Is lean mass quantity or quality the determinant of maximal fat oxidation capacity? The potential mediating role of cardiorespiratory fitness

BACKGROUND

Impaired fat oxidation is linked to cardiometabolic risk. Maximal fat oxidation rate (MFO) reflects metabolic flexibility and is influenced by lean mass, muscle strength, muscle quality - defined as the ratio of strength to mass - and cardiorespiratory fitness. The relationship between these factors and fat oxidation is not fully understood. The aim is to analyze the associations of lean-mass, muscle strength and quality with fat oxidation parameters in young adults, considering the mediating role of VO2max.

METHODS

A cross-sectional observational study. Eighty-one adults (50 males, 31 females; age 22.8 ± 4.4, BMI 25.70 ± 5.75, lean-mass 54.19 ± 8.78, fat-mass 18.66 ± 11.32) Body composition assessment by bioimpedance determine fat and lean-mass. Indirect calorimetry at rest and exercise was used for the calculation of fat oxidation. An incremental exercise protocol in a cycle ergometer with two consecutive phases was performed. The first to determine MFO consisted of 3 min steps of 15W increments with a cadence of 60rpm. The test was stopped when RQ ≥ 1. After 5 min rest, a phase to detect VO2max began with steps of 15W/min until exhaustion. Muscular strength was assessed by handgrip dynamometry and the standing longitudinal jump test. A strength cluster was calculated with handgrip and long jump adjusted by sex and age. Data were analyzed using multiple linear regression and mediation analyses.

RESULTS

Total lean-mass and leg lean-mass were not associated with MFO. Long jump, relativized by lean-mass and by leg lean-mass have a standardized indirect effect on MFO of 0.50, CI: 0.32-0.70, on MFO/lean-mass 0.43, CI:0.27-0.60 and MFO/leg lean-mass 0.44, CI: 0.30-0.06, which VO2max mediated, VO2max/lean-mass and VO2max/leg lean-mass, respectively (all p < 0.01). The handgrip/arm lean-mass had an indirect effect of 0.25 (CI: 0.12-0.38) on MFO/leg lean-mass, with VO2max/leg lean-mass as the mediator (p < 0.01). The Cluster/lean-mass and Cluster/Extremities lean-mass have a standardized indirect effect on MFO/lean-mass (0.34, CI: 0.20-0.48) and MFO/leg lean-mass (0.44, CI: 0.28-0.60), mediated by VO2max/lean-mass and VO2max/leg lean-mass (p < 0.01).

CONCLUSIONS

Muscular strength and quality have an indirect effect on MFO mediated by VO2max. These findings suggest the importance of muscle quality on MFO.

Sex Differences in Upper- and Lower-Limb Muscle Strength in Children and Adolescents: A Meta-Analysis

On average, adult men are physically stronger than adult women. The magnitude of this difference depends on the muscle tested, with larger sex differences observed in upper- than lower-limb muscles. Whether body region-specific sex differences in strength exist in children is unclear. The purpose of the current meta-analysis was to determine whether sex differences in muscle strength in children and adolescents differ between upper- and lower-limb muscles. Data were extracted from studies of participants aged ≤ 17 years who completed tests of maximal isometric or isokinetic strength of upper-limb muscles (e.g., elbow flexors and elbow extensors) or lower-limb muscles (e.g., knee extensors and ankle dorsiflexors). Participants were partitioned into three age groups: 5-10 years old, 11-13 years old, and 14-17 years old. The analysis included 299 effects from 34 studies. The total sample was 6634 (3497 boys and 3137 girls). Effect sizes of sex differences in upper- and lower-limb strength were g = 0.65 (95% confidence intervals (CI) [0.46, 0.84]) and 0.34 (95% CI [0.19, 0.50]) in 5-10-year-olds; g = 0.73 (95% CI [0.56, 0.91]) and 0.43 (95% CI [0.27, 0.59]) in 11-13-year olds; and g = 1.84 (95% CI [1.64, 2.03]) and 1.18 (95% CI [1.00, 1.37]) in 14-17-year-olds. Upper- and lower-limb strength were 17% and 8% greater in boys than girls when 5-10 years old, 18% and 10% greater when 11-13 years old, and 50% and 30% greater when 14-17 years old. Thus, boys are stronger than girls on average. This sex difference exists before puberty, increases markedly with male puberty, and is more pronounced in upper- than lower-limb muscles throughout development.

Effects of a physical activity-enhanced curriculum on increasing physical activity and improving physical fitness in preschoolers: Study protocol for a cluster randomized controlled trial (KID-FIT study)

Objective

Physical activity (PA) is critical for healthy development in preschoolers, with long-lasting benefits that can affect later life. The World Health Organization (WHO) recommends that children aged 5-17 years should engage in 60 min of moderate-to-vigorous PA per day. However, physical inactivity in children is on the rise globally, with declines in PA starting at the age of 4 years. Increasing PA during early childhood is important to delay adiposity rebound, promote behavioral changes, improve physical fitness, and facilitate future PA engagement. However, limited evidence has been established on the effects of school-based PA interventions on preschoolers. This study examines the effects and sustainability of a preschool-based PA intervention on increasing PA, improving physical fitness and health in preschoolers, with the exercise dose benchmarked to the WHO PA guidelines.

Methods

This assessor-blinded, two-arm cluster randomized controlled trial will include 3300 preschoolers (aged 5-6 years) from 110 kindergartens in Hong Kong, China. Kindergartens will be randomized into intervention and control groups in a 1:1 ratio. The control kindergartens will continue their usual curriculum of ∼2.5 h PA/week, whereas preschoolers in the intervention kindergartens will engage in an additional 75-min game-based PA class twice per week (extra 2.5 h PA/week) over the preschool year. This multi-component intervention will also target parents, teachers, and the kindergarten environment to further encourage PA in preschoolers and their families. Objectively measured PA, cardiorespiratory fitness and other physical fitness components (muscle strength and power, agility, balance, flexibility, body composition), and psychological health will be examined at the start (0 month) and end (10 months) of the preschool year. Maintenance effects will be assessed after preschoolers' transition into primary school (16 months). Generalized estimating equations or other appropriate statistical models will be used to examine the treatment effects with adjustment for baseline values.

Study impact

This study will investigate the effects of a preschool-based PA intervention with PA dose benchmarked to the WHO recommendations on promoting PA, physical fitness, and health in preschoolers, and its sustainability after preschoolers' transition into primary education. The findings will raise public awareness on the importance of PA in young children, and will inform policy making to facilitate early childhood educational reforms to incorporate adequate PA into preschool curriculums to improve children's health in the long run.

Trial registration

ClinicalTrials.gov (NCT05521490).

Physical Fitness Benchmarks for Preschool Children in South Korea: A Population-Based Study

Background: Physical fitness is vital for children's development and future health. However, Asian preschool-aged populations lack robust physical fitness benchmarks. Objectives: This study aimed to establish age- and sex-specific physical fitness reference values for Korean preschool children and examine associations with anthropometric measures. Methods: A retrospective analysis of data from 36,118 children aged 3 to 6 years was conducted, using five physical fitness tests (Sit and Reach Test, V-Sit Endurance Test, Standing Long Jump, Single-Leg Stand, and 5-Meter Shuttle Run). Percentile curves were generated via Generalized Additive Models for Location, Scale, and Shape (GAMLSS). Relationships between fitness and anthropometric measures were analyzed with LOESS regression. Results: Girls outperformed boys in flexibility, endurance, and balance, while boys excelled in jumping power. Physical fitness improved with age, with performance peaking near average height and weight z-scores. Conclusions: This study provides the first large-scale reference standards for physical fitness in Korean preschoolers, facilitating early identification of fitness deficits and guiding interventions.

Body composition and physical performance of mountain bike athletes

Body composition is a determining factor in the physical performance of cyclists, directly influencing efficiency and power during competitions. Understanding these aspects can help optimize training and maximize results. This study aimed to analyze the influence of body composition on physical performance in mountain bike athletes. His cross-sectional study evaluated 83 mountain bike athletes (11 females, 39.60 ± 11.52 years). Body composition assessment was carried out using bioimpedance analysis. Participants performed the standing long jump and handgrip strength tests, to assess their strength of the lower and upper limbs, respectively. Finally, we measured the completion time of a Mountain Bike Marathon, with the distance of 75 km). Pearson's correlation was analyzed to verify the influence of body composition on race time and physical performance tests. The race time was 168.14 ± 30.85 min. Standing long jump and handgrip strength tests were significantly correlated with all body composition parameters. Additionally, race time was significantly correlated with body fat percentage (r = 0.415, p = 0.000), skeletal muscle mass (r = - 0.427, p = 0.000), total body water (r = - 0.400, p = 0.000), intracellular water (r = - 0.420, p = 0.000), and extracellular water (r = - 0.370,p = 0.000). Body composition has a significant influence on the physical performance of mountain bike cyclists, with body water and muscle mass positively correlated with performance and body fat negatively correlated. A higher percentage of fat results in longer race times, while greater muscle mass and hydration result in shorter race times.

Remote assessment of physical fitness via videoconferencing: a systematic review

Physical fitness is a critical marker of overall health across all age groups, influencing longevity and quality of life. This systematic review assessed the use of remote physical fitness assessments, a crucial adaptation during the COVID-19 pandemic that broadened access to health monitoring outside traditional settings. The review included 35 studies, covering various age groups and health conditions, and evaluated 48 physical fitness tests across eight physical fitness components. Balance, muscular strength, and endurance were the most frequently assessed, with tests like the 30-second sit-to-stand (30s-STS) showing strong validity, reliability, and feasibility for remote use. However, the study population was mainly adults and older adults, with nearly no focus on children, revealing a significant gap in research for younger populations. Additionally, the review identified gaps in assessing components such as body composition, reaction time, and agility, which are crucial for a comprehensive assessment of physical fitness. These gaps underscore the need for further research and development of reliable and valid remote assessment tools. The findings of this review emphasize the importance of standardizing remote physical fitness assessments to ensure their validity, reliability, and feasibility making them effective tools for health monitoring across diverse populations and settings.

Applying intervention mapping to develop a program for promoting short physical activity breaks during class time in upper secondary schools: the MOVE12 protocol study

Introduction

Physical inactivity is a global health challenge, exacerbated by increased screen time and sedentary behaviors. Enhancing physical activity levels at schools offers a promising approach to promote lifelong healthy habits.

Methods

This protocol paper outlines the MOVE12 pilot study, a 12-week intervention study designed to increase physical activity among Norwegian upper secondary school students through 6-7-min daily MOVE-breaks integrated into lessons. Developed using the six-phase Intervention Mapping (IM) protocol, grounded in the social-ecological model and self-determination theory, the intervention focuses on fostering motivation and creating a supportive environment. Key steps include needs assessment, performance objectives, theoretical methods, and program structuring for sustainability.

Results

Linear mixed models, t-tests, and regression analyses will evaluate quantitative outcomes, while qualitative focus groups will explore engagement and behavior change.

Discussion

MOVE12 provides insights into scalable school-based interventions addressing physical inactivity, highlighting the potential of the IM framework to establish sustainable health promotion strategies.

Association Between Physical Fitness and Cardiovascular Health in Chilean Schoolchildren from the Metropolitan Region

Background: Cardiovascular diseases increasingly impact youth, with early development of risk factors such as obesity, hypertension, and inadequate nutrient intake. Proper nutrient intake and physical fitness are vital for reducing these risks, especially in pediatric populations. This study explores the connection between physical fitness, metabolic risk, and nutrient status among 1656 Chilean schoolchildren from diverse socio-economic backgrounds. Methods: Anthropometric measures included weight, height, skinfold thickness, waist circumference, and blood pressure. Physical fitness was assessed via handgrip strength, standing long jump, and a six-minute walk test. Nutrient intake was also evaluated, and a composite metabolic risk score was calculated based on waist circumference, skinfolds, and blood pressure. Results: Boys consistently outperformed girls in physical fitness tests, including grip strength and horizontal jump, with differences becoming more pronounced in higher grades and Tanner stages. Girls exhibited higher subcutaneous fat levels and obesity prevalence during later grades, highlighting gender-specific patterns in body composition. Better physical fitness was associated with lower waist circumference, skinfold thickness, and metabolic risk scores. A moderate correlation between aerobic fitness (distance/height) and blood pressure (r = 0.27, p = 0.01) was observed. Z-Score MR analysis revealed that students in the lowest fitness tertile exhibited significantly higher cardiovascular risk profiles compared to their fitter peers. Conclusions: Physical fitness plays a critical role in reducing cardiovascular risk in children. The findings underscore the importance of promoting gender- and age-specific interventions that include both aerobic and strength-based physical activities. Comprehensive school programs focusing on nutrition and physical activity are essential to mitigating cardiovascular risk and promoting long-term health outcomes. Future longitudinal studies are recommended to establish causal relationships and evaluate the impact of targeted interventions.

Do Strength and Anthropometric Size of the Lower Body Correlate with Serum Testosterone Levels?

PURPOSE

Although lower body strength and size are often regarded as symbols of masculinity, their relationship to testosterone is unclear. This study aimed to determine the correlation between lower body strength, size, and testosterone levels.

MATERIALS AND METHODS

Serum testosterone levels, waist circumference, and body mass index (BMI) were measured in 69 men with erectile dysfunction (age >40 years). The circumferences of the thigh and calf were measured, and the muscle strength of the knee joints was evaluated using an isokinetic dynamometer. Patients were classified into three groups according to testosterone levels (group 1, <230 ng/dL; group 2, 230 to 350 ng/dL; group 3, >350 ng/dL). Differences in calf and thigh circumference, bilateral knee extension, and flexion strength between the three groups were investigated using a one-way analysis of variance. Pearson's chi-square test was used to assess differences in lifestyle habits and underlying diseases. A partial correlation analysis was conducted to determine the association between testosterone levels and lower body size and strength.

RESULTS

There was no difference in BMI among the three groups, but waist circumference was significantly larger in group 1 than in groups 2 and 3. When comparing weight-adjusted values, bilateral thigh circumference showed a significant difference among the three groups. There was also a significant difference between the three groups in the weight-adjusted left calf circumference and in the weight-adjusted right knee extension strength. The partial correlation test showed a significant positive correlation between thigh and calf circumference values adjusted for weight and serum testosterone levels. Weight-adjusted knee extension strength demonstrated a significant positive correlation with serum testosterone levels.

CONCLUSIONS

Weight-adjusted thigh and calf circumferences, along with the thigh-to-waist ratio, showed a positive correlation with testosterone levels. Weight-adjusted knee extension strength was positively correlated with testosterone levels. Therefore, a robust thigh and strong lower body are related to testosterone.

Effects of 10 Weeks of Walking With Mobile Step-Tracking Apps on Body Composition, Fitness, and Psychological State in Adolescents Who Are Overweight and Obese: Randomized Controlled Trial

BACKGROUND

In recent decades, physical activity intervention programs have been developed to reduce overweight and obesity in adolescents. However, this population is considered hard to reach in physical activity programs due to lack of adherence and poor results. Interventions with mobile phones in the adolescent population with normal weight have shown benefits, so this line of research may provide benefits in adolescents with overweight or obesity, although it has not yet been explored in the scientific literature.

OBJECTIVE

This study aims to determine the changes produced by a 10-week intervention promoted during school lessons on physical education using step tracker mobile apps in out-of-school hours on physical activity, adherence to the Mediterranean diet, body composition, and the physical condition of adolescents who are overweight and obese, and to analyze the changes achieved by the 10-week intervention on the psychological state of adolescents who are overweight and obese.

METHODS

The study was based on a randomized controlled trial with an initial sample of 50 adolescents aged between 12 and 16 years (from the first to the fourth years of compulsory secondary education), whose body composition, physical activity level, physical condition, and psychological state were measured. Participants were divided into an experimental group (EG) and a control group (CG), where the EG performed a series of walking steps with a mobile app in their free time outside physical education classes. Adolescents in the CG continued to perform their physical activities as normal but did not use any mobile apps. Inclusion in the EG and CG was randomized, and the researchers were blinded.

RESULTS

An increase was found in the EG in corrected arm girth (mean difference -0.46; P=.05), curl-up repetitions (mean difference -6.35; P=.02) and push-up repetitions (mean difference -2.27; P=.04) after the intervention. In the CG, there was a significant increase in hip girth (mean difference -1.37; P=.05), corrected thigh girth (mean difference -1.28; P=.04), and muscle mass (mean difference -0.87; P=.04), as well as a significant decrease in competence (mean difference 3.08; P=.03). The covariates gender and age showed an effect on corrected arm girth (gender: P=.04), curl-up repetitions (gender: P=.04) and push-up repetitions (gender: P=.04) in the EG; while in the CG it affected corrected thigh girth (gender: P=.04), adherence to the Mediterranean diet (gender: P=.04 and age: P=.047) competence (gender: P=.04 and age: P=.04) and relatedness (gender: P=.05 and age: P=.04). No significant differences were found when comparing changes in the CG and EG.

CONCLUSIONS

A 10-week program of mobile app use by adolescents who are overweight and obese for physical activity outside of school hours does not appear effective in producing improvements in body composition, physical fitness, or adequate psychological state as it does not appear to significantly increase physical activity.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06089876; http://clinicaltrials.gov/ct2/show/NCT06089876.

Temporal trends in muscular fitness among French children and adolescents between 1999 and 2023

The aim was to estimate national temporal trends in muscular fitness for French youth between 1999 and 2023. Data were obtained from five cross-sectional studies on 53,314 children and adolescents (age range: 6-16 years). Lower- and upper-body strength were assessed by standing broad jump (SBJ) and handgrip strength (HGS). BMI z-scores (BMIz) were calculated using WHO growth curves. We found a statistically significant negligible decline in SBJ performance (standardised effect size (ES) trend per decade [95%CI]: -0.08 [-0.10, -0.07] or -2.1 cm [95%CI: -2.4, -1.8]) and a statistically significant negligible improvement in HGS (ES trend per decade [95%CI]: 0.11 [0.08, 0.13]) or 0.6 kg [(95%CI: 0.4, 0.8]). We found evidence of significant increases in distributional variability and asymmetry, with poorer trends in the low performers (<25th percentile) and better trends in the high performers (>75th percentile) compared to the average performers. Our data suggest negligible trends in mean SBJ and HGS, coupled with increased distributional variability and asymmetry. Trends were not uniform across the population distribution with data suggesting an increase over time in the gap between low and high performers. These results reinforce the importance of interventions and programmes aiming at improving muscular fitness specifically in children and adolescents with low muscular strength.

Global Comparisons of Age, Gender and Socioeconomic Status Differences of Physical Fitness Health Risk in South African Primary School Children: Longitudinal Data from the NW-CHILD Study

Global physical fitness (PF) levels have declined over the past 50 years, contributing to early health risks in children although it is still unclear how age, gender and socioeconomic status (SES) impact PF risk. This study aimed to identify unique health risks related to age, SES and gender that might influence muscular fitness (MF) and cardiorespiratory fitness (CRF) levels of primary school children in South Africa. Children (N = 349, boys = 165; girls = 184) of low (n = 201) and high SES (n = 148) underwent three time point measurements at 6, 9 and 12 years spanning seven primary school years. MF was assessed with the strength sub-test of the Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) and CRF with a 20 m shuttle run. Relationships between biographical data, anthropometric data and PF were analysed using mixed linear regression models. After controlling for covariates, findings from unadjusted interaction models were used, revealing significant (p < 0.05) two-way age and SES interactions in standing long jump (SLJ), push-ups, wall-sit, sit-ups and VO2max and age and gender interactions (p < 0.001) in sit-ups, push-ups and VO2max. Universal cut-points are considered valid monitoring guidelines of PF risk in South African school children. For comparison, standardised global protocols for sit-ups and push-ups should be prioritised and intervention strategies should focus on improving PF in girls, older children from the age of 9 and children from low SES backgrounds.

Ultrasound and shear wave elastography assessment of diaphragm thickness and stiffness in malnourished pediatric patients

Our objective was to obtain information about diaphragm muscle mass, strength, and quality using conventional US and US-based imaging method shear wave elastography (SWE) in pediatric patients with primary malnutrition. We also sought to evaluate the usability of SWE in the diagnosis and follow-up of sarcopenia. We evaluated the diaphragm thickness and stiffness of patients diagnosed with primary malnutrition in the pediatrics and pediatric gastroenterology outpatient clinic using US and US-based SWE. The data were compared with those of an age- and gender-matched healthy control group. The study included 115 volunteers. Of the cases included, 53 were healthy controls and 62 (54%) were patients with primary malnutrition. There was no significant difference between the groups in terms of age and gender (p = 0.891 and p = 0.923, respectively). The malnourished patient group had significantly lower diaphragm thickness and stiffness. There is a significant positive correlation between anthropometric measurement Z scores and diaphragm thickness and stiffness.

CONCLUSION

Our study indicated that there was a reduction in the thickness of the diaphragm and a decline in its stiffness, which could be an indirect indicator of the quality and strength of the diaphragm muscle. These findings suggest that US and SWE evaluation of the diaphragm muscle may have the potential for use in the diagnosis and follow-up of sarcopenia. However, further comprehensive randomized controlled studies are needed to confirm this.

WHAT IS KNOWN

• Magnetic resonance imaging, computed tomography, and dual-energy x-ray absorptiometry are commonly used in the evaluation of sarcopenia. • The psoas and paraspinal muscles are commonly used in the evaluation of sarcopenia.

WHAT IS NEW

• Ultrasound and shear wave elastography can be used in the evaluation of pediatric sarcopenia. • Diaphragm muscle can be used in the evaluation of pediatric sarcopenia.

Mediators of the association between physical activity and executive functions in primary school children

There is growing interest in identifying the mechanisms underpinning the effects of physical activity on executive functions (e.g. inhibitory control, cognitive flexibility) in children. Our study examined cardiorespiratory fitness, muscular fitness, and motor competence as potential mediators of this relationship. The study used baseline data from the Learning to Lead (L2L) cluster randomised controlled trial. In total, 675 children (7-11 years, 49.5% girls) completed measures of moderate-to-vigorous physical activity (MVPA), cardiorespiratory fitness, muscular fitness, motor competence, and executive functions. Structural equation modelling was used to examine the potential mediating roles of cardiorespiratory fitness, muscular fitness, and motor competence in the cross-sectional association between MVPA and executive functions. Cardiorespiratory fitness (β = 0.06, SE = 0.021, p = 0.004) partially mediated the association between MVPA and cognitive flexibility. Muscular fitness was a significant mediator of the association between MVPA and both inhibitory control (β = 0.03, SE = 0.014, p = 0.027) and cognitive flexibility (β = 0.06, SE = 0.021, p = 0.005). No significant mediated effects were found for motor competence. Our findings suggest cardiorespiratory and muscular fitness (but not motor competence) mediate the association between physical activity and executive functions in children.

Health-Related Field-Based Fitness Tests: Normative Values for Italian Primary School Children

Background/Objectives: conducting fitness tests in educational settings can lead to advantages for both individuals and groups, beyond just enhancing fitness. With the aim of appropriately interpreting performance, this study was conducted to establish sex- and age-specific percentile normative data for a physical fitness (PF) protocol and to define a compound measure of physical performance. Methods: In this cross-sectional study, a short, feasible, and easy-to-administer test battery was performed for 5106 school children, aged 6-10 years. Gender- and age-specific percentiles for the PF tests were constructed, and a Physical Fitness-Motor Competence Performance Index (PF-MC PI) was calculated according to the percentiles. Results: Boys scored higher in all the PF tests when compared to girls (p < 0.001). There was also a trend towards increased PF levels as the age increased in both genders (p < 0.0001). Correlations between scores on individual test items were moderate to high (r from 0.549 to 0.700), and all individual test item scores significantly correlated with the PF-MC PI (p < 0.0001). Conclusions: the provided percentile values will enable the correct interpretation and monitoring of the fitness status of children and the PF-MC PI can be used for easily rating children's health-related fitness qualities.

The Effects of Exergames on Physical Fitness, Body Composition and Enjoyment in Children: A Six-Month Intervention Study

BACKGROUND/OBJECTIVES

Physical inactivity in children can lead to decreased physical fitness and reduced enjoyment of physical activity. This study aimed to evaluate the impact of exergaming on physical fitness, body composition and perceived enjoyment in elementary school children.

METHODS

Sixty-four male students (mean age 9.5 years) were randomly assigned to an exergaming group (EG, n = 32), engaging in Kinect Adventures three times a week for six months, or a control group (CG, n = 32), which continued standard physical education. Assessments were conducted pre- and post-intervention, including anthropometric measures, physical fitness tests (standing long jump, countermovement jump, sit-and-reach, 20-m sprint), aerobic fitness (20-m shuttle run), and perceived enjoyment measured with the PACES scale.

RESULTS

The EG demonstrated significant reductions in body weight, BMI, and relative fat mass compared to the CG (p < 0.01). Improvements in physical fitness were evident in EG, with increases in standing long jump distance (+12.8%; p < 0.0001), countermovement jump height (+65%, p < 0.0001), and flexibility (+75%; p < 0.0001). Aerobic fitness improved significantly in EG (+87.8m) compared to CG. Perceived enjoyment was notably higher in EG, especially at week three, compared to CG (69.3 ± 5.8 vs. 44.2 ± 11.6; p < 0.0001).

CONCLUSIONS

Exergaming offers benefits for physical fitness and body composition in children, while also enhancing enjoyment. Incorporating exergames into physical education programs could be an effective strategy for addressing childhood obesity, improving physical skills, and increasing student enjoyment, encouraging long-term physical activity adherence.

Influence of vitamin D supplementation on muscle strength and exercise capacity in South African schoolchildren: secondary outcomes from a randomised controlled trial (ViDiKids)

Objective

To determine whether vitamin D supplementation influences grip strength, explosive leg power, cardiorespiratory fitness and risk of exercise-induced bronchoconstriction (EIB) in South African schoolchildren.

Methods

Substudy (n=450) in Cape Town schoolchildren aged 8-11 years nested within a phase 3 randomised placebo-controlled trial (ViDiKids). The intervention was weekly oral doses of 10 000 IU vitamin D3 (n=228) or placebo (n=222) for 3 years. Outcome measures were serum 25-hydroxyvitamin D3 (25(OH)D3) concentrations, grip strength, standing long jump distance, peak oxygen uptake (VO2peak, determined using 20 m multistage shuttle run tests) and the proportion of children with EIB, measured at end-study.

Results

64.7% of participants had serum 25(OH)D3concentrations <75 nmol/L at baseline. At 3-year follow-up, children randomised to vitamin D versus placebo had higher mean serum 25(OH)D3 concentrations (97.6 vs 58.8 nmol/L, respectively; adjusted mean difference 39.9 nmol/L, 95% CI 36.1 to 43.6). However, this was not associated with end-study differences in grip strength, standing long jump distance, VO2peak or risk of EIB.

Conclusion

A 3-year course of weekly oral supplementation with 10 000 IU vitamin D3 elevated serum 25(OH)D3 concentrations in South African schoolchildren but did not influence muscle strength, exercise capacity or risk of EIB.

Influence of vitamin D supplementation on muscle strength and exercise capacity in Mongolian schoolchildren: secondary outcomes from a randomised controlled trial

Objective

To determine whether weekly oral vitamin D supplementation influences grip strength, explosive leg power, cardiorespiratory fitness or spirometric lung volumes in Mongolian schoolchildren.

Methods

Multicentre, randomised, placebo-controlled clinical trial conducted in children aged 6-13 years at baseline attending 18 schools in Ulaanbaatar. The intervention was weekly oral doses of 14 000 IU vitamin D3 (n=4418) or placebo (n=4433) for 3 years. Outcome measures were grip strength, standing long jump distance and serum 25-hydroxyvitamin D (25(OH)D) concentrations (determined in all participants), peak oxygen uptake (VO2peak, determined in a subset of 632 participants using 20 m multistage shuttle run tests) and spirometric outcomes (determined in a subset of 1343 participants).

Results

99.8% of participants had serum 25(OH)D concentrations <75 nmol/L at baseline, and mean end-study 25(OH)D concentrations in children randomised to vitamin D versus placebo were 77.4 vs 26.7 nmol/L (mean difference 50.7 nmol/L, 95% CI 49.7 to 51.4). However, vitamin D supplementation did not influence mean grip strength, standing long jump distance, VO2peak, spirometric lung volumes or peak expiratory flow rate, either overall or within subgroups defined by sex, baseline 25(OH)D concentration <25 vs ≥25 nmol/L or calcium intake <500 vs ≥500 mg/day.

Conclusion

A 3-year course of weekly oral supplementation with 14 000 IU vitamin D3 elevated serum 25(OH)D concentrations in Mongolian schoolchildren with a high baseline prevalence of vitamin D deficiency. However, this intervention did not influence grip strength, explosive leg power, peak oxygen uptake or spirometric lung volumes, either overall or in subgroup analyses.

Trial registration number

NCT02276755.

Reliability, Objectivity, Validity, and Reference Levels of the Austrian Pole Climbing Test (APCT)-A Novel Monitoring Tool for Assessing General Fitness in Children, Adolescents, and Young Adults

Climbing is an activity involving many major muscle groups and, therefore, it is suitable for assessing general physical fitness. The Austrian pole climbing test (APCT) was developed as a reliable and valid test for the assessment of general fitness levels in children, adolescents, and young adults. In this cross-sectional pilot study, 677 participants (aged 6 to 19 years) were assessed via the APCT. Subsequently, test quality criteria (reliability and objectivity) were assessed, and the test's validity was evaluated through comparisons with other established fitness tests (hand grip strength, standing long jump, and pull- and push-ups). Additionally, age- and gender-specific reference values were generated. The reliability (ICC2.1 = 0.97, 95%CI 0.95 to 0.98) and objectivity (ICC2.1 = 0.99, 95%CI 0.99 to 0.99) of the APCT were found to be excellent. The APCT results correlated strongly with the hand strength per kilogram of body weight (right: r = 0.58; left: r = 0.53), number of pull-ups (with upper grip: r = 0.74; with lower grip: r = 0.69) and standing long jump (r = 0.61); a moderate correlation with the push-up test was observed (r = 0.44). The APCT is reliable, objective, and suitable for children, adolescents, and young adults with an affinity for sports. It offers a novel opportunity to assess fitness without time pressure, considering the anthropometric requirements.

Essential Improvements in Fat Percentage and Cardiometabolic Fitness After a Residential Stay for Socially Vulnerable Children-With and Without the "11 for Health" Concept

The Danish Christmas Seal Homes offer a 10-week residential stay for socially vulnerable children. We aimed to examine the effects on body composition and cardiometabolic fitness variables of the standard program (SG) and whether substituting physical activity sessions with sessions from a football-based health education program is beneficial for the participants ("11 for Health"; SG+). Three hundred and nine children participated in SG (12.4 [1.6] y) and 305 in SG+ (12.4 [1.4] y). Fat percentage was lowered by 6% for females (from 37% to 31%) and 8% for males (from 36% to 28%), with no between-group differences. We observed improvements in systolic and diastolic blood pressure (3 and 5 mm Hg, respectively), resting heart rate (10 beats/min), aerobic fitness, jump performance, and relative muscle mass with no between-group differences. Furthermore, there were between-group differences in insulin levels for females (1.7 pmol/L; 95% CI, 0.3 to 3.0) and postural balance for males (1.0 s; 95% CI, 0.0 to 2.0), both in favor of SG+, and covered distance in the Andersen test for females (26 m; 95% CI, 3 to 49) in favor of SG. In conclusion, a 10-week stay at the Danish Christmas Seal Home resulted in clinically relevant improvement in fat percentage and cardiometabolic fitness in socially vulnerable children, regardless of the program type.

Effects of Dance Music on Motor Skills and Balance in Children: An Observational Cohort Study

BACKGROUND/OBJECTIVES

During the COVID-19 pandemic, children in Japan were restricted from sports and outdoor activities. Regular physical activity is essential for healthy growth and development in children, with recommendations advocating for activities such as strength training. However, the long-term effects of the restrictions have not been fully investigated. This study aimed to evaluate the effectiveness of an "exercise class", specifically a dance program, designed to improve motor function in elementary school children affected by the coronavirus disease 2019 (COVID-19) pandemic, which may have compromised their motor function.

METHODS

The dance program was developed by a sports science teacher, a professional dancer, and a physical therapist, and it was evaluated in a community-based participatory study. Trained dance instructors conducted one-hour dance sessions in a medical center, held once a week for two months from June to August 2023. A physical therapist and dance instructors led the elementary school children. Outcome measures included grip strength, lower extremity muscle strength, back muscle strength, dynamic balance function during movement, physical activity time, and body fat percentages. Descriptive statistics were used for analysis.

RESULTS

Twenty-four children aged 6-9 years participated in the exercise class over a two-month period. Improvement was observed in grip strength, lower extremity muscle strength, and dynamic balance function during movement. However, physical activity time, body fat percentages, and back muscle strength did not change.

CONCLUSIONS

The results indicated a significant improvement in motor skills. Dance is an inexpensive program that elementary school children can enjoy while improving their motor skills.

Influence of Physical Activity, Physical Fitness, Age, Biological Maturity and Anthropometric Variables on the Probability of Suffering Lumbar, Neck and Shoulder Pain in Spanish Adolescents from the Region of Murcia

Background: Back pain in adolescents is a common injury, mainly affecting the lumbar, cervical and sometimes shoulder region. This has been related to various factors, such as lifestyle habits or physical capacity, but no previous research has shown conclusive results. The aims of this study was to analyze the risk of suffering lumbar, neck and shoulder pain according to anthropometric and physical fitness variables, physical activity level, age and biological maturity in adolescents, as well as the influence of sex in the study results. Methods: A descriptive cross-sectional study was performed, including a sample of 2015 adolescents (boys: n = 1006, mean age = 14.41 ± 1.35 years-old; girls: n = 1009, mean age = 14.48 ± 1.41 years-old). The participants underwent an anthropometric evaluation and physical fitness tests were carried out, including a 20 m shuttle run, a counter movement jump, a horizontal jump, a 20 m sprint and push-up tests, followed by the completion of lumbar, neck and shoulder pain questionnaires. Results: Higher values in age and peak height velocity (PHV) showed an increase in the risk of suffering lumbar, neck and shoulder pain (OR = 0.79-1.55; p = 0.000-0.025). The anthropometric variables related to adiposity showed an increase in the risk of suffering back pain, with significant incidence in the lumbar region (OR = 1.32-1.60; p = 0.000); while muscle mass showed a protective effect (OR = 0.59; p = 0.000). Regarding the fitness tests, a better physical fitness seemed to protect adolescents from suffering from the analyzed back pains in the general sample and in the boys sample (OR = 0.56-1.60; p = 0.000), while in the girls sample the influence of the physical fitness was less relevant. Conclusions: Both anthropometry and physical fitness may influence the occurrence of back pain in adolescents, with some variations in their importance according to sex.

Assessment of Motor Performance and Self-Perceived Psychophysical Well-Being in Relation to Body Mass Index in Italian Adolescents

BACKGROUND/OBJECTIVES

The relationship between psychophysical self-perception (PSP), body mass index (BMI) and motor performance (MP) levels, in quantitative and qualitative terms, can be a very interesting connection to investigate. This study aimed to assess MP and PSP according to gender and weight differences (normal weight-Nw/overweight-obese-Ov-Ob) and their relationship to BMI in Italian adolescents.

METHODS

In total, 144 students (F = 72; M = 72) aged between 11 and 13 y.o. participated in this study. They were divided into two groups by gender and into two subgroups based on weight (Nw/Ov-Ob). Standing long jump, sit-and-reach, 10 × 5 m shuttle and sit-up tests to assess MP were carried out, and an ad hoc questionnaire to evaluate PSP was administrated.

RESULTS

In comparing the Nw and Ov-Ob subgroups on the basis of BMI for each gender, statistically significant differences emerged in all motor skill tests administered. Regarding PSP, the Nw subgroup showed high and positive levels, while Ov-Ob showed low and negative levels, highlighting a relationship between high BMI and poor motor performance as well as negative psychophysical perception in the Ov-Ob subgroup.

CONCLUSIONS

this study supports the importance of physical sport activity to regulate excess weight but also contribute to better psychophysical well-being.

Process- and Product-Oriented Fundamental Movement Skills in Early Childhood as Predictors of Later Health-Related Fitness

INTRODUCTION

The skill domains of fundamental movement skills (FMS), emphasizing gross motor movements, including locomotor skills (LMS) and object control skills (OCS), along with process- and product-oriented measures of FMS, may predict cardiorespiratory fitness (CRF) and muscular fitness (MF) differently. This study investigates the longitudinal relationship from early childhood FMS, focusing on process-oriented LMS and OCS and product-oriented FMS, to CRF and MF in late childhood.

METHODS

The study involved 441 Finnish children (49.9% female; mean age at baseline, 5.5 yr) over a 6-yr period. FMS was evaluated using the Test of Gross Motor Development, third version, for process-oriented LMS and OCS, and the Körperkoordinationstest Für Kinder (KTK) was used to evaluate the product-oriented FMS. CRF was assessed through the total number of laps completed in the 20-m shuttle run test, whereas MF was measured via repetitions of curl-ups and push-ups. Employing a two-level cross-classified regression analysis and Cholesky decomposition, this study aimed to determine the contributions of product-oriented KTK and process-oriented LMS and OCS. Adjustments for variations in age, measurement intervals, and maturation were achieved through residualization. In addition, gender and body mass index were incorporated as covariates in the analysis.

RESULTS

The analysis revealed that process-oriented LMS (CRF: Δ R2 = 0.016; MF: Δ R2 = 0.014) significantly predicted later health-related fitness, whereas OCS did not. However, KTK exhibited a better ability to predict both CRF (Δ R2 = 0.092) and MF (Δ R2 = 0.032), overshadowing process-oriented measures.

CONCLUSIONS

In conclusion, the findings suggest that KTK, which potentially encompasses a broader spectrum of fitness elements along with FMS, more effectively predicts health-related fitness components than process-oriented FMS.

Criterion-related validity and reliability of the standing long jump test in adults: The Adult-Fit project

The purpose of this study was to analyze the criterion-related validity and the reliability of the standing long jump test (SLJ) for evaluating the lower-body explosive muscular strength in adults. A total of 410 adults participated in this study. Sociodemographic, anthropometric measurements, laboratory lower-body muscular strength tests, and the field-based SLJ were performed. In validity analysis, stepwise regression analysis showed that maximal horizontal power, sex, percentage of body fat, maximal horizontal force, and lean mass were significantly associated with the SLJ distance (R2 = 0.78; p < 0.001). Reliability analysis showed significant differences between test-retest in the SLJ test, with an overestimation of the second measurement compared to the first [12.14 ± 14.46 cm, intraclass correlation coefficient (ICC) = 0.94 (0.75-0.97), p < 0.001; Cohen's d = 0.31]. The coefficient of variation (CV) was 7.06% and the minimal detectable change (MDC90) was 29 cm. After a learning period, higher reliability values were found [0.45 ± 1.04 cm, ICC = 1.00 (0.99-1.00); p = 0.001; CV = 0.53 %; MDC90 = 1 cm]. The SLJ test may be a valid tool to assess lower-body explosive muscular strength in the adult population. A learning period may be necessary to provide reliability on the SLJ test.

Automatic Quantitative Assessment of Muscle Strength Based on Deep Learning and Ultrasound

Skeletal muscle is a vital organ that promotes human movement and maintains posture. Accurate assessment of muscle strength is helpful to provide valuable insights for athletes' rehabilitation and strength training. However, traditional techniques rely heavily on the operator's expertise, which may affect the accuracy of the results. In this study, we propose an automated method to evaluate muscle strength using ultrasound and deep learning techniques. B-mode ultrasound data of biceps brachii of multiple athletes at different strength levels were collected and then used to train our deep learning model. To evaluate the effectiveness of this method, this study tested the contraction of the biceps brachii under different force levels. The classification accuracy of this method for grade 4 and grade 6 muscle strength reached 98% and 96%, respectively, and the overall average accuracy was 93% and 87%, respectively. The experimental results confirm that the innovative methods in this paper can accurately and effectively evaluate and classify muscle strength.

A mobile app-based intervention improves anthropometry, body composition and fitness, regardless of previous active-inactive status: a randomized controlled trial

Introduction

The use of mobile apps to promote physical activity in adolescents can improve health-related parameters. However, previous studies have not evaluated whether the benefits depend on the users' prior active or inactive status. Therefore, the main objective was to analyze differences in physical activity levels, adherence to the Mediterranean diet (AMD), anthropometry, body composition, and physical fitness between active and inactive adolescents.

Methods

The study was conducted through a randomized controlled trial (RCT) with 462 adolescents, divided into experimental (EG) and control groups (CG), further categorized as active and inactive. Variables of physical activity, kinanthropometry, body composition, and physical fitness were measured before (pre-test) and after (post-test) a 10-week intervention using step-tracking apps (Strava, Pacer, MapMyWalk, and PokémonGo) at least three times per week.

Results

The results showed that inactive EG adolescents significantly increased their physical activity levels, body mass, and muscle mass, and improved in all fitness variables except the countermovement jump (CMJ). The sum of three skinfolds also significantly decreased. Active EG adolescents increased body and muscle mass and improved in all fitness variables. Additionally, they significantly reduced fat mass and the sum of three skinfolds. All covariates, mainly gender and maturity, had significant effects on the study variables. Comparing changes between the active EG and CG groups, significant differences were found in body mass index (BMI) and CMJ in favor of the EG. However, while significant differences were observed in the study variables when analyzing each app individually, there were no differences between the changes produced by each app in these variables.

Conclusion

After a 10-week program of physical activity promoted through step-tracking apps, improvements were observed in fat variables, cardiorespiratory fitness, and curl-up performance. Furthermore, only inactive adolescents perceived an increase in their level of physical activity. The measurement protocol was registered prior to the start of the intervention at ClinicalTrials.gov (code: NCT04860128).

Cross-country adaptation and feasibility of an evidence-based resistance training intervention in the school setting

Background

Physical activity that strengthens muscles and bones at least three times per week are recommended, but few adolescents meet this target. The aim of our study was to adapt and evaluate the feasibility and preliminary efficacy of the Resistance Training for Teens (RT4T) program in Danish lower secondary schools.

Methods

Developed and evaluated in Australia, the aim of RT4T is to provide adolescents with competence, confidence, knowledge, and motivation to participate in resistance training. Translation and adaptation were based on the PRACTIS-guide and involved workshops with physical education teachers. Three 7th-grade classes and three 9th-grade classes were recruited for the feasibility study and followed the program over eight weeks. Participants completed a push-up test, a standing long jump test, and a beep-test before and after the intervention. In addition, they completed a survey about their self-efficacy, motivation, and resistance training competency. Four qualitative interviews were performed with participants and their physical education teachers.

Results

The participating teachers were motivated for the program, but they had difficulties providing students with appropriate feedback. Students were motivated by the equipment, games, and their improvements in fitness, but motivation declined during the program. A total of 57 students completed the physical tests and answered the survey. Resistance training self-efficacy improved significantly, while most other measures improved over time, without reaching significance.

Conclusion

Overall, the RT4T was acceptable and feasible in lower secondary schools in Denmark, but adjustments need to be made to increase the reach and efficacy of the program.

Physical Activity, Body Composition, and Fitness Variables in Adolescents After Periods of Mandatory, Promoted or Nonmandatory, Nonpromoted Use of Step Tracker Mobile Apps: Randomized Controlled Trial

BACKGROUND

It is not known whether an intervention made mandatory as a physical education (PE) class assignment and aimed at promoting physical activity (PA) in adolescents can create a healthy walking habit, which would allow further improvements to be achieved after the mandatory and promoted intervention has been completed.

OBJECTIVE

The aims of this study were to (1) investigate whether, after a period of using a step tracker mobile app made mandatory and promoted as a PE class assignment, adolescents continue to use it when its use is no longer mandatory and promoted; (2) determine whether there are changes in the PA level, body composition, and fitness of adolescents when the use of the app is mandatory and promoted and when it is neither mandatory nor promoted; and (3) analyze whether the covariates maturity status, gender, and specific app used can have an influence.

METHODS

A total of 357 students in compulsory secondary education (age: mean 13.92, SD 1.91 y) participated in the study. A randomized controlled trial was conducted consisting of 2 consecutive 10-week interventions. Participants' PA level, body composition, and fitness were measured at baseline (T1), after 10 weeks of mandatory and promoted app use (T2), and after 10 weeks of nonmandatory and nonpromoted app use (T3). Each participant in the experimental group (EG) used 1 of 4 selected step tracker mobile apps after school hours.

RESULTS

The results showed that when the use of the apps was neither mandatory nor promoted as a PE class assignment, only a few adolescents (18/216, 8.3%) continued the walking practice. After the mandatory and promoted intervention period (T1 vs T2), a decrease in the sum of 3 skinfolds (mean difference [MD] 1.679; P=.02) as well as improvements in the PA level (MD -0.170; P<.001), maximal oxygen uptake (MD -1.006; P<.001), countermovement jump test (MD -1.337; P=.04), curl-up test (MD -3.791; P<.001), and push-up test (MD -1.920; P<.001) in the EG were recorded. However, the changes between T1 and T2 were significantly greater in the EG than in the control group only in the PA level and curl-up test. Thus, when comparing the measurements taken between T1 and T3, no significant changes in body composition (P=.07) or fitness (P=.84) were observed between the EG and the control group. The covariates maturity status, gender, and specific app used showed a significant effect in most of the analyses performed.

CONCLUSIONS

A period of mandatory and promoted use of step tracker mobile apps benefited the variables of body composition and fitness in adolescents but did not create a healthy walking habit in this population; therefore, when the use of these apps ceased to be mandatory and promoted, the effects obtained disappeared.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06164041; https://clinicaltrials.gov/study/NCT06164041.

A 10-week implementation of the FIT FIRST FOR ALL school-based physical activity concept effectively improves cardiorespiratory fitness and body composition in 7-16-year-old schoolchildren

Introduction

The purpose of the present study was to investigate the impact of the FIT FIRST FOR ALL school-based physical activity program on health-related physical fitness in Faroese schoolchildren. The program aimed to add three weekly sessions of organized high-intensity physical activity to the standard weekly physical education sessions for all pupils across the entire school.

Methods

A non-randomized controlled design was used to evaluate the effects of the program. Two schools participated, including one intervention school (INT; n =179) and one control school (CON; n =181), with pupils aged 7-16 years (grades 1-9). The FIT FIRST FOR ALL program consisted of three weekly 40-minute sessions of age-adjusted high-intensity physical activity over 10 weeks for the INT school, while the CON school continued their normal school program. Pre- and post-intervention assessments included cardiorespiratory fitness (Yo-Yo IR1C test), agility (Arrowhead Agility test), postural balance (Stork Stand), standing long jump performance, body composition, blood pressure, and resting heart rate.

Results

A significant time × group effect (p < 0.001) was observed for cardiorespiratory fitness, which increased by 31% [23;39] in INT (p < 0.001) and remained unaltered in CON (7% [-2;16], p = 0.13). In addition, a time × group effect (p < 0.001) was observed for agility, which improved by 2.1% [1.0;3.2] in INT (p < 0.001) and regressed by 3.3% [2.3;4.4] in CON (p < 0.001). No significant between-group effects were found for standing long jump and balance. A time × group effect (p < 0.001) was observed for changes in total muscle mass, which increased by 1.4 kg [1.2;1.5] in INT (p < 0.001) and by 0.4 kg [0.3;0.6] in CON (p < 0.05). Furthermore, a time × group effect (p < 0.001) was observed for total fat percentage, which decreased by -2.3% [-2.8;-1.9] in INT (p < 0.001) and remained unchanged in CON (-0.3% [-0.7;0.1], p = 0.16). No significant time × group effects were found for blood pressure and resting heart rate.

Discussion

The FIT FIRST FOR ALL program significantly improved cardiorespiratory fitness and agility, and it led to favorable changes in body composition in the intervention school. These findings suggest that the program is highly effective in enhancing physical fitness and health status across all investigated age groups when implemented at a school-wide level.

Cardiac rehabilitation in children and adolescents with long QT syndrome: the RYTHMO'FIT pilot study

BACKGROUND

To assess the feasibility, acceptability, safety, and short-term benefits of a tailored cardiac rehabilitation program for children and adolescents with long QT syndrome (LQTS).

METHODS

Eight participants, aged between 6 and 18, with a positive LQTS genotype and impaired cardiorespiratory fitness, were enrolled in a 12-week centre-based cardiac rehabilitation program. The program included supervised exercise training group sessions (aerobic, resistance, and outdoor activities) and patient education workshops. Feasibility, acceptability, and safety of the program were prospectively monitored. Feedback from the parents, children, and professionals involved was collected from qualitative interviews. Short-term effects on cardiorespiratory fitness, muscle fitness, physical activity, and health-related quality of life (HRQoL) were measured between baseline and the end of the program.

RESULTS

Retention (88% with one participant dropping out) and adherence (79%) rates were good, and no cardiac events occurred during the 12-week intervention period. Participants, parents, and healthcare professionals expressed a high level of satisfaction with the program. A significant increase between the beginning and the end of the program was observed for ventilatory anaerobic threshold (21.7±5.2 vs. 28.7±5.1 mL/kg/min, P=0.01, effect size=0.89), grip strength, (18±5.3 Kg vs. 20±4.7 Kg, P=0.02, effect size=0.90), lower limb explosive strength (142±36.5 cm vs. 148±24 cm, P=0.02, effect size=0.90), and parent-reported physical health dimension of HRQoL (65.6±9.75 vs. 84.4±20.35, P=0.03, effect size=0.87).

CONCLUSIONS

A 12-week tailored centre-based cardiac rehabilitation program was feasible, acceptable, and safe for children with LQTS. Cardiac rehabilitation for children with LQTS presents a new approach aligned with secondary prevention in youth with cardiac diseases.

TRIAL REGISTRATION

The trial was registered at Clinicaltrials.gov (NCT05964322, registration date: 27/07/2023).

Sex-specific associations of muscular fitness with overall academic performance and specific school subjects in adolescents: the EHDLA study

Introduction

Overalll, muscular fitness and academic performance are two variables widely studied in the literature. However, evidence on the relationship between muscular fitness and specific school subjects (e.g., physical education), as well as their differences by sex, is scarce.

Objective

The aim of this study was to examine the associations between muscular fitness and overall academic performance and between muscular fitness and specific subjects (i.e., language, math, foreign language, and physical education) in a sample of secondary Spanish school students.

Methods

For the present study, a sample of 766 students (45% boys, aged 12-17 years). From the Eating Healthy and Daily Life Activities (EHDLA) study was used. The Assessing the Levels of Physical Activity and Fitness (ALPHA-FIT) battery was used to determine handgrip strength and lower body muscular strength. The performance of the different school subjects was provided by the school centers.

Results

Overall, for both boys and girls, higher muscular fitness was associated with greater academic results, with the greatest differences in physical education. However, only significant differences were identified for girls.

Discussion and conclusion

Global muscular fitness is important for contributing to cognitive development, both in physical education and in the rest of the subjects of the educational curriculum for adolescents. At the same time, although the association appears to follow the same trend for both sexes, the results seem more evident for girls.

Impact of the ActTeens Program on physical activity and fitness in adolescents: a cluster randomized controlled trial

BACKGROUND

The aim of our study was to evaluate the impact of the ActTeens Program on physical activity and health-related physical fitness among adolescents in Brazil.

METHODS

The "ActTeens Program" was conducted using a cluster-randomized controlled trial during 24-week school term. The sample consisted of 317 adolescents (52.7% girls; 13.61 ± 0.70 years) from four secondary schools that were randomly assigned to intervention group (N = 169) or control group (N = 148). This school-based physical activity (PA) intervention involved two components: (i) structured physical activity sessions delivered within physical education (PE) and (ii) healthy lifestyle guidance (mHealth). The primary outcome was PA assessed using Physical Activity Questionnaire for Adolescents (PAQ-A); secondary outcomes included muscular (MF) and cardiorespiratory fitness (CRF) assessed using 90-push-up, handgrip dynamometer, standing long jump, and 20 m PACER shuttle run test. Assessments were conducted at baseline, 12- and 24-week. Intervention effects were assessed using linear mixed models (LMM).

RESULTS

For the primary outcome (PA), no significant group-by-time effects were observed for physical education based-PA (0.3 score; 95%CI: -0.1; 0.6; and - 0.01 score; 95%CI: -0.03; 0.03, at 12-wk and 24-wk respectively) and total PA (-0.02 score; 95%CI: -0.2; 0.2; and - 0.01score; 95%CI: -0.2; 0.2, at 12 and 24 weeks respectively). After 24 weeks, we observed a significant group by time effects for lower body muscular fitness (12.9 cm; 95%CI, 3.2 to 22.2).

CONCLUSION

The implementation of aerobic and muscle-strengthening exercises used in the ActTeens intervention did not lead to improvements in physical activity. The intervention resulted in improved lower body muscular fitness, however, we found no significant differences for upper body muscular and cardiorespiratory fitness.

Lifestyle as a Modulator of the Effects on Fitness of an Integrated Neuromuscular Training in Primary Education

The objective was to evaluate changes in fitness after an integrated neuromuscular training (INT) intervention in primary school children and to evaluate how lifestyle behaviors and parental education modulate these changes. One hundred and seventy children (7.45 ± 0.34 years; 52% girls) were included. Cardiorespiratory fitness (half-mile run test), a 10 × 5 m shuttle run test, standing broad jump (SBJ), handgrip dynamometer, body mass index (BMI) and fat mass percentage (FM%) were assessed before and after the 3-month intervention (20 min of INT in the physical education class, twice per week). The Mediterranean diet (MD), sleep time and parental education level (PEL) were evaluated by questionnaires, and adherence to physical activity (PA) recommendations was measured with a triaxial accelerometer before the intervention. After the intervention, there were improvements in the 10 × 5 test and the SBJ. Only girls had improvements in the handgrip test, BMI SDS and FM%. After correcting for confounding variables, only BMI was significantly improved whereas strength improved in the participants non-compliant with the PA recommendations or pertaining to families of high PEL. The INT produced improvements in fitness in a brief period and in different subgroups of pupils (inactive and with diverse sociocultural environments).

Effectiveness of an Ecological Model-Based Active Transport Education Program on Physical and Mental Health in High School Students (MOV-ES Project): Study Protocol for a Randomized Controlled Trial

The United Nations, through its 2030 Agenda and Sustainable Development Goals, advocates for the establishment of conducive environments for physical activity, following the ecological model. In line with this initiative, active transportation emerges as an accessible, cost-effective, and sustainable approach to augmenting daily physical activity levels. This study protocol endeavors to assess the impact of an active transportation education program rooted in the ecological model on the physical and mental well-being of high school students. Drawing upon scientific insights, we hypothesize that a 16-week active transportation intervention will lead to a 3% reduction in average body fat percentage and a noteworthy enhancement in executive function (including inhibition, cognitive flexibility, and working memory), physical fitness (comprising cardiorespiratory fitness and muscle strength), and mental health (encompassing mood disorders and cognitive functioning). If this intervention proves effective, it could offer a viable solution for the school community, especially in reducing congestion within the school environment. The study protocol aims to evaluate the impact of an active transportation educational program based on the ecological model on the physical and mental well-being of high school students. Three high schools located in the urban area of Talca, Chile, will be randomly selected (one public, one privately subsidized, and one private non-subsidized). Each high school will be randomly assigned an experimental group (n = 30) and a control group (n = 30; without intervention). The experimental groups will receive an active transportation educational intervention during their physical education classes for four months (60 to 90 min sessions, once a week), while the control group will receive no intervention. The primary outcome will provide information on body composition and executive function. Secondary outcomes will include objective physical activity level, physical fitness, mental well-being, academic achievement, health-related quality of life, perception of environmental urban features, physical activity barriers, and adherence to active transportation. It is expected that the results of the MOV-ES Project will transcend the physical health of schoolchildren and will have an impact on the school community, especially by decongesting the school environment.

Effect of core strength training on the badminton player's performance: A systematic review & meta-analysis

BACKGROUND

Core strength training (CST) has been shown to improve performance in several sports disciplines. CST is recognized as one of the crucial elements that enhance athletic performance, particularly impacting badminton skills. Despite its popularity as a strength training method among badminton players, there is a lack of comprehensive studies examining the effectiveness of CST on the performance of these athletes.

OBJECTIVE

This study aims to ascertain CST's effects on badminton players' performance.

METHOD

This study followed PRISMA principles and conducted comprehensive searches in well-known academic databases (SCOPUS, Pubmed, CNKI, Web of Science, Core Collection, and EBSCOhost) up to August 2023. The inclusive criteria were established using the PICOS framework. Following their inclusion based on PICOS criteria, the selected studies underwent literature review and meta-analysis. The methodological quality of the assessments was evaluated using Cochrane Collaboration's risk of bias tools bias risk tools and recommendations for a graded assessment, development, and evaluation.

RESULTS

The analysis included participants aged 10-19 years from 13 studies of moderate quality, totaling 208 individuals. The CST intervention s lasted between 4 to 16 weeks, with a frequency of 1 to 4 sessions per week and each session lasting 20 to 120 minutes. Sample sizes across these studies ranged from 8 to 34 participants. According to the meta-analysis, CST significantly influenced badminton performance, particularly in areas of explosive power (ES = 0.03 P = 0.04), front-court skill (ES = 2.53, P = 0.003), and back-court skill (ES = 2.33, P = 0.002).

CONCLUSION

CST enhances badminton players' fitness (strength, power, balance, and stability), in situ (front/back-court) skills, and movement position hitting. However, its effects on speed, endurance, agility, flexibility, and coordination are unclear, revealing a research gap. The precise benefits of CST, especially on flexibility and specific hitting skills (smashes, clears, drives, net shots, crosscourt, push, and lift shots), need more investigation. Additionally, research on CST's impact on female athletes is significantly lacking.

Age-specific comparisons in the rate of force development of toe pressure strength and its association with the timed up and go test

PURPOSE

It has recently been recommended that Rate of Force Development (RFD) be evaluated in addition to maximal muscle strength. There are no studies on RFD of toe pressure strength, and its importance in older adults and the extent to which it is associated with aging needs to be clarified. This study purpose was to examine the association between the RFD of toe pressure strength and timed up and go test (TUG) in an age-specific study.

METHODS

This study is a cross-sectional study. Participants in the study included 159 younger adults (26.3 ± 13.1 years, 52% male) and 88 older adults (75.0 ± 6.2 years, 26% male). The RFD of toe pressure strength was determined from the force-time curve obtained during the toe pressure strength assessment, and the ability to exert maximum muscle force in the shortest possible time was assessed. Regression analysis was performed for each group to test the association between RFD of toe pressure strength and TUG by age.

RESULTS

Younger adults showed no association between TUG and RFD of toe pressure strength, and significant association between TUG and RFD of toe pressure strength was found only in the older adults (standard regression coefficient =  - 0.19, p = 0.048).

CONCLUSION

This study showed a significant association between TUG and RFD of toe pressure strength in older adults. These findings show that RFD is one of the functions that should be assessed, particularly in older adults. Furthermore, it was suggested that approaching RFD could improve gait, standing, and sitting movements.

Could BIA-derived phase angle predict health-related musculoskeletal fitness? A cross-sectional study in young adults

OBJECTIVES

To our knowledge, little evidence exists on the relationships between body composition and health-related physical fitness; in particular, musculoskeletal fitness. Bioimpedance index phase angle (bioelectrical impedance analysis raw variables) is a candidate predictor of health-related fitness, a marker of fat-free and body cell mass, respectively. The aim of this study was to evaluate body composition, raw bioelectrical impedance analysis variables, and health-related fitness in young adults and investigate their mutual relationships to identify predictors of muscle strength.

METHODS

The study included 229 young adults (115 men and 114 women; 24.2 ± 3 y; body mass index 19-30 kg/m²). Anthropometry was measured with standardized procedures. Whole-body BIA (50 kHz) was performed for impedance and phase angle. Predictive equations estimated fat-free mass and percentage body fat. The bioimpedance index was calculated as stature²/impedance. Musculoskeletal fitness was assessed by handgrip strength, standing broad jump, squat jump, and countermovement jump.

RESULTS

In both sexes, health-related fitness had stronger associations with body composition than stature or weight. Handgrip strength was related to fat-free mass and bioimpedance index, while an inverse association with percent body fat emerged for standing broad jump, squat jump and countermovement jump. Phase angle is directly correlated with handgrip strength, standing broad jump, squat jump, and countermovement jump. In multiple regression analysis phase angle was an independent predictor of all health-related fitness tests, along with fat-free mass (or bioimpedance index) for handgrip strength, and with sex and percent body fat for the three jump tests.

CONCLUSIONS

The present study provided consistent information on the relationships between body composition and health-related fitness in young adults. Phase angle emerged as a significant predictor of all health-related fitness measures and might be useful for a more consistent assessment of musculoskeletal fitness.

Influence of vitamin D supplementation on muscle strength and exercise capacity in Mongolian schoolchildren: a randomised controlled trial

Objective

To determine whether weekly oral vitamin D supplementation influences grip strength, explosive leg power, cardiorespiratory fitness or spirometric lung volumes in Mongolian schoolchildren.

Methods

Multicentre, randomised, double-blind, placebo-controlled clinical trial conducted in children aged 6-13 years at baseline attending 18 schools in Ulaanbaatar. The intervention was weekly oral doses of 14,000 IU vitamin D3 (n=4418) or placebo (n=4433) for 3 years. Outcome measures were grip strength, standing long jump distance and serum 25-hydroxyvitamin D (25[OH]D) concentrations (determined in all participants), peak oxygen uptake (VO2peak, determined in a subset of 632 participants using 20-metre multi-stage shuttle run tests) and spirometric outcomes (determined in a subset of 1,343 participants).

Results

99.8% of participants had serum 25(OH)D concentrations <75 nmol/L at baseline, and mean end-study 25(OH)D concentrations in children randomised to vitamin D vs. placebo were 77.4 vs. 26.7 nmol/L (mean difference 50.7 nmol/L, 95% CI, 49.7 to 51.4). However, vitamin D supplementation did not influence mean grip strength, standing long jump distance, VO2peak, spirometric lung volumes or peak expiratory flow rate, either overall or within sub-groups defined by sex, baseline 25(OH)D concentration <25 vs. ≥25 nmol/L or calcium intake <500 vs. ≥500 mg/day.

Conclusion

A 3-year course of weekly oral supplementation with 14,000 IU vitamin D3 elevated serum 25(OH)D concentrations in Mongolian schoolchildren with a high baseline prevalence of vitamin D deficiency. However, this intervention did not influence grip strength, explosive leg power, peak oxygen uptake or spirometric lung volumes, either overall or in sub-group analyses.

The effects of an active breaks intervention on physical and cognitive performance: results from the I-MOVE study

BACKGROUND

The present quasi-experimental study aimed to evaluate the effects of active breaks intervention (ABs) to promote physical and cognitive improvement in primary school.

METHODS

The active breaks group (ABsG) performed 10 min of ABs three times per school day and the control group (CG) did normal lessons. The baseline and follow-up evaluation was conducted respectively in October 2019 and in May 2021. Cognitive performance was assessed using working memory test, physical performance was analyzed with ActiGraph accelerometers and physical fitness tests, quality of life was monitored using the Paediatric Quality of Life questionnaire (PedsQL) and classroom behavior was collected with an ad hoc questionnaire.

RESULTS

We enrolled 153 children (age: 7.61 ± 1.41, 54.2% males). Working memory significantly increased in the ABsG (ΔWM: 1.30 ± 1.17) than in CG (ΔWM: 0.96 ± 1.20). The 6 min Cooper test increased in the ABsG (Δ: 1.77 ± 136.03) but not in CG (Δ: -156.42 ± 187.53), P < 0.05. The weekly physical activity levels increased in both groups; however, the sedentary behavior significantly increased both in ABsG and CG. Children reported improvements in their quality of school life including feeling better in class and in school when using ABs; moreover, children improved their time on task behaviors in ABsG.

CONCLUSION

The present study has proven to be effective on children's physical and cognitive performance.

Effects of "Football and Nutrition for Health" program on body composition, physical fitness, eating behaviours, nutritional knowledge, and psychological status among 7 to 10 years school children

Introduction

Noncommunicable diseases and obesity are between the major health threat due to consumption of unhealthy foods and limited time spent on physical activities, a situation of particular concern among children. Since children spend most of their time at school, this study intends to investigate the effect of a school intervention program, which combines recreational football and nutrition education, on body composition, physical fitness, physical activity, blood pressure and heart rate, eating behaviours, nutritional knowledge, and psychological status in elementary school children.

Methods

A total of 67 children, between 7 and 10 years old, were allocated into three groups: the Football Group (FG) which held 2 weekly sessions of 60 min of recreational football, the Nutrition and Football Group (NFG) which held 2 sessions per week of 60 min of recreational football plus 60 min of nutritional education and the Control Group (CG) which maintained its usual curriculum. The intervention lasted 12 weeks. All measurements were collected before and after the intervention.

Results

Intervention groups significantly (p < 0.05) improved BMI Z-score, rest heart rate, horizontal jump and shuttle test, physical activity level, and psychosocial health. The NFG group significantly decreased (p < 0.05) waist-to-height ratio and blood pressure, and significantly increased (p < 0.05) nutritional knowledge, fruit, and fish consumption. While FG significantly decreased (p < 0.05) the percentage of fat mass and significantly increased (p < 0.05) muscle mass and performance in the 20 m sprint.

Discussion

The results have shown to improve nutritional status, explosive strength, aerobic and neuromuscular fitness, as well as increase the level of physical activity. The nutritional education sessions contributed to increase nutritional knowledge and to improve the consumption of healthy food groups in a ludic-educational way. The "Football and Nutrition for Health" program was able to induce short-term improvements in several health markers, highlighting the role of the school curriculum in children's health.

Reference values for body composition and physical fitness of young Brazilian elite soccer players

Objective: a) to verify whether body composition and physical fitness should be analyzed by chronological age and/or maturity stage in young Brazilian soccer players and b) to propose reference values for the evaluation of body composition and physical fitness by maturity stage in elite soccer players. Methods: A descriptive-correlational study was carried out in 206 young Brazilian soccer players (11-16 years old). The sample selection was non-probabilistic by convenience. Weight and standing height were evaluated. Body composition (BC) was assessed by dual X-ray absorptiometry (DXA). BC indicators [(percent fat (%F), Fat-free mass (FFM), Fat mass (FM) and Bone mass (BM)] were extracted. For physical fitness (PF), we applied the Flexibility (cm) sit and reach tests, explosive strength tests [Counter Movement Jump CMJ (cm) and horizontal jump HJ (cm)], speed [Speed 10, 20, 30 and 40 m (seconds)] and Yo-Yo endurance level I test. Percentiles were constructed for BC and PF using the LMS method [L (Lambda; skewness), M (Mu; median) and S (Sigma; coefficient of variation)]. Results: The explanatory power between chronological age (CA) with BC was: FM (R2 = 0.03%), FFM (R 2 = 0.66%) and BM (R 2 = 0.62%), while between maturity status (MS) with BC were: FM (R 2 = 0.04%), FFM (R 2 = 0.71%) and BM (R 2 = 0.66). The explanatory power between the CA with the physical fitness tests ranged from: (R 2 = 0.22-0.62%). While between MS with physical fitness the values ranged from: (R 2 = 0.23-0.64%). Percentiles per MS (P3, P5, P10, P15, P25, P50, P75, P85, P90, P95 and P97) were proposed for both BC and PF. Conclusion: The results of the study have shown that the evaluation of BC and PF of young soccer players should be performed by controlling for MS rather than for CA. The inclusion of a non-invasive method to control MS by means of percentiles during puberty may contribute to the development of retention and exclusion of young soccer players, thus, they may have a better chance of achieving sporting success.

Changes in fitness and fatness in Australian schoolchildren during the summer holidays: fitness lost, fatness regained? A cohort study

BACKGROUND

Emerging evidence suggests that children's fatness increases and fitness declines at a greater rate during the summer holiday period, compared with the school year. The aim of this study was to compare rates of change in fitness and fatness over the in-term and summer holiday periods among Australian schoolchildren. A secondary aim was to explore whether rates of change differed according to the child's sex, socio-economic status (SES), pubertal status and weight status.

METHODS

Children (n = 381) initially in Grade 4 (age 9) were recruited for this 2-year longitudinal study. Fatness (% body fat, BMI z-score, waist-to-height ratio) and fitness (20-m shuttle run and standing broad jump) were measured at the start and end of two consecutive years. Rates of change were calculated for the two in-school periods (Grades 4 and 5) and for the summer holiday period. Rates of change in fatness and fitness between in-school and holiday periods were compared, and differences in rates of change according to sex, socio-economic status, and weight status were explored.

RESULTS

During the holidays, percentage body fat increased at a greater rate (annualised rate of change [RoC]: +3.9 vs. Grade 4 and + 4.7 vs. Grade 5), and aerobic fitness declined at a greater rate (RoC - 4.7 vs. Grade 4 and - 4.4 vs. Grade 5), than during the in-school periods. There were no differences in rates of change for BMI z-score, waist-to-height ratio or standing broad jump. Body fatness increased faster in the holidays (relative to the in-school period) in children who are overweight and from low-SES families. Aerobic fitness declined more rapidly in the holidays in children who are overweight.

CONCLUSION

This study highlights that during the summer holiday period, children experience greater increases in fatness and declines in fitness, with children who live with low-SES families and are overweight being more affected. The findings suggest the need for targeted interventions during this period to address these negative health trends.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry, identifier ACTRN12618002008202. Retrospectively registered on 14 December 2018.

Effect of the hybridization of social and personal responsibility model and sport education model on physical fitness status and physical activity practice

Physical activity patterns, sedentary habits and obesity levels among children and teenagers are indicators of a worrying reality which has been aggravated by the COVID-19 pandemic. In this context, this study has analysed the impact that new methodologies in Physical Education have on physical health aspects. Two teaching methods, namely, Teaching Personal and Social Responsibility and Sport Education Model, were hybridized, in a Secondary School in Murcia (Spain). Controlled quasi-experimental research was completed with a sample of 76 Secondary Education students aged 12-14 (male: 32; female: 44), developing a hybridization of both models in the experimental group. The Physician-based Assessment and Counselling for Exercise (PACE) questionnaire and Eurofit and Alpha Fitness motor tests were run to collect the results. Those showed significant improvement in standing long jump and speed-agility results in the control group. In the experimental group, on the contrary, no significant improvement was registered for either test, but out-of-school physical activity rates were higher. Following this research, it is concluded that both models have positive influence on physical activity habits, but the teaching time devoted to the subject of Physical Education is not enough to improve them.

Secular trends in the physical fitness of Brazilian youth: Evidence that fitness is declining for the majority but not for a fit minority

BACKGROUND

There has been a decline in children's physical fitness in recent decades. Such concerns are largely based on evidence from North America, Europe, and Asia. The current study describes the secular trend and variation (spread) in the physical fitness scores of young Brazilians from 2005 to 2022.

METHODS

This study is a repeated, cross-sectional surveillance study (1999-2022). Children and adolescents (n = 65 139; boys = 36 539) participated between 2005 and 2022. In each cohort six physical fitness tests were conducted: (1) 20-m sprint speed (m s-1 ), (2) cardio-respiratory 6-min run test (m min-1 ), (3) abdominal strength test (sit-ups per min), (4) horizontal jump test (cm), (5) the agility test (m s-1 ), and (6) the medicine ball throw test (cm). Means and distributional characteristics of the population were assessed using ANOVA, ANCOVA adopting BMI as the body-size covariate, Levene's test of equality-of-error variances, and Box and whisker plots.

RESULTS

ANOVAs and ANCOVA's identified significant declines in physical fitness over time/year in 5 of the 6 physical fitness variables (e.g., 20-m sprint speed slope B = -0.018 (m s-1  y-1 ); 95% CI -0.019 to -0.017; p < 0.001), the only exception being the medicine ball throw test (cm). The Levene's test of equality-of-error variances also identified a systematic increase in the variances/standard deviations over time/years.

CONCLUSIONS

Results provide powerful evidence that children and adolescents' physical fitness is declining, a trend that is also diverging asymmetrically, becoming more extreme in more recent years. The "fit" appear to be getting fitter, but the fitness of the "less-fit" appears to be declining further. These results have important implications for sports medicine and government policy makers.

Assessing full body impulsive ability using a range of medicine ball loads for the backward overhead medicine ball throw

The potential for high performance in many sports can be assessed by quantifying whole-body explosiveness. The backwards overhead medicine ball (BOMB) throw is commonly-used to tests this ability, but the effect of varied loading on test execution is unknown. The purpose of this study was to determine the effect of different medicine ball (MB) loads on force, velocity, and power output during the BOMB throw. Female collegiate softball and rugby players (n=31) performed the BOMB throw on a force plate using 2.7, 3.6, 4.5, and 5.5 kg MBs, with three throws per load in a randomised order, and 30 seconds rest between throws. A series of Repeated Measures ANOVAs noted no differences (p>0.05) in peak power, peak force, peak velocity, force at the moment of peak power, or velocity at the moment of peak power, across MB loads. The lack of differences among these loads indicates that coaches can likely compare kinetic characteristics of the BOMB throw within this range (2.7-5.5 kg). Therefore, coaches can use the BOMB throw with 2.7-5.5 kg MBs for training or measurement among female athletes to obtain reference data for programming or evaluation.

Association of Socioeconomic Factors and Physical Activity with Health-Related Quality of Life in Italian Middle School Children: An Exploratory Cross-Sectional Study

Health-related quality of life (HRQoL) provides a broad assessment of an individual's well-being and can serve as a good prognosticator of life's outcomes later for children and adolescents. Understanding the factors associated with HRQoL is crucial for promoting better health and life satisfaction. This study investigated the cross-sectional association of socioeconomic status, cardio fitness, and physical activity levels with HRQoL in 224 Italian early adolescents attending secondary school in the Emilia-Romagna region located in Northern Italy. In a multivariate path regression model, younger students and females reported a higher quality of life (β = -0.139, p = 0.015, 95% CI: -0.254--0.023 and β = 0.142, p = 0.019, 95% CI: 0.011-0.273, respectively). Having both parents employed and having a higher familiar educational status were also associated with a higher quality of life (β = 0.142, p = 0.013, 95% CI 0.027-0.257 and β = 0.133, p = 0.017, 95% CI 0.022-0.244, respectively). Greater engagement in routine physical activity levels from moderate to vigorous intensity was positively associated with quality of life (β = 0.429, p < 0.001, 95% CI: 0.304-0.554). Endurance (speed) was positively associated with quality of life (β = 0.221, p = 0.001, 95% CI: 0.087-0.355), and students with longer times on the shuttle run reported less quality of life (β = -0.207, p = 0.002, 95% CI: -0.337--0.077). These relations remained intact even when controlling for socioeconomic factors. The current findings reinforce the importance of promoting regular physical activity among younger children and also addressing socioeconomic status disparities to improve children's well-being. Future studies may want to consider expanding the array of measures used to assess physical activity and include additional measures assessing nutrition, cultural factors, and family functioning, all of which can influence a child's willingness to engage in physical activity and their well-being. The emphasis on fitness and physical activity and their contribution to a child's well-being should be the prime focus for stakeholders who work in the education, public health, and health policy sectors.

Estimating the Standing Long Jump Length from Smartphone Inertial Sensors through Machine Learning Algorithms

The length of the standing long jump (SLJ) is widely recognized as an indicator of developmental motor competence or sports conditional performance. This work aims at defining a methodology to allow athletes/coaches to easily measure it using the inertial measurement units embedded on a smartphone. A sample group of 114 trained young participants was recruited and asked to perform the instrumented SLJ task. A set of features was identified based on biomechanical knowledge, then Lasso regression allowed the identification of a subset of predictors of the SLJ length that was used as input of different optimized machine learning architectures. Results obtained from the use of the proposed configuration allow an estimate of the SLJ length with a Gaussian Process Regression model with a RMSE of 0.122 m in the test phase, Kendall's τ < 0.1. The proposed models give homoscedastic results, meaning that the error of the models does not depend on the estimated quantity. This study proved the feasibility of using low-cost smartphone sensors to provide an automatic and objective estimate of SLJ performance in ecological settings.

Impaired cardiorespiratory and neuromuscular fitness in children and adolescents with juvenile idiopathic arthritis: a cross-sectional case-control study in the era of biologic drug therapies

BACKGROUND

In recent years, biologic drug therapies have altered the course of juvenile idiopathic arthritis (JIA) possibly also improving the patients' physical fitness. However, studies measuring both cardiorespiratory and muscular fitness in children with JIA are sparse and have failed to show consistent results. Our aim was to assess both cardiorespiratory and neuromuscular fitness and contributing factors in children and adolescents with JIA in the era of biologic drug therapies.

METHODS

This cross-sectional study consisted of 73 JIA patients (25 boys, 48 girls) aged 6.8- 17.5 years and 73 healthy age- and sex-matched controls, investigated in 2017-2019. Cardiorespiratory fitness was assessed by maximal ergospirometry and neuromuscular fitness by speed, agility, balance, and muscle strength tests.

RESULTS

Means (± SD) of maximal workload (W_max/kg) and peak oxygen uptake (VO2_peak/kg,) were lower in JIA patients than in controls (W_max/kg: 2.80 ± 0.54 vs. 3.14 ± 0.50 Watts, p < 0.01; VO2_peak/kg: 38.7 ± 7.53 vs. 45.8 ± 6.59 ml/min/kg, p < 0.01). Shuttle-run, sit-up and standing long jump test results were lower in JIA patients than in controls (p < 0.01). Mean (± SD) daily activity was lower (89.0 ± 44.7 vs. 112.7 ± 62.1 min/day, p < 0.05), and sedentary time was higher (427 ± 213 vs. 343 ± 211 min/day, p < 0.05) in JIA patients compared to controls. Physical activity and cardiorespiratory or neuromuscular fitness were not associated with disease activity.

CONCLUSIONS

JIA patients were physically less active and had lower cardiorespiratory and neuromuscular fitness than their same aged controls with no JIA. Therefore, JIA patients should be encouraged to engage in physical activities as a part of their multidisciplinary treatment protocols to prevent adverse health risks of low physical activity and fitness.

Impact of Functional Training on Functional Movement and Athletic Performance in College Dragon Boat Athletes

Functional training has become a popular training method in different sports, yet limited studies have focused on paddle sports. The purpose of this study was to evaluate the effects of functional training on functional movement and athletic performance in college dragon boat athletes. A total of 42 male athletes were divided into 2 groups: a functional training (FT) group (n = 21, 21 ± 1.47 years) and a regular training (RT) group (n = 21, 22 ± 1.50 years). The FT group participated in an 8-week (16-session) functional-training program, while the RT group trained with strength-training sessions. Functional movement screen (FMS), Y-balance test (YBT) and athletic performance evaluations were conducted before and after the intervention. Repeated measure ANOVA and t-test evaluations were employed to examine differences for both groups. The FT group was significantly improved in FMS scores (F = 0.191, p < 0.001) and YBT scores (F = 2.59, p = 0.027), and it also showed significantly improved muscular fitness (pull-ups: F = 0.127, p < 0.001; push-ups: F = 1.43, p < 0.001) and rowing speed (F = 4.37, p = 0.004). It is recommended to include functional training as a part of training and routine exercise, as it appears to be an effective way of improving FMS and athletic performance in paddle sports.