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

School-Based Circuit Training Intervention Improves Local Muscular Endurance in Primary School Students: A Randomized Controlled Trial

BACKGROUND

This study aimed to explore the effectiveness of a 12-week circuit training program in improving local muscular endurance in normal-weighted primary school students.

METHODS

The study involved a parallel-group randomized trial with 606 primary school boys assigned to an experimental or a control group. The participants underwent a 12-week circuit training program that involved multi-joint, total-body workouts using body weight, resistance bands, and medicine ball exercises. The study measured the participants' local muscular endurance during sit-ups, dynamic trunk extensions on a Roman bench (DTE), and push-ups.

RESULTS

After adjusting for the baseline, the treatment-grade interaction was significant for sit-ups (F = 7.74, p < 0.001, η_p² = 0.04), DTE (F = 6.49, p < 0.001, η_p² = 0.03), and push-ups (F = 9.22, p < 0.001, η_p² = 0.05), where the experimental treatment was more beneficial than the control. The treatment effect seemed to vary depending on the individual's baseline local muscle endurance capacity. As the baseline local muscular endurance values increased, the treatment and grade effects became less beneficial.

CONCLUSION

A 12-week circuit training program involving body weight, resistance bands, and medicine ball exercises suits school-based programs and can improve local muscular endurance in normal-weighted primary school boys. The experimental treatment was more effective than the control, and the individual baseline muscular endurance should be considered when designing training programs.

Socio-cultural attitudes toward the body as a predictor of motivation for physical activity in young people brought up in Asian and European culture-Chinese-Polish comparison

The influence of sociocultural attitudes toward the body on young people's physical activity has received increasing attention. However, there is a lack of cross-cultural research in this area. The main aim of this research was to identify the similarities and differences in the sociocultural attitudes toward the body of Polish and Chinese young people who grew up in European and Asian cultures and to analyze their effect on the motivation for physical activity. A cross-sectional research study was conducted among 18- to 30-year-old Polish (n = 259) and Chinese (n = 208) young people. The variables were measured using the Sociocultural Attitudes towards Appearance Questionnaire 3 (SATAQ 3) and the Inventory of Physical Activity Objectives (IPAO). Descriptive and comparative statistics, Spearman's rho, and the stepwise multiple regression analysis were used. The main analysis showed There are both similarities and significant differences in the performance of young Polish and Chinese men and women on the variables studied; Internalization-Athlete, Pressures, and Internalization-General are universal sociocultural predictors of motivation for physical activity among young people in Poland and China; Information is a specific sociocultural predictor of motivation for physical activity in Polish young people. The cultural nuances need to be considered in understanding young people's Motivation for undertaking physical activity.

Are the digit ratio (2D:4D) and hand grip strength related to Parkinson disease in elderly males?

BACKGROUND

Sex hormones affect the pathogenesis of Parkinson patients and it has been suggested that gender is the most important factor in the development and progression of Parkinson's disease. Studies have shown that the second to fourth digit ratio (2D:4D) is affected by the prenatal testosterone and estrogen levels and can predict predisposition to disease. In addition, decreased muscle strength in people with Parkinson's has been repeatedly reported. Hand grip strength (HGS) is a suitable measure to evaluate the musculoskeletal system among the elderly and it is considered as an indicator of the overall strength of the body. This study aimed at investigating the relationship between Parkinson's disease and HGS and 2D:4D ratio.

METHODS

In this study 117 elderly men with Parkinson disease (mean age of 61.66 ± 11.28 years) and 156 healthy control subjects (mean age of 61.86 ± 6.29 years) participated. After determining the level of disability of Parkinson patients by a neurologist (level of disability in the range of 1-4), anthropometric indices (height, weight, length of the second and fourth fingers) and maximum HGS were measured.

RESULTS

Although 2D:4D ratios (right and left hand) of male patients with Parkinson's disease were higher than those of healthy males, this difference was not statistically significant (P = 0.12, P = 0.40; respectively). Conversely, HGS for the right and left hands of Parkinson patients were significantly lower than those of healthy males (P = 0.02, P = 0.03; respectively). The results showed a significant negative relationship between Parkinson disease and the right and left HGS (R = -0.16, P = 0.005; R = -0.17, P = 0.003; respectively). Parkinson disease had no significant relationship with 2D:4D of the right hand, left hand, mean finger ratio and DR-L 2D:4D (P > 0.05). The regression results showed that the right and left HGS were not able to predict Parkinson disease (P = 0.25, P = 0.16; respectively).

CONCLUSION

We concluded that HGS was negatively associated with the Parkinson disease, but conversely, 2D:4D may not be a valuable biomarker of elevated risk of Parkinson in elderly males.

Physical fitness before and during the COVID-19 pandemic: Results of annual national physical fitness surveillance among 16,647,699 Japanese children and adolescents between 2013 and 2021

BACKGROUND

Limited nationally representative evidence is available on temporal trends in physical fitness (PF) for children and adolescents during the coronavirus disease 2019 (COVID-19) pandemic. The primary aim was to examine the temporal trends in PF for Japanese children and adolescents before and during the COVID-19 pandemic. The secondary aim was to estimate the concurrent trends in body size (measured as body mass and height) and movement behaviors (exercise, screen, and sleep time).

METHODS

Census PF data for children in Grade 5 (aged 10-11 years) and adolescents in Grade 8 (aged 13-14 years) were obtained for the years 2013-2021 from the National Survey of Physical Fitness, Athletic Performance, and Exercise Habits in Japan (n = 16,647,699). PF and body size were objectively measured, and movement behaviors were self-reported. Using sample-weighted linear regression, temporal trends in mean PF were calculated before the pandemic (2013-2019) and during the pandemic (2019-2021) with adjustments for age, sex, body size, and exercise time.

RESULTS

When adjusted for age, sex, body size, and exercise time, there were significant declines in PF during the pandemic, with the largest declines observed in 20-m shuttle run (standardized (Cohen's) effect size (ES) = -0.109 per annum (p.a.)) and sit-ups performance (ES = -0.133 p.a.). The magnitude of the declines in 20-m shuttle run and sit-ups performances were 18- and 15-fold larger, respectively, than the improvements seen before the pandemic (2013-2019), after adjusting for age, sex, body size, and exercise time. During the pandemic, both body mass and screen time significantly increased, and exercise time decreased.

CONCLUSION

Declines in 20-m shuttle run and sit-ups performances suggest corresponding declines in population health during the COVID-19 pandemic.

Efficacy of school-based interventions for improving muscular fitness outcomes in children: A systematic review and meta-analysis

The World Health Organization recommends that children should engage in an average of 60 min of moderate-to-vigorous physical activity (MVPA) per day and should perform activities that strengthen muscle and bone at least 3 days a week. Public health professionals as well as pediatric researchers have identified schools as a strategic place to promote muscular strength development. Thus, the aim of this systematic review and meta-analysis was to investigate the efficacy of school-based exercise interventions for improving muscular fitness (MF) in children. Searches were conducted in three databases. Eligible criteria were randomized and non-randomized controlled trials evaluating the effects of school-based exercise interventions on MF (i.e. muscular strength, muscular power, and local muscular endurance) in children under 13 years of age. Risk of bias by the National Institutes of Health tool was appraised, and pooled effect sizes (Hedges'g) were calculated using random-effects inverse-variance analyses. Seventeen studies enrolling 1653 children (28% girls were analyzed). Exercise interventions, mostly combined interventions targeting selected domains of MF, were associated with significant moderate increases in local muscular endurance (g = 0.65 95% CI, 0.13 to 1.17, p = 0.020; I²= 85.0%) and muscular strength and muscular power (g = 0.33 95% CI, 0.16 to 0.51, p = 0.001; I²= 59.3%), with higher effects using interventions with ≥3 sessions per week. Our findings indicate that school-based exercise that includes strength building exercises may improve MF in children and, consequently, prepare modern day youth for the demands of exercise and sport activities. HighlightsSchool-based muscle and bone strengthening exercises performed at least 3 days per week may serve to support the development of muscular fitness in girls and boysIntegrative interventions that include a variety of strength and conditioning activities seem to be a promising strategy to promote muscular fitness in school environmentFuture research should standardize assessment methods for use with children in the school context and should include interventions with girlsIt is of interest to a growing number of health care providers, fitness professionals and physical education teachers to encourage participation in well-designed muscle and bone strengthening exercises.

The Effect of Different Physical Exercise Programs on Physical Fitness among Preschool Children: A Cluster-Randomized Controlled Trial

BACKGROUND

Preschool children are in a period of rapid physical and psychological development, and improving their level of physical fitness is important for their health. To better develop the physical fitness of preschool children, it is very important to understand the behavioral attributes that promote the physical fitness of preschool children. This study aimed to determine the effectiveness of and the differences between different physical exercise programs in improving preschool children's physical fitness.

METHODS

A total of 309 preschool children aged 4-5 years were recruited from 5 kindergartens to participate in the experiment. They were cluster-randomly allocated into five groups: basic movements (BM) group, rhythm activities (RA) group, ball games (BG) group, multiple activities (MA) group, and control (CG) group. The intervention groups received designed physical exercise programs with a duration of 30 min 3 times per week for 16 weeks. The CG group received unorganized physical activity (PA) with no interventions. The physical fitness of preschool children was measured using the PREFIT battery before and after the interventions. One-way analysis of variance, a nonparametric test; generalized linear models (GLM); and generalized linear mixed models (GLMM) were used to examine differences during the pre-experimental stage among groups and to assess the differential effects of the intervention conditions on all outcome indicators. The intervention condition models were adjusted for potential confounders (baseline test results, age, gender, height, weight, and body mass index) explaining the main outcome variance.

RESULTS

The final sample consisted of 253 participants (girls 46.3%) with an average age of 4.55 ± 0.28 years: the BG group (n = 55), the RA group (n = 52), the BM group (n = 45), the MA group (n = 44), and the CG group (n = 57). The results of the generalized linear mixed model and generalized linear model analyses indicated significant differences for all physical fitness tests between groups, except for the 20 m shuttle run test and the sit-and-reach test after the interventions. Grip strength was significantly higher in the BG and MA groups than in the BM group. The scores for standing long jump were significantly higher in the MA group than in the other groups. The scores for the 10 m shuttle run test were significantly lower in the BG and MA groups than in the CG, BM, and RA groups. The scores for skip jump were significantly lower in the BG and MA groups than in the RA group. The scores for balance beam were significantly lower in the BG and MA groups than in the RA group and significantly lower in the BG group than in the BM group. The scores for standing on one foot were significantly higher in the BG and MA groups than in the CG and RA groups and significantly higher in the BM group than in the CG group.

CONCLUSIONS

Physical exercise programs designed for preschool physical education have positive effects on the physical fitness of preschool children. Compared with the exercise programs with a single project and action form, the comprehensive exercise programs with multiple action forms can better improve the physical fitness of preschool children.

Individual and combined impact of physical fitness on health-related quality of life during adolescence: DADOS Study

The purpose of the present study was to investigate the individual and combined impact of physical fitness components at baseline on health-related quality of life (HRQoL) at 24-month follow-up in adolescents. This longitudinal research included 199 adolescents (13.9±0.3 years at baseline) from the DADOS study. Cardiorespiratory fitness was assessed using the 20-m shuttle run test. Muscular strength was assessed using the standing broad jump test. Motor competence was assessed using the 4 × 10-m shuttle run test. A physical fitness z-score was calculated as the mean of the z-scores values of each fitness test. A fitness index ranging from 0 to 3 was created according to the number of physical fitness components in which participants achieved high levels according to normative values. HRQoL was evaluated by the KIDSCREEN-10 questionnaire. Linear regression analyses showed that cardiorespiratory fitness, muscular strength, and the physical fitness z-score at baseline were individually associated with HRQoL at follow-up (β ranging from 0.123 to 0.183; all p < 0.05). Moreover, logistic regression analysis revealed that adolescents with a fitness index ≥1 at baseline were more likely to achieve high HRQoL at 24-month follow-up, compared with their peers with an index of 0 (OR ranging from 3.554 to 9.087; all p < 0.05). Our results revealed an individual and cumulative positive impact of physical fitness at baseline on HRQoL at 24-month follow-up. These findings underline the key role of promoting the enhancement of overall physical fitness components in order to improve adolescents' health and well-being.Highlights Adolescents with high levels of cardiorespiratory fitness, muscular strength and motor competence will benefit from a greater physical and mental well-being over the time.The more physical fitness components with optimal levels, the greater likelihood of reaching better HRQoL over the time.Public health authorities should focus on the promotion of multiple physical fitness components to increase adolescent's likelihood of achieving greater HRQoL over the time.

Short-Term Muscle Power Is Related to Lower Limb Muscle Volume in Young Children

PURPOSE

Muscle power is a component of muscular fitness and is proportional to its volume. Reduced muscular fitness in children is linked to negative health outcomes. Associations between muscle volume (MV) and power have not been examined in young children and could reveal important insights into early neuromuscular development.

METHOD

Forty-four children (2-8 y) completed 3 tests of short-term muscular power: repeated anaerobic sprint test, vertical jump, and horizontal jump. MV was assessed using 3D ultrasound for 3 lower limb muscles (rectus femoris, medial gastrocnemius, and tibialis anterior) and summed for across legs. Associations between muscular power and summed MV were assessed using Pearson correlation (r). Sex-based differences in muscular power and MV were assessed using 1-way analysis of covariance.

RESULTS

Moderate-strong associations (r = .57 - .87) were found between muscular power and summed MV. No differences were found between boys and girls for height, weight, MV, or muscular power.

CONCLUSIONS

Young children who have larger lower limb muscles perform better at tasks dependent on short-term muscular power, such as running and jumping, compared with children with smaller muscles. Sex-based differences in short-term muscular power do not exist in young children and reflect similar anthropometry, including lower limb MV.

Relevance and Effectiveness of Combined Resistance and Balance Training to Improve Balance and Muscular Fitness in Healthy Youth and Youth Athletes: A Scoping Review

BACKGROUND

Balance and resistance training applied as single-mode interventions have proven to enhance measures of balance and/or muscular fitness in youth and youth athletes. Less is known on the effectiveness of combined or sequenced balance and resistance training in youth and youth athletes.

OBJECTIVE

The objective of this scoping review was to describe the effects of concurrently performed balance and resistance training (i.e., metastable resistance training) and different sequencing schemes of balance and resistance training on measures of balance and/or muscular fitness in healthy youth and youth athletes. We additionally aimed to identify knowledge gaps in the literature.

METHODS

According to the principles of a scoping review, we followed a broad research question, identified gaps in the literature, and reported findings on the level of single studies but did not aggregate and meta-analyze outcomes across studies. For this purpose, systematic literature searches were conducted in the electronic databases PubMed (including MEDLINE), Web of Science, and SPORTDiscus from inception until August 2022. We included metastable resistance training and sequenced balance and resistance training studies in healthy youth and youth athletes aged 6-18 years that investigated the training-induced effects on measures of balance (e.g., stork balance test) and muscular fitness (e.g., countermovement jump test) in contrast to active/passive controls. The Physiotherapy Evidence Database (PEDro) scale was used to assess the risk of bias. The Strength of Recommendation Taxonomy (SORT) was applied for the whole scoping review on levels A (high strength of recommendation) to C (low strength of recommendation) and for individual studies on levels 1 (high-quality evidence) to 3 (low-quality evidence).

RESULTS

The strength of recommendation for the scoping review was level B based on inconsistent or limited-quality evidence. Eleven randomized controlled trials were eligible to be included in this scoping review and each study was rated as 'limited-quality evidence'. A median PEDro score of 6 was computed across the included studies. Four studies examined the effects of metastable resistance training (e.g., plyometric training on unstable surfaces) on measures of balance and/or muscle fitness in youth athletes. The remaining seven studies investigated the impact of sequenced balance and resistance training (e.g., blocked balance training followed by blocked resistance training) on measures of balance and/or muscle fitness in youth and youth athletes. The duration of the intervention programs ranged from 6 to 10 weeks with 2-weekly to 3-weekly exercise sessions. Participants' age range was 10-18 years (mean 15 years). Ten studies examined young male and female athletes from different sports (i.e., basketball, handball, soccer) and one study physical education students. Metastable resistance training compared with plyometric training performed on stable surfaces showed no extra effect on measures of balance and muscular fitness. Stable plyometric training appears to be even more effective to improve jump performance. Sequenced balance and resistance training in the form of a mesocycle of balance followed by plyometric training seems to be particularly effective to improve measures of balance and muscular fitness in young athletes. This scoping review identified knowledge gaps that may indicate future research avenues: (i) comparative studies should be designed to examine how sex, age, maturity status, and expertise level impact on the adaptive potential following metastable resistance training or sequenced balance and resistance training in youth and youth athletes, (ii) at least one established measure of balance and muscular fitness should always be included in study designs to allow future comparison between studies and to aggregate (meta-analyze) findings across studies and (iii) studies are needed that examine neuromuscular and tendomuscular adaptations following these exercise types as well as dosage effects.

CONCLUSIONS

According to the results of this scoping review, balance training should be an essential training component for youth that is incorporated with the resistance training exercises or introduced at least a month before resistance and plyometric training within a periodized training program. More research is needed to examine the moderating roles of age, maturity status, and sex.

Inequalities in the association between adherence to the Mediterranean diet and physical fitness in the young population during the COVID-19 lockdown

OBJECTIVE

this study analyzed the association between adherence to the Mediterranean diet and proxy-reported physical fitness among Spanish and Brazilian youths during the COVID-19 lockdown according to several inequality indicators.

METHODS

we conducted a cross-sectional study with parents and guardians of children and adolescents from Spain and Brazil. The evaluation process was through the use of online questionnaires. Adherence to the Mediterranean diet was assessed using the Mediterranean Diet Quality Index in Children and Adolescents. Proxy-reported physical fitness was determined using the International Fitness Scale. Inequality indicators (gender, nationality, socioeconomic status, and parents/guardians' education level) were evaluated with a survey completed by the participants' parents/guardians. Binary logistic regression models estimated the association between adherence to the Mediterranean diet and proxy-reported physical fitness, with stratification according to inequality variables. A total sample of 1,099 Spanish and Brazilian individuals (47.6% girls, aged 3 to 17 years) were included in the analysis.

RESULTS

compared to the "improvement needed to Mediterranean diet" category, the "optimal Mediterranean diet" group was significantly associated with "very good" physical fitness in boys (OR = 1.5; 95 % CI: 1.0-2.1) and in participants with parents/legal guardians' education level without university studies (OR = 1.5; 95 % CI: 1.0-2.4).

CONCLUSIONS

gender and parents/guardians' education level plays a significant role in the association between the "optimal Mediterranean Diet" and "very good" physical fitness level in Spanish and Brazilian children and adolescents. Future prospective studies are needed to investigate the role of inequality indicators in this relationship.

Ability of the Sport Education Model to Promote Healthy Lifestyles in University Students: A Randomized Controlled Trial

Although studies on sports performance, leadership abilities, group cohesion, and learning motivation have revealed that the sport education model contributes considerably to the development of healthy lifestyles, few studies have explored the development of healthy lifestyles from an educational intervention perspective. This study fills this gap in the literature. In addition, studies have mostly recruited elementary or middle school students; few have explored the effectiveness of sport education for college students. To fill this gap, this study conducted quasi-experimental research on university students by using different teaching strategies, with healthy lifestyles as the dependent variable. The research participants consisted of 95 students from Ming Chuang University distributed to an experimental group or control group. The experimental group was taught using the sport education model; the control group was taught using direct instruction. The results indicate that the sport education model has a stronger ability to promote healthy lifestyles than conventional teaching. Additionally, the results suggest that teachers should apply specific teaching strategies to cultivate and reinforce exercise habits and healthy behaviors among students. On the basis of the results, the researchers suggest that physical education teachers establish effective teaching strategies and promote healthy lifestyles to students.

Cardiorespiratory fitness, muscle fitness, and physical activity in children with long QT syndrome: A prospective controlled study

Background

In children with congenital long QT syndrome (LQTS), the risk of arrhythmic events during exercise commonly makes it difficult to balance exercise restrictions versus promotion of physical activity. Nevertheless, in children with LQTS, cardiorespiratory fitness, muscle fitness, and physical activity, have been scarcely explored.

Materials and methods

In this prospective, controlled, cross-sectional study, 20 children with LQTS (12.7 ± 3.7 years old) and 20 healthy controls (11.9 ± 2.4 years old) were enrolled. All participants underwent a cardiopulmonary exercise test, a muscular architecture ultrasound assessment, (cross-sectional area on right rectus femoris and pennation angle), a handgrip muscular strength evaluation, and a standing long broad jump test. The level of physical activity was determined using with a waist-worn tri-axial accelerometer (Actigraph GT3X).

Results

Peak oxygen uptake (VO2peak) and ventilatory anaerobic threshold (VAT) were lower in children with LQTS than in healthy controls (33.9 ± 6.2 mL/Kg/min vs. 40.1 ± 6.6 mL/Kg/min, P = 0.010; 23.8 ± 5.1 mL/Kg/min vs. 28.8 ± 5.5 mL/Kg/min, P = 0.007, respectively). Children with LQTS had lower standing long broad jump distance (119.5 ± 33.2 cm vs. 147.3 ± 36.1 cm, P = 0.02) and pennation angle (12.2 ± 2.4° vs. 14.3 ± 2.8°, P = 0.02). No differences in terms of moderate-to-vigorous physical activity were observed (36.9 ± 12.9 min/day vs. 41.5 ± 18.7 min/day, P = 0.66), but nearly all children were below the WHO guidelines.

Conclusion

Despite similar physical activity level, cardiorespiratory fitness and muscle fitness in children with LQTS were lower than in healthy controls. The origin of this limitation seemed to be multifactorial, involving beta-blocker induced chronotropic limitation, physical and muscle deconditioning. Cardiovascular rehabilitation could be of interest in children with LQTS with significant physical limitation.

Trends in means and distributional characteristics of cardiorespiratory endurance performance for Italian children (1984-2010)

Cardiorespiratory endurance (CRE) is an important health marker. The aim of this study was to examine temporal trends of CRE performance for Italian children between 1984 and 2010. Using a repeated cross-sectional study design, 5303 CRE test results were available for 2520 children aged 11-13 years from a single Northern Italian middle-high school between 1984 and 2010. CRE was measured as 1000-m and 12-min run test performance. With adjustments for BMI, temporal trends in means were estimated using linear regression, with trends in distributional characteristics described visually and estimated as the ratio of coefficients of variation (CVs). There was a significant small increase in BMI (effect size (ES) [95%CI]: 0.40 [0.32, 0.48]) over the entire period. When adjusted for BMI, there were significant small to moderate declines in mean running speed (ES [95%CI]: 1000-m, - 0.34 [-0.39, - 0.29]); 12-min, - 0.65 [-0.70, - 0.60]). Declines were larger for boys compared to girls. Variability substantially increased over time (ratio of CVs: range, 1.7-2.9), with larger declines in children with low running speed compared to children with average or high running speed. Our findings may be important to public health because low CRE is significantly related to current and future health.

Fitness, body composition, and metabolic risk scores in children and adolescents: the UP&DOWN study

We aimed to analyse the longitudinal association between physical fitness (PF) and body composition (BC) with a metabolic risk score (Met4) in children and adolescents and to elucidate whether the association between PF and Met4 differs when using relativized or absolute fitness variables. A total of 188 children (86 females) and 195 adolescents (97 females) were included. Cardiorespiratory fitness (CRF) was determined by the 20-m shuttle run test, and muscular fitness (MF) was determined by hand grip and standing long jump tests. Height and weight were measured, and the body mass index (Kg/m²) was calculated. Triceps and subscapular skinfolds were assessed to compute body fat percentage. Met4 was computed from systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, and glucose levels. Relative CRF was longitudinally and negatively associated with Met4 in female children (β =  -0.031, p = 0.025), while absolute CRF was positively associated with Met4 in male children and adolescents (β = 0.000, p < 0.05). Relative upper and lower-body MF were longitudinally and negatively associated with Met4 in female adolescents (β =  -1.347, β =  -0.005, p < 0.05), while absolute lower-body MF was positively associated with Met4 in male children (β = 0.000, p = 0.019). BC was longitudinally and positively associated with Met4 in male children (β-ranging from 0.011 to 0.055, all p < 0.05) and male adolescents (β-ranging from 0.011 to 0.046, all p < 0.05).  Conclusion: BC is more strongly associated with Met4 than PF in children and adolescents. An optimal body weight status should be considered the main objective of health-promoting programs at childhood and adolescence. Furthermore, the way of expressing the fitness variables determines the direction of the association with Met4. What is Known: • Physical fitness is an important health indicator in children and adolescents, with great amount of previous evidence supporting the preventive role of maintaining optimal levels of both cardiorespiratory and muscular fitness for future cardiometabolic issues. What is New: • The way of reporting physical fitness variables can affect the associations between physical fitness features and cardiometabolic outcomes. Since body composition variables have a great impact on both physical fitness and cardiometabolic health, relativizing physical fitness performance by body composition could lead to erroneous conclusions.

Top 10 International Priorities for Physical Fitness Research and Surveillance Among Children and Adolescents: A Twin-Panel Delphi Study

BACKGROUND

The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts.

OBJECTIVE

This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents.

METHODS

Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel.

RESULTS

There was strong between-panel agreement (panel 1: r_s = 0.76, p < 0.01; panel 2: r_s = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) "conduct longitudinal studies to assess changes in fitness and associations with health". This was followed by (ii) "use fitness surveillance to inform decision making", and (iii) "implement regular and consistent international/national fitness surveys using common measures".

CONCLUSIONS

The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

Fat-free mass and maturity status are determinants of physical fitness performance in schoolchildren and adolescents

OBJECTIVES

The objective of the study was to verify whether (FFM), maturity status (MS) and chronological age (CA) are determinants of physical fitness performance, and to analyze FFM and physical performance aligned by CA and MS in children and adolescents.

METHODS

A descriptive correlational study was carried out in 863 schoolchildren. Weight, height, and waist circumference (WC) were evaluated. Body mass index (BMI), FFM, fat mass (FM), MS (Age at peak height velocity, APHV) were calculated. The physical tests of velocity 20 m, agility 5 m x 10rep, and horizontal jump (HJ) were evaluated.

RESULTS

The APHV was estimated in boys at 14.0 ± 0.36APHV and in girls at 11.96 ± 0.49APHV. The relationships between CA and APHV with FFM was r = 0.80 in boys and r = 0.44 to 0.45 in girls. The relationships between FFM and physical tests in boys were [HJ (r = 0.70), agility 5m x 10rep (r = -0.68), velocity (r = -0.61)] and in girls [HJ (r = 0.42), agility 5m x 10rep (r = -0.52), velocity (r = -0.20)]. The differences in FFM and physical fitness tests were more pronounced when aligned by APHV than by CA.

CONCLUSION

It was verified that both FFM, CA, and APHV are determinants of physical fitness performance. In addition, the APHV should be introduced in physical education as a means of ranking physical performance among schoolchildren.

Effects of fundamental movement skills on health-related quality of life in Chinese school-age children: the mediating role of physical fitness level

Background

The primary purpose of this study is to analyze the relationship between school-age children's fundamental movement skills (FMS), physical fitness levels, and the health-related quality of life (HRQoL); To explore the mediating role of physical fitness levels between school-age children's FMS and HRQoL.

Methods

In the cross-sectional survey in 2021, 334 school-age children aged 6-10 (8.20 ± 1.16) were recruited from primary schools in Jinhua City, Zhejiang Province, China. Test of Gross Motor Development 2 (TGMD-2), National Standards for Students' Physical Health, and Pediatric Quality of Life Inventory TM Version 4.0 (PedsQL™ 4.0) were used to investigate the FMS, physical fitness level, and HRQoL of school-age children. Hierarchical regression was used to analyze the relationship among FMS, physical fitness levels, and HRQoL. Bootstrap is used to evaluate the mediating role of physical fitness levels in the relationship between FMS and HRQoL.

Results

The higher the FMS and physical fitness, the higher the school-age children's HRQoL, physical functioning, social functioning, and school functioning (r = 0.244-0.301, p < 0.01). In addition, developing children's FMS promotes physical fitness levels (r = 0.358, p < 0.01). The regression analysis results of controlling gender, age, and body mass index z (BMI-z) scores showed that FMS significantly positively predicted the physical functioning (β = 0.319, p < 0.01), social functioning (β = 0.425, p < 0.01), and school functioning (β = 0.333, p < 0.01) of school-age children. When the physical fitness level enters the regression equation, the absolute value of the regression coefficient of FMS decreases. However, it can still significantly predict the physical functioning (β = 0.211, p < 0.01) and school functioning (β = 0.142, p < 0.05) of school-age children. Simple intermediary analysis shows that physical fitness level plays an intermediary role between FMS, physical functioning (indirect effect = 0.089 [95% Confidence interval (CI) = 0.015,0.195]), and school functioning (indirect effect = 0.065 [95% CI = 0.007,0.150]).

Conclusion

This study shows that physical fitness levels mediate the relationship between FMS and HRQoL. Encouraging the development of FMS and promoting physical fitness levels of school-age children can effectively improve the HRQoL of school-age children.

Association of muscular strength with total and central adiposity in adolescents with intellectual disability

BACKGROUND

It has been established that for youth without disabilities, muscular strength (MS) is negatively associated with total and central adiposity. However, this relationship has not been clearly established for youth with intellectual disability (ID). The purpose of this study was to examine the association of MS with total and central adiposity in adolescents with ID.

METHOD

Participants were 59 adolescents (40 males and 19 females: age 16.29 ± 1.66 years) with ID. Total and central adiposity were evaluated with dual-energy x-ray absorptiometry (DXA), body mass index (BMI), BMI z-score, waist circumference (WC), and conicity index (C-index). MS was evaluated with the score on the Bruininks-Oseretsky Test of Motor Proficiency (range, 0 to 42, with higher scores indicating better performance). Sex-specific maturity offset equations were used to evaluate somatic maturity. Spearman's correlation coefficients and sequential multiple regression were used to examine associations between MS and adiposity.

RESULTS

Muscular strength score was negatively associated with BMI (sr = -0.32; P < 0.05), percent body fat (%BF; total, trunk, android and gynoid regions) (sr = -0.51 to -0.58; P < 0.01), and android-to-gynoid fat ratio (sr = -0.29; P < 0.05). After control for somatic maturity and sex, regression analysis indicated that MS score explained 10%-17% of the variance in BMI, BMI z-score, %BF (total, trunk, android and gynoid regions), WC, C-index and android-to-gynoid fat ratio.

CONCLUSIONS

These findings suggest that MS is associated with DXA- and anthropometric-determined total and central adiposity among adolescents with ID.

Regulatory Mechanisms of Muscle Mass: The Critical Role of Resistance Training in Children and Adolescent

Muscle mass and strength are subjected to several regulations. We found endocrine signals such as growth hormone, insulin-like growth factor 1, testosterone, thyroid hormones, and glucocorticoids among them. Neural inputs also influence muscle development, modulating mass and strength. Among the external stimuli that modulate these muscular features is physical training such as resistance and endurance training. Specifically, resistance training can mediate an increase in muscle mass by hypertrophy in adults, but the effects in children and adolescents are full of myths for most of the population. However, the evidence shows that the impact of resistance training on children and adolescents is clear and provides a wide range of benefits. However, qualified professionals must be available since exercise prescription and subsequent supervision must follow this population's abilities, needs, and interests.

Handgrip Strength Is Associated with Metabolic Syndrome and Insulin Resistance in Children and Adolescents: Analysis of Korea National Health and Nutrition Examination Survey 2014-2018

Background

Reduced handgrip strength (HGS) is associated with adverse cardiometabolic health outcomes. We examined HGS, metabolic syndrome (MetS), and insulin resistance (IR) in children and adolescents.

Methods

The following population-based data from 2,797 participants (aged 10-18 years) of the Korea National Health and Nutrition Examination Survey 2014-2018 were analyzed: complete anthropometric measures, HGS, MetS, and IR (subgroup with fasting insulin, n=555). HGS was analyzed as the combined HGS (CHGS) and the normalized CHGS (nCHGS=CHGS divided by body weight).

Results

At a mean age of 14.4 years, 276 participants (9.9%) had abdominal obesity, 56 (2.0%) had MetS, and 118 (20.9%) had IR. Individual components of MetS and IR were inversely associated with the nCHGS. The odds ratios (ORs) for MetS and IR decreased significantly with higher nCHGS after adjustment for sex, age, physical activity, and sedentary times. The optimal cut-off values that predicted MetS were 0.80 kg/kg (males) and 0.71 kg/kg (females), with significant associations with MetS (OR: 7.4 in males; 5.7 in females) and IR (OR: 3.3 in males; 3.2 in females) observed when nCHGS values were lower than those cut-offs.

Conclusion

HGS is associated with MetS and IR and might be a useful indicator of cardiometabolic risk factors in children and adolescents.

Relationship between health-related quality of life and physical fitness in Norwegian adolescents

AIMS

This cross-sectional study investigated the association between health-related quality of life (HRQoL), cardiorespiratory fitness (CRF) and muscular fitness in 14-year-old adolescents.

METHODS

Norwegian adolescents (N = 1985) carried out a 10-min running test to assess cardiorespiratory fitness and three different muscular fitness tests (handgrip, sit-ups, and standing broad jump) and answered the KIDSCREEN-27 questionnaire to provide HRQoL data. Linear-mixed effect models were applied to detect relationships among the variables.

RESULTS

Running-test results were positively associated with higher scores in the following KIDSCREEN domains: physical well-being, psychological well-being, autonomy and parent relationships, and school environment (β = 0.01-0.04; p < .01 for all). Performance in sit-ups test was positively associated with higher scores in three out of five KIDSCREEN domains: physical well-being (β = 0.31; p < .001), social support and peers (β = 0.16; p = .023), and school environment scores (β = 0.19; p = .006). An inverse association was found between the handgrip test results and the score on psychological well-being domain (β = - 0.10; p = .013).

CONCLUSIONS

The associations between HRQoL and physical fitness were trivial (abdominal strength and handgrip strength) to small (CRF) but confirmed that earlier findings from children also are applied to adolescents. Explosive strength in the lower body showed no association with HRQoL. Further research should investigate the direction of causality.

TRIAL REGISTRATION

Clinicaltrials.gov ID nr: NCT03817047. Registered 01/25/2019 'retrospectively registered'.

Relationship between Fitness and Healthy Lifestyle

Background: In our study we will refer to the benefits of practicing appropriate fitness exercises that can contribute to maintaining or returning to a closer weight, to achieving an ade-quate physical condition reflected in self-confidence and to adopting a healthy lifestyle.; (2) Methods:.Our theoretical study is based on the analysis of perspectives offered by specialists in fields complementary to physical education, in order to understand not only from a medical but also a social perspective, the importance of fitness in the lives of young people. (3) Results: We believe that the physical exercises that make up the fitness set have beneficial effects on the hu-man body, from the point of view: morphogenetic, physiological, educational, prophylactic and curative. (4) Conclusions: In this context, we believe that it is necessary to reconsider the benefits of fitness - a good remedy against sedentarism and aging, being able to delay, diminish or com-pletely prevent the mechanisms associated with these processes (arterial diseases, diabetes, high cholesterol, etc.). Fitness is part of a healthy lifestyle Keywords: Fitness, Health Lifestyle, Physical exercises

A systematic review and meta-analysis of the benefits of school-based, peer-led interventions for leaders

The aim of our systematic review and meta-analysis was to quantitatively synthesise the effects of school-based peer-led interventions on leaders' academic, psychosocial, behavioural, and physical outcomes. Eligible studies were those that: (i) evaluated a school-based peer-led intervention using an experimental or quasi-experimental study design, (ii) included an age-matched control or comparison group, and (iii) evaluated the impact of the intervention on one or more leader outcomes. Medline, Sportdiscus, Psychinfo, Embase, and Scopus online databases were searched on the 24th of October, 2022 which yielded 13,572 results, with 31 included in the narrative synthesis and 12 in the meta-analysis. We found large positive effects for leaders' attitudes toward bullying (d = 1.02), small-to-medium positive effects for leaders' literacy (d = 0.39), and small positive effects for leaders' self-esteem (d = 0.18). There were mixed findings for behavioural outcomes and null effects for physical outcomes. Notable limitations of this research are the inclusion of a relatively small number of studies, and high heterogeneity in those included. Our findings have the potential to inform educational practice, but also highlight the need for further research examining the mechanisms that might account for the observed effects. Our systematic review was prospectively registered with PROSPERO (CRD42021273129).

Florentine Normative Values for Physical Fitness in Adolescents Aged 14-15 Years

Physical fitness during youth is linked to the health of today's young people and future adults. Therefore, fitness evaluation can direct any physical exercise interventions and verify improvements. The study aims to provide normative values of the physical fitness of the Florentine adolescent population. This cross-sectional study enrolled 1915 subjects aged 14 and 15 from the first and second high school classes. Tests were performed to assess cardiovascular endurance, upper and lower limb strength, running speed and agility, and lower limb muscle flexibility. Sex and age-related percentiles were elaborated. The study included 1028 subjects in the first class (aged 14.3 ± 0.8 years; 54.5% females) and 887 in the second class (aged 15.3 ± 0.7 years; 53.4% females). Males showed higher values than females except for flexibility. Furthermore, both genders show increased results in transitioning from the first to the second class, except for muscle flexibility and running speed. The percentiles of the present study provide normative values of the physical fitness of the 14-15-year-old Florentine adolescent population. These results, characterized by a sociocultural specificity linked to the territory from which they were collected, can contribute to the assessment and improvement of the physical status of young people, promoting current and future health.

The Developing Brain: Considering the Multifactorial Effects of Obesity, Physical Activity & Mental Wellbeing in Childhood and Adolescence

Obesity during childhood has been associated with many important physiological and neurological health considerations. Specifically concerning are the associations between youth obesity and declines in mental health, as shown with increasing rates of adolescent depression and anxiety worldwide. The emergence of mental health disorders commonly arises during adolescent development, and approximately half the global population satisfy the criteria for at least one psychiatric disorder in their lifetime, suggesting a need for early intervention. Adolescence is critical time whereby brain structure and functions are not only negatively associated with obesity and declines in mental health, while also coinciding with significant declines in rates of physical activity among individuals in this age group. Physical activity is thus a prime candidate to address the intersection of obesity and mental health crises occurring globally. This review addresses the important considerations between physiological health (obesity, aerobic fitness, physical activity), brain health (structure and function), and mental wellbeing symptomology. Lastly, we pose a theoretical framework which asks important questions regarding the influence of physiological health on the association between brain health and the development of depression and anxiety symptoms in adolescence. Specifically, we hypothesize that obesity is a mediating risk factor on the associations between brain health and psychopathology, whereas physical activity is a mediating protective factor. We conclude with recommendations for promoting physical activity and reducing sedentary time.

Elevated Risk of Overweight/Obesity-Related Markers and Low Muscular Fitness in Children Attending Public Schools in Chile

In Chile, children of low socioeconomic status usually attend public schools and have few opportunities to engage in healthy behaviors. This may increase their risk of overweight/obesity and low muscular fitness. Therefore, we aimed to determine the association between the school type attended with overweight/obesity-related markers and the muscular fitness of children in Chile. We included 1410 children (6-13 years old) attending public, subsidized, or private schools. Overweight/obesity-related markers included BMI Z-scores, waist circumference, and body fat percentage. Muscular fitness assessment included handgrip strength and standing long jump. The odds ratios [95% CI] of overweight/obesity, elevated waist circumference, elevated body fat, low handgrip strength, and low standing long jump were compared between school types. Compared with boys attending public schools, those attending subsidized or private schools had lower odds ratios of low handgrip strength (0.63 [0.42-0.94] and 0.44 [0.25-0.78], respectively). Girls attending subsidized schools, compared with those in public schools, had lower odds of overweight/obesity (0.63 [0.44-0.90]) and of having low handgrip strength (0.51 [0.34-0.78]). Compared with girls in public schools, those attending private schools had lower odds (vs. public schools) of overweight/obesity (0.45 [0.28-0.74]), of having elevated body fat (0.53 [0.29-0.96]), and of having low standing long jump (0.41 [0.21-0.77]). The elevated risk of overweight/obesity-related markers and lower muscular fitness in children, particularly girls, attending public schools increase their current and future disease risk. This suggests that childhood socioeconomic status plays a central role in determining disease risk. Health-promoting interventions specifically focused on children from disadvantaged contexts are required.

Comparison of Motor Difficulties Measured in the First Year of School among Children Who Attended Rural Outdoor or Urban Conventional Kindergartens

BACKGROUND

Kindergartens can potentially contribute substantially to the daily level of physical activity and development of motor skills and might be an ideal setting for improving these as a public health initiative. We aimed to examine whether children from rural outdoor kindergartens had a lower risk of motor difficulties than children from urban conventional kindergartens.

METHODS

Motor test results were measured during the first school year by school health nurses using a six-item test of gross- and fine motor skills (jumping, handle a writing tool, cutting with a scissor following a line, one-leg stand on each leg, throwing and grabbing). Register-based information was available on potential confounding factors.

RESULTS

We included 901 children from outdoor kindergartens and 993 from conventional kindergartens with a mean (SD) age of 6.5 years (0.4). The children from the two types of kindergarten differed according to demographic information, with outdoor kindergarten children more often being from more affluent families (long maternal education level: 47.5% vs. 31.0%, p < 0.0001) and fewer girls attending the outdoor kindergartens (42.7% vs. 49.5%, p = 0.003). In the adjusted models, we found no evidence of differences in the risk of motor difficulties between children attending either type of kindergarten (OR: 0.95, 95%CI: 0.71; 1.27, p = 0.72).

CONCLUSION

Our results do not support outdoor kindergartens as a potential intervention to improve motor abilities among children. Randomized controlled trials are needed to confirm these findings.

Multiscale Impact of Environmental and Socio-Economic Factors on Low Physical Fitness among Chinese Adolescents and Regionalized Coping Strategies

As low physical fitness in adolescents increases their risk of all-cause mortality in future adulthood as well as regional public health budgets, many scholars have studied the factors influencing physical fitness in adolescents. However, the spatial non-stationarity and scale between physical fitness and influencing factors in adolescents are often neglected. To rectify this situation, this study constructed a multi-scale geographically weighted regression model based on data from the China National Student Fitness Survey and the China Statistical Yearbook in 2018 to investigate the spatial patterns of factors influencing low physical fitness among adolescents. The results showed that the influencing factors for measuring the physical fitness of Chinese adolescents had significant spatial heterogeneity and multi-scale effects. The local R² values were relatively low in the western region of China. Consideration should be given to increasing the lifestyle and ethnic and cultural characteristics of local residents when selecting influencing factors in the future. The physical fitness of men was mainly influenced by socio-economic factors, while that of women was influenced by natural environmental factors. According to the different spatial distribution patterns of MGWR, this study suggests that each region should develop regionalized strategies to cope with the low physical fitness of adolescents, including taking advantage of the natural environment to develop physical fitness promotion projects, accelerating the upgrading of industrial structures in the north-eastern and western regions, and the need to remain cautious of rapid urbanization in the east.

"Sharpening Your Mind, Strengthening Your Body" Parental Perceptions on the Use of Strength and Conditioning in Children and Youth

Although strength and conditioning is beneficial and safe for children to engage in there remain myths and misconceptions form parents regarding its use which prevent its widespread take up. This study explored parents' attitudes and beliefs about strength and conditioning in their children. Thirty-one parents (21 dads, 10 mums) took part in one of four focus groups exploring the topic. Thematic analysis was used resulting in themes and sub themes centred on: Beliefs; Determinants; Coach Education; Coach Communication; and Relationship to the Game. There were also smaller aspects of the focus groups which touched upon autonomy as a concept related to implementation of strength and conditioning specifically. Overall, parents of children who play grassroots sport hold generally positive perceptions on use of strength and conditioning with their children, considering it beneficial for both physical and mental development. Key factors relating to successful implementation of strength and conditioning for children focus on having a qualified coach in that particular area (rather than a generic sports coach), effective communication between coach and parents, and coach and children in terms of the benefits of engaging with strength and conditioning.

Physical fitness in children and adolescents with inflammatory bowel disease: protocol for a case-control study

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic disorder of the gastrointestinal tract, associated with adverse health consequences that may adversely influence physical activity and body composition in youth. These effects may lead to changes in physical fitness, which is positively associated with health-related outcomes. The aim is to assess health-related physical fitness levels in paediatric patients with IBD and to compare these levels with those in healthy matched controls.

METHODS AND ANALYSIS

This trial is a bicentric case-control study. Fifty paediatric patients with IBD and 50 matched healthy controls will be recruited (1:1), and physical fitness levels (cardiorespiratory fitness, muscular strength, speed/agility and flexibility) will be assessed. The primary outcome is cardiorespiratory fitness, which will be compared between children and adolescents with IBD and healthy controls matched for age, sex and body mass index class. We will assess whether the two groups differ with respect to other physical fitness components and cardiovascular risk in adulthood according to sex-specific cut-offs for a healthy cardiorespiratory fitness level in adolescents. We will identify relationships between physical fitness and characteristics of IBD, quality of life and daily physical activity.

ETHICS AND DISSEMINATION

This study was approved by the Research Ethics Committee (Comité de Protection des Personnes, Centre-Ouest I, Tours, France; No 2019-A02651-56) and was declared to the Commission Nationale de l'Informatique et des Libertés. All procedures will be performed according to the ethical standards of the 1975 Declaration of Helsinki, as revised in 2008, and the European Union's Guidelines for Good Clinical Practice. Written informed consent will be obtained from the youths and their parents. Research findings will be disseminated in peer-reviewed journals and scientific meetings, as well as in social media and IBD family support groups.

TRIAL REGISTRATION NUMBER

NCT04647578.

Association between Physical Fitness, Physical Activity Level and Sense of Coherence in Swedish Adolescents; An Analysis of Age and Sex Differences

INTRODUCTION

The aim of this study was to investigate the association between physical fitness, physical activity, and sense of coherence (SOC) in Swedish adolescents (n = 2028 males, n = 1287 females) aged 14 to 18 using a cross-sectional design.

METHODS

Using the Swedish Physical power Mental harmony and Social capacity (FMS) student profile, participants performed physical tests measuring their cardiovascular ability (CV) and muscular strength. Questionnaires were used to measure physical activity levels (PA), the participation in organized physical training, sedentary behavior (SB), screen time, and SOC value. Multiple linear regression analyses were used to analyze the association between SOC and independent variables.

RESULTS

The regression analyses explained a small, shared variance between SOC and the independent variables in boys (4.3%) and girls (3.3%). SB showed a positive association with SOC both in girls (β = 0.114, p = 0.002) and boys (β = 0.109, p = 0.013). Abdominal strength was positively associated, while VO₂max was inversely associated, with SOC (β = 0.113, p = 0.022; β = -0.109, p = 0.026, respectively) in boys. Girls had poorer fitness than boys did across all age groups except at age 18. PA levels decreased from age 14 to 18 in girls and boys, but without differences between sexes. Abdominal strength decreased from age 14 to 18 in girls and boys. In general, girls had lower SOC than boys across all age groups.

CONCLUSIONS

Poor sedentary behavior was significantly associated with weaker SOC for both genders, indicating overall physical activity as the most important factor for stronger SOC. However, emotional support in vulnerable environments may have a bigger impact than physical activity or sedentary behavior on the SOC value for adolescents.

Correlations between muscle strength and psychological health in Chinese adolescents: a cross-sectional analysis

Background

Studies indicate that muscle strength is associated with good mental health. However, it remains unclear whether muscle strength is directly correlated with psychological symptoms in Chinese adolescents. Given the declining muscle strength and worrying mental health status of Chinese adolescents, the present study aimed to estimate the correlation between muscle strength and psychological symptoms as well as explore the gender differences in those correlations in Chinese adolescents.

Method

From April to July 2018, a total of 14,344 Chinese adolescents from eight provinces were selected using a stratified clustered sampling method. Psychological symptoms were evaluated using the Multidimensional Sub-health Questionnaire of Adolescents (MSQA), a verified and validated questionnaire that assesses three psychological areas: emotional symptoms, behavioral symptoms, and social adaptation difficulties. Muscle strength was assessed using grip strength, sit-ups, and standing long jump. The Chi-square test was used to compare the detection rates of the different categories of psychological symptoms. A logistic regression analysis was used to analyze the correlations between muscle strength and psychological symptoms and explore the gender differences in those correlations in Chinese adolescents.

Results

In general, the detection rate of psychological symptoms for Chinese adolescents was 21.39%. Males had a higher detection rate of psychological symptoms (22.12%) than females (20.66%, p < 0.05). Psychological symptoms were present in significantly fewer Chinese adolescents with a muscle strength index >P75 (19.26%) than among Chinese adolescents with a muscle strength index ≤P25 (23.00%) (χ² = 23.417, p < 0.01). Compared with females, the OR values for males in most groups were over one (OR = 1.04-1.43), indicating that males have a higher risk of psychological symptoms than females.

Conclusions

The psychological symptom detection rate of Chinese adolescents is correlated with muscle strength. Psychological symptoms were more correlated to muscle strength in males than in females. The significance of the present study lies in the important insights for integrated mental and physical fitness intervention strategies that promote muscle strength and psychological symptoms simultaneously.

The Feasibility and Acceptability of an Online CPD Programme to Enhance PE Teachers' Knowledge of Muscular Fitness Activity

Schools provide an opportunity to enhance muscular fitness of English youth during physical education (PE). Continued professional development (CPD) among teachers may improve muscular fitness activity delivery in schools. This study sought to assess the feasibility and acceptability of an online CPD programme to enhance PE teachers' knowledge of muscular fitness activity.

METHODS

Co-production of an online CPD platform was undertaken with five secondary school PE teachers. A quasi-experimental pre-post control group design for the CPD was adopted (CPD group n = 76, control n = 32). Upon CPD completion feedback was solicited for qualitative analysis.

RESULTS

Pre-and-post CPD knowledge quiz data were available from 65 participants (55.4% male). The median knowledge quiz change score was significantly higher in the CPD group than in the wait list control group (CPD score vs. control score; U =37, z = -5.96, p < 0.01). Three primary themes reflecting factors associated with the acceptability and feasibility were (1) practical application, (2) support and resources, and (3) knowledge and confidence.

CONCLUSIONS

Co-production of an online CPD programme can improve knowledge and affect practice. PE teachers that completed the CPD reported the online platform was beneficial to overcoming the limitations of face-to-face CPD such as time and financial constraints and suggested the content covered was beneficial and appropriate to their teaching. Future work is required to establish links between teachers' learning following CPD, the translation into PE practice and student MF outcomes.

School-Based Comprehensive Strength Training Interventions to Improve Muscular Fitness and Perceived Physical Competence in Chinese Male Adolescents

Purpose. This research was to see how effective and feasible school-based comprehensive strength training programs are in improving muscular fitness and perceived physical competence in Chinese male adolescents. Methods. A total of 123 participants ( $13.46\pm 0.60$ years) were randomized to comprehensive strength training intervention group (CST) ( $n=62$ ) and the control group (CON) ( $n=61$ ). The training sessions were performed three times a week for ten weeks in CST. Muscular fitness (i.e., muscular strength, power, and muscular endurance) and perceived physical competence were assessed at initial testing and final testing. Results.The subjects in the CST significantly improved their mean performance in standing long jump ( $p<0.05$ ), vertical jump ( $p<0.05$ ), 1 min push-ups ( $p<0.05$ ), 1 min sit-ups ( $p<0.05$ ), handgrip strength ( $p<0.05$ ), and perceived physical competence ( $p<0.05$ ) after the intervention. Moreover, the CST were greater in standing long jump ( $p<0.05$ ), vertical jump ( $p<0.05$ ), 1 min sit-ups ( $p<0.05$ ), handgrip strength ( $p<0.05$ ), and perceived physical competence ( $p<0.05$ ) compared to the CON, but no in 1 min push-ups ( $p>0.05$ ). Conclusions. The comprehensive strength training interventions designed in this study can significantly increase male adolescents’ muscular fitness, especially in the lower extremity muscle power and abdominal core endurance, and can enhance their perceived physical competence.

The Benefits of Resistance Training in Obese Adolescents: A Systematic Review and Meta-analysis

BACKGROUND

Physical activity is essential in acquiring healthy lifestyle behaviors in the early years of maturational development and preventing various diseases. Resistance training (RT) is fundamental for improving body composition and is increasingly recommended for obese adolescents. A systematic review and meta-analysis were performed to synthesize and analyze data on the effects of RT programs in this population, seeking to develop useful recommendations for health and sports professionals.

METHODS

A search was performed using four databases (Web of Science, Scopus, PubMed, and ScienceDirect). According to specific inclusion criteria, twenty-one studies were selected to evaluate the impact of RT on body mass index (BMI), body fat, waist circumference, muscle strength, insulin sensitivity, lean mass and cardiorespiratory fitness.

RESULTS

After the RT programs, the adolescents improved their muscle strength (SMD, 1.44; 95% CI: 0.76-2.12), cardiorespiratory fitness (SMD, 1.09; 95% CI: 0.15-2.04), BMI (SMD, 0.21; 95% CI: 0.07-0.35), waist circumference (SMD, 0.27; 95% CI: 0.06-0.47) and body fat (SMD, 0.20; 95% CI: 0.05-0.34). However, insulin sensitivity (SMD, 0.32; 95% CI: - 0.47 to 1.10) and lean mass (SMD, 0.12; 95% CI: - 0.06 to 0.31) did not reveal any changes. Different RT programs were used but it seems that 2-3 times/week ∼60 min/session of RT for 12 weeks should be recommended for positive changes.

CONCLUSIONS

RT seems to be effective when the objective is to improve muscle strength, cardiorespiratory fitness and can be an efficient strategy to reduce obesity in adolescents by reducing body fat, waist circumference and body mass index. PROSPERO Registration number: CRD42022333411.

Concurrent Validity of Lower Limb Muscle Strength by Handheld Dynamometry in Children 7 to 11 Years Old

CONTEXT

The assessment of pediatric muscle strength is necessary in a range of applications, including rehabilitation programs. Handheld dynamometry (HHD) is considered easy to use, portable, and low cost, but validity to measure lower limb muscle strength in children has not been assessed.

OBJECTIVE

To determine the concurrent validity of lower limb torque from HHD compared with isokinetic dynamometry (ID) in children aged from 7 to 11 years old.

DESIGN

A descriptive assessment of concurrent validity of lower limb joint torques from HHD compared with ID.

METHODS

Sixty-one typically developing children underwent assessment of maximal hip, knee, and ankle isometric torque by HHD and ID using standardized protocols. Joint positions were selected to represent maximal strength and were replicated between devices. Concurrent validity was determined by Pearson correlation, limits of agreement, and Bland-Altman plots.

RESULTS

Correlations between HHD and ID were moderate to large for knee extension (r 95% CI, .39 to .73), small to large for plantar flexion (r 95% CI, .29 to .67), knee flexion (r 95% CI, .16 to .59), hip flexion (r 95% CI, .21 to .57), hip extension (r 95% CI, .18 to .54), and hip adduction (r 95% CI, .12 to .56), and small to moderate for dorsiflexion (r 95% CI, -.11 to .39) and hip abduction (r 95% CI, -.02 to .46). Limits of agreement for all joint torques were greater than 10% indicating large error in HHD measured torque compared with ID. A positive proportional bias was detected for plantarflexion, indicating that HHD underestimated torque to a greater extent in participants with higher torque values.

CONCLUSIONS

Maximal torque values from HHD and ID are consistent with those previously reported in the literature. Poor concurrent validity of HHD may have arisen from issues around joint position, joint stabilization, and the experience of the tester to prevent an isokinetic contraction. Pediatric lower limb muscle strength assessed by HHD should be interpreted with caution.

Muscle-strengthening exercise and positive mental health in children and adolescents: An urban survey study

Background

Much evidence has indicated that physical activity is associated with mental health benefits, such as fewer depression symptoms. Psychological resilience captures a broader mental health phenomenon that may be influenced by other factors as well. Yet, there are few studies examining the association between muscle-strengthening exercises (MSEs) with mental health outcomes, especially positive outcomes (e.g., subjective wellbeing). The study aimed to test the association between MSE with subjective wellbeing and resilience among a large sample of Chinese adolescents.

Materials and methods

A cross-sectional study was conducted among primary and middle school students in Shenzhen, China. MSE frequency, subjective wellbeing, and resilience were measured. Data from a total of 67,281 children and adolescents aged 10–17 years (51.9% men and 48.1% women) were included in the analysis. Mixed effect models were performed to assess how weekly MSE frequency (0–7 days) related to the levels of subjective wellbeing and resilience, adjusting for potential confounding variables (e.g., sex and grade). Sensitivity analyses were also conducted.

Results

Compared to participants with no MSE, the levels of subjective wellbeing were higher in those with higher MSE frequencies [range of β: 0.29 (1 day per week) to 1.98 (7 days per week)]. The frequency of MSE was also positively correlated to better resilience [range of β: 0.50 (1 day per week) to 4.40 (7 days per week)]. All associations remained significant in sensitivity analyses.

Conclusion

More frequent MSE was associated with superior subjective wellbeing and resilience of Chinese children and adolescents. Increasing MSE may be beneficial for promoting positive mental health outcomes among children and adolescents.

Improving physical activity behaviors, physical fitness, cardiometabolic and mental health in adolescents - ActTeens Program: A protocol for a randomized controlled trial

This trial aims to investigate the effects of the ActTeens physical activity program, on adolescents’ physical activity level, health-related fitness, cardiometabolic and mental health. The trial will aim to recruit ~140 adolescents (aged 13–14 years). Participants will be randomized into either intervention or control groups. The intervention will be guided by social cognitive theory and self-determination theory and implemented over one school term (24-weeks). The ActTeens Program will include: (1) structured physical activity sessions delivered within physical education, including movement-based games and dynamic stretching warm-ups; resistance training skill development; high-intensity training workouts; and cool-downs; (2) self-monitoring plus goal setting for physical activity by pedometer-smart wearable; and (3) healthy lifestyle guidance (social support) by WhatsApp® messages about healthy eating and regular physical activity for the intervention and parents groups. Study outcomes will be assessed at baseline, 24-weeks from baseline, and 12-months from baseline. Physical activity (accelerometer) is the primary outcome. Secondary outcomes include muscular and cardiorespiratory fitness, cardiometabolic profile, and mental health. A process evaluation will be conducted (i.e., recruitment, retention, attendance, and program satisfaction). This project will have the potential to address many questions and debates regarding the implementation of physical activity interventions in low-and- middle-income countries.

Trial registration: ClinicalTrials.gov NCT05070377. Registered on 7 October 2021.

Multidisciplinary Neuromuscular and Endurance Interventions on Youth Basketball Players: A Systematic Review with Meta-Analysis and Meta-Regression

The main aims of this systematic review with meta-analysis and meta-regression were to describe the effect of multidisciplinary neuromuscular and endurance interventions, including plyometric training, mixed strength and conditioning, HIIT basketball programs and repeated sprint training on youth basketball players considering age, competitive level, gender and the type of the intervention performed to explore a predictive model through a meta-regression analysis. A structured search was conducted following PRISMA guidelines and PICOS model in Medline (PubMed), Web of Science (WOS) and Cochrane databases. Groups of experiments were created according to neuromuscular power (vertical; NPV and horizontal; NPH) and endurance (E). Meta-analysis and sub-groups analysis were performed using a random effect model and pooled standardized mean differences (SMD). A random effects meta-regression was performed regressing SMD for the different sub-groups against percentage change for NPV and NPH. There was a significant positive overall effect of the multidisciplinary interventions on NPV, NPH and E. Sub-groups analysis indicate differences in the effects of the interventions on NPV and NPH considering age, gender, competitive level and the type of the intervention used. Considering the current data available, the meta-regression analysis suggests a good predictability of U-16 and plyometric training on jump performance. Besides, male and elite level youth basketball players had a good predictability on multidirectional speed and agility performance.

Field-based physical fitness assessment in preschool children: A scoping review

Physical fitness, which can be measured using various health- and skill-related components, is an important indicator of child development and health status. This study undertakes a scoping review on physical fitness assessment methods in preschool children to summarize the most widely used field-based physical fitness batteries and specific test items for preschool children. A search of the literature in English was undertaken using two major electronics databases, which yielded 76 literatures that met the inclusion and exclusion criteria. These literatures took the quantitative indicators of physical fitness as the outcome variables in 3-6-year-old children. This review found that of these 76 literatures analyzed, 71.1% came from Europe and 89.5% were published after 2010. The results showed six physical fitness test batteries, with the assessing FITness in PREschoolers (PREFIT) battery is the most widely used, and specific test items such as body mass index (BMI), standing long jump, handgrip, one-leg stance, sit and reach, 20 m shuttle run test (SRT)-PREFIT, and 4 × 10 m SRT are widely used in corresponding components. Therefore, we recommend that an international standard for some specific test items should be developed for preschool children to facilitate more widespread adoption and promote physical fitness assessment for preschool children.

Getting a Grip on Strength Measurement in Children (6-13 Y): Impact of Typical Error of Measurement

PURPOSE

To identify the smallest change in handgrip strength (HGS) in children that can be considered of practical significance.

METHOD

A total of 290 male and female children, aged 6-13 years, performed a HGS testing protocol 3 times within a 7-day period. The typical error of measurement (TE), coefficient of variation, and smallest worthwhile change (SWC) were calculated for each sex and age group (grade).

RESULTS

The TE for the combined group of grade 1 to 7 children was 1.3 kg. Changes in HGS associated with a small change were 1.3 kg, making it difficult for the HGS test to detect these changes. The TE was less than the medium (3.3 kg) and large (5.3 kg) changes in HGS for all the grades and sexes, making changes of these magnitudes more interpretable as they exceed the "noise" (TE) of the measurement.

CONCLUSION

Changes in HGS greater than the TE and SWC can be considered real changes of practical significance. This provides researchers with an extra level of analysis when trying to determine the practical relevance of the observed changes.

A comparison of the physical fitness of individuals with intellectually disabilities autism spectrum disorders and Down syndrome diagnosis

Introduction: This article reports the physical abilities and physical wellness of three groups of children with different neurodevelopmental disabilities: Autism, Down Syndrome and Intellectual Disability. Methods: The causal-comparative research method was implemented in this study. The participants comprised 32 students with moderate intellectual disabilities, 18 with autism spectrum disorder, and 22 with down syndrome. The body mass index (BMI), flexibility, standing long jump, sitting height, stroke length, and medicine ball throwing levels were measured for physical fitness, and the groups were compared afterward. The Kruskal Wallis-H Test and Mann-Whitney U Test were applied to determine the differences between the groups' physical fitness averages for the statistical analysis. Results: Statistically significant differences were obtained in BMI, standing long jump, stroke length, and medicine ball throwing variables (p < 0.05). However, no statistically significant difference was discovered for the flexibility and sitting height variables (p > 0.05). The BMI, sitting height, and stroke length levels for the group with autism spectrum disorder were higher than the other groups, as the flexibility levels of the group with down syndrome were higher than the other groups. Students with intellectual disabilities were demonstrated to have better values than other groups regarding standing long jump and medicine ball throwing performances. Conclusions: Objective information about the physical fitness of individuals with children with different neurodevelopmental disabilities was obtained. In addition, the data obtained with these children will contribute to future plans for movement training as well as the content and frequency of the interventions, and will guide the development of new strategies to develop physical abilities and physical wellness.

Increasing Children's physical Activity by Policy (CAP) in preschools within the Stockholm region: study protocol for a pragmatic cluster-randomized controlled trial

Background

Systematic reviews suggest that preschool environmental/organizational changes may be effective in increasing physical activity (PA) levels of preschool children, but evidence is scarce regarding feasible, effective, and equitable interventions that can be scaled up. Specifically, it is essential to understand whether introducing a multicomponent organizational change in terms of policy in the preschool context may be beneficial for children’s PA levels and concomitant health outcomes. To bridge this knowledge gap, our main aim is to examine the feasibility and effectiveness of a policy package in increasing PA levels in preschool children, using a large-scale pragmatic cluster-randomized controlled trial.

Methods

This proposed study is a pragmatic cluster-randomized controlled trial with two conditions (intervention and control with a 1:1 ratio) with preschools as clusters and the unit of randomization. We aim to recruit approximately 4000 3–5-year-old children from 90 preschools and retain more than 2800 children from 85 preschools to provide adequate statistical power for the analyses. The intervention to implement is a co-created, multicomponent policy package running for 6 months in preschools randomized to intervention. Change in accelerometer measured PA levels in children between intervention and control from pre- and post-intervention will be the primary outcome of the study, while secondary outcomes include health outcomes such as musculoskeletal fitness, psychosocial functioning, and absence due to illness in children among others. Implementation will be studied carefully using both quantitative (dose, fidelity) and qualitative (interview) methodologies. The change in primary and secondary outcomes, from pre- to post-intervention, will be analyzed with linear mixed-effect models (to allow both fixed and random effects) nested on a preschool level.

Discussion

This is a large-scale co-creation project involving the City of Stockholm, childcare stakeholders, preschool staff, and the research group with the potential to influence more than 30,000 preschool children within the Stockholm area. The study will add reliable evidence for the implementation of PA policies at the organizational level of preschools and clarify its potential effect on objectively measured PA and health markers in children.

Trial registration

ClinicalTrials.govNCT04569578. Prospectively registered on September 20, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06513-4.

Correlations between Physical Fitness and Body Composition among Boys Aged 14-18-Conclusions of a Case Study to Reverse the Worsening Secular Trend in Fitness among Urban Youth Due to Sedentary Lifestyles

A secular trend can be observed throughout the world with an increase in childhood obesity and a decrease in fitness. The research aimed to examine the results of tests measuring the conditional abilities of young boys aged 14-18 in fitness tests and their correlations with body composition indicators. That was supported by research that has been prepared in Hungary so far. This research focuses on the results of fitness tests conducted on 14- to 18-year-old boys, presented along with body composition data. The authors sought to describe the development of the fitness profiles of males at a Budapest secondary school participating in the research, based on the results of the Hungarian National Student Fitness Test (NETFIT®), and also how their physical characteristics affect the results of NETFIT® tests in the sample measured. A total of 735 male high school students at a Budapest secondary school (14-18 years old) (mean ± SD, 16.05 ± 1.18 years) participated in the survey. The data were collected in the 2018/2019 academic year, and it was compared with the national data. The correlation between the performance indicators of the NETFIT® tests and the physical characteristic indicators was analyzed using the two-block Partial Least Squares method. In the resulting groups, Kruskal-Wallis variance analysis was performed to investigate the differences in performance. In contrast, pairs of group differences were tested with the Mann-Whitney test. Boys with a short physique were at some advantage in trunk-lifts and push-ups, compared to taller boys. It was also obvious that being overweight is a hindrance regarding the PACER test or the standing broad jump. The handgrip in the left and right hand was mostly of similar strength or weakness. Tall-heavy children performed better in this test. The grip strength of tall-thin students was also strong, but not as strong as in the tall-heavy group. Reducing the percentage of body fat (PBF) and creating the optimal BMI index is important for the younger age group, as our results have clearly demonstrated that overweight is a hindrance in the PACER, VO2 max, standing broad jump, back-saver sit-and-reach, and push-up tests.

Physical Fitness and Dietary Intake Improve Mental Health in Chinese Adolescence Aged 12-13

Background

Mental health has become a major public health issue worldwide. Biological and epidemiological studies have suggested that diet and physical fitness play a role in the prevention or cure of mental disorders. However, further research is required to elucidate the relationship between diet, physical fitness, and mental health. The study aims to provide a theoretical basis for promoting an adolescent healthy lifestyle and preventing mental problems by exploring the relationship between physical fitness, calcium intake, calorie intake, and adolescent mental health.

Methods

A cross-sectional study of a sample of adolescents (N = 253, 12-13 years) was conducted. The study involved adolescents from three middle schools in Central Jiangsu Province, including 136 boys and 117 girls. Weight, height, and body mass index were measured. Physical fitness was scored using the Chinese National Student Physical Fitness Standard. Diet data were collected using a weighed 7-day food diary to estimate energy intake and dietary calcium intake. The mental health status of the participants was assessed using the Chinese Middle School Student Mental Health Scale. A T-test and analysis of variance were used to analyze the differences of variables between different genders and body mass index, and Pearson correlation and stepwise multiple regression were used to explore the relationship between physical fitness, dietary intake, and mental health.

Results

The height (165.13 ± 8.07), weight (55.24 ± 13.00), and strength quality (64.93 ± 21.66) of boys are higher than those of girls (161.67 ± 6.44,48.99 ± 8.97, 58.40 ± 23.75, P < 0.05), and the flexibility quality (74.59 ± 14.75) of girls is higher than that of boys (68.30 ± 20.84) (P < 0.05). There were significant differences in the total scores of speed and physical fitness (F values were 4.02187.73, 3.07, 5.95, 10.33, and 9.52, respectively, P < 0.05). There was a significant positive correlation between calcium intake, cardiopulmonary fitness, and mental health (r = 0.276, P < 0.01; r = 0.159, P < 0.05). Calcium intake and cardiopulmonary fitness could explain 8.4% of the changes in the mental health of adolescents aged 12-13(ΔR2 = 0.084, P < 0.05).

Conclusion

Adequate calcium intake and the improvement of cardiopulmonary fitness in adolescents aged 12-13 are essential for the good development of their mental health. Future research in this field should examine the prospective associations between multiple measures of physical fitness composition and other nutrients ingested and mental health outcomes, as well as intervention studies that seek to provide evidence of causality.

Is There a "Window of Opportunity" for Flexibility Development in Youth? A Systematic Review with Meta-analysis

BACKGROUND

Flexibility is an important component of physical fitness for competitive and recreational athletes. It is generally suggested that flexibility training should start from childhood (6-11 years of age) to optimize joint range of motion (ROM) increases; however, evidence is limited and inconsistent.

OBJECTIVE

To examine whether there is a difference in the effect of stretching training on flexibility during childhood (6-11 years of age) and adolescence (12-18 years of age).

DESIGN

Systematic review and meta-analysis.

METHODS

We searched PubMed Central, Web of Science, Scopus, Embase, and SPORTDiscus, to conduct this systematic review. Randomized controlled trials and non-randomized controlled trials were eligible. No language and date of publication restrictions were applied. Risk of bias was assessed using Cochrane RoB2 and ROBINS-I tools. Meta-analyses were conducted via an inverse variance random-effects model. GRADE analysis was used to assess the methodological quality of the studies.

RESULTS

From the 2713 records retrieved 28 studies were included in the meta-analysis (n = 1936 participants). Risk of bias was low in 56.9% of all criteria. Confidence in cumulative evidence was moderate. We found that stretching was effective in increasing ROM in both children (SMD = 1.09; 95% CI = 0.77-1.41; Z = 6.65; p < 0.001; I² = 79%) and adolescents (SMD = 0.90; 95% CI = 0.70-1.10; Z = 8.88; p < 0.001; I² = 81%), with no differences between children and adolescents in ROM improvements (p = 0.32; I² = 0%). However, when stretching volume load was considered, children exhibited greater increases in ROM with higher than lower stretching volumes (SMD = 1.21; 95% CI = 0.82-1.60; Z = 6.09; p < 0.001; I² = 82% and SMD = 0.62; 95% CI = 0.29-0.95; Z = 3.65; p < 0.001; I² = 0%, respectively; subgroup difference: p = 0.02; I² = 80.5%), while adolescents responded equally to higher and lower stretching volume loads (SMD = 0.90; 95% CI = 0.47-1.33; Z = 4.08; p < 0.001; I² = 83%, and SMD = 0.90; 95% CI = 0.69-1.12; Z = 8.18; p < 0.001; I² = 79%, respectively; subgroup difference: p = 0.98; I² = 0%).

CONCLUSIONS

Systematic stretching training increases ROM during both childhood and adolescence. However, larger ROM gains may be induced in childhood than in adolescence when higher stretching volume loads are applied, while adolescents respond equally to high and low stretching volume loads.

REGISTRATION

INPLASY, registration number: INPLASY202190032; https://inplasy.com/inplasy-2021-9-0032/.

Concussion Nondisclosure in Youth Sports

CONTEXT

Researchers conducting studies about sport-related concussion (SRC) reporting behaviors and reasons for nondisclosure primarily focus on older athletic populations. Youth athletes participating in contact sports are also at risk for SRC; however, little is known about their SRC disclosure patterns and reasons for nondisclosure.

OBJECTIVE

To examine the self-reported SRC history and reasons for SRC nondisclosure of youth athletes aged 8-14 years.

DESIGN

Cross-sectional study.

SETTING

Youth athletes in organized football, ice hockey, lacrosse, or soccer.

PATIENTS OR OTHER PARTICIPANTS

A total of 411 youth athletes (boys = 70.0% [n = 287/410]; median age = 11 [interquartile range = 10-13] years).

MAIN OUTCOME MEASURE(S)

A 15-minute survey including self-reported demographics, diagnosed and nondisclosed SRC history, and reasons for nondisclosure of suspected SRCs.

RESULTS

Ten percent of respondents (n = 41/411) recounted ≥1 diagnosed SRC, 12.7% (n = 52/411) did not report a suspected SRC, 13.1% (n = 53/404) indicated they continued to practice, and 12.3% (n = 50/406) reported they continued to play in a game after a suspected SRC. Significant associations between sport and nondisclosure existed (P values < .001) but not with self-reported concussion history (P = .14). In sex-comparable analyses, boys' lacrosse players had a higher frequency of nondisclosure than girls (P = .05). The most common reasons for nondisclosure were not wanting to lose playing time (66.7%, n = 32/48), miss a game (56.3%, n = 27/48), and let the team down (43.8%, n = 21/48) and uncertainty over injury severity and the presence of SRC (43.8%, n = 21/48).

CONCLUSIONS

Ten percent of youth athletes self-reported at least 1 diagnosed SRC. However, they also described continuing to practice or play in a game after a suspected SRC. Reasons for nondisclosure at this age were similar to those reported in high school and collegiate athletes. Recent researchers suggested negative consequences of continued play with SRC, especially in the acute stages. Anyone conducting future educational initiatives should emphasize these risks and focus on reasons why athletes of both sexes withhold reporting.

Scaling-Up Adolescent High-Intensity Interval Training Programs for Population Health

High-intensity interval training (HIIT) has become a polarizing form of exercise. In this article, we argue that adolescent HIIT programs can have population health impact if they are (i) integrated into existing opportunities, (ii) designed to develop physical literacy, (iii) delivered in an engaging manner, and (iv) guided and supported by an implementation framework that addresses relevant barriers and facilitators.

Effects of Strength Training on Body Fat in Children and Adolescents with Overweight and Obesity: A Systematic Review with Meta-Analysis

Childhood overweight and obesity represent a growing public health problem worldwide. Since the 1980s, the global prevalence of overweight and obesity in childhood and adolescence has increased by 47%. The promotion of exercise is an important intervention to reduce the physical damage of obesity. The meta-analysis was conducted in accordance with the general guidelines for the reporting of systematic reviews and meta-analyses (PRISMA). The PubMed, SciELO, ScienceDirect and Google Scholar databases were searched from August to December 2021. The search yielded 722 titles published between 2000 and 2021. After screening the titles and abstracts, 64 duplicate articles were detected, and 27 articles were ultimately included in the systematic review, including 26 articles published in English and one published in Spanish. There was a statistically significant effect of the strength training interventions on the percentage of body fat, Test of 0 i = (p = 0.00, z = 6.92), Test of 0 = (p = 0.00, Q (9) = 42.63). The findings reveal that strength training has a positive impact on the treatment of body fat in children and adolescents with overweight and obesity.