The health benefits of muscular fitness for children and adolescents: a systematic review and meta-analysis

Cardiorespiratory fitness and muscular fitness correlates in youth: A hierarchy of behavioral, contextual, and health-related outcomes

OBJECTIVES

Despite the health importance of identifying correlates of physical fitness in youth, no investigation to date has explored the influence of behavioral, health-related, and contextual correlates simultaneously. We investigated the hierarchical relationship of multiple modifiable correlates favoring or diminishing cardiorespiratory and muscular fitness in youth.

DESIGN

Cross-sectional investigation.

METHODS

In a sample of 5174 children and adolescents, 31 correlates were hierarchized according to their impact on cardiorespiratory and muscular fitness assessed using the FITESCOLA® fitness battery. A Chi-squared Automatic Interaction Detection approach was employed and measures of correlation and association were used to investigate the relationship between physical fitness and correlates.

RESULTS

In children, body mass index was the most relevant factor to discriminate between high and low cardiorespiratory and muscular fitness of the upper, middle, and lower body. While body mass index was more important than any other correlate to differentiate levels of upper and lower body muscular fitness during adolescence, specific characteristics of sports participation emerged as key factors to discriminate between high and low cardiorespiratory fitness and middle body muscular fitness. Other correlates, including the self-report of active recess time, active commuting to school, favorable neighborhood conditions, and limited time on screens and cellphones, were demonstrative of favorable physical fitness levels.

CONCLUSIONS

Both body composition and sports-related characteristics emerged as the two most relevant factors of physical fitness in youth. Additional health benefits may be obtained from building supportive environments for sports and healthy exercise habits within the household and at different school education levels.

A multivariate multilevel approach to unravel the associations between individual and school factors on children's motor performance in the REACT project

OBJECTIVE

The aim was to (1) estimate the relationship between physical fitness (PF) and object control fundamental movement skills (FMS), (2) identify child characteristics that relate with PF and FMS, and (3) examine associations between the school environment, PF, and FMS.

METHODS

The sample included 1014 Portuguese children aged 6-10 years from the REACT project. PF was assessed via running speed, shuttle run, standing long jump, handgrip, and the PACER test. Object control FMS were assessed with stationary dribble, kick, catch, overhand throw, and underhand roll. Test performances were transformed into z-scores, and their sum was expressed as overall PF and FMS. Child-level variables included body mass index (BMI) z-scores, accelerometer-measured sedentary time and moderate-to-vigorous physical activity, and socioeconomic status (SES). School size, physical education classes, practice areas, and equipment were also assessed.

RESULTS

Approximately, 90% of the variance in object control PF and FMS was at the child level, and 10% at the school level. The correlation between PF and object control FMS was .62, which declined to .43 with the inclusion of covariates. Older, more active, and higher SES children had higher object control PF and FMS, and boys outperformed girls. BMI was negatively associated with PF but not with object control FMS. Sedentary time and number of physical education classes were not significant predictors. Most school predictors did not jointly associate with PF and object control FMS.

CONCLUSION

PF and object control FMS z-scores were moderately related. Not all child characteristics were associated with both PF and object control FMS, and their effect sizes were different. School characteristics only explained 10% of the total variation in PF and object control FMS.

Physical Fitness Surveillance and Monitoring Systems Inventory for Children and Adolescents: A Scoping Review with a Global Perspective

Surveillance of health-related physical fitness can improve decision-making and intervention strategies promoting health for children and adolescents. However, no study has comprehensively analyzed surveillance/monitoring systems for physical fitness globally. This review sought to address this gap by identifying: (1) national-level surveillance/monitoring systems for physical fitness among children and adolescents globally, (2) the main barriers and challenges to implementing surveillance/monitoring systems, and (3) governmental actions related to existing surveillance/monitoring systems. We used a scoping review to search, obtain, group, summarize, and analyze available evidence. Our review involved three stages: (1) identification of surveillance systems through a systematic literature review, with complementary search of the grey literature (e.g., reference lists, Google Scholar, webpages, recommendations), (2) systematic consultation with relevant experts using a Delphi method to confirm/add systems and to gather and analyze information on the barriers and challenges to implementing systems, and (3) Web searches for public documents on government sites and surveillance/monitoring system pages, and direct internet searches to identify relevant governmental actions related to surveillance systems. A total of 15 fitness surveillance/monitoring systems met our inclusion criteria. Experts identified a lack of government support and funding, and the low priority of fitness on the public health agenda as the main barriers/challenges to implementation. Several governmental actions related to surveillance systems were identified, including policies, strategies, programs, and guidelines. We propose a Global Observatory of Physical Fitness to help address these issues.

A Novel Summer Camp Integrating Physical, Psychological, and Educational Health in Youth: The THINK Program

Numerous youth summer programs focus upon physical fitness, nutritional health, psychological well-being, or education. Few, however, have integrated all of these elements into a single program. The Translational Health in Nutrition and Kinesiology (THINK) program provides an integrative nutrition and exercise science curriculum that is interfaced with social emotional learning (SEL) and STEM education to enhance healthy behaviors in youth. The purpose of this study was to determine whether the THINK program could improve physical fitness, nutrition habits, SEL, and STEM education in a 6-week summer program covering a 3-year period. Participants from South Miami were enrolled in THINK (n = 108, 58 males, 50 females, 12.03 + 0.56 years). Physical fitness assessments, the Positive Youth Development Inventory (PYDI), the Students' Attitude Towards STEM Survey, and the Adolescent Food Habits Checklist (ADFH) were recorded at baseline and post-testing. Means and standard error values were evaluated for all dependent variables. Paired samples t-tests (SPSS version 27) were used to determine changes. Improvements in cardiorespiratory fitness (p < 0.001), power (p < 0.006), flexibility (p < 0.001), agility (p < 0.001), muscular endurance (p < 0.001), lean body mass (p < 0.001), ADFH (p < 0.001), and PYDI (p = 0.038) were found. An integrative summer fitness program can result in improvements in physical fitness, nutrition habits, and SEL in as little as six weeks.

The Influence of Kindergarten Environment on the Development of Preschool Children's Physical Fitness

The aim of this research is to find out to what extent the special qualifications of physical education teachers and the physical environment of kindergartens influence the physical development of preschoolers. Forty-four kindergartens across Estonia participated in the study, half of which had a physical education teacher (PEt), whereas the remaining 22 kindergartens were taught by non-qualified kindergarten teachers (NoPEt). Six Eurofit fitness tests were used to assess the physical development of children (n = 704; aged 6-7 years old, with an average age of 6.55 ± 0.5 years). An analysis of variance was used to compare the mean values of the fitness test results of the two groups. Linear regression analysis was applied to clarify the influence of individual and environmental factors on children's fitness scores. In kindergartens where the position of a PEt had been created, the results of children's physical fitness were statistically significantly better, more specifically in handgrip strength (m = 12.0, 95% CI = 11.8-12.3 vs. m = 11.5, 95% CI = 11.2-11.7) and in speed tests (m = 23.0, 95% CI = 22.8-23.2 vs. m = 23.6, 95% CI = 23.3-23.8). According to the teacher interviews, these kindergartens also had more rooms and areas specially created for physical exercises. The study revealed that the physical development of children is, when controlling for other individual and environmental factors, influenced by the professional qualification of the PE teacher (95% CI = 0.06-0.56) as well as children's participation in sports training (95% CI = 0.29-0.83). These findings are important for preschool institutions and municipalities in designing the optimal physical environment for facilitating children's physical fitness.

High muscular fitness level may positively affect bone strength and body composition in children with overweight and obesity

Muscular fitness plays a major role in bone health and body composition in overweight and obese children. It is key that the development of this muscle fitness is affected by absolute isometric strength and dynamic strength.

PURPOSE

To compare bone health and body composition between overweight/obese children considering muscular fitness (MF) levels, and to investigate whether weight-bearing dynamic or absolute isometric strength, both involved in the development of this muscular fitness, are more related with bone health.

METHODS

MF of 59 overweight or obese children (10.1 ± 0.9 years, 27 females) was measured by a countermovement jump (CMJ), handgrip, and maximal isometric strength of knee extension. Participants were divided into four groups depending on their MF level performing a cluster analysis: 16 children with high MF (HMF) in all tests, 18 with high performance in isometric strength (HIS), 15 with high performance in CMJ (HCMJ) and 10 low isometric and low dynamic force values (LMF). Body composition values were measured by dual energy X-ray absorptiometry, and bone strength values were assessed by peripheral quantitative computed tomography. Motor skills were evaluated using TGMD-3. Multivariate analysis of covariance test was applied to analyse bone strength differences between children in the different MF groups, using maturity offset, height and weight as covariates, and correlations were investigated.

RESULTS

HMF excelled in bone health. HIS had higher cortical bone area, periosteal circumference, bone mass, polar strength strain index and fracture load than LMF, while HCMJ only showed better results in trabecular bone area than LMF. HMF had significantly better values of fracture load and periosteal and endosteal circumferences than HCMJ, but not than HIS.

CONCLUSIONS

High MF level shows positive effects on bone health in overweight/obese children. Those with highest isometric strength had better bone health compared to those with higher dynamic strength.

TRIAL REGISTRATION

The research project was registered in a public database Clinicaltrials.gov in June 2020 with the identification number NCT04418713.

Comparison of Estonian Schoolchildren's Physical Activity and Fitness Indicators before and after the COVID-19 Pandemic's Period of Restricted Mobility

It is recognized that the time adolescents spend on physical activity, and the corresponding physical fitness indicators, have diminished over time. However, the exact impact of the COVID-19 pandemic restriction period on physical activity and health-related physical fitness indicators remains unclear. This study sought to determine if and to what degree the primary indicators of physical activity (exercise frequency, exercise intensity, and outdoor physical activity) and health-related physical fitness (strength and endurance) among schoolchildren have shifted, by comparing data from before and after the coronavirus pandemic period. Students aged 12-17 years took part in the study. The physical activity questionnaire and fitness tests were conducted in the autumn of 2017 and spring of 2022. The main results show that moderate- and vigorous-intensity physical activity time and time spent actively outdoors have decreased among adolescents (p < 0.05). There were no significant changes in exercise frequency (p > 0.05). However, there was a statistically significant decline in strength (standing broad jump, bent arm hang) (p < 0.05) and endurance (20 m shuttle run, curl-up) (p < 0.01) when comparing results from before and after the COVID-19 pandemic restriction period. In conclusion, restricted mobility had the greatest impact on the time spent outdoors and, in turn, on physical fitness.

Effects of School-Based High-Intensity Interval Training on Hemodynamic Parameters and Heart Rate Variability: A Randomized Controlled Trial

ABSTRACT

Ketelhut, S, Ketelhut, K, Ketelhut, SR, and Ketelhut, RG. Effects of school-based high-intensity interval training on hemodynamic parameters and heart rate variability: A randomized controlled trial. J Strength Cond Res 38(6): 1033-1040, 2024-The purpose of this study was to assess the effects of a child-specific school-based high-intensity interval training (HIIT) implemented into physical education (PE) classes on various hemodynamic parameters and heart rate variability indices. Forty-six students (age 11 ± 1 year) were randomized into an intervention (INT n = 22) and a control group (CON n = 24). During a 12-week period, the INT and CON groups participated in regular PE twice weekly (45-90 minutes). The INT group received HIIT during the first 20 minutes of the 2 PE classes. Systolic and diastolic blood pressure, total peripheral resistance, aortic pulse wave velocity (aPWV), heart rate, SD of normal to normal heartbeat intervals, the root mean square of successive differences between normal heartbeats (RMSSD), the proportion of differences between adjacent normal to normal heartbeat intervals of more than 50 ms, low-frequency power, high-frequency power, and the LF/HF ratio were assessed before and after the experimental period. A p value ≤0.05 was considered statistically significant. Forty students (20 INT; 20 CON) were included in the analysis. A significant time × group interaction was detected for aPWV ( p = 0.05, η2 = 0.099), RMSSD ( p = 0.010, η2 = 0.161), low-frequency power ( p = 0.009, η2 = 0.165), high-frequency power ( p < 0.001, η2 = 0.272), and the LF/HF ratio ( p < 0.001, η2 = 0.354). The INT group revealed significant improvements for the respective parameters. School-based HIIT can induce improvements in cardiovascular parameters. These results highlight the potential of embedding HIIT within the school setting, offering a time-efficient exercise intervention.

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.

Longitudinal Associations Between Enjoyment of Physical Education, Cardiorespiratory Fitness, and Muscular Fitness Among Finnish Adolescents

INTRODUCTION

Students' experiences in physical education (PE) can shape future physical activity (PA) behaviors. PE enjoyment is associated with PA; however, the relationship between PE enjoyment and fitness has not been extensively investigated. The aim of this study was to examine if changes in PE enjoyment were associated with changes in cardiorespiratory fitness (CRF) and muscular fitness (MF) among Finnish adolescents.

METHODS

Study participants were students (n = 1147; 11.27 [±0.32] years at baseline) attending public schools in Finland. Data were collected yearly (2017-2021). The 20 m shuttle run assessed CRF, curl-up/push-up tests assessed MF, and the enjoyment subscale of the Sport Commitment Questionnaire-2 measured PE enjoyment. The random intercept cross-lagged panel model, including repeated measures (within-level) and latent levels (between-level) of PE enjoyment, CRF and MF, was tested. Sex, body mass index, moderate to vigorous PA, and peak height velocity were included as covariates in the analysis.

RESULTS

Over 5 years, PE enjoyment decreased, CRF increased until Timepoint 3, and MF remained stable. Positive associations between PE enjoyment and fitness were observed, indicating the greater the PE enjoyment, the higher the fitness. For PE enjoyment, CRF and MF repeated measures were positively associated with measurement of the next year. PE enjoyment was positively related to CRF and MF the years thereafter.

CONCLUSION

Our findings highlight the importance of quality PE experiences for enjoyment and fitness gains during the transition from primary to secondary school. These findings are important given youth fitness levels are associated with future health status.

A multimodal approach integrating cognitive and motor demands into physical activity for optimal mental health: Methodological issues and future directions

Physical activity is known for its positive effects on cognition and affect, with existing literature suggesting that these mental health benefits may be optimally experienced by incorporating cognitive and motor demands during physical activity (PA). However, the existing body of literature lacks a comprehensive guideline for designing the qualitative characteristics of a PA program. Accordingly, this narrative review aimed to (1) provide a working two-dimension model that operationally defines the cognitive and motor demands involved in PA and the rationale for systematically studying these qualitative aspects of PA, (2) identify methods to assess the cognitive and motor demands of PA and address associated methodological issues, and (3) offer potential future directions for research on the cognitive and motor aspects of PA in support of the development of PA programs designed to maximize PA-induced cognitive and affective benefits. We anticipate this article to inform the need for future research and development on this topic, aiming to create clear, evidence-based guidelines for designing innovative and effective PA interventions.

A comparison of the effects of two protocols of concurrent resistance and aerobic training on physical fitness in middle school students

Objective

This study aimed to compare the effects of two concurrent training (CT) protocols on the physical fitness of middle school students.

Method

A 12-week quasi-experimental pre-test/post-test study was conducted with 157 middle school students (age = 12.48 ± 0.34, n = 90 females) divided into three groups: CT group A (CT-0h) received combined resistance training (RT) and aerobic training (AT) in each physical education session, CT group B (CT-48h) received RT and AT across two separate physical education classes 48 h apart, and a control group (Con) received no training. Training occurred twice a week. Test indicators included cardiorespiratory fitness (CRF) measured by estimated VO2max and 20 m shuttle run (laps), as well as muscle strength assessed through long jump, vertical jump, and handgrip strength.

Results

The intervention groups exhibited significant increases in estimated VO2max and muscle strength compared to their baseline values (p < 0.05). Both CT-0h and CT-48h groups demonstrated significant improvements in 20 m shuttle run (laps) (mean difference: 8.88 laps, p < 0.01; mean difference: 4.81 laps, p < 0.01, respectively), standing long jump (mean difference: 6.20 cm, p < 0.01; mean difference: 3.68 cm, p < 0.01, respectively), vertical jump (mean difference: 4.95 cm, p < 0.01; mean difference: 4.04 cm, p < 0.01, respectively), and handgrip strength (mean difference: 11.17 kg, p < 0.01; mean difference: 6.99 kg, p < 0.01, respectively). CT-0h group exhibited significantly increased estimated VO2max (mean difference: 1.47 ml/kg/min, p < 0.01) compared to the CT-48h group.

Conclusion

Both CT programs effectively improved adolescents' physical fitness indicators. However, the program that integrated RT and AT within the same physical education class demonstrated superior enhancement in adolescents' CRF.

The impact of pediatric obesity on biomechanical differences across the gait cycle at three walking speeds

BACKGROUND

Obesity impacts a child's ability to walk with resulting biomechanical adaptations; however, existing research has not comprehensively compared differences across the gait cycle. We examined differences in lower extremity biomechanics across the gait cycle between children with and without obesity at three walking speeds.

METHODS

Full gait cycles of age-matched children with obesity (N = 10; BMI: 25.7 ± 4.2 kg/m2) and without obesity (N = 10; BMI: 17.0 ± 1.9 kg/m2) were analyzed at slow, normal, and fast walking speeds. Main and interaction effects of group and speed across hip, knee, and ankle joint angles and moments in sagittal, frontal, and transverse planes were analyzed using one-dimensional statistical parametric mapping.

FINDINGS

Compared to children without obesity, children with obesity had greater hip adduction during mid-stance, while also producing greater hip extensor moments during early stance phase, abductor moments throughout most of stance, and hip external rotator moments during late stance. Children with obesity recorded greater knee flexor, knee extensor and knee internal rotator moments during early stance, and knee external rotator moments in late stance than children without obesity; children with obesity also demonstrated greater ankle plantarflexor moments throughout mid and late stance. Interaction effects existed within joint kinetics data; children with obesity produced greater hip extensor moments at initial contact and toe-off when walking at fast compared to normal walking speed.

INTERPRETATION

While few kinematic differences existed between the two groups, children with obesity exhibited greater moments at the hip, knee, and ankle during critical periods of controlling and stabilizing mass.

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.

Normative values of motor performance and their relationship with BMI status in Hong Kong preschoolers

This study aimed to establish sex- and age-specific reference values for motor performance (MP) in Hong Kong preschoolers aged 3-5 years old and examine the relationship between MP and BMI status. A cross-sectional study was conducted among 5579 preschoolers in Hong Kong. Three MP tests were administered, and height and weight information were collected. GAMLSS was used to compute the normative values of the motor tests. Boys outperformed girls in activities requiring muscle strength and power, while girls outperformed boys in activities requiring balance and coordination. The MP scores increased with age for both overarm beanbag throw and standing long jump for both sexes, while the one-leg balance scores showed larger differences between P50 and P95 in older preschoolers. Children with excessive weight performed worse in standing long jump and one-leg balance compared to their healthy weight peers. This study provides valuable information on the MP of preschoolers in Hong Kong, including sex- and age-specific reference values and the association between BMI status and MP scores. These findings can serve as a reference for future studies and clinical practice and highlight the importance of promoting motor skill development in preschoolers, particularly those who are overweight or obese.

Association between soya food consumption and muscle strength in Chinese adolescents: evidence from a cross-sectional study

There is a strong association between soya food consumption and health, but there are few studies on the association with muscular strength, especially in adolescent groups. This study was conducted to understand the status of soya food consumption and its association with muscular strength among secondary school students in southern China. A stratified whole-group sampling method was used to investigate and test the status of soya food consumption and muscular strength of 13 220 secondary school students in southern China. Linear regression analysis and logistic regression analysis were used to analyse the correlations between soya food consumption and muscular strength. Logistic regression analysis showed that compared with secondary school students with soya food consumption ≥ 3 times/week, male students with soya food consumption ≤ 1 time/week (OR = 1·896, 95 % CI: 1·597,2·251) and female students with soya food consumption ≤ 1 time/week (OR = 2·877, 95 % CI: 2·399, 3·449) students had a higher risk of developing lower grip strength (P < 0·001). The frequency of soya food consumption among secondary school students in southern China was 49·00 %, 28·77 % and 22·23 % for ≥ 3 times/week, 2-3 times/week and ≤ 1 time/week, respectively. There is a positive association between soya food consumption and muscle strength among secondary school students in southern China. In the future, increasing the consumption of soybean products can be considered for the improvement of muscle strength.

Effect of Motor Competence and Health-Related Fitness in the Prevention of Metabolic Syndrome Risk Factors

Purpose: In the last decades we have seen an increase in sedentary behaviors and a decrease in physical activity in children when compared to past generations. This lifestyle is commonly associated with the development of clustering risk factors that define metabolic syndrome (MetS). Knowing that motor competence (MC) development can influence lifelong physical activity habits, it is reasonable to assume that children's MC will directly link to clustered cardiometabolic health outcomes. The aim of this study was to analyze the role of MC in MetS risk factors. Methods: Seventy children with a mean age of 7.49 (SD = 1.28) years were evaluated on motor competence (MCA-Motor Competence Assessment instrument), cardiovascular fitness (PACER test), upper body strength (UBS; handgrip), and the components of MetS, hypertriglyceridemia, hypertension, abdominal obesity, low concentration of high-density lipoprotein cholesterol, and high fasting blood glucose. The composite value of MetS was calculated according to Burns et al. (2017). Multiple standard regressions were performed to explore the effect of different variables on MetS. Motor competence and health-related fitness (cardiovascular fitness and relative upper body strength) were used as independent variables (predictors) and MetS as dependent variable. Results: Overall, the results showed that motor competence (β = -.072; p < .05) is a significant predictor and this model explained 7,1% of the variance in MetS. Conclusion: Although more studies are needed, our results indicate that MC seems to have a positive role in children's health markers.

Youth Sport Participation Trends Across Europe: Implications for Policy and Practice

Purpose: Despite the known health and wellbeing benefits of taking part in sport for children and adolescents, it is reported that sports participation declines during adolescence. The purpose of this study was to explore current organized youth sport participation rates across Europe for both males and females and update current understanding. Method: Sport participation registration data was collected for 18 sports from 27 countries. In total, participation data was collected from over 5 million young people from Under 8s (U8s) to Under 18s (U18s). Differences in the participation rates between age categories were investigated using a generalized linear mixed effects model. Results: Overall, males were four times more likely to participate in organised youth sport than females' participants, with this trend apparent across all age categories and across most sports. There was a significant decrease across sports in participation rates for males during adolescence from U14-U16 and U16-U18. There was a significant decrease in participation rates for females from U14-U16 for most sports except but an increase in participation rates from U16-U18 for 12 out of 18 sports. Soccer (1262%), wrestling (391%) and boxing (209%) were the sports that had greater male sport participation rates. In contrast, dance sports (86%) and volleyball (63%) had more female participants than males. This research shows male sports participation is significantly greater than female in youth sport across Europe. Conclusion: Furthermore, findings showed that for both male and female participants, participation rates increased from U8-U14 for the majority of sports followed by reduced participation rates during adolescence. Findings of this research can be used by national governing bodies and sporting organizations to inform youth sport participation initiatives.

Muscle Strength Indexes and Its Association With Cardiometabolic Risk Factors in Adolescents: An Allometric Approach

Background and aims: Muscle strength (MS) has been associated with better cardiometabolic health prognosis. However, the result for the beneficial relationship seems to be dependent on the influence of body size in determining MS levels. We investigate the association between allometric MS indexes and its association with cardiometabolic risk factors in adolescents. Methods: It was a cross-sectional study comprising 351 adolescents (male: 44.4%; age range 14-19 years) from Southern Brazil. MS was assessed by handgrip strength and three different allometric approaches were adopted: 1) MS index based on theoretical allometric exponent; 2) MS index including body mass and height; 3) MS index including fat-free mass and height. Obesity, high blood pressure, dyslipidemia, glucose imbalance and high-sensitivity C-reactive protein were investigated as individual factors or as combinations (either as combinations of components - presence of two adverse conditions, or number of components present in an individual - 0, 1, 2, 3+ cardiometabolic risk factors). Logistic and multinomial logistic regression analyses adjusted for confounding factors were used. The statistical significance adopted was 5%. Results: MS index based on theoretical allometric exponent was associated with lower likelihood (OR: 0.54; 95% CI: 0.28 - 0.89) for the presence of three or more cardiometabolic risk factors in the same individual. Conclusion: This study suggests that MS index based on the theoretical allometric exponent can be superior to allometric MS indexes that included body mass and height, or fat-free mass and height in representing the presence of high number of cardiometabolic risk factors in adolescents.

Longitudinal Relationships Between Physical Fitness With Physical Self-Concept and Self-Esteem in Adolescents

Purpose: Physical fitness has shown to be positively related with young people's general mental health, mainly due to the changes in body composition derived from a regular sportive practice. Thus, the aim of this study was three-fold: 1) to analyze the relationship between physical fitness with the mental health status assessed as physical self-concept and self-esteem, 2) to study whether self-esteem offers longitudinal relationships with physical fitness three months after the first assessment, and 3) to know the most implicated variables of physical fitness in mental health variables. Method: A total of 1441 adolescents aged 12 to 19 years (mean=14.52; standard deviation=1.96 years), being the 49.5 % of them girls, from 4 high schools in Andalusia, Spain, participated in the study. The EUROFIT battery test was administered to the participants, as well as some questionaries to assess the physical self-concept and the self-steem. Physical tests and self-concept were assessed in an only temporal point, while self-esteem was analyzed longitudinally. Results: The results obtained indicated that physical self-concept was related to physical fitness, while self-esteem was especially related to the Course Navette test. Conclusions: These results suggest that having great levels of physical fitness, especially related to aerobic endurance, may help to have higher levels of physical self-concept and self-esteem as components of mental health in Spanish adolescents.

The impact of reduced muscular fitness on cardiometabolic risk factors in children aged 9-11 years

AIM

To analyse the relationships between muscular fitness (MF), fat mass (FM), fat-free mass (FFM) and its combined ratio with cardiometabolic risk (CMR) and whether the relationship between MF and CMR is mediated by body composition in schoolchildren.

METHODS

A cross-sectional study was conducted on schoolchildren from Cuenca, Spain, between September and November 2017. FM and FFM were estimated using bioimpedance analysis. The CMR index was calculated from triglycerides-HDL-c ratio, arterial pressure and fasting insulin. The MF index was assessed using handgrip and standing long jump tests. Analysis of covariance models assessed CMR index differences across the MF index and the FM/FFM ratio categories. Mediation analysis examined whether the MF index and the CMR index association were mediated by FM, FFM or FM/FFM ratio.

RESULTS

The analyses involved 485 schoolchildren aged 9-11 years (55.4% girls). Children with a higher MF index had a lower CMR index (p < 0.05). This association did not persist after controlling for FM/FFM. FM, FFM and FM/FFM ratio mediated the relationship between the MF index and the CMR index.

CONCLUSION

Better levels of MF are associated with better cardiometabolic profile, but a healthy body composition is determinant to improve future health.

Advances in Understanding the Interplay between Dietary Practices, Body Composition, and Sports Performance in Athletes

The dietary practices of athletes play a crucial role in shaping their body composition, influencing sports performance, training adaptations, and overall health. However, despite the widely acknowledged significance of dietary intake in athletic success, there exists a gap in our understanding of the intricate relationships between nutrition, body composition, and performance. Furthermore, emerging evidence suggests that many athletes fail to adopt optimal nutritional practices, which can impede their potential achievements. In response, this Special Issue seeks to gather research papers that delve into athletes' dietary practices and their potential impacts on body composition and sports performance. Additionally, studies focusing on interventions aimed at optimizing dietary habits are encouraged. This paper outlines the key aspects and points that will be developed in the ensuing articles of this Special Issue.

Evaluation of physical fitness and health of young children aged between 3 and 6 based on cluster and factor analyses

BACKGROUND

As life improves and sedentary time increases, young children's physical fitness gradually declines.

METHODS

Multi-stage stratified whole cluster sampling was utilized to sample 5584 preschoolers. Young infants' morphology, function, and quality were revealed using cluster and factor analysis.

RESULTS

The cluster analysis separated 3-6-year-olds into two genders: 1,551 men in group A "high physical fitness" 1,499 men in group B "low physical fitness"; 1,213 women in group A and 1,321 women in group B. Young children's fitness was measured by standing long jump(1.00), weight(1.00), and height(1.00). A cluster analysis of 3-4-year-olds classified them into three groups: 272 "muscular strength," 75 "average physical fitness," and 250 "low agility." Young children's health depends on weight (1.00), height (0.57), and chest circumference (0.54). A cluster analysis of the 4-5-year-olds classified them into two groups: 1070 "balance" and 806 "muscular strength." Young children's health depends on weight (1.00), height (0.74), and chest circumference (0.71). A cluster analysis of the 5-6-year-olds divided them into three groups: 1762 "high physical fitness," 384 "obese," and 105 "low physical fitness." Young children's physical health depends on BMI (1.00), weight (1.00), and chest circumference (1.00). Factor analysis demonstrated that muscle strength, body shape, cardiovascular variables, and physical fitness composite components affected young children's health.

CONCLUSION

Women should focus on motor function and strength, while men on flexibility. Male group B "low physical fitness" should focus on strength, motor function, and balance, whereas male group A "high physical fitness" should focus on flexibility. Then, female group A "high physical fitness" should emphasize variety.2) For 3-4-year-olds, group A "muscular strength" should focus on flexibility, and group C "low agility" on motor function. 3) For 4-5-year-olds, group A "balanced" should focus on strength and motor function; 4) For 5-6-year-olds, group B "obese" should emphasize weight loss, and group C "low fitness" should emphasize strength, motor function, and flexibility; 5) Young children's physical fitness depends on muscle strength, body shape, cardiovascular factors, and physical fitness composite.

Reliability of field- and laboratory-based assessments of health-related fitness in preschool-aged children

OBJECTIVES

Reliable measurements of health-related fitness-cardiorespiratory endurance, muscular endurance, muscular strength, body composition, and flexibility-are imperative for understanding and tracking health-related fitness from the preschool age. This study aimed to examine the test-retest reliability of field-based (i.e., sit and reach [standard and back-saver], standing long jump, grip strength); and laboratory-based (i.e., Bruce Protocol Treadmill Test, Wingate Anaerobic Test) assessments of health-related fitness in preschool aged children (4-5 years).

METHODS

Forty-two typically developing children participated in both assessment time points separated by 2-3 weeks. All fitness assessments were administered individually and repeated in the same order by the same assessor. Heteroscedasticity was examined for each parameter. Intraclass correlation coefficients were calculated to assess test-retest reliability.

RESULTS

All parameters were homoscedastic. Test-retest reliability for the field-based tests and Bruce Protocol Treadmill Test parameters were moderate to good. Test-retest reliability for the Wingate Test parameters were good to excellent for maximum pedal rate, peak power, and peak power/kg; mean power and fatigue measured at 10 and 30 s demonstrated moderate to excellent test-retest reliability.

CONCLUSION

The standard sit and reach, grip strength, and short-term muscle power from the Wingate test are reliable assessments of health-related fitness in preschool-aged children.

Paediatric dominant and non-dominant handgrip reference curves and the association with body composition

BACKGROUND

Lack of paediatric reference data limits the utility of handgrip strength as a measure of fitness and well-being.

AIM

To develop paediatric handgrip reference curves and evaluate associations with body size and composition and race/ethnicity group.

SUBJECTS AND METHODS

Handgrip, body size and composition data were obtained from National Health and Nutrition Examination Survey 2011-2014 participants aged 6-20 years. Densitometry-derived fat and appendicular lean soft tissue mass index Z-scores (FMIZ, ALSTMIZ) were generated in participants >8 years. Dominant and non-dominant handgrip reference curves were created using the LMS method. Analyses included sample weights to produce nationally representative estimates.

RESULTS

Differences in handgrip strength according to hand dominance increased with age. Handgrip strength was associated with height and arm length Z-scores (R = 0.42 to 0.47) and ALSTMIZ (R = 0.54). Handgrip strength was higher in the non-Hispanic Black group and lower in the Mexican American compared to non-Hispanic White group. Group differences were attenuated when adjusted for height, arm length or ALSTMIZ.

CONCLUSION

Paediatric handgrip reference curves were generated from which individual Z-scores can be calculated separately for dominant versus non-dominant hand and adjusted for body size. Association with ALSTMIZ suggests handgrip Z-score may be used as a measure of functional body composition.

Musculoskeletal fitness: relative handgrip strength and vertical jump power from 10 to 18 years old

Background

There is an increasing consensus on the relevance of musculoskeletal fitness for health throughout the life cycle, requiring evaluation approaches and description of results capable of characterizing different age groups and body sizes. This study aimed to describe the musculoskeletal fitness of young Portuguese people aged 10-18 through handgrip strength (HGS) and vertical jump power (VJP) and investigate differences between the sexes.

Methods

The sample included 736 participants (359 girls recruited from schools. HGS (kg) was assessed using a handheld dynamometer, and VJP (W) was assessed using a force platform; both measurements were standardized for body mass.

Results

Higher HGS and VJP were observed in boys than in girls from 13 years old (13 years: p ≤ 0.05; 14-18 years: p ≤ 0.001), with no significant differences before this age. The percentile distributions of HGS and VJP are described for each sex using the lambda, mu, sigma (LMS) method. The pattern of development of these variables as a function of age is presented.

Conclusions

Handgrip strength and vertical jump power show differences between the sexes from 13 years of age and similar trajectories to populations in other countries in the same age group.

Moderating role of 1-minute abdominal test in the relationship between cardiometabolic risk factors and adiponectin concentration in adolescents

BACKGROUND

Adiponectin is an anti-inflammatory cytokine secreted by adipose tissue, has been associated with adiposity and cardiometabolic risk, and has controversial results with muscular fitness. The aim of this study was to analyze the interaction of 1-minute abdominal test in the relationship between adiposity, body composition, cardiometabolic risk and adiponectin concentration in adolescents.

METHODS

This is a cross-sectional study conducted with 62 adolescents of both sexes, aged 11 to 16 years, approved by the Ethics Committee of Research in Humans (CAEE: 62963916.0.0000.5223). Body mass, height, abdominal circumference (AC), waist circumference (WC), fat mass (FM), fat-free mass (FFM), high density lipoprotein (HDL-c), low density lipoprotein (LDL-c), triglycerides (TG), adiponectin, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP), 1-minute abdominal test (ABD) were measured. Body mass index (BMI), z-score BMI (BMI-z), triponderal mass index (TMI), and waist-to-height ratio (WHtR) were calculated. The macro PROCESS for SPSS v.24.0 was used for moderation analyses, with linear regression models.

RESULTS

Inverse interactions were found for adiposity (BMI, BMI-z, TMI, AC, WC, WHtR), body composition (FM, FFM) and CMRF (SBP, DBP, MBP, TG) versus 1-minute abdominal test with adiponectin concentration, demonstrating that abdominal test is a moderator in these relationships.

CONCLUSION

We conclude that 1-minute abdominal test may play an important role in the relationship between obesity and cardiometabolic risk. We found that muscular fitness can confer a protective effect on adolescents with high levels of abdominal test.

The association of adolescent fitness with cardiometabolic diseases in late adulthood: A 45-year longitudinal study

OBJECTIVES

The aim of this study was to examine the associations of adolescent cardiorespiratory fitness (CRF), muscular fitness (MF), and speed-agility fitness (SA) with middle-aged cardiometabolic disease risk and explore sex differences.

METHODS

This 45-year prospective cohort study examined the associations between objectively measured fitness at adolescence (12-19 years) and physician-ascertained diabetes mellitus, elevated blood pressure (BP), and coronary heart disease reported either in early (37-44 years) or late (57-64 years) middle age, and self-measurement of waist circumference (WC) in late middle age. Fitness measurements for healthy adolescents in baseline included CRF (1.5 km [girls] and 2 km [boys] run), MF (standing broad jump, sit-ups, pull-ups [boys], and flexed-arm hang [girls]), and SA (50 m dash and 4 × 10 m shuttle run). Logistic regression and general linear models were adjusted for baseline age, sex, and body mass index (BMI), involving data from baseline and at least one follow-up measurement (N up to 1358, 47% males).

RESULTS

Adolescent CRF was inversely, and regardless of adiposity, associated with middle age accumulated burden of cardiometabolic conditions in the whole sample (N = 562, ß = -0.10, 95% confidence intervals [CI] [-0.18, -0.03], p = 0.006), and elevated BP in females (N = 256, OR = 0.71, 95% CI [0.51, 0.91]). Overall, we observed stronger associations in females than in males. An inverse association of adolescent MF and SA with middle-aged WC was observed, but it did not show as consistent associations as with CRF.

CONCLUSIONS

In this study, adolescent fitness, particularly CRF, was inversely associated with the burden of cardiometabolic conditions up to 45 years. Promotion of fitness in youth may be beneficial in preventing adulthood cardiometabolic diseases.

Combined aerobic and muscle-strengthening activity guidelines and their association with obesity in US adolescents

Most of the evidence on physical activity for maintaining a healthy weight in adolescents is based solely on aerobic physical activity alone, with little attention given to the muscle strength component. This study aimed to investigate the associations between aerobic activities and muscle-strengthening activities (MSA) and overweight/obesity among a representative sample of adolescents. Data from the United States-based Youth Risk Behavior Surveillance System for the 2011-2019 cycle were used in this cross-sectional study. Adolescents self-reported their adherence to aerobic and MSA guidelines, as well as their height and weight. Overweight and obesity were defined using the age- and sex-specific criteria of the Centers for Disease Control and Prevention, with a body mass index (BMI) ≥85th and ≥95th percentiles, respectively. We examined the associations between adherence to physical activity guidelines (reference: not meeting either of the physical activity guidelines) and overweight/obesity or obesity using binary logistic regressions. These analyses were adjusted for race/ethnicity, sex, age, screen time, sleep duration, tobacco, alcohol, fruit, vegetables, and soda consumption. A total of 42 829 adolescents (48.98% girls) were included in the study. Of these, 22.23% met both guidelines for physical activity, 30.47% had overweight/obesity, and 14.51% had obesity. Compared with meeting neither guideline, meeting both aerobic and MSA guidelines was associated with lower odds of having overweight/obesity (odds ratio [OR] = 0.64, 95% confidence interval [CI], 0.60 to 0.68) and obesity (OR = 0.52, 95% CI 0.48 to 0.56). These results were consistent across years of assessment, sex, and race/ethnicity. In conclusion, our results highlight the importance of MSA, which is often overlooked in physical activity recommendations in many studies, in combating childhood obesity in the United States.

Effect of Yoga or Physical Exercise on Muscle Function in Rural Indian Children: A Randomized Controlled Trial

BACKGROUND

Synergistic effects of yoga or physical exercise (PE) along with protein supplementation on children's muscle function in rural India have not been studied. Hence, we aimed to study the effect of yoga and PE along with protein supplementation on muscle function in healthy 6- to 11-year-old rural Indian children post 6 months of intervention.

METHODS

A randomized controlled trial on 232 children, recruited into 3 groups, each receiving 1 protein-rich ladoo (148 kcal, 7 g protein/40 g ladoo-an Indian sweet snack) daily and performing (1) yoga (n = 78) for 30 minutes 5 times per week, (2) PE (n = 76) for 30 minutes 5 times per week, or (3) control group (n = 78) no additional exercise. Maximum power, maximum voluntary force (Fmax), and grip strength (GS) were measured. Data were analyzed using paired t tests and a 2-way mixed analysis of variance with post hoc Bonferroni adjustment.

RESULTS

GS, maximum power, and Fmax within yoga group increased significantly (P < .05) from baseline to endline. GS and Fmax increased significantly within PE group postintervention (P < .001). In controls, GS increased (P < .05) at endline. No significant effect of the intervention was observed on the change in maximum power (P > .05) postintervention. The 2 exercise groups showed significant increase in Fmax compared with the control group (P < .05). Similarly, increase in GS was significantly higher in both the exercise groups compared with the control group (P < .05). No significant difference was observed in change in muscle function between the 2 exercise groups (P > .05).

CONCLUSIONS

Structured physical activity along with protein supplementation resulted in improved muscle function in children. Yoga and PE showed a comparable impact on muscle force.

The Effects of Using a Cycling Desk at School on Executive Function, Physical Fitness, and Body Composition in Primary School Children: Impact of Socioeconomic Status

CONTEXT

Physical inactivity and sedentary behaviors are associated with adverse health outcomes in both adults and children. The purpose of this study was to investigate the effects of a 9-week program using a Cycle Desk during school time in French primary school children from high or low socioeconomic status (SES) on body composition, physical fitness (PF), and executive function.

METHODS

Seventy-five (n = 75) children completed a test battery before and after 9 weeks of use of Cycle Desk to evaluate anthropometric characteristics, body composition, PF, and executive function.

RESULTS

Body mass index increased significantly (P = .0095), while body fat decreased after the use of Cycle Desks (P < .0001). Specifically, lean mass increased in the high-SES group while it decreased in the low-SES group (P < .0001). After 9 weeks, there was an improvement in motor skills (P < .0001), upper and lower limbs' strength (P < .0001), and executive function performance (P < .0001). More specifically, the low-SES group had a greater improvement in motor skills and maximal aerobic speed between T0 and T1, compared to the high-SES group (P = .001, P = .023, respectively). In contrast, the high-SES group had a greater improvement in executive function at 9 weeks of use of Cycle Desk compared with the low-SES group (P = .0084).

CONCLUSIONS

The promotion of low-intensity physical activity with the use of a Cycle Desk at school may help offset some adverse effects of excess sedentary behavior among children. Moreover, this strategy appears to be particularly effective in children from low-SES backgrounds. What's New: The use of a Cycle Desk during school time has no deleterious effects on PF as well as cognitive executive functions in primary children. Modifications are more beneficial in children from low SES.

Association of aerobic fitness and grip strength with cognitive and academic performance in Arab children

This study investigated the association between aerobic and muscular fitness with the cognitive control and academic performance of preadolescent Arab children. Ninety-three children aged 10-13years (mean=11.5, SD=0.5) representing eight Arab nations (Egypt, Saudi Arabia, Sudan, Syria, Jordan, Lebanon, Yemen, and Morocco) participated in this cross-sectional study. The participants completed tests for aerobic (progressive aerobic cardiovascular endurance run) and muscular (maximum grip strength) fitness, and cognitive control (flanker task). We assessed their academic performance based on their overall grade point average (GPA). Our analyses revealed that greater aerobic fitness was associated with higher GPA scores and greater muscular fitness was associated with a shorter response time in a task condition requiring extensive cognitive control (incongruent condition). No association was found between aerobic fitness and flanker task performance nor between muscular fitness and GPA. These results bridge the knowledge gap on the associations of physical fitness to the cognitive control and academic performance of Arab children, suggesting that the positive associations found in Western and Asian literature can be generalized to the Arab context.

Influence of physical fitness components on personality factors and risk perception of children and adolescents: a cross-sectional study

OBJECTIVES

To examine the associations of cardiorespiratory fitness (VO2 max) and muscular strength with indicators related to the risk scale, such as perceived competence, sensation seeking, competitiveness, risk taking and risk perception in sports.

DESIGN

Cross-sectional study.

SETTING

High schools from the Region of Murcia (Spain).

PARTICIPANTS

Three-hundred-and-seventeen adolescents participated (mean age: 13.69±1.2 years old).

PRIMARY AND SECONDARY OUTCOME MEASURES

Body mass, body height, Course-Navette test, upper limb strength and psychoeducational factors that determine the propensity towards sports accidents in school children, the Sports Accident Propensity Scale were evaluated. It was performance t-test for independent samples, stepwise multiple linear regression models and a multiple mediation analysis.

RESULTS

The analysis showed significant differences with respect to sex in height, VO2 max, handgrip strength and in all factors of the questionnaire (p=0.02-<0.01). Adolescents who presented greater VO2 max, strength in the handgrip test and age showed a higher score in factors 1 and 3. Higher scores in factor 2 were associated with better VO2 max and strength in handgrip test. Youngers and better values of strength in the handgrip showed higher score in factors 4 and 5. The mediation analysis with two mediating variables (handgrip strength and VO2 max) showed a significant indirect effect. When handgrip strength and VO2 max were included in the equations, the association between sex and each factor ceased to be significant.

CONCLUSION

This study highlights the potential benefits of muscular strength (handgrip) and VO2 max in the perceived risk scale, and the variable of age on this.

TRIAL REGISTRATION NUMBER

Clinical trial: NCT05544370 (pre-results).

Normative-referenced values for health-related fitness among Czech youth: Physical fitness data from the study IPEN Adolescent Czech Republic

OBJECTIVES

The aim of this study was to developed sex- and age-specific normative-referenced percentile values for health-related fitness among 12 to 18 years old Czech youth.

METHODS

This study included cross-sectional data from 1,173 participants (50.7% boys) collected between 2013 and 2016. Participants were recruited from 32 elementary or secondary schools across eight cities located in the Czech Republic. Health-related fitness was objectively measured using both anthropometric (height, body mass, and sum of skinfolds) and performance (20-m shuttle run for cardiorespiratory endurance, modified push-ups for muscular strength/endurance, and V sit-and-reach for flexibility) tests. Sex- and age-specific normative values were calculated using the Lambda Mu Sigma method. Sex- and age-related differences in means were expressed as standardized effect sizes.

RESULTS

Normative percentiles were tabulated and displayed as smoothed curves. Among boys, measures of health-related fitness generally increased with age, except for an age-related decline in the sum of skinfolds and a plateau in V sit-and-reach. Among girls, most measures of health-related fitness increased from age 12 to 16 years before stabilizing, except for the sum of skinfolds, which remained stable from age 12 to 18 years. The sex-related differences were large with boys having higher cardiorespiratory endurance and muscular strength/endurance than girls. Girls compared to boys had higher flexibility.

CONCLUSIONS

This study presents the most up-to-date sex- and age-specific normative-referenced percentile values for health-related fitness among Czech youth. Normative values may be useful for fitness and public health screening and surveillance, for example, by helping to identify youth with low fitness who might benefit from a fitness-enhancing intervention.

Short-Term Impact of Exercise Fitness Testing in a Pediatric Metabolic and Obesity Clinic: Initiative to Improve Health Care Quality

This 2-phase pilot initiative determined whether (1) fitness testing could feasibly be implemented in pediatric practice, and (2) short-term changes in fitness and body mass index occur with Specific, Measurable, Attainable, Relevant, and Time-based (SMART) goals. Phase 1 (N = 580), clinic feasibility: evidence-based prognostic tests were successfully performed to measure cardiorespiratory fitness (CRF; 3-minute bench step), strength (handgrip dynamometry), and flexibility (sit-and-reach distance). Mean CRF percentile was 58.1 (worst >95 percentile, best <5 percentile), strength percentile was 73.5, and flexibility was 42.3 (worst <5 percentile, best >95 percentile). Phase 2, goal setting and follow-up: SMART fitness goals were developed. In phase 2, patients demonstrated 11.9% and 12.4% improvements in CRF and strength percentiles (P < .05) respectively. All patients who were assigned a strength goal improved handgrip strength. Body mass index percentile changes were not different by SMART goal target. Fitness testing was feasible and successfully improved CRF and strength in children at high risk of metabolic complications and future disability.

Impact of the COVID-19 lockdown on physical fitness among college women living in China

PURPOSES

The purpose of this study was to evaluate the effects of the COVID-19 lockdown on physical fitness among college women living in China and to explore how fitness changed with different physical conditions.

METHODS

We performed repeated measures of BMI, 800 m running and sit-up performance assessment on college women from one university in China pre and post the COVID-19 lockdown. A total of 3658 (age 19.15 ± 1.08 yr.) college women who completed the same assessment pre and post the COVID-19 lockdown were included in the analysis. We analyzed the data using one way ANOVA and paired-samples t-test.

RESULTS

Due to the COVID-19 lockdown, the result shows a significant increase in BMI by 2.91% (95% CI =0.33, 0.40) and a significant decline in 800 m running and sit-up by 7.97% (95% CI =0.69, 0.77) and 4.91% (95% CI = -0.27, -0.19), respectively. College women in the highest quartile level of physical condition (Quartile 4) had more decreases than college women in the lowest quartile level (Quartile 1). Their BMI level was increased by 3.69% and 0.98% in college women in Quartile 4 and Quartile 1, respectively. Their performance of 800 m running was decreased by 9.32% and 7.37% in college women in Quartile 4 and Quartile 1, respectively. Their performance of sit-up was decreased by 13.88% in college women in Quartile 4 while it increased by 10.91% in college women in Quartile 1, respectively.

CONCLUSIONS

The COVID-19 lockdown might increase the BMI level and decrease 800 m running and sit-up performance among college women living in China. The decrease for college women in higher quartile level of physical condition (Quartile 4) were more seriously while college women in lower quartile level of physical condition (Quartile 1) were modest.

Current situation and factors influencing physical fitness among adolescents aged 12 ∼ 15 in Shandong Province, China: A cross-sectional study

Adolescent physical fitness serves not merely as a current barometer of well-being but as a significant prognosticator of future health trajectories. Amidst the tumult of socioeconomic metamorphoses and pronounced lifestyle transitions enveloping China-mirroring global trends-the imperative to elucidate the present landscape of adolescent physical fitness intensifies. Moreover, discerning the myriad determinants underpinning it becomes paramount. In this context, our research endeavored to meticulously delineate the physical fitness milieu of adolescents residing in Shandong Province, systematically unpacking the multifarious influencers thereof. The insights garnered herein furnish an empirical foundation, primed to guide the sculpting of calibrated interventions, targeting the enhancement of health in this pivotal population cohort. In an extensive evaluative survey conducted in 2023 concerning the physical fitness of Shandong's student populace, a cohort of 33,211 adolescents aged 12 to 15 years was delineated utilizing a stratified random cluster sampling technique. This exercise meticulously quantified the physical fitness indices across diverse gender, age, and household registration classifications, subsequently computing the concomitant qualified rates. Employing multivariable logistic regression analysis, this investigation delved into the determinants modulating the adolescents' physical fitness qualified rate. For 2023, the aggregate fitness qualified rate stood at 91.94 % for the adolescents aged 12 ∼ 15 in Shandong Province. Gender-wise, female adolescents registered a qualified rate of 92.25 %, marginally eclipsing their male peers at 91.63 % (P < 0.05). An age-related trend in qualified rates was discernible, with marked variations across different age bands (P < 0.05): 91.37 % for 12-year-olds, 91.79 % for 13-year-olds, 91.81 % for 14-year-olds, and a zenith of 92.87 % for 15-year-olds. A geographical dichotomy emerged wherein rural adolescents distinctly outperformed their urban counterparts, notching up a 92.28 % qualified rate versus 91.64 % in urban settings (P < 0.05). The multivariable logistic regression analysis showed that after adjusting for gender, age, and household registration characteristics, adolescents had a lower odds of failing the physical fitness tests whose parents both liked physical exercises, whose parents supported children's participation in physical exercise, who participated in physical exercise sessions 3 ∼ 5 times per week or more than 5 times per week, who exercised for 0.5 ∼ 1 h each time or more than 1 h each time, who engaged in moderate intensity physical exercise, who slept 6 ∼ 8 h per day or more than 8 h per day, who consumed breakfast 3 ∼ 6 times per week or daily. On the other hand, adolescents had a higher odds of failing the physical fitness tests who always exposed to passive smoking, who spent 1 ∼ 3 h on screen per day or more than 3 h on screen per day, who spent more than 3 h doing homework per day, who consumed fast food 2 ∼ 3 times per week or more than 3 times per week. The physical fitness trajectory of adolescents residing within Shandong Province is tethered to a mosaic of determinants. This underscores the imperative for a synergistic strategy, harmonizing parental, scholastic, and societal vectors, to cultivate the salubrious maturation of this pivotal cohort.

Association between muscle strength and executive function in Tibetan adolescents at high altitude in China: Results from a cross-sectional study at 16-18 years of age

BACKGROUND

In recent years, adolescents have shown a trend of decreasing muscle strength, especially in the upper limbs, and it affects the development of executive functions. However, few studies have been conducted on Tibetan adolescents in high-altitude regions of China. To this end, this study investigated upper limb muscle strength and executive function in Tibetan adolescents in Tibetan regions of China and analyzed the association between them.

METHODS

A three-stage stratified whole-group sampling method was used to test and investigate grip strength, executive function, and basic information in 1093 Tibetan adolescents from Tibet, a high-altitude region of China. A chi-square test and one-way ANOVA were used to compare the basic status and executive function of Tibetan adolescents with different muscle strength. Multiple linear regression analysis and logistic regression analysis were used to analyze the correlations that existed between muscle strength and each sub-function of executive function.

RESULTS

The differences between the inconsistently and congruent reaction times of Tibetan adolescents with different grip strength levels (P75 ) at high altitude in China were statistically significant (F-values of 32.596 and 31.580, respectively; P-values <.001). The differences between the 1-back and 2-back response times for the refresh memory function were also statistically significant (F-values of 9.055 and 6.610, respectively; P-values <.01). Linear regression analysis showed that after adjusting for the relevant covariates, the 1-back reaction time of Tibetan adolescents in the grip strength < P25 group increased by 91.72 ms (P < .01); the 2-back reaction time of Tibetan adolescents in the grip strength < P25 group increased by 105.25 ms (P < 0.01), using grip strength > P75 as the reference group. Logistic regression analysis showed that, after adjusting for relevant covariates, Tibetan adolescents in the grip strength < P25 group had a higher risk of developing 2-back dysfunction (OR = 1.89, 95% CI: 1.24,2.88), using grip strength >P75 as the reference group (P < .01). The risk of cognitive flexibility dysfunction (OR = 1.86, 95% CI: 1.16, 2.98) was also increased (P < .05).

CONCLUSION

There was a significant correlation between grip strength and executive function of refresh memory function and cognitive flexibility in Tibetan adolescents in high altitude areas of China. Those with higher upper limb muscle strength had shorter reaction time, that is, better executive function. In the future, we should focus on improving the upper limb muscle strength of Tibetan adolescents at high altitude in China to better promote the development of executive function.

Supporting adolescents' participation in muscle-strengthening physical activity: protocol for the 'Resistance Training for Teens' (RT4T) hybrid type III implementation-effectiveness trial

INTRODUCTION

In Australia, only 22% of male and 8% of female adolescents meet the muscle-strengthening physical activity guidelines, and few school-based interventions support participation in resistance training (RT). After promising findings from our effectiveness trial, we conducted a state-wide dissemination of the 'Resistance Training for Teens' (RT4T) intervention from 2015 to 2020. Despite high estimated reach, we found considerable variability in programme delivery and teachers reported numerous barriers to implementation. Supporting schools when they first adopt evidence-based programmes may strengthen programme fidelity, sustainability, and by extension, programme impact. However, the most effective implementation support model for RT4T is unclear.

OBJECTIVE

To compare the effects of three implementation support models on the reach (primary outcome), dose delivered, fidelity, sustainability, impact and cost of RT4T.

METHODS AND ANALYSIS

We will conduct a hybrid type III implementation-effectiveness trial involving grade 9 and 10 (aged 14-16 years) students from 90 secondary schools in New South Wales (NSW), Australia. Schools will be recruited across one cohort in 2023, stratified by school type, socioeconomic status and location, and randomised in a 1:1:1 ratio to receive one of the following levels of implementation support: (1) 'low' (training and resources), (2) 'moderate' (training and resources+external support) or 'high' (training and resources+external support+equipment). Training includes a teacher workshop related to RT4T programme content (theory and practical sessions) and the related resources. Additional support will be provided by trained project officers from five local health districts. Equipment will consist of a pack of semiportable RT equipment (ie, weighted bars, dumbbells, resistance bands and inverted pull up bar stands) valued at ~$A1000 per school. Study outcomes will be assessed at baseline (T0), 6 months (T1) and 18 months (T2). A range of quantitative (teacher logs, observations and teacher surveys) and qualitative (semistructured interviews with teachers) methods will be used to assess primary (reach) and secondary outcomes (dose delivered, fidelity, sustainability, impact and cost of RT4T). Quantitative analyses will use logistic mixed models for dichotomous outcomes, and ordinal or linear mixed effects regression models for continuous outcomes, with alpha levels set at p<0.025 for the outcomes and cost comparisons of the moderate and high support arms against the low support arm.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the University of Newcastle (H-2021-0418), the NSW Department of Education (SERAP:2022215), Hunter New England Human Research Ethics Committee (2023/ETH00052) and the Catholic Schools Office. The design, conduct and reporting will adhere to the Consolidated Standards of Reporting Trials statement, the Standards for Reporting Implementation Studies statement and the Template for Intervention Description and Replication checklist. Findings will be published in open access peer-reviewed journals, key stakeholders will be provided with a detailed report. We will support ongoing dissemination of RT4T in Australian schools via professional learning for teachers.

TRIAL REGISTRATION NUMBER

ACTRN12622000861752.

Physical fitness among children with diverse weight status during and after the COVID-19 pandemic: a population-wide, cohort study based on the Slovenian physical fitness surveillance system (SLOfit)

Background

COVID-19 public health crisis has exerted immediate negative impacts on children's physical fitness, but the longer-term effects are not clear, and the impact on children with excess weight is yet unknown. We examined changes in multiple components of physical fitness in response to COVID-19 imposed restrictions, but also a year after the restrictions were terminated, and compared these trends in groups of boys and girls with normal weight, overweight, or obesity before the pandemic.

Methods

Information was gathered through Slovenia's national fitness surveillance system, and included 41,330 children (19,890 girls), aged 5-17, who had their fitness levels measured yearly from 2019 to 2022. Multilevel linear mixed models, fitted separately for boys and girls, were used to model the individual-level trends over time in centile score for each fitness test across 3 weight groups.

Findings

Overall fitness levels decreased markedly across all weight categories between 2019 and 2020, with the largest decreases in Total Fitness Index observed in children with normal weight and overweight (-8.4 and -7.7 centiles for boys and -8.3 and -8.8 for girls, respectively, p < 0.001). While there was some recovery in the overall fitness level between 2020 and 2022, it remained much lower in 2022 compared to 2019 across most groups, apart from boys with obesity. Fitness components that had the largest impact on general fitness trends were cardiorespiratory fitness, lower body power, body core, and upper body strength.

Interpretation

A severe decline in fitness that has not come close to returning to pre-pandemic levels in most population groups of youth begs for urgent population-wide initiatives that will provide additional opportunities for physical activity to youth. Among vulnerable groups, girls with overweight and obesity deserve a special focus of these policies.

Funding

Horizon 2020 (Grant no. 774548), Slovenian National Research Agency (Grant no. P5-0142), Croatian Science Foundation (Grant no. DOK-2020-01-3728).

Dose-response associations of Monitor-Independent Movement Summary with health-related fitness in youth

The purpose of this study was to determine the dose-response associations between Monitor-Independent Movement Summary (MIMS) units and health-related fitness in youth. The sample comprised US children and adolescents who participated in the 2012 National Youth Fitness Survey (NNYFS; N = 1158, 48.9% female). Health-related fitness domains were assessed using tests of cardiorespiratory endurance (timed maximal and graded treadmill tests), muscular strength (modified pull-up and grip tests), and muscular endurance (plank test). Movement data were collected using wrist-worn ActiGraph accelerometers with raw data processed using MIMS and the calculated metrics of average MIMS/day, Peak 60-min MIMS, and Peak 30-min MIMS. Weighted regression models examined linear associations between MIMS metrics and fitness test scores. Nonlinear associations were examined using weighted spline models with knots placed at the 10th, 50th, and 90th percentiles. Models were adjusted for covariates and fit was examined using the coefficient of determination (R2 ). The strongest adjusted linear relationships included a positive association between MIMS/day (per every 1000 units) and maximal endurance times (b = 5.5 s, p < 0.001) and between Peak 60-min MIMS (per every 10 units) and estimated aerobic capacity (b = 1.7 mL/kg/min, p < 0.001), modified pull-ups (b = 0.7 reps, p < 0.001), and plank test scores (b = 5.0 s, p < 0.001). Linear spline models had slightly higher R2 values (R2 range = 16.9%-74.8%) compared to linear models (R2 range = 15.0%-74.5%). The relationship between MIMS metrics and fitness test scores was best modeled as piecewise linear functions. Although all MIMS metrics associated with cardiorespiratory endurance, Peak 60-min MIMS showed stronger associations with tests of muscular strength and endurance.

Effects of Resistance Training on Academic Outcomes in School-Aged Youth: A Systematic Review and Meta-Analysis

BACKGROUND

The primary aim of our systematic review and meta-analysis was to investigate the effect of resistance training on academic outcomes in school-aged youth.

METHODS

We conducted a systematic search of six electronic databases (CINAHL Complete, PsycINFO, SCOPUS, Ovid MEDLINE, SPORTDiscus and EMBASE) with no date restrictions. Studies were eligible if they: (a) included school-aged youth (5-18 years), and (b) examined the effect of resistance training on academic outcomes (i.e., cognitive function, academic achievement, and/or on-task behaviour in the classroom). Risk of bias was assessed using the appropriate Cochrane Risk of Bias Tools, funnel plots and Egger's regression asymmetry tests. A structural equation modelling approach was used to conduct the meta-analysis.

RESULTS

Fifty-three studies were included in our systematic review. Participation in resistance training (ten studies with 53 effect sizes) had a small positive effect on the overall cognitive, academic and on-task behaviours in school-aged youth (standardized mean difference (SMD) 0.19, 95% confidence interval (CI) 0.05-0.32). Resistance training was more effective (SMD 0.26, 95% CI 0.10-0.42) than concurrent training, i.e., the combination of resistance training and aerobic training (SMD 0.11, 95% CI - 0.05-0.28). An additional 43 studies (including 211 effect sizes) examined the association between muscular fitness and cognition or academic achievement, also yielding a positive relationship (SMD 0.13, 95% CI 0.10-0.16).

CONCLUSION

This review provides preliminary evidence that resistance training may improve cognitive function, academic performance, and on-task behaviours in school-aged youth.

PROSPERO REGISTRATION

CRD42020175695.

Long-term function, body composition and cardiometabolic health in midlife former athletes: a scoping review

While sports medicine has traditionally focused on recovering from injury and returning athletes to sport safely after injury, there is a growing interest in the long-term health of athletes. The purpose of this scoping review was to (1) summarise the literature (methodologies and findings) on physical function, body composition and cardiometabolic health in midlife (age 40-65 years) former competitive athletes compared with non-athlete controls, (2) identify areas for future study in long-term health in athletes and (3) determine outcomes that could be evaluated in a future systematic review(s). We searched PubMed, CINAHL, Web of Science and SPORTDiscus for studies published between 2000 and 2022 evaluating former athletes and controls on physical function, body composition and/or cardiometabolic measures using MeSH terms. We identified 20 articles that met our criteria. Outcomes varied considerably across studies, most of which were cross-sectional and evaluated only males. Limited data suggest that former endurance athletes have leaner body compositions, higher aerobic capacity and better cardiometabolic indicators than controls; former athletes who maintain higher physical activity (ie, self-reported exercise) are healthier than those who do not; and former team sport athletes, who have higher injury prevalence, may have poorer functional performance than controls who were recreationally active in college. Studies rarely evaluated functional performance, did not control for prior injury or diet and seldom assessed current physical activity levels. Future research should include females and evaluate sex differences, control for prior sports-related injury(ies), quantify physical activity, use standardised outcome measures including performance-based functional assessments and incorporate longitudinal designs.

[Movement as a Neuromodulator: How Physical Activity Influences the Physiology of Adolescent Depression]

Movement as a Neuromodulator: How Physical Activity Influences the Physiology of Adolescent Depression Abstract: In the context of adolescent depression, physical activity is becoming increasingly recognized for its positive effects on neuropathology. Current scientific findings indicate that physical training affects the biological effects of depression during adolescence. Yet the pathophysiology of adolescent depression is not yet fully understood. Besides psychosocial and genetic influences, various neurobiological factors are being discussed. One explanation model describes a dysfunction of the hypothalamus-pituitary-adrenal axis (HPA axis) with a sustained elevation in cortisol concentration. Recent studies highlight neuroimmunological processes and a reduced concentration of growth factors as causative factors. These changes appear to lead to a dysregulation of the excitation and inhibition balance of the cerebral cortex as well as to cerebral morphological alterations. Regular physical training can potentially counteract the dysregulation of the HPA axis and normalize cortisol levels. The release of proinflammatory cytokines is inhibited, and the expression of growth factors involved in adult neurogenesis is stimulated. One should ensure the synergistic interaction of biological and psychosocial factors when designing the exercise schedule (endurance or strength training, group or individual sports, frequency, duration, and intensity). Addressing these open questions is essential when integrating physical activity into the guidelines for treating depressive disorders in children and adolescents.

Can Moving More and Sitting Less Improve the Academic Engagement of Adolescents?- A Study Based on Junior High School Students in Shanghai, China

Purpose

The purpose of this study was to examine the relationships between academic engagement and moderate-to-vigorous physical activity (MVPA), muscle-strengthening exercise (MSE) and sedentary behavior (SB) among adolescents, so as to provide evidence from the perspective of exercising for students to learn efficiently, teachers to improve classroom teaching, and schools to improve educational quality.

Methods

A questionnaire survey was conducted in 12 junior high schools in Shanghai, China, which were selected by a multi-stage stratified cluster sampling method. Then, with the valid data of 2078 students collected from the survey. A data analysis was performed using SPSS Statistics 26.0. Multiple linear regression models were adopted to analyze the factors affecting adolescent academic engagement and to determine whether MVPA, MSE, and SB play roles in it.

Results

(1) The differences in academic engagement depended on the exercise adherence to the recommended amount of MVPA, MSE, and screen-based SB. (2) In terms of the three independent variables of total time, MSE (β = 0.206) and MVPA (β = 0.175) showed a significant positive correlation with academic engagement, while SB (β = -0.155) was negatively correlated with academic engagement. (3) From the linear regression model of eight combination groups divided by the exercise adherence to the recommended amount of MVPA, MSE and SB, the group that met none of the recommendations (β = -0.235) showed a significant negative effect on academic engagement, while the groups that met any two or all three of the recommendations demonstrated strong positive correlations with academic engagement (P < 0.001).

Conclusion

Increasing adolescents' muscle-strengthening exercise and moderate-to-vigorous physical activity and reducing sedentary behavior can effectively promote academic engagement. Therefore, adolescents are suggested to reach the recommended amounts of physical activity, muscle-strengthening exercise, and sedentary behavior so as to improve academic engagement more effectively.

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

Background/Objective

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

Methods

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

Results

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

Conclusion

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

A scalable school-based intervention to increase early adolescents' motor competence and health-related fitness

Schools are key settings for the promotion of students' physical activity, fitness, and motor competence. The purpose of our study was to investigate the efficacy of a 5-month-long intervention program that aimed to increase students' motor competence and health-related fitness during school days. We conducted a quasi-experimental study with 325 Finnish Grade 5 (Mage  = 11.26, SD = 0.33) students from five schools. Two schools were allocated to the intervention group and three schools to the control group. The intervention consisted of three components: (a) weekly 20 min session during regular PE lessons, (b) weekly 20 min session during recess, and (c) daily 5-minute-long classroom activity breaks. All activities were designed to systematically develop different elements of motor competence and fitness. The following assessments were conducted at baseline and 5-months: cardiorespiratory fitness levels were measured by 20-meter shuttle run test, muscular fitness by curl-up and push-up tests, and motor competence by 5-leaps and throwing-catching combination tests. We analyzed the data using a multi-group latent change score modeling. Results showed that students in the intervention group developed significantly better in 20-meter shuttle run test (β = 0.269, p = 0.000, 95% CI [0.141, 0.397]; +5.0 laps), push-up (β = 0.442, p = 0.000, 95% CI [0.267, 0.617]; +6.5 repetitions), curl-up (β = 0.353, p = 0.001, 95% CI [0.154, 0.552]; +7.8 repetitions), and throwing-catching combination tests (β = 0.195, p = 0.019, 95% CI [0.033, 0.356]; +1.1 repetitions) than students in the control group. The intervention program appeared to be feasible and effective in increasing students' cardiorespiratory fitness, muscular fitness, and object control skills. This indicates that guided school-based physical activity programs can be influential in promoting physical fitness and motor competence among early adolescent students.

A Functional Drink Containing Kaempferia parviflora Extract Increases Cardiorespiratory Fitness and Physical Flexibility in Adult Volunteers

Owing to the reputation of Kaempferia parviflora and the crucial role of oxidative stress on the disturbance of physical fitness, the effect of a functional drink containing K. parviflora extract (KP) on the physical fitness of healthy adult volunteers was assessed. Healthy male and female volunteers (19-60 years old) were randomly divided into placebo, KP90, and KP180 groups. All the subjects in KP90 and KP180 were directed to consume a functional drink containing K. parviflora extract at doses of 90 and 180 mg per serving per 80 mL, respectively. Parameters of physical fitness, including cardiovascular endurance, muscular strength and endurance, flexibility, and body composition, together with changes in lactate, creatinine kinase, and oxidative stress markers were assessed before the intervention, and at 6 and 12 weeks of intervention. The oxidative stress markers, creatine kinase, and lactate were also measured. Subjects who consumed the developed drink had increased VO2 max and improved performance in a timed shuttle run test and 5 min distance run, and exhibited decreased oxidative stress and lactate; therefore, K. parviflora extract can be successfully used for developing a KP drink to improve cardiorespiratory fitness and physical performance by improving oxidative stress and lactate.

Temporal trends in the physical fitness of Hong Kong children aged 6-12 years between 2003-04 and 2015-16

Low physical fitness in childhood is linked with poor health now and in later life. This study estimated temporal trends in physical fitness for Hong Kong children aged 6-12 years from 2003-04 to 2015-16. Objectively measured body size and physical fitness data for 27,513 children were obtained from four population-representative surveys of Hong Kong primary school students. Temporal trends in means were estimated by population-weighted linear regression. Trends in distributional characteristics were visually described. Overall, there was a small increase in mean height (effect size (ES) = 0.20 (95%CI: 0.13, 0.28)), with a negligible increase (ES < 0.2) in mean body mass. When adjusted for trends in age, gender, and body size, there was a small decline in sit-and-reach performance (ES = -0.43 (95%CI: -0.43, -0.42)), a small improvement in 9-min run/walk performance (9-to-12-year-olds, ES = 0.26 (95%CI: 0.26, 0.27)), with negligible declines in handgrip strength, 6-min run/walk (6-to 8-year-olds), and sit-ups performance. Temporal trends were not always uniform across the population distribution, with declines in run/walk, sit-ups, and sit-and-reach performance generally largest in children with low fitness. Increased national health promotion strategies that address culturally specific factors are encouraged to further improve the existing trends, especially for children with low fitness.