Fitness Effects of 10-Month Frequent Low-Volume Ball Game Training or Interval Running for 8-10-Year-Old School Children

Process evaluation of school-based high-intensity interval training interventions for children and adolescents: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Several systematic reviews have been published to investigate the effectiveness of high-intensity interval training (HIIT) in schools. However, there has been limited attention given to understanding the functioning of the intervention processes, which is of paramount importance for interpreting and translating the intervention effectiveness. The aim of this systematic review is to determine the extent to which process evaluation is measured in school-based HIIT interventions and to explore the effects of process evaluation and intervention characteristics on cardiorespiratory fitness (CRF), body composition, muscular strength, and blood pressure.

METHODS

A comprehensive search was conducted in SPORT Discus (EBSCOhost), Web of Science, Scopus, Medline (Ovid) and Cochrane Central Register of Controlled Trials. The extent to which process evaluation is measured was narratively reported, alongside with the guidance of process evaluation of complex interventions by UK Medical Research Council. Meta-analyses and meta-regressions were conducted to determine the effects of process evaluation and intervention characteristics to the intervention outcomes.

RESULTS

The literature search identified 77 studies reporting on 45 school-based HIIT interventions. In total, five interventions reported process evaluation in a section or in a separate study, and only one intervention adopted a process evaluation framework. On average, 6 out of 12 process evaluation measures were reported in all interventions. Subgroup analyses did not indicate any beneficial treatment effects for studies with process evaluation group, whereas all pooled data and studies without process evaluation group showed significant improvement for CRF and body composition.

CONCLUSION

Process evaluation is frequently omitted in the literature of school-based HIIT in children and adolescents. Although reporting of process evaluation measures may not directly associate with better intervention outcomes, it allows accurate interpretation of intervention outcomes, thereby enhancing the generalisability and dissemination of the interventions.

"11 for Health" in China - Effects on physical fitness in 9-11-year-old schoolchildren

ABSTRACTPrevious studies have shown that the school-based physical activity programme entitled "11 for Health" has been effective in improving the physical fitness, well-being and overall health profile of European children. The main purpose of the present study was to examine whether the "11 for Health" programme can have a positive impact on the physical fitness of primary school pupils in China. A total of 124 primary school pupils aged 9-11 years were included in the experiment, randomly divided into the experimental group (EG, n = 62) and the control group (CG, n = 62). EG carried out three weekly 35-minute sessions of small-sided football for a total of 11 weeks. All data were analysed by a mixed ANOVA with the Student-Newman-Keuls post hoc test. The results showed greater improvements (p<0.001) in EG than CG in relation to systolic blood pressure (-2.9 vs +2.0 mmHg). Moreover, greater improvements (all p<0.05) were observed in postural balance (13 vs 0%), standing long jump (5.0 vs 0.5%), 30-metre sprint (4.1 vs 1.3%) and Yo-Yo IR1C running performance (17% vs 6%). In both EG and CG, physical activity enjoyment was observed to be higher (P<0.05) compared to the start of the intervention with increases of 3.7 and 3.9 AU respectively. In conclusion, the study revealed that the "11 for Health" programme has positive effects on aerobic and muscular fitness, and it appears to be a relevant tool in the physical activity promotion in the Chinese school system.

Making a HIIT: Methods for quantifying intensity in high-intensity interval training in schools and validity of session rating of perceived exertion

Using the data from Making a HIIT, this paper aimed to: 1) investigate the different heart rate (HR) quantification methods reported in school-based high-intensity interval training (HIIT) studies; and 2) assess the criterion validity of session rating of perceived exertion (RPE). During an 8-week HIIT intervention, 213 students (13.1 (0.6) years; 46% female) completed 10-minute HIIT workouts during physical education lessons. In total, 1057 HR and RPE measurements were collected across 68 HIIT workouts. For aim 1, the average and peak HR across all participants and workouts were 79% (8%) and 92% (6%) of HRmax, respectively. The average RPE was 6 (2) points on a 10-point scale. An average of 51% of students in a class had an average HR ≥ 80% for each workout. The between-person variation for peak and average HR were 19% and 30% , respectively. Both average and peak HR decreased by 0.5% each week (p < 0.001). To assess aim 2, a within-participant correlation was calculated for the internal training load produced using HR and RPE data. The correlation was 0.39 (p < 0.001), which suggests utility of using RPE when HR is not a viable option.

Comparative effectiveness of school-based exercise interventions on physical fitness in children and adolescents: a systematic review and network meta-analysis

Background

Schools provide a favorable setting for health education, however, the most effective school-based exercise mode for improving physical fitness remains unclear. This network meta-analysis was designed to assess and rank the comparative efficacy of six exercise modalities on physical fitness indicators in a school-based setting.

Methods

An online search of the Web of Science, PubMed, SPORTDiscus, and Scopus databases was conducted. Randomized and quasi-randomized controlled trials were considered. Outcomes included measures of anthropometry and body composition, muscular fitness, and cardiorespiratory fitness. Data were pooled with a random effects model using the frequentist framework.

Results

A total of 66 studies with 8,578 participants (48% girls) were included. High-intensity interval training was the most effective intervention reducing body mass index (mean difference (MD) = -0.60 kg·m^-2, 95% confidence interval (95%CI) = -1.04 to -0.15, p = 0.009), elevating VO_2max (MD = 3.59 mL·kg^-1·min^-1, 95% CI = 2.45 to 4.74, p < 0.001), and 20-meter sprint performance (MD = -0.35 s, 95% CI = -0.55 to -0.14, p = 0.001). Aerobic training had the highest probability of reducing waist circumference (standardized mean difference (SMD) = -0.60, 95% CI = -0.88 to -0.32, p < 0.001). Active video games emerged as a promising modality for improving countermovement jump (MD = 2.43 cm, 95% CI = 0.06 to 4.80, p = 0.041) and shuttle running performance (SMD = 0.86, 95% CI = 0.29 to 1.43, p = 0.003). Strength training was the best exercise mode for improving standing long jump performance (SMD = 1.03, 95% CI = 0.07 to 1.98, p = 0.035) while combined training was rated the first for decreasing body fat percent (MD = -2.56%, 95% CI = -4.73 to -0.40, p = 0.022) and increasing push-up repetitions (SMD = 3.59, 95% CI = 0.81 to 6.37, p = 0.012).

Conclusion

School-based exercise interventions have multiple effects on physical fitness. The findings of this study will help to inform physical education teachers and coaches how best to deliver exercise programs in a school setting. Since the study was limited by the original research, the conclusions will require further verification using high-quality randomized controlled trials.

Systematic Review Registration

PROSPERO, Identifier: CRD42023401963.

An 11-week school-based "health education through football" programme improves musculoskeletal variables in 10-12-yr-old Danish school children

Purpose

To investigate the effects of the "11 for Health" programme on musculoskeletal fitness.

Methods

A total of 108 Danish children aged 10-12 years participated in the study, with 61 children in the intervention group (IG, 25 girls and 36 boys) and 47 children in the control group (CG, 21 girls and 26 boys). Measurements were conducted before and after an 11-week intervention consisting of twice-weekly 45-min football training sessions for IG or continuation of normal Physical Education program for CG. Whole-body dual X-ray absorptiometry was conducted for evaluation of leg and total bone mineral density as well as bone, muscle and fat mass. Standing Long Jump and Stork balance tests were employed to assess musculoskeletal fitness and postural balance.

Results

During the 11-week study period, leg bone mineral density as well as leg lean body mass increased more (p < 0.05) in the intervention group (IG) compared to the control group (CG) (0.021 ± 0.019 vs 0.014 ± 0.018 g/cm² and 0.51 ± 0.46 vs 0.32 ± 0.35 kg, respectively). Moreover, body fat percentage decreased more in IG than in CG (-0.6 ± 0.1 vs 0.1 ± 0.1 %-points, p < 0.05). No significant between-group differences were found in bone mineral content. Stork balance test performance increased more in IG than in CG (0.5 ± 2.6 vs -1.5 ± 4.4 s, p < 0.05), whereas no between-group differences were found in jump performance.

Conclusions

The school-based football programme, 11 for Health, with twice-weekly 45-min training sessions over 11 weeks improves various, but not all evaluated parameters related to musculoskeletal fitness in 10-12-yr-old Danish school children.

Recreational Soccer Training Effects on Pediatric Populations Physical Fitness and Health: A Systematic Review

This systematic review analyzed the effects of recreational soccer programs on physical fitness and health-related outcomes in youth populations. Studies were sought in the following databases: (i) PubMed, (ii) Scopus, (iii) SPORTDiscus, and (iv) Web of Science. The eligibility criteria included (1) population: youth (<18 years old) populations with no restrictions on sex or health condition; (2) intervention: exposure to a recreational soccer training program of at least four weeks duration; (3) comparator: a passive or active control group not exposed to a recreational soccer training program; (4) outcomes: physical fitness (e.g., aerobic, strength, speed, and change-of-direction) or health-related measures (e.g., body composition, blood pressure, heart rate variability, and biomarkers); (5) study design: a randomized parallel group design. The search was conducted on 6 September 2022 with no restrictions as to date or language. The risk of bias was assessed using the PEDro scale for randomized controlled studies. From a pool of 37,235 potentially relevant articles, 17 were eligible for inclusion in this review. Most of the experimental studies revealed the beneficial effects of recreational soccer for improving aerobic fitness and its benefits in terms of blood pressure and heart-rate markers. However, body composition was not significantly improved by recreational soccer. The main results revealed that recreational soccer training programs that are implemented twice a week could improve the generality of physical fitness parameters and beneficially impact cardiovascular health and biomarkers. Thus, recreational soccer meets the conditions for being included in the physical education curriculum as a good strategy for the benefit of the general health of children and young people.

School-based high-intensity interval training programs in children and adolescents: A systematic review and meta-analysis

PURPOSE

1) To investigate the effectiveness of school-based high-intensity interval training (HIIT) interventions in promoting health outcomes of children and adolescents compared with either a control group or other exercise modality; and 2) to explore the intervention characteristics and process outcomes of published school-based HIIT interventions.

METHODS

We searched Medline, Embase, CINAHL, SPORTDiscus, and Web of Science from inception until 31 March 2021. Studies were eligible if 1) participants aged 5-17 years old; 2) a HIIT intervention within a school setting ≥ 2 weeks duration; 3) a control or comparative exercise group; 4) health-related, cognitive, physical activity, nutrition, or program evaluation outcomes; and 5) original research published in English. We conducted meta-analyses between HIIT and control groups for all outcomes with ≥ 4 studies and meta-regressions for all outcomes with ≥ 10 studies. We narratively synthesised results between HIIT and comparative exercise groups.

RESULTS

Fifty-four papers met eligibility criteria, encompassing 42 unique studies (35 randomised controlled trials; 36 with a high risk of bias). Meta-analyses indicated significant improvements in waist circumference (mean difference (MD) = -2.5cm), body fat percentage (MD = -1.7%), body mass index (standardised mean difference (SMD) = -1.0), cardiorespiratory fitness (SMD = +1.0), resting heart rate (MD = -5bpm), homeostatic model assessment-insulin resistance (MD = -0.7), and low-density lipoprotein cholesterol (SMD = -0.9) for HIIT compared to the control group. Our narrative synthesis indicated mixed findings between HIIT and other comparative exercise groups.

CONCLUSION

School-based HIIT is effective for improving several health outcomes. Future research should address the paucity of information on physical activity and nutrition outcomes and focus on the integration and long-term effectiveness of HIIT interventions within school settings.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42018117567.

Twelve-Week Game-Based School Intervention Improves Physical Fitness in 12-14-Year-Old Girls

The aim of this study was to determine the effects of a twelve-week game-based school intervention on physical fitness in girls aged 12–14 years. Fifty-nine adolescent girls (13.2 ± 0.3 years) were randomly assigned to a group that participated in a game-based after-school program (EXP) or a control group (CON) that participated only in mandatory physical education. The EXP group had the additional program twice a week after school for 40 min/session for 12 weeks alongside with regular physical education classes. The EXP program consisted mainly of small-sided games of football, basketball, handball, and volleyball. The assessment included a physical fitness assessment with standardized tests for this age group: countermovement jump (CMJ), standing long jump, bent arm hang, overhead medicine ball throw, sit-ups for 30 s, and Yo-Yo Intermittent Recovery Level 1 Test (YYIRT1). There was a significant interaction between group (EXP vs. CON) and time (pre-test vs. post-test) for the standing long jump (p < 0.001), overhead medicine ball throw (p < 0.001), 30 s sit-ups (p = 0.030), bent- arm hang (p < 0.001), and YYIRT1 score (p = 0.004). In addition, a significant main effect was found for time in countermovement jump (p < 0.001). The results of this study indicate that the after-school game-based intervention significantly improves adolescent girls' physical fitness compared to regular physical education. The overall conclusion suggests that as few as two additional sessions per week are sufficient to produce significant changes in physical fitness in adolescent girls.

Effects of school-based high-intensity interval training on body composition, cardiorespiratory fitness and cardiometabolic markers in adolescent boys with obesity: a randomized controlled trial

Background

With accumulating evidence suggesting that CVD has its origins in childhood obesity. The purpose of this study was to determine the effect of a real-world school-based high-intensity interval training intervention on body composition, cardiorespiratory fitness and cardiometabolic markers in obese boys aged 10 to 13 years.

Methods

Forty-five adolescent boys with obesity (age = 11.2 ± 0.7 years, BMI = 24.2 ± 1.0 kg/m²), were randomized to high-intensity interval training group (HIIT, n = 15), moderate-intensity continuous training group (MICT, n = 15), or a control group (CON, n = 15). The intervention groups performed three weekly exercise sessions over 12 weeks. HIIT group performed two sets of eight bouts of 15 s run at high-intensity [90 ~ 100% maximal aerobic speed (MAS)] separated by eight bouts of 15 s recovery run at low-intensity (50% MAS), MICT group performed 30 min run at moderate intensity (60 ~ 70% MAS) and CON group were instructed to continue their normal behaviors. All participants had indices of body composition, cardiorespiratory fitness (CRF) and cardiometabolic markers measured at baseline and post-intervention. Statistical differences between and within groups were determined by use of two-way analysis of variance (ANOVA) with repeated measures.

Results

Following the school-based training program, BMI and body fat mass decreased (BMI: − 1.8 kg/m² vs. – 1.2 kg/m², P < 0.01; FM: − 1.6 kg, P < 0.05 vs. -3.7 kg, P < 0.01) in HIIT and MICT group, but there was no significant difference between the two interventions; \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}{\mathrm{O}}_{2\mathrm{peak}}$$\end{document}V˙O2peak both increased significantly in two intervention groups, and the increment of HIIT group was significantly greater than that of MICT (6.1 mL/kg/min vs. 3.8 mL/kg/min, P < 0.01), Visceral adipose tissue was significant decrease in HIIT group (− 53 g vs. -17 g, P < 0.01) whilst the MICT group experienced a significant decrease in body fat percentage (− 3.1 ± 1.0 kg, P < 0.01), but there were no significant difference between the two interventions. Low-density lipoprotein cholesterol decreased only in HIIT group (− 17.2%, P < 0.05). Significant decrease in the usual index of insulin resistance (HOMA-IR) occurred in HIIT and MICT groups (− 27.3 and − 28.6%, respectively; P < 0.05).

Conclusions

Our results demonstrated that high-intensity interval training based on running can be used to improve the physical health of obese adolescents in school. Further investigations involving a larger cohort of participants, taken from different schools, is recommended.

Trial registration

title Effect of High Intensity Interval Training on Obese Children and Adolescents, time 16/12/2017, IDChiCTR-IOR-17013992, websitehttp://www.chictr.org.cn

The effects of football practice on children's fundamental movement skills: A systematic review and meta-analysis

The purpose of this systematic review and meta-analysis was to explore the effects of different soccer practices on fundamental movement skills (FMS) of children of different ages and genders, in order to help children to improve their fundamental movement skills through soccer practice more effectively. The databases of CNKI, Wanfang database, Pubmed, Web of science and Cochrane library were searched to collect relevant studies on the effects of soccer practices on FMS, and the quality of the included studies was evaluated by using the Cochrane Risk of Bias Tool, and Meta-analysis was conducted by Review Manager 5.4 software. 16 studies were finally included, with a total of 3,121 subjects were included. The results showed that soccer had a positive effect on linear sprint ability [SMD 95% CI = -0.37 (-0.61, -0.14), P = 0.002], horizontal jump [SMD 95% CI = 0.22 (-0.34, 0.77), P = 0.003], object control [SMD 95% CI = 1.32 (0.8, 1.85), P = 0.0003], Closed-eye single-leg test [SMD 95% CI = 0.87(0.48,1.25), P < 0.0001],while countermovement jump [SMD 95% CI = 0.50(-0.35,1.35), P = 0.25] and flamingo balance [SMD 95% CI = -0.16(-0.31,-0.02), P = 0.03] had a less significant effect. Meanwhile, the effect of the practice was mainly influenced by the total duration of the intervention, age and gender of the intervention subjects, in which the total intervention time longer than 1,800 min promoted linear sprint ability, horizontal jump and flamingo balance test better than those below 1,800 min; the promotion effect of linear sprint ability and horizontal jump was better in children aged 7-9 years than 10-13 years, while Children aged 10-13 years showed better improvement in Closed-eye single-leg test after the intervention than 7-9 years; Girls were better promoted in linear sprint ability and Closed-eye single-leg test, but the horizontal jump is better for boys to improve the effect. It is recommended that the effects of different soccer practice contents on fundamental movement skills can be further explored in the future to improve the relevance and efficiency of fundamental movement skill development for children.

School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18

BACKGROUND

Physical activity among children and adolescents is associated with lower adiposity, improved cardio-metabolic health, and improved fitness. Worldwide, fewer than 30% of children and adolescents meet global physical activity recommendations of at least 60 minutes of moderate to vigorous physical activity per day. Schools may be ideal sites for interventions given that children and adolescents in most parts of the world spend a substantial amount of time in transit to and from school or attending school.

OBJECTIVES

The purpose of this review update is to summarise the evidence on effectiveness of school-based interventions in increasing moderate to vigorous physical activity and improving fitness among children and adolescents 6 to 18 years of age. Specific objectives are: • to evaluate the effects of school-based interventions on increasing physical activity and improving fitness among children and adolescents; • to evaluate the effects of school-based interventions on improving body composition; and • to determine whether certain combinations or components (or both) of school-based interventions are more effective than others in promoting physical activity and fitness in this target population.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, BIOSIS, SPORTDiscus, and Sociological Abstracts to 1 June 2020, without language restrictions. We screened reference lists of included articles and relevant systematic reviews. We contacted primary authors of studies to ask for additional information.

SELECTION CRITERIA

Eligible interventions were relevant to public health practice (i.e. were not delivered by a clinician), were implemented in the school setting, and aimed to increase physical activity among all school-attending children and adolescents (aged 6 to 18) for at least 12 weeks. The review was limited to randomised controlled trials. For this update, we have added two new criteria: the primary aim of the study was to increase physical activity or fitness, and the study used an objective measure of physical activity or fitness. Primary outcomes included proportion of participants meeting physical activity guidelines and duration of moderate to vigorous physical activity and sedentary time (new to this update). Secondary outcomes included measured body mass index (BMI), physical fitness, health-related quality of life (new to this update), and adverse events (new to this update). Television viewing time, blood cholesterol, and blood pressure have been removed from this update.  DATA COLLECTION AND ANALYSIS: Two independent review authors used standardised forms to assess each study for relevance, to extract data, and to assess risk of bias. When discrepancies existed, discussion occurred until consensus was reached. Certainty of evidence was assessed according to GRADE. A random-effects meta-analysis based on the inverse variance method was conducted with participants stratified by age (children versus adolescents) when sufficient data were reported. Subgroup analyses explored effects by intervention type.

MAIN RESULTS

Based on the three new inclusion criteria, we excluded 16 of the 44 studies included in the previous version of this review. We screened an additional 9968 titles (search October 2011 to June 2020), of which 978 unique studies were potentially relevant and 61 met all criteria for this update. We included a total of 89 studies representing complete data for 66,752 study participants. Most studies included children only (n = 56), followed by adolescents only (n = 22), and both (n = 10); one study did not report student age. Multi-component interventions were most common (n = 40), followed by schooltime physical activity (n = 19), enhanced physical education (n = 15), and before and after school programmes (n = 14); one study explored both enhanced physical education and an after school programme. Lack of blinding of participants, personnel, and outcome assessors and loss to follow-up were the most common sources of bias.  Results show that school-based physical activity interventions probably result in little to no increase in time engaged in moderate to vigorous physical activity (mean difference (MD) 0.73 minutes/d, 95% confidence interval (CI) 0.16 to 1.30; 33 studies; moderate-certainty evidence) and may lead to little to no decrease in sedentary time (MD -3.78 minutes/d, 95% CI -7.80 to 0.24; 16 studies; low-certainty evidence). School-based physical activity interventions may improve physical fitness reported as maximal oxygen uptake (VO₂max) (MD 1.19 mL/kg/min, 95% CI 0.57 to 1.82; 13 studies; low-certainty evidence). School-based physical activity interventions may result in a very small decrease in BMI z-scores (MD -0.06, 95% CI -0.09 to -0.02; 21 studies; low-certainty evidence) and may not impact BMI expressed as kg/m² (MD -0.07, 95% CI -0.15 to 0.01; 50 studies; low-certainty evidence). We are very uncertain whether school-based physical activity interventions impact health-related quality of life or adverse events.

AUTHORS' CONCLUSIONS

Given the variability of results and the overall small effects, school staff and public health professionals must give the matter considerable thought before implementing school-based physical activity interventions. Given the heterogeneity of effects, the risk of bias, and findings that the magnitude of effect is generally small, results should be interpreted cautiously.

The Effects of Football Practice on Nutritional Status and Body Composition in Children: A Systematic Review and Meta-Analysis

Dietary patterns, exercise, sport, and physical activity have been shown to improve body composition in children. This systematic review with meta-analysis analyzed the effects of practicing football on body composition (fat mass, lean body mass, and bone mineral content) in children. An initial search in PubMed, Web of Science, and SPORTDiscus was carried out in April 2021 to identify relevant articles. Inclusion criteria required children up to 12 years of age with a minimum football intervention duration of 10 weeks. Methodological quality of the articles was evaluated using the PEDro scale. Between the 1803 articles originally founded, only 14 articles were included in the meta-analysis. A total of 1643 subjects between the 14 studies were identified. The review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and used Review Manager and Full Meta-Analysis software. The results between the control and experimental groups showed significantly better lean body mass and fat mass values in the experimental group (p < 0.05). Football practice was positively associated with increases in lean body mass (mean difference of 1.55; 95% CI, 0.96, 2.15), decreases in fat mass (mean difference of -0.81; 95% CI, -1.49, -0.13), and increases in whole body bone mineral content (mean difference of 117.68; 95% CI, 83.69, 151.67). In conclusion, the results of this systematic review with meta-analysis suggest that football positively affects body composition in children. However, further research is needed to confirm the results for bone mineral content.

Internal and External Load Variations in Young Students: Comparisons between Small-Sided Games and Small-Sided Games Combined with Strength Training during Physical Education Classes

The purpose of this study was to compare the effects of internal and external load in soccer small-sided games (SSGs) and a strength program based on CrossFit combined with SSGs for 7 weeks. Fifty-five students participated in this research (age: 9.04 ± 0.19 years) and were randomly assigned to SSGs (n = 27) or strength combined with SSGs (n = 29) group. Two sessions/week were implemented. The results revealed that internal load on SSGs promoted higher levels (p ≤ 0.001; d = 0.35) of light physical activity (PA) (12.24 cpm) compared with strength combined with SSGs (11.46) and % heart rate (%HR) max (p = 0.002; d = 0.48) between SSGs (96.21) regarding strength combined with SSGs (92.09). On external load, significant differences appear in total distance (p ≤ 0.001; d = 0.80) on SSGs (1326 m) compared with strength combined with SSGs (1004 m) and mean velocity (p ≤ 0.001; d = 0.63) in both groups; 2.71 km/h on SSGs and 2.26 km/h on strength combined with SSGs. The SSGs seem to be more appropriate at the beginning of sessions, but as the weeks advance, strength combined with SSGs results in improved internal load compared with SSGs.

Reducing Aggression and Improving Physical Fitness in Adolescents Through an After-School Volleyball Program

This study aimed to determine the effects of an after-school volleyball program on aggression and physical fitness in 14–16 years old students. One hundred and seven participants were randomized to a small-sided volleyball (SSV) training group or a control group (CON). The SSV group completed 8 months of small-sided volleyball training twice a week after school in addition to the regular physical education classes. Yo-Yo Intermittent Recovery Level 1 test (YYIRT1), medicine ball throw (MED), vertical jump (VJ), and Buss and Perry’s aggression questionnaire were evaluated before and after 8 months of training. Results revealed a significant interaction effect (group × time) in total sample for physical aggression [F(1, 105) = 17.688; p < 0.001], verbal aggression [F(1, 105) = 4.973; p = 0.028], anger [F(1, 105) = 7.662; p = 0.007], medicine ball throw [F(1, 105) = 36.143; p < 0.001], and YYIRT1 [F(1, 105) = 12.508; p = 0.001]. After-school small-sided volleyball for adolescents was accompanied by a significant decrease in aggression compared to physical education classes only. Additionally, adolescents from SSV group showed better results in physical fitness compared to the control group. Our findings significantly contribute to the understanding of possible mechanisms for reducing adolescents’ aggression, which include enjoyment, motivation, and self-control through sport intervention.

Cardiovascular adaptations after 10 months of daily 12-min bouts of intense school-based physical training for 8-10-year-old children

The present study examined cardiovascular adaptations in 8-10-year-old schoolchildren after a full school year (10 months) of 5 × 12 min/wk. of intense physical training, including small-sided ball games (soccer, basketball and floorball) or interval running. The study involved 8-10-year-old healthy Danish schoolchildren (n = 232), who were cluster-randomized to a small-sided games group (SSG, n = 60), an interval running group (IR, n = 57) or a control group (CON, n = 115). Comprehensive transthoracic echocardiography, resting heart rate and blood pressure measurements were performed at baseline and post intervention. For interval running, analysis of baseline-to-10-months changes showed significant (P < 0.05) between-group differences in delta scores for diastolic blood pressure (BP) and mean arterial BP (IR -3.2 ± 5.7 and - 2.2 ± 6.5 mmHg vs. CON 0.2 ± 5.3 and 0.4 ± 6.4 mmHg, respectively). Delta scores also showed a trend for reduction of mean arterial BP in SSG compared to CON (-2.1 ± 6.0 vs. 0.2 ± 5.3 mmHg, P = 0.067). Moreover, there were between-group differences in delta scores (P < 0.05) for selected echocardiographic parameters, i.e. in SSG vs. CON for interventricular septum thickness and peak transmitral flow velocity in early diastole, and in IR vs. CON for left ventricular systolic diameter. In conclusion, 10 months of 5 × 12 min/wk. of IR in 8-10-year-old children decreased diastolic BP, while both IR and SSG elicited cardiac adaptations. The results suggest that frequent low volume, intense physical training can have effects on the cardiovascular health profile in healthy children.

Normative Yo-Yo Intermittent Recovery Level 1 and Yo-Yo Intermittent Endurance Level 1 test values of boys aged 9-16years

OBJECTIVES

To provide age- and sex-specific reference values of Yo-Yo tests in children and adolescents.

DESIGN

Systematic review.

METHODS

A literature search for articles on Yo-Yo Intermittent (YYI) tests was performed in MEDLINE, SPORTDiscus, Web of Science and Google Scholar. Original reports on healthy children/adolescents 6-16years of age were eligible. For each test, age- and sex-related reference values were calculated using global means and percentiles.

RESULTS

Ninety-two studies (7398 participants) fulfilled the eligibility criteria. The YYI tests most frequently used were the Yo-Yo Intermittent Recovery Level 1 test (YYIR1, 57.8%), Yo-Yo Intermittent Endurance Level 1 test (YYIE1, 14.7%), Yo-Yo Intermittent Recovery Level 1 Children's test (YYIR1C, 12.7%), Yo-Yo Intermittent Endurance Level 2 test (YYIE2, 8.8%) and the Yo-Yo Intermittent Recovery Level 2 test (YYIR2, 5.9%). Of these, 71.6% reported test results of boys, 17.6% reported mixed test results and 10.8% reported test results of girls. Smoothed centile curves for the YYIR1 and YYIE1 over the entire age range were generated for boys, revealing constantly increasing performance with increasing age.

CONCLUSIONS

YYI tests values differ with respect to age and sex. In boys, development of YYIR1 and YYIE1 test values (6-16years of age) was different, suggesting better applicability of the YYIR1 test for boys >13years of age. The results may be used to rate YYI test performance for continuous screening and to identify children with low physical fitness. Since limited data was available of females, further research on YYI tests is needed with respect to sex-specific results.

Heart Rate and Perceived Experience Differ Markedly for Children in Same- versus Mixed-Gender Soccer Played as Small- and Large-Sided Games

This study examines heart rate (HR) and perceived experience during same- versus mixed-gender soccer played as small- (SSG) and large-sided (LSG) games. HR, rating of perceived exertion (RPE), and fun scores were determined in 134 pupils (50 girls, 84 boys) randomly assigned to same- and mixed-genders formats playing 2x15-min of SSG (2v2, 4v4) and LSG (12v12) in a random order (~50 m²/player). HR was lower (p≤0.03) for girls when playing together with boys than when playing alone (71±10 versus 77±7%HRmax), while being similar for boys playing mixed- or same-gender games (74±7 versus 77±4%HRmax). Boys perceived less fun when playing together with girls than when playing alone (4.4±2.3 versus 6.3±2.3, p<0.001). Irrespective of gender, higher (p<0.001) HRmean, %time>80%HRmax, and RPE were observed during 2v2 (78±9%HRmax, 43±33%, 5.5±2.5) and 4v4 (76±9%HRmax, 39±32%, 5.5±2.7) than during 12v12 (70±10%HRmax, 23±27%, 3.8±2.9). Cardiovascular strain was lower for girls when playing together with boys than when playing alone in LSG. SSG were more intense than LSG when girls played mixed-gender games and when boys played mixed- and same-gender games. When boys played mixed-gender games, SSG were considered more fun than LSG. Physical education teachers and coaches should consider gender and game format differences when using soccer.

Effects of traditional balance and slackline training on physical performance and perceived enjoyment in young soccer players

The aim of this study was to evaluate the effects of 12-week balance and slackline training programs on physical performance and perceived enjoyment scale in young soccer players. Forty-one preadolescent soccer players were assigned to two experimental groups performing traditional balance (BLT) or slackline training (SLT), and a control group. Pre-post assessment encompassed Balance Error Scoring System (BESS), Star Excursion Balance test (SEBT), sprint with 90° turns (S90), and countermovement jump (CMJ). The rate of perceived enjoyment scale (PACES) was applied at the end of the experimental period. SLT and BLT improved similarly in BESS, SEBT and S90. No changes were detected in the CMJ. Regarding PACES score, SLT presented significantly higher values than BLT. Young athletes may benefit from a motivating training approach, thus, a designed program based on slackline drills should be preferable to improve physical performance in terms of balance and change of direction ability in preadolescent soccer players.