Household food insecurity among child and adolescent athletics practitioners: A cross-sectional, descriptive, and exploratory study

OBJECTIVE

The aim of the study was to explore the prevalence of food insecurity among child and adolescent athletics practitioners and to investigate factors associated with exercise performance, dietary habits, body composition, sleep, and socioeconomic status based on food security status.

METHODS

This was a cross-sectional, descriptive, and exploratory study conducted in Campinas, São Paulo, Brazil, between June and July 2023. The convenience sample included children and adolescents (7-17 y old) of both sexes. We evaluated exercise performance, household food insecurity (HFI), dietary-related parameters, and other body composition, lifestyle, and social-related variables. Exercise performance was assessed using the counter movement jump (CMJ), squat jump (SJ), horizontal long jump (HLJ), 50-m sprint test (50-m ST) and throwing strength test (TST). The assessment of HFI was conducted using the food insecurity experience scale (FIES). Comparisons and associations were investigated based on food security status.

RESULTS

The total sample size was comprised of 138 children (n = 42; 30.4%) and adolescents (n = 96; 69.6%). We found an association between food security status and sex (X2(138,1) = 4.42; P = 0.036). SJ was higher in the food security group than in the HFI group (t(117) = 2.112; P = 0.037; ES = 0.39). Sleep- and dietary-related factors did not differ between the groups.

CONCLUSIONS

In summary, the prevalence of HFI among child and adolescent athletics participants was approximately 40%. Regarding exercise performance, SJ was better in the food security group than in the HFI group. Concerning dietary-related data, the HFI group had a lower number of meals per day than the food security group, and other dietary data did not differ between the groups. Body composition and sleep-related parameters were similar between the groups.

Effect of vertical, horizontal, and combined plyometric training on jump, sprint and change of direction performance in male soccer players

PURPOSE

The purpose of this study was to compare the effects of vertical (VPT), horizontal (HPT) and combined vertical and horizontal (V+HPT) plyometric training on sprint, jump and change of direction (COD) performance in adult male soccer players.

METHOD

Participants were randomly allocated into VPT (n = 8), HPT (n = 8) and V+HPT (n = 8) groups which undertook eight weeks of PT, executing 100 foot contacts per session, twice weekly.

RESULTS

Though demonstrably effective, no specific one of the three applied programmes enhanced performance to a greater extent than another with only the 40 m sprint for the HPT group (mean difference = 0.07 s [HPT] vs. 0.04 s [VPT] and 0.04 s [V+HPT]) and the vertical jump for the V+HPT group (mean difference = 4.5 cm [V+HPT] vs. 4.0 cm [VPT] and 3.25 cm [HPT]) appearing to deviate from a uniform pattern of group level adaptation across the performance tests.

CONCLUSION

A total volume of 100 foot contacts per session, twice per week for eight weeks was sufficient to achieve the observed changes. Though jump and changing direction performance were enhanced, linear sprint performance was largely unchanged and so a more complete and intense programme may have been warranted. No method was superior to another in eliciting changes across these tests and a directionally-specific pattern of adaptation was not apparent.

Association between time of assessment within a school year and physical fitness of primary school children

The dissociation of effects of age, time of assessment and cohort is a well-known challenge in developmental science. We examined effects of time of assessment in the school year on children's physical fitness using data from 75,362 German third-graders from seven cohorts. Children were tested once either in the first or second school term of third grade. Tests examined cardiorespiratory endurance (6-min run), coordination (star-run), speed (20-m sprint), lower (standing long jump) and upper (ball-push test) limbs muscle power, and flexibility (stand-and-reach test). We estimated the effect of time of assessment using a regression discontinuity design specified in a linear mixed model with random factors child and school and adjusted for age, sex, and cohort effects. Coordination, speed, and upper limbs muscle power were better in second compared to first school term, with boys exhibiting a larger increase of upper limbs muscle power than girls. There was no evidence for changes in cardiorespiratory endurance, lower limbs muscle power, and flexibility between assessments. Previously reported age and sex effects as well as secular fitness trends were replicated. There is thus evidence for improvement of some physical fitness components beyond age and cohort effects that presumably reflects the benefit of physical activity in physical education and other settings. Effects of assessment time should be taken into consideration in performance-based grading or norm-based selection of children.

Perinatal HIV infection is associated with deficits in muscle function in children and adolescents in Zimbabwe

OBJECTIVES

To determine how muscle strength, power, mass, and density (i.e. quality) differ between children living with HIV (CWH) and those uninfected, and whether antiretroviral therapy (ART) regime is associated with muscle quality.

DESIGN

A cross-sectional study in Harare, Zimbabwe.

METHODS

The study recruited CWH aged 8-16 years, taking ART for at least 2 years, from HIV clinics, and HIV-uninfected children from local schools. Muscle outcomes comprised grip strength measured by hand-held Jamar dynamometer, lower limb power measured by standing long-jump distance, lean mass measured by dual-energy X-ray absorptiometry, and muscle density (reflecting intramuscular fat) by peripheral quantitative computed tomography. Linear regression calculated adjusted mean differences (aMD) by HIV status.

RESULTS

Overall, 303 CWH and 306 without HIV, had mean (SD) age 12.5 (2.5) years, BMI 17.5 (2.8), with 50% girls. Height and fat mass were lower in CWH, mean differences (SE) 7.4 (1.1) cm and 2.7 (0.4)kgs, respectively. Male CWH had lower grip strength [aMD 2.5 (1.1-3.9) kg, P  < 0.001], long-jump distance [7.1 (1.8-12.5) cm, P  = 0.006], muscle density [0.58 (0.12-1.05) mg/cm 3 , P  = 0.018, but not lean mass 0.06 (-1.08 to 1.21) kg, P  = 0.891) versus boys without HIV; differences were consistent but smaller in girls. Mediation analysis suggested the negative effect of HIV on jumping power in boys was partially mediated by muscle density ( P  = 0.032). CWH taking tenofovir disoproxil fumarate (TDF) had lower muscle density [0.56 (0.00-1.13)mg/cm 3 , P  = 0.049] independent of fat mass, than CWH on other ART.

CONCLUSION

Perinatally acquired HIV is associated, particularly in male individuals, with reduced upper and lower limb muscle function, not mass. Intra-muscular fat (poorer muscle quality) partially explained reductions in lower limb function. TDF is a novel risk factor for impaired muscle quality.

Muscle strength deficits are associated with low bone mineral density in young pediatric cancer survivors: The iBoneFIT project

BACKGROUND

Pediatric cancer survivors are at increased risk of muscle weakness and low areal bone mineral density (aBMD). However, the prevalence of muscle strength deficits is not well documented, and the associations of muscle strength with aBMD are unknown in this population. Therefore, this study aimed to investigate the prevalence of upper- and lower-body muscle strength deficits and to examine the associations of upper- and lower-body muscle strength with age-, sex, and race-specific aBMD Z-scores at the total body, total hip, femoral neck, and lumbar spine.

METHODS

This cross-sectional study included 116 pediatric cancer survivors (12.1 ± 3.3 years old, mean ± SD; 42.2% female). Upper- and lower-body muscle strength were assessed by handgrip and standing long jump test, respectively. Dual‑energy X‑ray absorptiometry was used to measure aBMD (g/cm2). Associations between muscle strength and aBMD were evaluated in multivariable linear regression models. Logistic regression was used to evaluate the contribution of muscle strength (1-decile lower) to the odds of having low aBMD (Z-score ≤ 1.0). All analyses were adjusted for time from treatment completion, radiotherapy exposure, and body mass index.

RESULTS

More than one-half of survivors were within the 2 lowest deciles for upper- (56.9%) and lower- body muscle strength (60.0%) in comparison to age- and sex-specific reference values. Muscle strength deficits were associated with lower aBMD Z-scores at all sites (B = 0.133-0.258, p = 0.001-0.032). Each 1-decile lower in upper-body muscle strength was associated with 30%-95% higher odds of having low aBMD Z-scores at all sites. Each 1-decile lower in lower-body muscle strength was associated with 35%-70% higher odds of having low aBMD Z-scores at total body, total hip, and femoral neck.

CONCLUSION

Muscle strength deficits are prevalent in young pediatric cancer survivors, and such deficits are associated with lower aBMD Z-scores at all sites. These results suggest that interventions designed to improve muscle strength in this vulnerable population may have the added benefit of improving aBMD.

Healthy fitness zone prevalence and age-specific fitness profile of young people in seven European countries in 2022: The EUFITMOS project

BACKGROUND

Physical fitness is a health marker in youth and is associated with current and future health.

OBJECTIVE

Present the healthy fitness zone (HFZ) prevalence and age-specific fitness profile of young people from seven European countries.

METHODS

This study used data from the European Fitness Monitoring System project. The sample comprised 4965 (51.4% boys) youths aged 9 to 18 years. Fitness data were collected by physical education teachers using field-based tests. Raw data from the fitness tests were used to calculate the prevalence and 95% confidence intervals (CI) of participants in the HFZ.

RESULTS

The overall prevalence of boys and girls in the HFZ for all tests was 16.6% (95% CI = 14.7, 18.1) and 14.9% (95% CI = 13.2, 16.6), respectively. Boys have a mainly positive HFZ profiles, except for the 9-year-olds in the sit and reach (z-score difference = -1.20) and the 20 m run for boys 13-18-year-olds (z-score difference range: -0.09 to -0.01). Girls have worse HFZ profiles than boys, being out of the HFZ in several tests. Furthermore, a decreasing trend in z-score difference from the HFZ with age was observed in VO2 peak for boys and girls and sit and reach for girls. Notwithstanding, several country-related, sex and age differences were observed.

CONCLUSIONS

Boys presented mostly healthy age-specific fitness profiles in several fitness tests and ages. These differences should be considered when promoting youth's health through physical activity and fitness, as different fitness levels may require different approaches to implementing health-enhancing physical activity policies.

Community strategies for health promotion and prevention of chronic non-communicable diseases with a focus on physical activity and nutrition: the URO/FOCOS study protocol

Non-communicable diseases (NCDs) account for 71% of all annual deaths, totaling 41 million people worldwide. The development and progression of these diseases are highly related to the environment and lifestyle choices, among which physical inactivity and excess malnutrition stand out. Currently, in Chile, there is no evidence at the regional and local level on the impact of physical activity and healthy nutrition plans and interventions on health promotion, prevention, and timely treatment of NCDs. The following protocol delineates the URO/FOCOS (Universidad Regional de O'Higgins/FOrtaleciendo COmunidades Saludables- Regional University of O'Higgins/Strengthening Healthy Communities) study, which will assess pilot community intervention strategies using a participatory action research approach by identifying barriers and facilitators on the practice of physical activity and healthy eating habits. In this project, the community from the O'Higgins region will be involved throughout the entire research process to develop strategies that promote regular physical activity and healthy eating practices. We propose three interrelated strategies: (1) Participatory Action Research, (2) Community interventions for promoting physical activity and healthy nutrition practices, and (3) health education. The URO/FOCOS study offers a unique opportunity in the O'Higgins region to develop participatory strategies and interventions based on the community's needs and motivations with regard to physical activity and healthy eating habits. We believe these strategies will help to improve the community's overall health through effective changes in their decision and preferences toward a more active lifestyle and healthier nutrition practices.

Effect of integrative neuromuscular training and detraining on performance indices in young female volleyball players

BACKGROUND

Aim of this study was to determine the effect of: 1) integrative neuromuscular training (INT); and 2) detraining on power and skill performance indices in young female volleyball players.

METHODS

Sixty-one pre- and early pubescent female volleyball players participated in this study divided into two groups, integrative neuromuscular training (INTG) and control (CG). The INTG followed a 12-week INT program twice weekly and both groups participated in volleyball training sessions. During 8-week detraining, both groups keep practicing volleyball. Participants were assessed on upper and lower limb power and skill accuracy tests prior, at the end and 8 weeks after INT. A repeated measures Analysis of Variance was used to examine groups' changes in performance for each variable and significance level was set at P<0.05.

RESULTS

INTG improved all power parameters more than CG after 12 weeks of INT (significant interaction, P<0.001) whilst the CG improved only countermovement jump (CMJ) height (P<0.05) and medicine ball (MB) throw (P<0.05). Both groups improved their technical skills accuracy (P<0.001) with INTG presenting higher improvements (P<0.001). During detraining, INTG maintained performance gains in CMJ and Cod (P<0.001). MB throw distance and technical skills accuracy kept on improving for both groups (P<0.01) with higher improvements observed in INTG (P<0.001).

CONCLUSIONS

INT may cause improvements in specific power and skill performance indices during in season training in young female volleyball players which may be maintained or even improved for at least 8-week detraining when players remain active through volleyball training.

Physical fitness trend after COVID-19 restrictions in Italian school-aged children: a cross-sectional study

BACKGROUND

Physical fitness (PF) is a marker of health in children. Muscular strength and speed-agility PF components play a crucial role in musculoskeletal development and bone health. The outbreaks of COVID-19 pandemic changed the daily and sports activities in younger increasing sedentary habits with a detrimental effect on PF. We aimed to investigate the impact of COVID-19 restrictions on PF in Italian school-aged children.

METHODS

We recruited 286 elementary school children, and they were tested through an internationally validated battery test, which evaluate muscular strength and speed-agility (as a multifactorial performance) prior (2018) and after the outbreak of COVID-19 pandemic (2021).

RESULTS

Our results showed a reduction in the lower limb strength (SBJ in boys mean difference (MD) -0.42 m; SBJ in girls MD=-0.20 m; P<0.05) and in the speed-agility ability (10x5 m in boys MD=14.1 s; 10x5 m in girls MD=11.2 s; P<0.05), while the upper limb strength remained steady before and after the restrictions. Specifically, for boys of all ages there was a reduction in lower limb strength and in speed-agility but not in upper limb strength. For girls of all ages there was not a recurrent trend, while for 6-8 girls there was a reduction only speed-agility, for 9-11 girls there was a reduction in lower limb and speed-agility.

CONCLUSIONS

Our results could be useful to help teachers and sport specialists to evaluate and improve strength and speed-agility in children. We encourage trainers and sport specialists to implement programs to help children to become more active and healthier during their lifespan.

Covid Pandemic Effects on the Physical Fitness of Primary School Children: Results of the German EMOTIKON Project

BACKGROUND

In spring of 2020, the Sars-CoV-2 incidence rate increased rapidly in Germany and around the world. Throughout the next 2 years, schools were temporarily closed and social distancing measures were put in place to slow the spread of the Covid-19 virus. Did these social restrictions and temporary school lockdowns affect children's physical fitness? The EMOTIKON project annually tests the physical fitness of all third-graders in the Federal State of Brandenburg, Germany. The tests assess cardiorespiratory endurance (6-min-run test), coordination (star-run test), speed (20-m sprint test), lower (powerLOW, standing long jump test), and upper (powerUP, ball-push test) limbs muscle power, and static balance (one-legged stance test with eyes closed). A total of 125,893 children were tested in the falls from 2016 to 2022. Primary analyses focused on 98,510 keyage third-graders (i.e., school enrollment according to the legal key date, aged 8 to 9 years) from 515 schools. Secondary analyses included 27,383 older-than-keyage third-graders (i.e., OTK, delayed school enrollment or repetition of a grade, aged 9 to 10 years), who have been shown to exhibit lower physical fitness than expected for their age. Linear mixed models fitted pre-pandemic quadratic secular trends, and took into account differences between children and schools.

RESULTS

Third-graders exhibited lower cardiorespiratory endurance, coordination, speed and powerUP in the Covid pandemic cohorts (2020-2022) compared to the pre-pandemic cohorts (2016-2019). Children's powerLOW and static balance were higher in the pandemic cohorts compared to the pre-pandemic cohorts. From 2020 to 2021, coordination, powerLOW and powerUP further declined. Evidence for some post-pandemic physical fitness catch-up was restricted to powerUP. Cohen's |ds| for comparisons of the pandemic cohorts 2020-2022 with pre-pandemic cohorts 2016-2019 ranged from 0.02 for powerLOW to 0.15 for coordination. Within the pandemic cohorts, keyage children exhibited developmental losses ranging from approximately 1 month for speed to 5 months for cardiorespiratory endurance. For powerLOW and static balance, the positive pandemic effects translate to developmental gains of 1 and 7 months, respectively. Pre-pandemic secular trends may account for some of the observed differences between pandemic and pre-pandemic cohorts, especially in powerLOW, powerUP and static balance. The pandemic further increased developmental delays of OTK children in cardiorespiratory endurance, powerUP and balance.

CONCLUSIONS

The Covid-19 pandemic was associated with declines in several physical fitness components in German third-graders. Pandemic effects are still visible in 2022. Health-related interventions should specifically target those physical fitness components that were negatively affected by the pandemic (cardiorespiratory endurance, coordination, speed).

International fitness scale (IFIS): association with motor performance in children with obesity

Background

Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health; and compared with their normal-weight peers, these individuals tend to have a lower level of self-confidence, and consequently lower physical activity adherence. Due to these self-perceived barriers, the aim of our study was to evaluate the efficacy of an online training program on self-reported physical fitness (SRPF) in children with obesity (OB).

Methods

A total of 32 children with OB carried out physical fitness (PF) tests and were asked to complete the International Fitness Enjoyment Scale (IFIS) questionnaire. The physical fitness tests were the Standing Broad Jump (SBJ), the 6-Min Walking Test (6MWT) and the 4 × 10 m sprint test. Children participated in a 3-weekly 60-min training session through Zoom platform. Before the beginning of the training protocol, OB children were compared with normal weight (NW) ones for PF batteries and the IFIS questionnaire. Changes in performances after the training were assessed by paired Student t and Wilcoxon tests.

Results

After the online training program children increased their performance in 6MWT (mean difference (MD) = 54.93; p < 0.0001) in SBJ (MD = 10.00; p = 0.0001) and in 4 × 10 m sprint test (MD = -0.78; p < 0.0001). No differences were found in children's physical fitness perception.

Discussion

Our study highlighted how a structured online training program can lead to improvements in PF of children with OB. Instead, the lack of differences in SRPF after the training suggests interesting questions to be explored on the aspects linked to self-perception. Therefore, even if our training protocol could not directly improve SRPF in children with obesity, the enhancement of their PF could be a starting point for achieving this result with a longer training period and consequently improve PA participation for children with OB.

Plyometric Training Practices of Brazilian Olympic Sprint and Jump Coaches: Toward a Deeper Understanding of Their Choices and Insights

Plyometric training is extensively used by coaches to enhance neuromuscular performance in a wide variety of sports. Due to the high demands of sprint speed and power output in elite sprinters and jumpers, sprint and jump coaches are likely to have great knowledge on this topic. Undoubtedly, this expertise is even more pronounced for Olympic coaches, who work with some of the fastest and most powerful athletes in the world, and who are required to continually maintain these athletes at optimal performance levels. Describing and discussing the practices commonly adopted by these coaches in detail and extrapolating this experience to other sport coaching contexts and disciplines may be extremely relevant. The current article presents, explores, and illustrates the plyometric training practices of Brazilian Olympic sprint and jump coaches, with a special focus on training programming and exercise selection.

A comparative study between traditional and sports school uniforms on cardiorespiratory and muscular fitness and waist-height-to-ratio in adolescents

Background

Improving health of children and adolescents is crucial for their overall development. Therefore, it is essential to explore factors that may influence their health at both the public health and school system levels.

Objective

This study compares physical fitness components and waist-height-to-ratio (WHtR) in adolescents according to school uniforms, namely the traditional uniform (i.e., shirt and school necktie in boys and skirt and blouse in girls) and the sports uniform (i.e., polo shirts or t-shirts and sport or short trousers). Additionally, it seeks to investigate potential differences in these measures based on sex and school type (i.e., public, subsidized, and private).

Methods

This cross-sectional study used data from the Chilean national learning outcome assessment system (SIMCE)-2014 and involved 8,030 adolescents. Cardiorespiratory fitness (CRF) and muscular fitness (MF) were measured. WHtR was assessed as a health cardiovascular indicator. Mixed models and ANCOVA were performed to compare uniform types, adjusting for multiple covariates. value of p and effect size (ES) was used to establish significant results.

Results

Overall, sports uniforms (SU) were linked to higher CRF (p < 0.001) than the traditional uniform (TU). Boys from private schools wearing SU presented higher CRF (p = 0.016; ES = 0.37), and a positive trend was observed for MF (p = 0.645; ES = 0.21). In subsidized, a trend was found in CRF (p = 0.005; ES = 0.16). Girls wearing SU from private schools showed a positive trend in CRF (p = 0.167; ES = 0.28). Trends in WHtR were found in both sexes from private (p = 0.555; ES = 0.24; p = 0.444; ES = 0.25, respectively).

Conclusion

Wearing SU seems a promissory alternative to promote healthy physical fitness and body composition at the educational level. However, the relationship between higher physical activity and CRF, MF, and lower WHtR due to SU must be verified. Finally, when deciding to implement this measure, special attention must be paid to boys from public schools and girls from all types of schools.

Reliability of Selected Health-Related Fitness Tests for Children With Developmental Coordination Disorder

Aim: To quantify test-retest reliability and minimal detectable change for 90 and 95% confidence levels (90MDC, 95MDC) for health-related fitness tests in children with developmental coordination disorder (DCD). Methods: Lower limb muscle strength [hand-held dynamometry (HHD), unilateral heel rise test (UHRT), standing broad jump (SBJ)], muscle endurance [Muscle Power Sprint Test (MPST)] and cardiorespiratory endurance [20-metre Shuttle Run Test (20mSRT)] were evaluated twice (2-7 day interval) in 31 children with DCD (20 males, 9.4 years old ± 2.0). Results: Test-retest reliability was reported as intraclass correlation coefficient (ICC) (2, 1) 95% confidence interval lower bounds. Values were excellent for MPST (peak and mean power: 0.93, 0.95), good for HHD (0.81-0.88), SBJ (0.82), and the 20mSRT (0.87) and moderate for UHRT (0.74). For HHD, the 90MDC and 95MDC were the largest for hip extensors (14.47, 12.14 Nm) and the smallest for ankle dorsiflexors (1.55, 1.30 Nm). For UHRT, SBJ, MPST and the 20mSRT, these MDC values were 11.90, 9.98 repetitions; 25.49, 21.38 cm; 4.70, 3.94 W (mean power), and 6.45, 5.42 W (peak power) and 0.87, 0.73 (number of stages), respectively. Conclusion: These tests yield reliable test-retest results that can be used to evaluate fitness changes in this group.

Physical fitness of primary school children differs depending on their timing of school enrollment

Previous research has shown that children who were enrolled to school according to the legal key date (i.e., keyage children, between eight and nine years in third grade) exhibited a linear physical fitness development in the ninth year of life. In contrast, children who were enrolled with a delay (i.e., older-than-keyage children [OTK], between nine and ten years in third grade) exhibited a lower physical fitness compared to what would be expected for their age. In these studies, cross-sectional age differences within third grade and timing of school enrollment were confounded. The present study investigated the longitudinal development of keyage and OTK children from third to fifth grade. This design also afforded a comparison of the two groups at the same average chronological age, that is a dissociation of the effects of timing of school enrollment and age. We tested six physical fitness components: cardiorespiratory endurance, coordination, speed, power of lower and upper limbs, and static balance. 1502 children (i.e., 1206 keyage and 296 OTK children) from 35 schools were tested in third, fourth, and fifth grade. Except for cardiorespiratory endurance, both groups developed from third to fourth and from fourth to fifth grade and keyage children outperformed OTK children at the average ages of 9.5 or 10.5 years. For cardiorespiratory endurance, there was no significant gain from fourth to fifth grade and keyage and OTK children did not differ significantly at 10.5 years of age. One reason for a delayed school enrollment could be that a child is (or is perceived as) biologically younger than their chronological age at the school entry examination, implying a negative correlation between chronological and biological age for OTK children. Indeed, a simple reflection of chronological age brought the developmental rate of the chronologically youngest OTK children in line with the developmental rate observed for keyage children, but did not eliminate all differences. The mapping of chronological and biological age of OTK children and other possible reasons for lower physical fitness of OTK children remain a task for future research.

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.

Benefits in Cardiac Function from a Remote Exercise Program in Children with Obesity

Physical activity (PA) is a crucial factor in preventing and treating obesity and related complications. In this one-arm pre−post longitudinal prospective study, we evaluated the effects of a 12-week online supervised training program on cardiac morphology, function and blood pressure (BP) in children with obesity. The training program consisted of three sessions per week, each lasting 60 min. Advanced echocardiographic imaging (tissue Doppler and longitudinal strain analysis) was used to detect subclinical changes in heart function. Categorical variables were described as counts and percentages; quantitative variables as the mean and standard deviation (SD) as they were normally distributed (Shapiro−Wilks test). Pre−post comparisons were made with a paired t-test. A total of 27/38 (71%) enrolled patients (18M/9F, 11 ± 2 years) completed the training protocol and were considered in the analysis. At baseline, no hypertensive patient was noted; all echocardiographic variables were within the normal range. After training, we observed a significant reduction in BP parameters, including systolic BP values and Z-score, diastolic BP values, centiles and Z-score, and mean arterial pressure (all p < 0.05). Significant variations in echocardiographic interventricular septum (IVSd) thickness (p = 0.011), IVSd Z-score (p = 0.001), left ventricular (LV) end-diastolic diameter (p = 0.045), LV posterior wall thickness Z-score (p = 0.017), and LV global longitudinal strain (p = 0.016) were detected. No differences in LV diastolic function and right ventricular strain were noted. PA plays a decisive role in improving BP control and has benefits on left ventricle systolic function, representing a strategic approach to limit CV risk. Online exercise could be an excellent method of training in children with obesity.

The effect of volume equated 1- versus 2-day formats of Nordic hamstring exercise training on fitness in youth soccer players: A randomised controlled trial

PURPOSE

This randomised controlled trial examined the effect of an 8-week volume-equated programme of Nordic hamstring exercise (NHE) training, executed at frequencies of 1- or 2-days per week, on fitness (10 m and 40 m sprint, '505' change of direction [COD] and standing long jump [SLJ]) in male youth soccer players (mean age: 16.4 ± 0.81 years).

METHOD

Players were divided into an experimental group (n = 16) which was further subdivided into 1-day (n = 8) and 2-day (n = 8) per week training groups and a control group (n = 8).

RESULTS

There were significant group-by-time interactions for 10-m sprint (p<0.001, η2 = 0.120, d = 2.05 [0.57 to 3.53]), 40-m sprint (p = 0.001, η2 = 0.041, d = 1.09 [-0.23 to 2.4]) and COD (p = 0.002, η2 = 0.063, d = 1.25 [-0.09 to 2.59). The experimental group demonstrated a 'very large' effect size (d = 3.02 [1.5 to 4.54]) in 10-m sprint, and 'large' effect sizes in 40-m sprint (d = 1.94 [0.98 to 2.90]) and COD (d = 1.84 [0.85 to 2.83). The control group showed no significant changes. There were no significant differences between the 1-day and 2-day training groups. In three of the four tests (40 m, COD, SLJ) the 2-day group demonstrated larger effect sizes. Ratings of perceived exertion (RPE) were significantly lower in the 2-day group (p<0.001, 3.46 [1.83 to 5.04).

CONCLUSION

The NHE increases fitness in youth soccer players and there may be advantages to spreading training over two days instead of one.

Motor Competence Assessment (MCA) Scoring Method

The Motor Competence Assessment (MCA) is a quantitative test battery that assesses motor competence across the whole lifespan. It is composed of three sub-scales: locomotor, stability, and manipulative, each of them assessed by two different objectively measured tests. The MCA construct validity for children and adolescents, having normative values from 3 to 23 years of age, and the configural invariance between age groups, were recently established. The aim of this study is to expand the MCA’s development and validation by defining the best and leanest method to score and classify MCA sub-scales and total score. One thousand participants from 3 to 22 years of age, randomly selected from the Portuguese database on MC, participated in the study. Three different procedures to calculate the sub-scales and total MCA values were tested according to alternative models. Results were compared to the reference method, and Intraclass Correlation Coefficient, Cronbach’s Alpha, and Bland–Altman statistics were used to describe agreement between the three methods. The analysis showed no substantial differences between the three methods. Reliability values were perfect (0.999 to 1.000) for all models, implying that all the methods were able to classify everyone in the same way. We recommend implementing the most economic and efficient algorithm, i.e., the configural model algorithm, averaging the percentile scores of the two tests to assess each MCA sub-scale and total scores.

The validity and reliability of counter movement jump height measured with the Polar Vantage V2 sports watch

The purpose of the present study was to assess the validity and reliability of the jump height measured by the Polar Vantage V2 sports watch in comparison to a gold-standard force plate measurement. Fifteen healthy adults, seven female, age 20-42 years participated in the study and performed six sets of three CMJs, on two consecutive days. The participants wore the Polar Vantage V2 sports watch (Polar Electro Oy, Kempele, Finland) whilst performing the jumps on two force plates (AMTI, Watertown, Massachusetts, United States). Jump height was on the one hand extracted directly from the watch ("leg recovery test") and on the other hand calculated by the flight time method with the force plate data. To assess validity, we calculated the mean absolute error, constructed Bland-Altman plots and applied an ordinary least squares regression analysis. To test for left-to-right and day-to-day reliability, we calculated Pearson and intraclass correlations. We found a mean error of ≈5% and a high correlation (r = 0.96; p < 0.001) for the jump height measured by the Polar Vantage V2 sports watch compared to the force plate measurement. The Bland-Altmann plot together with the ordinary least squares regression analysis showed no systematic bias between the methods with a minimal difference at a jump height of 30 cm. For reliability of left-to-right and day-to-day measurements, we found high Pearson and ICC correlations and no indications for systematic bias by Bland-Altmann analysis. The present study has demonstrated that the "leg recovery test" of the Polar Vantage V2 sports watch provide a valid and reliable measurement of the mean vertical jump height of three consecutive CMJs. For the first time the jump height of a CMJ can be measured solely by a sports watch without the need to attach additional sensors or measurement devices. Thus, the "leg recovery test" is an easy to administer, valid and reliable test, that can be used in future studies to measure CMJ-height in the field when lab-based assessments are unavailable or inconvenient. This opens new avenues for cross-sectional and longitudinal assessments of neuromuscular power of the lower extremities in a large number of participants.

Effects of Eight-Week Circuit Training with Core Exercises on Performance in Adult Male Soccer Players

Core exercises have been widely promoted in the last 25 years. However, the scientific debate about its efficacy for improving individual and team sports performance is still open. Thus, the present study aims to investigate the effects of circuit training with a core exercise program on physical performance in competitive amateur soccer players. The training was conducted during the off-season period, two times per week for 8 weeks. Pre- and post-evaluations were conducted using the following tests: Y-Balance Test (YB), standing long jump (SLJ), medicine ball chest press (MBC), curl-up (CU), and Illinois Agility Test (IAT). A total of 19 adults were divided into an experimental group (EG, n = 11, age 22 years, weight 71.2 ± 4.8 kg, height 174 ± 5.8 cm) and a control group (CG, n = 8, age 22 years, weight 73.2 ± 4.1 Kg, height 176 ± 6.3 cm). The EG showed significant improvements in lower and upper body strength, core endurance and balance, whereas the CG did not report significant changes in the pre- and post-test comparison. Despite study limitations, our positive results show that circuit training with core exercises appears to be a good strategy for performance improvement in adult soccer players.

Differences in body composition and physical fitness parameters among prepubertal and pubertal children engaged in extracurricular sports: the active health study

Background

This study aimed to analyze the associations of maturity status, chronological age and sex with physical fitness and body composition among active children.

Methods

A total of 1682 children (72% boys; age = 11.22 ± 2.64 years; height = 147.57 ± 15.87 cm; weight = 44.55 ± 15.29 kg) from rural areas participating in extracurricular sports were divided into four groups according to their sex and maturity status (prepubertal and pubertal according to stages described by Tanner). Body composition (body mass index, muscle mass and fat mass) and physical fitness (20-m shuttle-run test, handgrip strength and vertical jump) were assessed using standardized procedures. A two-way ANOVA and product–moment correlations were performed.

Results

Prepubertal boys had more fat mass (%) than pubertal boys [P<0.001; effect size (ES): 0.45], while prepubertal girls had more muscle mass (%) than pubertal girls (P<0.001; ES: 0.47). The pubertal group displayed higher fitness outcomes (absolute values) regardless of sex (P<0.05). However, the prepubertal group had higher percentile values in the 20-m shuttle-run test and vertical jumps than the pubertal group regardless of sex (P < 0.001; ES: 0.29–0.48). All the measures of physical fitness were positively associated with chronological age and muscle mass (%).

Conclusions

Although absolute values of body composition and physical fitness appear to increase among pubertal children participating in extracurricular sports, the percentiles indicate that puberty is accompanied with a loss of a physical fitness levels. Thus, extracurricular sports might not be enough to enhance fitness among adolescents.

Making a HIIT: study protocol for assessing the feasibility and effects of co-designing high-intensity interval training workouts with students and teachers

Background

High-intensity interval training (HIIT) is an effective strategy for improving a variety of health outcomes within the school setting. However, there is limited research on the implementation of school-based HIIT interventions and the integration of HIIT within the Health and Physical Education (HPE) curriculum. The aims of the Making a HIIT study are to: 1) describe the methodology and evaluate the feasibility of co-designing HIIT workouts with students and teachers in HPE; 2) determine the effect of co-designed HIIT workouts on cardiorespiratory and muscular fitness, and executive function; 3) understand the effect of co-design on students’ motivation, enjoyment, and self-efficacy towards the workouts; and 4) evaluate the implementation of the intervention.

Methods

Three schools will participate. Within each school, three different groups will be formed from Year 7 and 8 classes: 1) Co-Designers; 2) HIIT Only; and 3) Control. The study will include two phases. In phase one, Group 1 will co-design HIIT workouts as part of the HPE curriculum using an iterative process with the researcher, teacher, and students as collaborators. This process will be evaluated using student discussions, student surveys, and teacher interviews. In phase two, Groups 1 and 2 will use the co-designed 10-minute HIIT workouts in HPE for 8-weeks. Group 3 (control) will continue their regular HPE lessons. All students will participate in cardiorespiratory fitness, muscular fitness, and executive function assessments before and after the HIIT program or control period. Students will complete questionnaires on their motivation, enjoyment, and self-efficacy of the workouts. Differences between groups will be assessed using linear regressions to account for covariates. Heart rate and rating of perceived exertion will be collected during each HIIT session. The implementation will be evaluated using the Framework for Effective Implementation. Ethical approval was granted by the University of Queensland Human Research Ethics Committee and other relevant bodies.

Discussion

This study will be the first to co-design HIIT workouts with teachers and students within the HPE curriculum. As this study relies on co-design, each HIIT workout will differ, which will add variability between HIIT workouts but increase the ecological validity of the study.

Trial registration

ACTRN, ACTRN12622000534785, Registered 5 April 2022 – Retrospectively registered, https://www.anzctr.org.au/ACTRN12622000534785.aspx

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03440-w.

Effects of an Online Supervised Exercise Training in Children with Obesity during the COVID-19 Pandemic

COVID-19 restrictions have dramatically reduced the active lifestyle and physical activity (PA) levels in the whole population, a situation that can contribute to weight gain and to develop obesity. To improve physical fitness (PF) in children with obesity during COVID-19 restrictions, sport specialists started to deliver physical training through tele-exercise. For these reasons, the aim of this study was to evaluate the effects of a 12-week online supervised training program in children with obesity on different PF components and PA levels. We enrolled a total of 40 Caucasian children (9 F/31 M; aged 11 ± 1.9 years) with obesity. The data collection consisted of a series of anthropometric measures, the PAQ-C questionnaire, and PF tests, valid and reliable tools to assess PF in children. We used a Wilcoxon’s t-test and a Student’s t-test, as appropriate, to assess the differences before and after the training protocol. A total of 37 patients completed the training protocol and were considered in the analysis. Our results show an improvement in all the PF tests, a reduction in the BMI z-score, the waist circumference, and in the waist-to-height ratio, and an increased PA level. In conclusion, the results of our study show that an online supervised training program is effective to promote PA, improving PF and reducing the BMI z-score in children with obesity.

Associations Between Kindergarten Participation in Organized Physical Activity and Subsequent Healthy Body Weight and Leg Strength by the End of Second Grade

BACKGROUND

Childhood sport helps children develop growth and maturation, while simultaneously offering self-regulation, motor, and social skills training. This study aims to estimate the influence of sport participation at age 6 years on indicators of health at age 8 years, using a prospective longitudinal birth cohort design.

METHODS

Participants were 1492 children aged 6-8 years from the Quebec Longitudinal Study of Child Development. Lower muscular power was measured with the standing long jump test. Girth used the children's waist circumference in centimeters. Body mass index was computed from child height and weight. We regressed these directly measured health indicators at age 8 years on parent-reported physical activity at age 6 years using linear Ordinary Least Squares regression.

RESULTS

Boys who participated in more physical activity at age 6 years had better lower muscular power (b = 2.368; 95% CI, 0.341 to 4.395) and higher body mass index (b = 0.340; 95% CI, 0.055 to 0.626). No significant results were found for girls.

CONCLUSIONS

Our findings suggest that physical activity in kindergarten has a positive impact on muscular power by the end of the second grade in boys. This supports the pertinence of implementing physical activity to a routine early in life to help children improve their general health.

Neuroergonomic assessment of developmental coordination disorder

Until recently, neural assessments of gross motor coordination could not reliably handle active tasks, particularly in realistic environments, and offered a narrow understanding of motor-cognition. By applying a comprehensive neuroergonomic approach using optical mobile neuroimaging, we probed the neural correlates of motor functioning in young people with Developmental Coordination Disorder (DCD), a motor-learning deficit affecting 5-6% of children with lifelong complications. Neural recordings using fNIRS were collected during active ambulatory behavioral task execution from 37 Typically Developed and 48 DCD Children who performed cognitive and physical tasks in both single and dual conditions. This is the first of its kind study targeting regions of prefrontal cortical dysfunction for identification of neuropathophysiology for DCD during realistic motor tasks and is one of the largest neuroimaging study (across all modalities) involving DCD. We demonstrated that DCD is a motor-cognitive disability, as gross motor /complex tasks revealed neuro-hemodynamic deficits and dysfunction within the right middle and superior frontal gyri of the prefrontal cortex through functional near infrared spectroscopy. Furthermore, by incorporating behavioral performance, decreased neural efficiency in these regions were revealed in children with DCD, specifically during motor tasks. Lastly, we provide a framework, evaluating disorder impact in ecologically valid contexts to identify when and for whom interventional approaches are most needed and open the door for precision therapies.

Relationships Between Sports Club Participation and Health Determinants in Adolescents and Young Adults

Physical fitness is a powerful marker of health in adolescents and young adults. The purpose of this study was to measure the relationships between age, sex, body mass index, and sports club participation on physical fitness. The population included 49,988 participants (23,721 girls and 26,267 boys) who were divided into five age groups (11–12, 13–14, 15–16, 17–18, and 19–21 years). Body mass index was calculated. Physical fitness was assessed with the Diagnoform^® Tonic battery. Sports club participation was also documented. The practiced sport was collected. The effects of age, sex, body mass index class, and sports club participation were tested. Boys' PF increased with age at a faster rate and was better than that of girls, except for flexibility (p < 0.001). For girls, a decrease was observed in endurance, speed and flexibility at 17-18 years. Sports club participation was greater for boys at every age. Obese participants had the lowest physical fitness and sports club participation. Sports club participation increased physical fitness. Team sports seemed best for improving physical fitness, except flexibility. The study shows that sports club participation may be a key element for building health in adolescents. Preventive healthcare projects that promote sports club are needed to target sports club dropouts (obese adolescents and girls). Bridges should be built between physical education classes and sports clubs in adolescence to improve the health status of young people.

Players with high physical fitness are at greater risk of injury in youth football

The aim of this study was to investigate physical fitness, football-specific skills, and their association with injury risk in youth football. Altogether 447 male and female players aged 9-14 years (median 12 years) participated in performance tests and prospective follow-up. The physical fitness tests included five-jump test for distance, 30-m sprint, football-specific figure of eight agility, countermovement jump, and Yo-Yo intermittent endurance test level 1. The football-specific skill tests included dribbling and passing tests. Injuries and exposure were registered during the 20-week follow-up. Our candidate risk factors were low/high level of physical fitness measured with a composite score of physical fitness tests and low/high level of football-specific skills measured with a composite score of dribbling and passing tests. Secondarily, we investigated performance in individual tests and their association with injury risk. During the follow-up, players reported 565 injuries (264 acute and 301 overuse injuries). High level of physical fitness was associated with increased rate of all injuries (age-, sex-, and mean team exposure-adjusted IRR: 1.28, 95% CI: 1.04-1.58). The level of football-specific skills had no influence on the overall injury rate. Burden of overuse injuries, but not acute injuries was significantly higher in most fit players compared with the players in the reference group (IRR: 2.09, 95% CI: 1.04-4.24). In conclusion, most fit players were at greater risk of sustaining injuries in youth competitive football.

Potential Energy as an Alternative for Assessing Lower Limb Peak Power in Children: A Bayesian Hierarchical Analysis

The aim of this study was to analyze the use of potential energy (PE) as an alternative method to assess peak power of the lower limbs (PP) in children. 815 Spanish children (416 girls; 6–11 years old; Body Mass Index groups (n): underweight = 40, normal weight = 431, overweight = 216, obese = 128) were involved in this study. All participants performed a Countermovement Jump (CMJ) test. PP was calculated using Duncan (PP_DUNCAN), Gomez-Bruton (PP_GOMEZ) and PE_CMJ formulas. A model with PE_CMJ as the predictor variable showed a higher predictive accuracy with PP_DUNCAN and PP_GOMEZ than CMJ height (R² = 0.99 and 0.97, respectively; ELPD_diff = 1037.0 and 646.7, respectively). Moreover, PE_CMJ showed a higher linear association with PP_DUNCAN and PP_GOMEZ across BMI groups than CMJ height (β_PECMJ range from 0.67 to 0.77 predicting PP_DUNCAN; and from 0.90 to 1.13 predicting PP_GOMEZ). Our results provide further support for proposing PE_CMJ as an index to measure PP of the lower limbs, taking into account the children’s weight and not only the height of the jump. Therefore, we suggest the use of PE_CMJ in physical education classes as a valid method for estimating PP among children when laboratory methods are not feasible.

Effect of timing of school enrollment on physical fitness in third graders

Timing of initial school enrollment may vary considerably for various reasons such as early or delayed enrollment, skipped or repeated school classes. Accordingly, the age range within school grades includes older-(OTK) and younger-than-keyage (YTK) children. Hardly any information is available on the impact of timing of school enrollment on physical fitness. There is evidence from a related research topic showing large differences in academic performance between OTK and YTK children versus keyage children. Thus, the aim of this study was to compare physical fitness of OTK (N = 26,540) and YTK (N = 2586) children versus keyage children (N = 108,295) in a representative sample of German third graders. Physical fitness tests comprised cardiorespiratory endurance, coordination, speed, lower, and upper limbs muscle power. Predictions of physical fitness performance for YTK and OTK children were estimated using data from keyage children by taking age, sex, school, and assessment year into account. Data were annually recorded between 2011 and 2019. The difference between observed and predicted z-scores yielded a delta z-score that was used as a dependent variable in the linear mixed models. Findings indicate that OTK children showed poorer performance compared to keyage children, especially in coordination, and that YTK children outperformed keyage children, especially in coordination. Teachers should be aware that OTK children show poorer physical fitness performance compared to keyage children.

Relationships between Athletic Motor Skill Competencies and Maturity, Sex, Physical Performance, and Psychological Constructs in Boys and Girls

The purpose of this study was to examine the relationships between athletic motor skill competencies (AMSC), maturation, sex, body mass index, physical performance, and psychological constructs (motivation to exercise, physical self-efficacy, and global self-esteem). Two-hundred and twenty-four children aged 11–13 years old were included in the study and sub-divided by sex. The athlete introductory movement screen (AIMS) and tuck jump assessment (TJA) were used to assess AMSC, while standing long jump distance assessed physical performance. Online surveys examined participants’ motivation to exercise, physical self-efficacy, and self-esteem. Trivial to moderate strength relationships were evident between AMSC and BMI (boys: r_s = −0.183; girls: r_s = −0.176), physical performance (boys: r_s = 0.425; girls: r_s = 0.397), and psychological constructs (boys: r_s = 0.130–0.336; girls r_s = 0.030–0.260), with the strength of relationships different between the sexes. Higher levels of AMSC were related to significantly higher levels of physical performance (d = 0.25), motivation to exercise (d = 0.17), and physical self-efficacy (d = 0.15–0.19) in both boys and girls. Enhancing AMSC may have mediating effects on levels of physical performance and psychological constructs in school-aged children, which may hold important implications for physical activity levels and the development of physical literacy.

Declining fitness and physical education lessons in UK adolescents

Objectives

The objective was to determine recent cross-sectional trends in health-related fitness (HRF) in secondary school students by studying the 13–14 years old age group repeatedly over 6 years, considering parallel national trends in physical education (PE).

Methods

Height, weight, broad jump, grip strength, 20 m shuttle run and throwing and catching skills were measured by the same research team using standardised techniques from 2014 to 2019. Trends in these HRF measures were assessed by linear regression, adjusting for school, sex and height. Interactions with fitness and body mass index (BMI) were tested. The number of PE lessons reported in the UK Annual School Workforce Census between 2010 and 2019 for all state-funded secondary schools was analysed.

Results

Grip strength (B=−0.60, 95% CI −0.78 to –0.41), broad jump (B=−1.16, 95% CI −1.99 to –0.34), 20 m shuttle run (B=−1.85, 95% CI −2.58 to –1.12) and throwing and catching skills (B=−0.12, 95% CI −0.15 to –0.08) declined significantly over the study period. There was a greater reduction in broad jump and grip strength in adolescents with low fitness and a greater reduction in fitness and motor competence in adolescents with normal BMI. These declines coincided with a 16% reduction nationally in secondary school PE between 2010 (333 800 hours) and 2019 (280 725 hours).

Conclusion

Adolescent HRF has declined in recent years, in parallel with PE lessons. Declines were observed across all young people and particularly those of low fitness and normal BMI. To reach the majority of young people, policy makers could increase PE in schools to increase activity and prevent worsening fitness and health in future generations.

Promoting healthy lifestyle behaviours in youth: Findings from a novel intervention for children at risk of cardiovascular disease

Objectives

Obesity is the most prevalent risk factor for cardiovascular disease (CVD) in children. We developed a 2-year lifestyle intervention for youth at risk of CVD. We assessed changes in body mass index z-scores (zBMI) and key cardiometabolic risk factors, physical fitness, and capacity among those who completed the program.

Methods

The CIRCUIT program is a multidisciplinary lifestyle intervention for children aged 4 to 18 years at risk of CVD, based on a personalized plan to improve cardiometabolic outcomes by increasing physical activity and reducing sedentary behaviours. Both at baseline and 2-year follow-up, we measured zBMI, blood pressure z-scores (zBP), adiposity (%body and %trunk fat), fasting blood glucose and lipid profile, aerobic (VO2max) and anaerobic (5×5 m shuttle run test) fitness, and physical capacity indicators. Differences between baseline and follow-up were examined using paired t-tests (for age-sex standardized outcomes) and multivariable mixed effect models, adjusted for age and sex (for other outcomes).

Results

Among the 106 participants (53 males) who completed the 2-year program, mean age at baseline was 10.9 years (SD=3.2). After 2 years, zBMI and diastolic zBP decreased by 0.30SD (95% CI: −0.44; −0.16) and 0.43SD (95% CI: −0.65; −0.23), respectively. Participants improved %body and %trunk fat, lipid profile, aerobic and anaerobic fitness levels, and physical capacity (p&lt;0.02). No changes in systolic zBP nor in fasting plasma glucose were observed.

Conclusion

Our findings showed improved zBMI, cardiometabolic outcomes, physical fitness, and capacity among children at risk of CVD, suggesting that CIRCUIT is a promising intervention.

Identifying actual and perceived motor competence based profiles among children

This study aimed to develop motor competence (MC) profiles in children based on their actual and perceived MC, and to investigate differences in physical activity (PA) behaviour and motivation towards PA between profiles. Two hundred and sixteen British children (7-10 years) took part in this study. Perceived motor competence (PMC) was assessed using the pictorial scale of movement competence. MC was assessed using process-oriented and product-oriented measures. A validated questionnaire assessed motivation towards PA and an objective measure of PA was employed. K-means cluster analysis was used to create profiles. Differences in PA and motivation towards PA were examined using ANCOVAs. Four groups of divergent and convergent levels were identified based on the contribution of either product or process MC with PMC. Motivation towards PA differed by profiles that included actual-process and PMC. Children with high actual process and high PMC had significantly higher levels of autonomous motivation than children with high actual process but low PMC. No significant differences were found between PA levels and profiles. Developing the quality and execution of actual motor competence (AMC) and PMC is key to stimulate motivation towards PA. Furthermore, maintaining AMC and PMC simultaneously may be imperative to children's future PA behaviour.

Acute effect of a static- and dynamic-based stretching warm-up on standing long jump performance in primary schoolchildren

The aim of the present study was to compare the acute effect of a static- vs dynamic-based stretching warm-up on standing long jump (SLJ) performance in primary schoolchildren. The sample was composed of 76 schoolchildren, 43 girls and 33 boys, aged 9–10 years old from three fourth-grade classes of Primary Education. The three groups were cluster-randomly assigned to the control (CG), static (SG) or dynamic (DG) groups. All the schoolchildren performed a standardized warm-up consisting of mobility exercises (five minutes), jogging (five minutes) and the SLJ test. Afterwards the CG schoolchildren received jump theory (eight minutes), the SG performed static stretching (eight minutes) and the DG performed dynamic-bounces stretching (eight minutes). Afterwards, all of them performed the SLJ test again. The results of the one-way ANOVA (F_2,73 = 34.184; p < 0.001; η²p = 0.484), followed by the pairwise comparisons with the Bonferroni adjustment, showed that the DG students (M_Δ = 11.07, SE = 1.42) made a significant statistical improvement in their SJL levels compared with the CG (M_Δ = -3.00, SE = 1.89; p < 0.001, d = 1.51) and SG students (M_Δ = -1.85, SE = 0.67; p < 0.001, d = 1.38). However, statistically significant differences between the CG and SG students were not found (p > 0.05, d = 0.12). The dynamic-bouncing stretch as a final part of a warm-up improves explosive strength performance in primary schoolchildren, and seems to be a good option before carrying out explosive strength activities of the lower body.

Age and sex effects in physical fitness components of 108,295 third graders including 515 primary schools and 9 cohorts

Children's physical fitness development and related moderating effects of age and sex are well documented, especially boys' and girls' divergence during puberty. The situation might be different during prepuberty. As girls mature approximately two years earlier than boys, we tested a possible convergence of performance with five tests representing four components of physical fitness in a large sample of 108,295 eight-year old third-graders. Within this single prepubertal year of life and irrespective of the test, performance increased linearly with chronological age, and boys outperformed girls to a larger extent in tests requiring muscle mass for successful performance. Tests differed in the magnitude of age effects (gains), but there was no evidence for an interaction between age and sex. Moreover, "physical fitness" of schools correlated at r = 0.48 with their age effect which might imply that "fit schools" promote larger gains; expected secular trends from 2011 to 2019 were replicated.

Effects of three 8-week strength training programs on jump, speed and agility performance in prepubertal children

BACKGROUND: Supervised strength training has been shown to promote physiological adaptations in children and youth that can be beneficial to the process of physical growth and developed, and general health status. METHODS: Sixty-three children (9.2 ± 0.5 years old) were randomly assigned to training groups: multi jumps (MJ) (n= 20), sled towing (ST) (n= 21), or uphill running (UR) (n= 22). The following tests were applied before and after each intervention: vertical jump (ABK, CMJ, SJ), standing broad jump (SBJ), velocity/agility 4 × 10 m, and 20 m sprint test (ST20m). RESULTS: After 8 weeks of training, statistically significant changes were found in all study variables for all groups, but with different effect sizes. In the ABK jump, the largest effect size was observed in UR (1.40, 0.97–1.85), while in ST and MJ it was medium (0.67, 0.44–0.98 and 0.48, 0.17–0.82, respectively). Similarly, the effect size in the SJ jump was large for the UR and ST groups (1.10, 0.78–1.51 and 1.30, 0.98–1.64, respectively) and medium in MJ (0.56, 0.24–0.97). However, the magnitude of the effect registered in SBJ was large in MJ (0.80, 0.55–1.15) and medium in UR and ST (0.56, 0.32–0.86 and 0.64, 0.42–1.013, respectively). CONCLUSIONS: All three training programs improve jumping and velocity/agility performance but based on clinical significance, UR and ST methods can be considered more efficient to improve physical performance in children.

Integrative Neuromuscular Training Enhances Physical Fitness in 6- to 14-Year-Old Rugby Players

ABSTRACT

Alonso-Aubin, DA, Picón-Martínez, M, Rebullido, TR, Faigenbaum, AD, Cortell-Tormo, JM, and Chulvi-Medrano, I. Integrative neuromuscular training enhances physical fitness in 6- to 14-year-old rugby players. J Strength Cond Res 35(8): 2263-2271, 2021-The purpose of this study was to assess the effects of an 8-week integrative neuromuscular training (INT) program on physical fitness measures in young rugby players. A sample of 138 male rugby players (age range, 6-14 years) was divided into 5 age-related groups: group 1 (G1) (n = 20; age, 7.05 ± 0.58), group 2 (G2) (n = 27; age, 8.57 ± 0.49), group 3 (G3) (n = 31; age, 11.02 ± 0.56), group 4 (G4) (n = 33; age, 13.12 ± 0.58, and group 5 (G5) (n = 27; age, 14.85 ± 1.53 and additionally into 2 game position groups: forwards (FOR) (n = 69) and backs (BAC) (n = 69). Physical fitness measures included the Functional Movement Screen (FMS), dominant and nondominant hand-to-eye coordination, sprint capacity, core muscular endurance, and lower- and upper-body power. Integrative neuromuscular training (INT) included progressive strength, coordination, and speed exercises performed twice per week for 20 minutes. Following INT, significant improvements in selected age-related groups (p < 0.01) were found in total FMS score G3 (effect size [ES] = 0.47), G4 (ES = 0.88), and G5 (ES = 0.58); dominant hand-to-eye coordination G1 (ES = 1.48), G2 (ES = 0.71), G3 (ES = 0.55), G4 (ES = 1.47), and G5 (ES = 1.15), nondominant hand-to-eye coordination G2 (ES = 0.74), G4 (ES = 1.34), and G5 (ES = 1.09); lower-body power G2 (ES = 0.44), G4 (ES = 0.39), and G5 (ES = 0.43); core muscular endurance G1 (ES = 0.82), G3 (ES = 0.68), and G4 (ES = 1.04); upper-body power G2 (ES = 0.53); and sprint capacity G4 (ES = 0.69). Significant improvements were also found between player's positions for all tests. These findings indicate that a progressive INT program can enhance functional movement abilities and selected physical fitness measures in young rugby players regardless of game position and age.

Relationships between sports club participation and physical fitness and body mass index in childhood

BACKGROUND

Physical fitness (PF) is a powerful determinant of health. The aim of this study was to examine the relationships between sports club (SC) participation and PF, and body mass index (BMI) in children.

METHODS

The population included 15,625 children (8,029 boys and 7,596 girls) 5 to 10 years old divided into three aged groups. PF was assessed with the Diagnoform® Kid from 5 tests measuring different components: cardiorespiratory endurance, muscular strength, speed, coordination, agility and flexibility. BMI was calculated. SC participation was documented. The sports were classified into four categories based on the educational goal (C1, C2, C3, C4). The relationships between sex, age, BMI class and SC participation were tested.

RESULTS

The children who practiced in SC had better PF than those who did not. C1 (track and field, swimming, triathlon and cycling) and C4 (team, combat and racket sports) sports seemed to be associated with a better PF.

CONCLUSIONS

This study showed that SC participation may be an element for building health. Preventive healthcare projects for SC dropouts (obese children and girls) are needed.

Children's school footwear: The impact of fit on foot function, comfort and jump performance in children aged 8 to 12 years

BACKGROUND

There is a common perception that poorly fitting footwear will negatively impact a child's foot, however, there is limited evidence to support this.

AIM

To determine the effect of shoe size on foot motion, perceived footwear comfort and fit during walking, maximal vertical jump height and maximal standing broad jump distance in children aged 8-12 years.

METHODS

Fourteen participants completed 3D walking gait analysis and jumping tasks in three different sizes of school shoes (one size bigger, fitted for size, one size smaller). In-shoe motion of the hindfoot, midfoot and 1st metatarsophalangeal joint (1st MTPJ) were calculated using a multi-segment kinematic foot model. Physical performance measures were calculated via maximal vertical jump and maximal standing broad jump. Perceived footwear comfort and fit (heel, toes and overall) was assessed using a 100 mm visual analog scale (VAS). Differences were compared between shoe sizes using repeated measures ANOVA, post-hoc tests and effect sizes (Cohen's d).

RESULTS

Compared to the fitted footwear, the smaller sizing restricted hindfoot eversion (-2.5°, p = 0.021, d = 0.82), 1st MTPJ dorsiflexion (-3.9°, p = 0.012, d = 0.54), and compared to the bigger footwear, smaller sizing restricted sagittal plane midfoot range-of-motion during walking (-2.5°, p = 0.047, d = 0.59). The fitted footwear was rated as more comfortable overall with the smaller size rated as too tight in both the heel (mean difference 11.5 mm, p = 0.042, d = 0.58) and toes (mean difference 12.1 mm, p = 0.022, d = 0.59), compared to the fitted size. Vertical and standing broad jump distance were not impacted by footwear size (p = 0.218-0.836).

SIGNIFICANCE

Footwear that is too small restricts foot motion during walking in children aged 8-12 years. Jump performance was not affected. Children were able to recognise shoes that were not correctly matched to their foot length, reinforcing that comfort is an important part of the fitting process.

Physical fitness reference standards in Italian children

Physical fitness in childhood is considered a marker of current and future health. For this reason, there is a need for a simple but reliable test to assess the different components of physical fitness even at school during physical education lessons. However, standard values are required to correctly interpret the results of such tests. Hence, this study aimed to generate sex- and age-specific normative percentile values for health-related physical fitness in Italian children. To this aim, 30,472 children aged 6-11 years from the Friuli Venezia-Giulia region (Italy) were examined. The fitness test battery included the Léger test (cardiorespiratory), the shuttle test (agility), standing long jumps, frontal throws of a basketball (lower and upper limb strength), the sit-and-reach test (flexibility), and the standing balance test. Sex- and age-percentile curves were determined using the General Additive Model for Location Scale and Shape (GAMLSS).Conclusion: The reference standards are provided as 1st, 3rd, 10th, 25th, 50th, 75th, 90th, 97th, and 99th percentiles in the form of both tables and charts and are roughly comparable with those of other European children. What is Known: • Physical fitness in childhood is considered a marker of current and future health; • Several tests have been developed to assess physical fitness in children; • There are general European reference standards for a series of tests of the main fitness components for children. What is New: • The present study provides specific reference standards for a series of tests that are indicative of the main fitness components and easily applied in children, particularly those in the Italian population; • Standing balance test and basketball frontal throw test references in a wide sample of children; • The performance of children in the present study was roughly comparable to that of other European children.

Model invariance of the Motor Competence Assessment (MCA) from early childhood to young adulthood

The Motor Competence Assessment (MCA) is an innovative instrument to assess motor competence along the lifespan. The MCA model and normative values were recently established from the age of 3-to-23 years old. The purpose of this study was to validate MCA from early childhood to young adulthood.One thousand participants representing four age groups (3-6, 7-10, 11-16, 17-22 years) with 250 participants each, were assessed. Invariance of the MCA model along the age groups - configural, metric and structural - was tested using multigroup CFA.The MCA model showed to fit well all age groups. The multigroup unconstrained model showed a very good fit (NFI=0.99; TLI=0.99; CFI=0.99; RMSEA=0.03). A formal test for the invariance of loading coefficients returned a non-satisfactory goodness-of-fit adjustment and a significant difference with the unconstrained model (Δχ² = 539.57; Δdf = 18; p= .00) . The structural invariance testing did not show formal invariance between factor correlations (Δχ² = 73.04; Δdf = 9; p= .00) but the fit of the model was acceptable (above 0.96 and a RMSEA of 0.05), indicating that correlation values inter factors are stable.This study adds information for the validation of the MCA as a useful instrument for assessing motor competence throughout the life cycle.

Temporal Trends in the Standing Broad Jump Performance of 10,940,801 Children and Adolescents Between 1960 and 2017

BACKGROUND

The standing broad jump (SBJ) is an excellent functional measure of explosive lower-body strength that is significantly related to health among children and adolescents.

OBJECTIVES

The aim of this study was to estimate national (country-level) and international (pooled global data) temporal trends in SBJ performance for children and adolescents, and to examine the relationships between national trends in SBJ performance and national trends in health-related and socioeconomic/demographic indicators.

METHODS

Data were obtained from a systematic search of studies reporting temporal trends in SBJ performance for 9- to 17-year-olds, and by examining national fitness datasets. Sample-weighted regression models estimated trends at the study/dataset-country-sex-age level, with national and international trends estimated by a post-stratified population-weighting procedure. Pearson's correlations quantified relationships between national trends in SBJ performance and national trends in health-related and socioeconomic/demographic indicators.

RESULTS

Data from 34 studies/datasets were extracted to estimate trends for 10,940,801 children and adolescents from 24 high-, 4 upper-middle-, and 1 low-income countries between 1960 and 2017. Collectively, there was a negligible (per decade) improvement in SBJ performance of 1.73 cm (95% CI 1.71-1.75), 0.99% (95% CI 0.97-1.01) or a standardized effect size of 0.07 (0.07-0.07) over the entire period, with the rate of improvement steady from the 1960s to the 1980s, slowing in the 1990s, before declining. Sex- and age-related temporal differences were negligible. Trends differed between countries, with most countries experiencing declines. National trends in SBJ performance were not significantly related to national trends in health-related and socioeconomic/demographic indicators.

CONCLUSIONS

SBJ performance of children and adolescents has declined since 2000 (at least among most of the countries in this analysis) and is suggestive of a modern decline in functional explosive lower-body strength. Growing recognition of the importance of muscular fitness as a marker of population health highlights the need for continued tracking of temporal trends in SBJ, especially among low- and lower-middle-income countries for which temporal data are lacking.

PROSPERO REGISTRATION NUMBER

CRD42013003657.

Muscle Damage and Performance after Single and Multiple Simulated Matches in University Elite Female Soccer Players

The present study aimed to compare changes in muscle damage and performance parameters after playing single versus multiple soccer matches to examine fixture congestion effects on performance. Twelve elite female university soccer players performed single, three and six consecutive 90-min bouts of the Loughborough Intermittent Shuttle Test (LIST) with ≥12-weeks between conditions in a pseudo-randomized order. Heart rate, blood lactate, rating of perceived exertion and covering distance in each LIST were examined. Changes in several types of muscle damage (e.g., maximal voluntary isometric torque of the knee extensors: MVC-KE) and performance measures (e.g., Yo-Yo Intermittent Recovery Test level 1: YYIR1) were taken before each LIST, 1 h, and 1–5 d after the last LIST. The total distance covered during the LIST was shorter (p < 0.05) in the 2nd–3rd, or 2nd–6th LISTs when compared with the 1st LIST. Changes (p < 0.05) in all measures were observed after the LIST, and the greatest changes were observed after the six than after the three LISTs followed by one LIST (e.g., largest changes in MVC-KE: −26 > −20 > −14%; YYIR1: −31 > −26 > −11%). Many of the variables did not recover to the baseline for 5 d after six LISTs. These suggest that fixture congestion induces greater muscle damage and performance decline than a single match.

Sensitivity and Specificity of a Multimodal Approach for Concussion Assessment in Youth Athletes

CONTEXT

Current international consensus endorses a multimodal approach to concussion assessment. However, the psychometric evaluation of clinical measures used to identify postconcussion performance deficits once an athlete is asymptomatic remains limited, particularly in the pediatric population.

OBJECTIVE

To describe and compare the sensitivity and specificity of a multimodal assessment battery (balance, cognition, and upper and lower body strength) versus individual clinical measures at discriminating between concussed youth athletes and noninjured controls when asymptomatic.

DESIGN

Prospective cohort study.

SETTING

Hospital laboratory setting.

PARTICIPANTS

A total of 32 youth athletes with a concussion and 32 matched (age and sex) noninjured control participants aged 10-18 years.

INTERVENTION(S)

Participants were administered preinjury (baseline) assessments of cognition (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT]), balance (BioSway), and upper and lower body strength (grip strength and standing long jump). Assessments were readministered when concussed participants reported symptom resolution (asymptomatic time point). Noninjured control participants were reassessed using the same time interval as their concussion matched pair. Sensitivity and specificity were calculated using standardized regression-based methods and receiver operating characteristic curves.

MAIN OUTCOME MEASURES

Outcome measures included baseline and postinjury ImPACT, BioSway, grip strength, and standing long jump scores.

RESULTS

When asymptomatic, declines in performance on each individual clinical measure were seen in 3% to 22% of the concussion group (sensitivity = 3%-22%) compared with 3% to 13% of the noninjured control group (specificity = 87%-97%) (90% confidence interval). The multimodal battery of all combined clinical measures yielded a sensitivity of 41% and a specificity of 77% (90% confidence interval). Based on discriminative analyses, the multimodal approach was statistically superior compared with an individual measures approach for balance and upper and lower body strength, but not for cognition.

CONCLUSIONS

Results provide a foundation for understanding which domains of assessment (cognition, balance, and strength) may be sensitive and specific to deficits once symptoms resolve in youth athletes. More work is needed prior to clinical implementation of a preinjury (baseline) to postinjury multimodal approach to assessment following concussion in youth athletes.

Dual-Task Effect on Gait in Healthy Adolescents: Association between Health-Related Indicators and DT Performance

The purpose of this study was to determine how dual-task (DT) effect on gait differs among adolescents with different fitness and health profiles. The gait performances of 365 adolescents aged 13-14 years were assessed at single and DT walking. The proportional changes in gait parameters from single to dual were regressed against gender, body mass index (BMIz), three components of MABC-2 (balance, aiming &catching and manual dexterity), group (high vs low motor competence), body strength, physical fitness level using multiple regression analyses; and gender and four items of balance subtest of MABC-2 in the secondary analysis. The analyses showed that being female was associated with greater reduction in gait speed and stride length and an increase in double support time and step time; and having lower score in balance was related to greater reduction in gait speed, and cadence, and an increase in step time. Only zig-zag hopping item of the balance subtest was associated with DT effect on gait speed and stride length. No significant relationships were found between DT effect on gait and the rest of the predictors. Females and adolescents with lower level of balance function may be at higher risk of having DT deficit during walking.

The Effects of Strength and Conditioning in Physical Education on Athletic Motor Skill Competencies and Psychological Attributes of Secondary School Children: A Pilot Study

Leading global physical activity guidelines advocate that young children need to engage in activities that strengthen musculoskeletal tissues and improve movement skill competency. The purpose of this study was to examine the effects of delivering strength and conditioning as part of the physical education curriculum on athletic motor skill competencies (AMSC), physical performance, and psychosocial factors. Forty-six school children aged 11–14 were included in the study, and sub-divided firstly by sex and then into intervention and control groups. Intervention groups received nine lessons of strength and conditioning based activities over a six-week period, while the control groups continued with traditional physical education curricula. The resistance training skills battery (RTSB) and tuck jump assessment (TJA) assessed AMSC. Standing long jump distance assessed lower limb strength, and online surveys examined motivation, physical self-efficacy and self-esteem. Male and female intervention groups significantly improved RTSB (p > 0.05) whereas no changes were observed in the control groups. No changes were observed in the intervention groups TJA and only trivial and small non-significant changes in standing long jump performance. Significant increases in motivation of the male intervention group occurred. Strength and conditioning integrated in physical education can improve AMSC in short-term interventions.

Field-Based Tests of Strength and Anaerobic Capacity Used in Children With Developmental Coordination Disorder: A Systematic Review

OBJECTIVE

Children with developmental coordination disorder (DCD) are reported to have lower levels of strength and anaerobic capacity. The purpose of this study was to (1) identify field-based tests for strength and anaerobic capacity used in studies comparing children with DCD and children who were typically developing (TD), (2) examine the methodological quality of studies reporting psychometric properties and rate the psychometric properties of the examined test, and (3) summarize available evidence by combining the methodological quality of the studies and the quality of the psychometric properties of the test.

METHODS

An electronic search was conducted in July 2019 in 4 electronic databases. For purpose 1, primary studies were included with no exclusion of study design in which children aged 4 to 18 years with DCD were compared with children who were TD on strength and/or anaerobic capacity measures. For purpose 2, primary studies were included with no exclusion of study design in which a psychometric property was investigated. The Consensus-Based Standards for Selection of Health Measurement Instruments (COSMIN) was used to evaluate the methodological quality of the 34 studies and rate the psychometric properties of the tests used.

RESULTS

Hand-held dynamometer, bent knee push-up, vertical jump, standing long-jump, functional strength measurement, fitness test, and test battery can be recommended for TD, and the shuttle run item of the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition and 10 m × 5 m sprints (straight and slalom) can be recommended for DCD.

CONCLUSION

Information regarding psychometric properties of field-based tests for strength and anaerobic capacity in children with DCD is lacking.

IMPACT

Information about the psychometric properties of field-based tests for strength and anaerobic capacity in children with DCD is lacking. More information is available on TD children, but it is also not complete; information regarding validity and responsiveness, especially, is missing. When using measures in children with DCD, it is important to keep in mind this lack of evidence for the validity and reliability of the outcomes for this target group.