery. ANOVA and ANCOVA statistical models were used. Results showed that with increasing age, girls and boys were significantly stronger in all PF tests, except for the case of flexibility in girls. In 2019, girls were stronger (handgrip) and more flexible than in 2009; but lower values were evident in standing long jumps in both sexes. Age-by-year interactions were statistically significant for agility in both sexes, with significant differences occurring at different ages. These trends did not change when adjusted for temporal changes in height and weight. Our research provides important data for local governments to implement public policies and practices to improve physical fitness levels in children.

Assessment of the Relationship between Body Weight Status and Physical Literacy in 8 to 12 Year Old Pakistani School Children: The PAK-IPPL Cross-Sectional Study

(1) Background: Physical literacy (PL) is a multidimensional concept, since it fosters lifetime engagement in physical activities and reduces obesity; however, empirical evidence is lacking to support this association. This study first aimed to establish PL levels stratified by normal weight children and children with overweight and obesity. Furthermore, this study determined a correlation between PL domains and BMI by weight status among South Punjab school children. (2) Methods: This cross-sectional study involved 1360 (Boys: 675 and Girls: 685) children aged 8 to 12, and was conducted using CAPL-2. T-tests and chi-square were used to determine the difference between categorical variables, with MANOVA used to compare weight statuses. Spearman correlation was employed to determine the correlation between variables; p < 0.05 was considered significant. (3) Results: Normal weight children had significantly higher PL and domain scores, except for the knowledge domain. Most children with normal weights were at the achieving and excelling levels, while children with overweight and obesity were at the beginning and progressing levels. The correlation among PL domains in normal and overweight and obese children ranged from weak to strong (r = 0.001 to 0.737), and the knowledge domain was inversely correlated with the motivation domain (r = -0.023). PL and domain scores were inversely correlated to BMI, except for the knowledge domain. (4) Conclusions: Children with normal weight tend to have higher PL and domain scores, while those with overweight or obesity tend to have lower scores. There was a positive relationship between normal weight and higher PL and domain scores, and an inverse relationship was observed between BMI and higher PL scores.

The association between muscle strength and executive function in children and adolescents: Based on survey evidence in rural areas of China

Background

In recent years, muscle strength in children and adolescents has continued to decline, especially in rural areas. Executive function as a higher function of the brain, is closely related to the future achievement of children and adolescents. For this reason, this study analyzed the correlation between muscle strength and executive function in children and adolescents in rural areas of China to better promote the development of muscle strength and executive function.

Methods

Demographic factors, muscle strength, and executive function were tested in 1,335 children and adolescents in rural China using a three-stage stratified whole-group sampling method. One-way ANOVA and chi-square test were used to compare the differences in executive function among children and adolescents with different muscle strengths. Multiple linear regression analysis and logistic regression analysis were used to analyze the association that exists between muscle strength and executive function.

Results

When comparing the inconsistently, congruent, 1back, 2back, conversion, size parity, and cognitive flexibility response times of children and adolescents with different muscle strength indexes in rural China, the differences were statistically significant (F = 46.592, 45.610, 10.809, 32.068, 24.095, 19.260, 11.501, p < 0.001). Logistic regression analysis was performed using children and adolescents with muscle strength index >P80 as the control group. The results showed that the risk of 1back dysfunction was higher (OR = 1.764, 95% CI:1.094, 2.843) in children and adolescents with muscle strength index <P20 (p < 0.05). The risk of 2back dysfunction was higher in children and adolescents with a muscle strength index <P20 (OR = 2.129, 95% CI:1.329, 3.410) (p < 0.01). Compared with children and adolescents with muscle strength index >P80. The muscle strength index <P20 group had a higher risk of cognitive flexibility dysfunction (OR = 1.820, 95% CI:1.111, 2.982) (p < 0.05).

Conclusion

There is a association between muscle strength and executive function in children and adolescents in rural areas of China. Those with higher muscle strength have shorter executive function reaction times and are at lower risk of developing executive dysfunction. Future measures should be taken to improve muscle strength and executive function levels in children and adolescents in rural areas to promote healthy physical and mental development.

Changes in Anthropometric Measurements and Physical Fitness of Polish Students in 20-Year Period

BACKGROUND

Intergenerational changes are still being recorded worldwide, although their magnitude and direction may vary in different countries. The aim of this study was to determine changes in the magnitude and direction of changes in the body morphology and motor abilities of physically active adults over 20 years.

METHODS

Two hundred and fifty-two individuals aged 18-28 years volunteered to participate in the study. The changes were analyzed over a 20-year period (March 2001; P₁ vs. March 2022; P₂). The measured parameters were body height, weight, and body fat. Further, hand grip strength with dynamometer measurement, a sit-up test, a sit and reach test, and a standing long jump were performed to examine motor abilities. The results of the conducted tests were compared between subjects from both periods.

RESULTS

Our study confirms changes in trends concerning body morphology and motor ability performance. Higher values of body mass index and body fat were observed in P₂ women, whereas these differences were not significant in men. Additionally, in terms of physical performance, the P2 group noted worse results than their peers from the past.

CONCLUSION

Despite young adults claiming to have similar physical activity levels to those observed in the past, they demonstrate poorer physical performance and higher body fat levels. The observed changes can be considered negative.

Predicting VO2max in Children and Adolescents Aged between 6 and 17 Using Physiological Characteristics and Participation in Sport Activities: A Cross-Sectional Study Comparing Different Regression Models Stratified by Gender

Background: The aim of this study is to use different regression models to capture the association between cardiorespiratory fitness VO2max (measured in mL/kg/min) and somatometric characteristics and sports activities and making better predictions. Methods: multiple linear regression (MLR), quantile regression (QR), ridge regression (RR), support vector regression (SVR) with three different kernels, artificial neural networks (ANNs), and boosted regression trees (RTs) were compared to explain and predict VO2max and to choose the best performance model. The sample consisted of 4908 children (2314 males and 2594 females) aged between 6 and 17. Cardiorespiratory fitness was assessed by the 20 m maximal multistage shuttle run test and maximal oxygen uptake (VO2max) was calculated. Welch t-tests, Mann−Whitney-U tests, X2 tests, and ANOVA tests were performed. The performance measures were root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2). All analyses were stratified by gender. Results: A comparison of the statistical indices for both the predicted and actual data indicated that in boys, the MLR model outperformed all other models in all indices, followed by the linear SVR model. In girls, the MLR model performed better than the other models in R2 but was outperformed by SVR-RBF in terms of RMSE and MAE. The overweight and obesity categories in both sexes (p < 0.001) and maternal prepregnancy obesity in girls had a significant negative effect on VO2max. Age, weekly football training, track and field, basketball, and swimming had different positive effects based on gender. Conclusion: The MLR model showed remarkable performance against all other models and was competitive with the SVR models. In addition, this study’s data showed that changes in cardiorespiratory fitness were dependent, to a different extent based on gender, on BMI category, weight, height, age, and participation in some organized sports activities. Predictors that are not considered modifiable, such as gender, can be used to guide targeted interventions and policies.

Age- and Sex-Specific Physical Fitness Reference and Association with Body Mass Index in Hong Kong Chinese Schoolchildren

There is lacking a population-based study on the fitness level of Hong Kong schoolchildren, and it seems that increasing childhood obesity prevalence has shifted the classification of healthy fitness, with 'underfit' as normal. This cross-sectional territory study aimed to develop an age- and sex-specific physical fitness reference using a representative sample of children aged 6-17 and to determine the associations with body mass index in schoolchildren. The study analyzed Hong Kong School Physical Fitness Award Scheme data covering grade 1 to grade 12 students' physical fitness and anthropometric measurements from 2017 to 2018. This reference was established without the impact due to COVID-19. Four aspects of physical fitness tests were measured using a standardized protocol, including (i) upper limb muscle strength, (ii) one-minute sit-up, (iii) sit-and-reach, and (iv) endurance run tests. The generalized additive model for location, scale, and shape was used to construct the reference charts. A Mann-Whitney U test was used to compare the mean differences in age, weight, and height, and a Pearson's chi-square test was used to examine the distributions of sex groups. A Kruskal-Wallis test was used to compare the group differences in BMI status, followed by the Dunn test for pairwise comparisons. A 5% level of significance was regarded as statistically significant. Data of 119,693 students before the COVID-19 pandemic were included in the analysis. The association between physical fitness level and BMI status varied depending on the test used, and there were significant differences in fitness test scores among BMI groups. The mean test scores of the obese group were lower in most of the tests for both boys and girls, except for handgrip strength. The underweight group outperformed the obese group in push-ups, one-minute sit-ups, and endurance run tests, but not in handgrip strength. In conclusion, a sex- and age-specific physical fitness reference value for Hong Kong Chinese children aged 6 to 17 years old is established, and this study demonstrated a nonlinear relationship between BMI status and physical fitness. The reference will help to identify children with poor physical fitness to offer support and guidance on exercise training. It also serves as a baseline for assessing the impact of the COVID-19 pandemic on Hong Kong students' physical fitness.

The Association between Body Mass Index and Muscular Fitness in Chinese College Freshmen

(1) Background: The present study aimed to investigate the association between body mass index (BMI) and muscular fitness in Chinese college freshmen. (2) Methods: A total of 6425 college freshmen in mainland China were recruited. BMI was classified as underweight (<18.5 kg/m²), normal weight (18.5~23.9 kg/m²), overweight (24~27.9 kg/m²), and obese (≥28 kg/m²), according to the Working Group on Obesity in China. Health-related physical fitness components including cardiorespiratory fitness, lower body explosive power, upper body muscular endurance, abdominal muscular endurance, flexibility, and vital capacity were assessed. Physical fitness index and muscular fitness index were calculated, respectively, as the sum score of the standardized values (z-score) of the corresponding components. Three regression models were used to evaluate the potential associations: a linear regression model, a polynomial regression model, and a restricted cubic spline regression model. Adjust R square was used to compare among models. (3) Results: Significant differences were observed among different BMI categories in nearly all physical fitness components as well as physical fitness z-score and muscular fitness z-score (p < 0.001), regardless of gender. Significant linear associations were found between BMI and physical fitness z-score as well as muscular fitness z-score among total, male, and female groups (p < 0.05). However, the restricted cubic spline regression model showed a better fitting effect (adjust R² was 7.9%, 11.2%, and 4.8% in total, male, and female for physical fitness and 7.7%, 15.7%, and 4.0%, for muscular fitness, respectively), compared with the linear and polynomial regression models, presented by a higher adjusted R². Restricted cubic splines analysis showed that BMI value and physical fitness z-score showed a non-linear relationship with an approximate inverted U curve in all groups, while an approximate reversed J-shaped association was observed between BMI and muscular fitness z-score in all groups. (4) Conclusions: The present study showed a nonlinear negative relationship between BMI and physical fitness with underweight and overweight/obese college freshmen having poorer physical fitness and muscular fitness than their normal BMI peers, which may provide useful evidence to the development of public health recommendations and encourage the health management of young adults. Future studies should further explore the relationship between BMI and muscular fitness with multi-centered large sample size studies.

Lower fitness levels, higher fat-to-lean mass ratios, and lower cardiorespiratory endurance are more likely to affect the body mass index of Saudi children and adolescents

Background

Several studies suggest that health-related physical fitness may play a prominent role in preventing obesity in children and adolescents.

Objectives

The present study examined fitness levels using five components of health-related fitness in Saudi students aged 10-17 years (fat-to-lean mass ratio, cardiorespiratory endurance, upper body strength and endurance, abdominal muscle strength and endurance, and flexibility). Subsequently, the association between BMI and a health-related fitness index (HR-PFI) based on the five fitness components was investigated.

Methods

The study was conducted on 1,291 students with a mean age of 12.95 ± 1.72 years. Participants included 1,030 boys aged 12.80 ± 1.79 years, with 479 young boys (11.24 ± 0.81b years), and 551 adolescents (14.16 ± 1.21 years). Moreover, the study examined 261 girls averaging 13.54 ± 1.2 years old, with 66 young girls (11.92 ± 0.27 years), and 195 teenage girls (14.09 ± 0.85 years). Each participant's health-related fitness level was assessed by the following tests: Bioelectrical Impedance Analyzer (BIA) for body composition, one-mile run/walk test for cardiorespiratory endurance, curl-up test for abdominal muscle strength and endurance (AMSE), push-up test for upper body strength and endurance (UBSE), and back-saver sit-and-reach test for flexibility.

Results

The overall prevalence of overweight and obesity was 10.4 and 24.7% in boys and 10 and 8.4% in girls, respectively. The mean Z-scores of performances decreased from the underweight to the obese groups. BMI was positively associated with the ratio of fat mass to lean mass and negatively associated with cardiorespiratory endurance in the overall group of participants as well as in the subgroups by sex and age categories. BMI was also negatively associated with flexibility and HR-PFI in the total group, UBSE, AMSE, and HR-PFI in prepubertal boys, and UBSE in prepubertal girls. The coefficient of determination values was 0.65 in the total group, 0.72 in prepubertal boys, 0.863 in adolescent boys, 0.956 in prepubertal girls, and 0.818 in adolescent girls.

Conclusions

Overall health-related physical fitness, fat-to-lean mass ratio, and cardiorespiratory endurance are the factors that most affect BMI in Saudi students aged 10 to 17.

Physical, Psychological, and Body Composition Differences between Active and Sedentary Adolescents According to the "Fat but Fit" Paradigm

The practice of physical activity during adolescence is essential for the proper development of the population. In recent decades, the relevance of physical activity has been increasing, due to the development of the "fat but fit" paradigm. This paradigm shows that adolescents with a high level of physical fitness are healthier than adolescents with poorer physical fitness, regardless of their weight, giving importance to sports practice over other aspects. However, few previous studies have analyzed the differences in physical and body composition between active and sedentary adolescents in this paradigm. For this reason, the objectives of the present study were to establish the differences in body composition, physical performance, and adherence to the Mediterranean diet between active and sedentary adolescents; and to analyze the differences between active and sedentary adolescents according to the "fat but fit" paradigm. The sample consisted of 791 adolescent whose body composition, level of physical activity, adherence to the Mediterranean diet, and physical fitness were measured. It was found significant between active and sedentary adolescents in most of the anthropometric, AMD, and physical fitness variables, with a significant effect of the covariates gender, age, BMI, and biological maturation on the model. The binary logistic regression analysis performed shows that anthropometric variables, AMD, and VO2 max can be considered as primary outcomes to distinguish between active and sedentary groups of adolescents. Furthermore, the results showed that the active adolescents, regardless of their weight status, had lower fat mass and greater muscle mass, as well as a higher performance in the physical fitness tests, and greater adherence to the Mediterranean diet than the sedentary adolescents. To conclude, the practice of physical activity is a determinant for the improvement of body composition, physical performance, and adherence to the Mediterranean diet of the adolescent population, regardless of their gender, age, weight, or maturity status.

Moderate Effects of School-Based Time Increasing Physical Education Intervention on Physical Fitness and Activity of 7-Year Pupils—A Report from a Follow-Up of a HCSC Study

We evaluated the effectiveness of a 15-week intervention that increased from three to five lessons of physical education (PE) a week on 7-year-old boys’ and girls’ physical fitness (PF), physical activity (PA) and sedentary behaviour on week and weekend days. A total of 212 first grade pupils (mean age 6.95 ± 0.43) from two urban schools in Poznań were randomly assigned to the experimental or control groups. The PF was measured with a battery of field tests, while health-related behaviours were assessed with the Healthy Children in Sound Communities questionnaire. There were some interaction effects noticed in the PF scores in the case of a 20-min run for boys (F_2,196 = 5.29, p = 0.0058) and for girls (F_2,220 = 3.31, p = 0.0382) and the sit-ups test for boys (F_2,196 = 1.93, p = 0.1478) and for girls (F_2,220 = 3.98, p = 0.0201) and for the sit and reach test in the case of girls (F_2,220 = 3.98, p = 0.0201). In terms of outdoor PA levels, there were no major differences between any of the examined groups. Differences were found between girls from the experimental and control groups in the post-test (p = 0.0107) and follow-up (p = 0.0390) during the weekdays, with no differences between the groups of boys. Despite the moderate effects of the extended PE time programme right after the intervention, there were some indications of progress in the follow-up experiments.

Muscular Fitness and Cardiometabolic Variables in Children and Adolescents: A Systematic Review

BACKGROUND

The importance of muscular fitness (MF) in the performance of activities of daily living is unequivocal. Additionally, emerging evidence has shown MF can reduce cardiometabolic risk in children and adolescents.

OBJECTIVES

The purpose of this study was to examine and summarize the evidence regarding the relationship between MF phenotypes (i.e., maximum muscular strength/power, muscular endurance, and maximum muscular strength/power/endurance) and cardiometabolic variables (obesity, blood pressure, lipids, glucose homeostasis, inflammatory markers, and clustered cardiometabolic variables) in children and adolescents.

DESIGN

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with PROSPERO, number CRD42020179273.

DATA SOURCES

A systematic review was performed on five databases (PubMed, EMBASE, SciELO, Scopus, and Web of Knowledge) from database inception to May 2020, with complementary searches in reference lists.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (1) a study sample of youth aged ≤ 19 years, (2) an assessment of MF with individual or clustered cardiometabolic variables derived from adjusted models (regardless of test/measurement adopted or direction of reported association), and (3) a report of the association between both, using observational studies. Only original articles published in peer-reviewed journals in English, Portuguese, and Spanish languages were considered. The quality of the included studies was assessed by using the National Heart, Lung, and Blood Institute checklist. The percentage of results reporting a statistically significant inverse association between each MF phenotype and cardiometabolic variables was calculated.

RESULTS

Of the 23,686 articles initially identified, 96 were included (77 cross-sectional and 19 longitudinal), with data from children and adolescents from 35 countries. The score for the quality of evidence ranged from 0.33 to 0.92 (1.00 maximum). MF assessed by maximum muscular strength/power was inversely associated with lower obesity (64/113 total results (56.6%)) and reduction in clustered cardiometabolic risk (28/48 total results (58.3%)). When assessed by muscular endurance, an inverse association with obesity (30/44 total results (68.1%)) and cardiometabolic risk (5/8 total results (62.5%)) was identified. Most of the results for the relationship between MF phenotypes with blood pressure, lipids, glucose homeostasis, and inflammatory markers indicated a paucity of evidence for these interrelationships (percentage of results below 50.0%).

CONCLUSION

MF assessed by maximum muscular strength/power or muscular endurance is potentially associated with lower obesity and lower risk related to clustered cardiometabolic variables in children and adolescents. There is limited support for an inverse association between MF with blood pressure, lipids, glucose homeostasis biomarkers, and inflammatory markers in children and adolescents.

Factors related to lower limb performance in children and adolescents aged 7 to 17 years: A systematic review with meta-analysis

BACKGROUND

The literature identifies several factors that are associated with lower limb performance (LLP). However, there is little consensus on which factors have the major associations with LLP.

OBJECTIVE

Examine, analyze and summarize the scientific evidence on the factors associated with the performance of LLP in children and adolescents of both sexes aged between 7 and 17 years.

DESIGN

This systematic review was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and was registered in PROSPERO.

DATA SOURCES

A systematic literature search of five electronic databases (i.e., SPORTDiscus, PubMed, CINAHL, Google Scholar, and SCOPUS) with date restrictions was conducted (2010 to 2021).

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (i) a study published between 2010 and 2021; (ii) a research study with observational design; (iii) a study analyzing LLP; and (iv) a sample composed of young people between 7 and 17 years old (regardless of sex).

ANALYSES

Literature analysis was carried out in English and Portuguese between 2018 and 2021, "blindly" by two researchers. For data sorting, Rayyan® was used. Data extraction and evidence analysis were performed "blindly", using the Loney scale. The minimum items for observational studies were analyzed by the STROBE checklist. Meta-analyses were conducted based on age group (Childhood [7 to 11 Yrs] and Adolescence [12 to 17 Yrs]) and puberty stages (i.e., Prepupertal and Pubertal). The heterogeneity between the samples of the studies was assessed using the "Cochran's Q" and "I^2" statistics. Meta-regression analyses were performed to check the factors related to heterogeneity of the studies and to check the associations between chronological age and LLP.

RESULTS

The literature search resulted in 1,109,650 observational studies of which 39 were included in this review. Through Meta-analysis and Meta-regressions, it was possible to indicate that advancing chronological age related to increased LLP (p<0.01), and that in relation to puberty stages pubertal subjects had higher LLP than their pre-pubertal peers (p<0.01).

DISCUSSION

The main findings of the present systematic review suggest that as chronological age advances (childhood to adolescence), neuromuscular systems mature and this may be due to advancing puberty, which is also associated with an increase in LLP.

CONCLUSION

The factors associated with lower limbs performance are still inconsistent in the literature. However, advancing chronological age and stage of puberty are both associated with increased lower limbs performance.

TRIAL REGISTRATION

ID-PROSPERO-CRD42020137925.

The Assessment of Functional Movement in Children and Adolescents: A Systematic Review and Meta-Analysis

Background

The Functional Movement Screen™ (FMS™) is an assessment of human movement that may signal potential deficits that could predispose an otherwise healthy person to injury risk. FMS™ scores are well reported in both athletic and adult samples. However, to date, there has been no comprehensive systematic review and meta-analysis of FMS™ data among school-aged children and adolescents.

Objective

We aimed to systematically review and analyse functional movement proficiency of children and adolescents, specifically when assessed using the FMS™, and to establish initial normative values for the FMS™ in this population group and to further estimate differences in functional movement proficiency between the sexes, by school level (i.e., between primary and secondary school-level children and adolescents), and based on differences in child and adolescent body mass index (BMI).

Methods

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, prospective studies were identified from searches across eight databases (MEDLINE, SPORTDiscus, CINAHL, Web of Science, EMBASE, ERIC, PsychINFO and PubMed), without any date restrictions, up to December 2020. The primary meta-analysis estimated the overall FMS™ score for school-aged children and adolescents across published studies. An additional three subgroup meta-analyses estimated comparisons for FMS™ data with school level, sex, and BMI across published studies. FMS™ data were meta-analysed using a number of different meta packages (Schwarzer et al. in Meta-Analysis with R, 1st ed, Springer International Publishing, Berlin, 2015), available in R Studio.

Results

A total of 19 articles were included in the systematic review. Meta-analysis revealed a weighted FMS™ mean score of 14.06, with a standardised Tau value of 0.56, signalling a moderate-to-large degree of variability in FMS™ means between studies. The difference in FMS™ means between samples of males (weighted FMS™ mean 13.91) and females (weighted FMS™ mean 14.56) was compatible with a possible small effect size (standardised mean difference − 0.27). The variability in FMS™ means between studies was approximately five times greater in samples of secondary school children (factor difference in Tau values 5.16). The final meta-regression identified a negative association between BMI and FMS™ scores (r =  − 0.42), which signalled a moderate-to-large difference in FMS™ scores between healthy weight and overweight children/adolescents.

Conclusion

This systematic review and meta-analysis represents a novel and important synthesis of published FMS™ data from groups of children and adolescents. The study signals possible sex- and age-related differences in FMS™ scores, as well as a clear negative relationship between BMI and functional movement proficiency. More longitudinal research is needed to better understand the developmental trajectory and the effects of maturation milestones on FMS™ proficiency. Additional research is also needed to identify the types of interventions that could improve functional movement proficiency among ‘at risk’ groups, who are susceptible to functional movement deficiency, and whether changes in body composition mediate the relationship between these interventions and the improvement of FMS™ scores.

Can Anthropometry and Body Composition Explain Physical Fitness Levels in School-Aged Children?

Physical fitness (PF) is closely related to various health outcomes and quality of life among children. However, the associations between anthropometry, body composition (BC), and PF are not fully elucidated. This cross-sectional study aimed to investigate the associations between demographic metrics (age, sex), anthropometric measures (body mass index z-score (BMI z-score) waist/height ratio (WHtR)), BC parameters (body-fat percentage (BF%), muscle weight), and PF levels (800-m run, sit-and-reach, 1-min sit-ups, standing long jump) in school-aged children. Continuous variables were dichotomized by median splits. The results of 180 girls and 180 boys (mean age: 10.0 ± 0.7 years; mean BMI z-score: 0.366 ± 1.216) were analyzed. Multivariable linear regressions revealed that BF% (regression coefficient (B) = 3.4, 95% confidence interval (CI) = 2.5-4.3) was independently correlated with the 800-m run. Sex (B = 4.6, 95% CI = 3.0-6.3), age (B = 3.1, 95% CI = 1.9-4.3), and BMI z-score (B = -0.7, 95% CI = -1.4--0.1) were independently related to sit-and-reach. Age (B = 3.3, 95% CI = 2.0-4.7), BF% (B = -0.3, 95% CI = -0.4--0.2), and muscle weight (B = 0.7, 95% CI = 0.2-1.2) were independently associated with 1-min sit-ups. In addition to demography, anthropometry and BC provided additional information concerning some PF levels in school-aged children. Weight management and PF promotion should be addressed simultaneously in terms of preventive medicine and health promotion for children.

Motor skills in relation to body-mass index, physical activity, TV-watching, and socioeconomic status in German four-to-17-year-old children

BACKGROUND

The present study describes motor skills in a large sample of German children and adolescents and investigates associations with age, gender, body-mass index, physical activity, television time, and socioeconomic status.

METHODS

2,106 children (1076 boys, 1030 girls) aged 4 to 17 years performed five different motor tests for strength (pushups, standing long jump), coordination (backward balancing, jumping side-to-side) and flexibility (forward bend) within the framework of the LIFE Child study (Leipzig, Germany). Anthropometric parameters were assessed through standardized measurement. Data on physical activity, television time, and socioeconomic status were collected via questionnaires. Linear regression analyses were applied to assess relations.

RESULTS

Strength and coordination performance were higher in older than in younger children. While boys showed a higher performance in strengths tests than girls, girls performed better in flexibility and coordination during precision tasks (backward balancing). In terms of coordination under time constraint (jumping side-to-side), both genders produced similar results. Lower body-mass index, higher physical activity, and higher socioeconomic status were significantly related to better motor skills. Longer television times were significantly associated with lower performance in long jump.

CONCLUSIONS

The present findings are similar to data collected at the beginning of the century, indicating that motor skills have hardly changed in recent years. The findings furthermore suggest that children from lower social strata, children with higher body weight, and children who move little have a higher risk of developing insufficient motor skills and should therefore be given special support.

Health profile with body mass index and physical fitness in Swedish adolescents: a cross-sectional study

Objectives Physical inactivity and poor physical fitness in children and adolescents are growing public health problems globally. This study aimed to investigate the correlation between Body Mass Index (BMI) and three physical fitness components, including overall fitness, according to the Swedish Physical power, Mental harmony and Social capacity profile (FMS profile). Another aim was to investigate the test-retest reliability of the FMS questionnaire and fitness tests. Methods A total of 3,692 male and female adolescents in Sweden, between year 2004 and 2013, aged from 16 to 18 years old, were included. Height and weight data were collected to calculate the Body mass index (BMI). The participants performed physical fitness tests, which measure cardio-respiratory fitness, muscular strength and flexibility. The test-retest study included 18 adolescents, aged 16. They answered the FMS questionnaire and participated in the fitness tests with one-week interval. Results A weak inverse relationship between BMI and physical fitness was found: r=-0.06 to -0.07 (p<0.05) for flexibility, r=-0.13 to 0.10 (p<0.001) for strength, r=-0.14 to -0.33 (p<0.001) for cardiorespiratory fitness, and r=-0.15 to -0.27 (p<0.001) for overall fitness. In the test-retest study, the ICC's for strength, flexibility and balance were 0.94, 0.96 and 0.89, respectively. The ICC's for the questions regarding lifestyle ranged from 0.75 to 1.00 and for diet, physical activity and drugs were 0.56, 0.44 and 0.58, respectively. The correlation was stronger in overweight/obese individuals compared to normal weight individuals. Conclusion Overweight and obese individuals scored lower in the fitness tests compared to their normal weight counterparts. The test-retest study revealed that the FMS questionnaire and fitness tests are reliable tools.

Influence of Body Composition on Physical Fitness in Adolescents

Background and objectives: Childhood obesity is one of the main public health issues facing advanced societies. The Spanish population presents 28.6% overweight or obese adolescents, and Extremadura, 22.3%. Physical fitness is considered one of the most important health markers and a common predictor of morbidity and mortality caused by cardiovascular diseases. Thus, fitness tests are needed for health monitoring, especially in overweight and obese adolescents. Therefore, this study aimed to explore the relationship between body composition and physical fitness in adolescents and to analyse if there are differences in physical condition and body composition between the sexes, as well as to compare the different body mass index (BMI) categories to each other. This project also tried to find regression equations to predict the physical fitness test results. Materials and Methods: A total of 225 adolescents were recruited. Weight status was classified according to WHO 2007 standards. Body composition variables (i.e., BMI, fat mass (FM), FM percentage (FM%), and fat-free mass (FFM)) and physical fitness (standing long jump (SLJ), speed–agility (SA), cardiorespiratory fitness (CF), and handgrip strength (HS)) were assessed. Results: Significant differences were found between the sexes in body composition (FM%, FM, and FFM) and physical fitness (SLJ, SA, CF, and HS) (p < 0.001) in favour of males. Significant differences were also found in speed (p = 0.002), CF (p < 0.001), and SLJ (p = 0.004) in favour of normal-weight adolescents compared to overweight and obese adolescents. Contrarily, the outcomes revealed a significantly greater HS (p = 0.014) in favour of overweight and obese participants compared to normal-weight adolescents. Moreover, the results showed that CF and SLJ correlated inversely with BMI, FM%, and total FM. There was also a direct relationship between SA and FM percentage, as well as between HS and FFM. Finally, four fitness test predictive models are proposed based on body composition, age, sex, and BMI. Conclusions: Overweight and obese adolescents have lower levels of physical fitness than their normal-weight peers, regardless of their sex. Normal-ranged body composition values are related to a greater physical fitness in adolescents. Furthermore, this study presents several equations that can help to predict the performance of different fitness tests in adolescents.