Characteristics of physical activity interventions and effects on cardiorespiratory fitness in children aged 6-12 years-A systematic review

Predictive approach of health indicators from the physical activity habits of active youth

The aim of this study is to analyse the relationship between sport modalities practiced, physical fitness, body composition, and healthy habits in an active young population, using a statistical model for prediction. A total of 2255 (1528 boys and 727 girls) children and adolescents aged 6-17 years old who were involved in extracurricular sports from rural areas of Spain participated. Physical fitness was assessed through validated field test and, body composition was determinated using bioelectrical impedance analysis. Adherence to the Mediterranean diet was assessed by KIDMED questionnaire. The general sport variable was significant in VO2max when comparing the invasion and combat modalities to the reference level (court/net). The sex and age variables revealed significant differences in all physical fitness and body composition parameters. Health parameters, such as hours of additional practice, adherence to the Mediterranean diet, and previous experience, showed significant differences. The study concludes that the sport modality variables of training, sex, age, and maturational period have an impact on body composition and fitness parameters in this population. Therefore, by focusing on factors associated with lower values in health indicators, we can prevent health problems during adulthood, such as cardiorespiratory deficits.

Effects of a physical education intervention on children's physical activity and fitness: the PROFIT pilot study

BACKGROUND

Physical education classes are widely accepted as one of the most effective settings for promoting physical activity and health and have often been used to implement physical activity interventions. The aim of this pilot study was to test a physical education intervention program on physical activity levels and physical fitness in a sample of school-age children.

METHODS

Participants were a convenience sample of 50 children (34 experimental group and 16 in the comparative group) aged between 6 and 11 years old (Mean = 8.28 years). A 21-week intervention was implemented, consisting of high-intensity and physical fitness-focused exercises, in addition to a once-a-month extra class nutritional education. The following variables were evaluated before and post-intervention: physical fitness, sedentary behavior (SB), light physical activity (LPA), moderate physical activity (MVA), and vigorous physical activity (VPA). Propensity score analyses calculated the average treatment effect on the treated (ATET) within a quasi-experimental framework.

RESULTS

Physical fitness variables showed improvements after the intervention, specifically for agility (ATET = -0.67 s; p < 0.001), cardiorespiratory fitness (ATET = 89.27 m; p = 0.045), lower limbs power (ATET = 4.47 centimeters; p = 0.025), and speed (ATET = -1.06 s; p < 0.001). For physical activity and SB levels, there were no improvements after intervention implementation.

CONCLUSION

The intervention program showed preliminary effectiveness to improve physical fitness of children, but not SB nor physical activity.

Effects of running-based versus body-weight-based high-intensity interval training on physical fitness in healthy adolescents

Objectives: High-intensity interval training improves aerobic endurance, but the effectiveness of different training protocols is unclear. This study compared the effects of running-based high-intensity interval training (R-HIIT) and body weight-based high-intensity interval training (B-HIIT) on physical fitness in adolescents. Methods: This was a pre-and post-test quasi-experimental design in which a seventh-grade natural class was randomly selected from three homogeneous middle schools, and then the three natural classes were randomly divided into three groups: the R-HIIT group (n = 54), the B-HIIT group (n = 55), and the control group (Con, n = 57). Both intervention groups exercised twice a week for 12 weeks with a 2:1 (1 min:30 s) load-interval ratio and exercise intensity controlled at 70%-85% maximum heart rate. R-HIIT was in the form of running, and B-HIIT was in the form of resistance exercises using the participants' body weight. The control group was instructed to continue their normal behavior. cardiorespiratory fitness, muscle strength and endurance, and speed were measured before and after the intervention. Statistical differences between and within groups were determined using repeated measures analysis of variance. Results: Compared to the baseline, both the R-HIIT and B-HIIT intervention groups significantly improved CRF, muscle strength, and speed (p < 0.05). The B-HIIT group was significantly better than R-HIIT in improving CRF (4.48 mL/kg/min vs 3.34 mL/kg/min, p < 0.05), and only the B-HIIT improved sit-up muscle endurance (ηp 2 = 0.30, p < 0.05). Conclusion: The B-HIIT protocol was significantly more effective than the R-HIIT protocol in developing CRF and improving muscle health indicators.

The effectiveness of school-based run/walk programmes to develop physical literacy and physical activity components in primary school children: A systematic review

The objectives of this review were to systematically review the research on school-based run/walk programmes and their measurements of physical literacy (PL) and physical activity (PA)-related components and to assess the different intervention methods and their impact on encouraging PL and PA. To be included in the review, studies had to satisfy all inclusion criteria. An electronic search was conducted on six databases, the last date search was 25 April 2022. All outcome measures were grouped using the Shearer et al. (2021) PL checklist and additional PA related outcomes. Ten studies were included in the final review. Five different run/walk interventions were identified and six studies followed or referred to The Daily Mile (TDM) protocol. Outcomes relating to the physical domain were most commonly explored, and no studies explored the cognitive domain. Four studies reported significant differences in cardiovascular endurance measures. Positive findings were also reported for outcomes relating to motivation and self-perception/self-esteem in the affective domain. Overall, run/walk programmes appear to provide promising results in favour of physical and affective development in PL. However, further high-quality studies are needed to draw firm conclusions. This review highlights the popularity of TDM and its potential to contribute to PL development.

School-Based Exercise Programs for Promoting Cardiorespiratory Fitness in Overweight and Obese Children Aged 6 to 10

The aim of this study was to conduct a systematic review of the school-based exercise programs for promoting cardiorespiratory fitness in overweight and obese children aged 6 to 10. Electronic databases (Web of Science and PubMed) were used as searching tools for collecting adequate studies published in the past 20 years. A total of 13 studies met the criteria for inclusion in this review, with a total of 2810 participants, both male and female. According to the results of this systematic review, overweight and obese children aged 6 to 10 who underwent certain interventions had their CRF improved. Furthermore, evidence suggested that interventions carried out during a longer period of time suggested led to greater improvement of cardiorespiratory fitness than a shorter one, but the level of cardiorespiratory fitness gradually decreases after the intervention.

Effects of High-Intensity Interval Training in School on the Physical Performance and Health of Children and Adolescents: A Systematic Review with Meta-Analysis

Background

Performance of high-intensity interval training (HIIT) by children and adolescents improves physical and health-related fitness, as well as cardiometabolic risk factors.

Objectives

To assess the impact of HIIT performed at school, i.e. both in connection with physical education (intra-PE) and extracurricular sports activities (extra-PE), on the physical fitness and health of children and adolescents.

Methods

PubMed and SPORTDiscus were searched systematically utilizing the following criteria for inclusion: (1) healthy children and adolescents (5–18 years old) of normal weight; (2) HIIT performed intra- and/or extra-PE for at least 5 days at an intensity ≥ 80% of maximal heart rate (HR_max) or peak oxygen uptake (VO_2peak) or as Functional HIIT; (3) comparison with a control (HIIT versus alternative interventions); and (4) pre- and post-analysis of parameters related to physical fitness and health. The outcomes with HIIT and the control interventions were compared utilizing Hedges’ g effect size (ES) and associated 95% confidence intervals.

Results

Eleven studies involving 707 participants who performed intra-PE and 388 participants extra-PE HIIT were included. In comparison with the control interventions, intra-PE HIIT improved mean ES for neuromuscular and anaerobic performance (ES jump performance: 5.89 ± 5.67 (range 1.88–9.90); ES number of push-ups: 6.22 (range n.a.); ES number of sit-ups: 2.66 ± 2.02 (range 1.24–4.09)), as well as ES fasting glucose levels (− 2.68 (range n.a.)) more effectively, with large effect sizes. Extra-PE HIIT improved mean ES for neuromuscular and anaerobic performance (ES jump performance: 1.81 (range n.a.); ES number of sit-ups: 2.60 (range n.a.)) to an even greater extent, again with large effect sizes. Neither form of HIIT was more beneficial for parameters related to cardiorespiratory fitness than the control interventions.

Conclusion

Compared to other forms of exercise (e.g. low-to-moderate-intensity running or walking), both intra- and extra-PE HIIT result in greater improvements in neuromuscular and anaerobic performance, as well as in fasting levels of glucose in school children.

Children’s Changes in Perceptions and Body Composition Following a Family-Based Fitness Intervention

Physical fitness is associated with decreased weight in children, which helps improve youth obesity rates. Family programs can provide practical approaches to improving physical fitness for children. The purpose of this study was to assess the influence of a family-based fitness intervention on changes in body composition, fitness status, and perceptions of obese children. Families attended exercise and education sessions for 60–90 min once per week for 10 weeks. Participants consisted of 10 children who participated in semi-structured interviews, body composition, and fitness assessments at pre- and posttest. Following the intervention, results showed that children had a significant increase in sit-ups (p = .03, effect size = 0.79), lean mass (p < .001, Cohen’s d = 1.95), and bone mineral content (p < .001, Cohen’s d = 0.46). Using thematic analysis, four main themes emerged from the pre- and postintervention interviews: an increase in after-school and weekend intentional physical fitness, rules regarding sedentary behavior and screen time, more prevalent physical fitness reinforcements, and a shift in perception of exercise. Results from this study indicate a family-based intervention had an influence on children’s appreciation for and engagement in physical fitness, as well as healthy body composition and fitness outcomes.

Effects of Screen Time and Season on Cardiovascular System Indicators in Primary Schoolchildren

Indicators of the cardiovascular system, including heart rate (HR) and blood pressure (BP) variability parameters, were analyzed in primary school students with different computer screen times. The study included 4084 students of grades 1–4 (age 7–12 years) from 66 Moscow schools. The screen time at school and out of school was assessed by teachers, based on the national Sanitary Rules and Regulations: 0, no screen time; 1, screen time matching hygienic standards; 2, screen time at least twice greater than recommended. Physiological examinations were carried out by spiroarteriocardiorhythmography with a face mask, the conditions corresponding to the functional stress test (mild hypercapnia/hypoxia). Testing took place in spring and autumn (independent samples). Statistical data processing was performed using nonparametric criteria. It was revealed that the introduction of computer technologies in school lessons within the limits of hygienic standards was accompanied by an increase, within the normal range, of systolic BP in girls at the end of grade 2 and 4 and in boys at the beginning and end of grade 4. Screen time at least twice higher than the hygienic standard did not have an additional effect on BP, but provoked shifts in the function of autonomic regulation. Boys were more sensitive to the influence of this environmental factor. Their pattern of seasonal variability in total power (TP) of the HR variability spectrum was reversed compared to that of children who did not use computers at school; i.e., higher TP values were observed in spring. In grade 4, the process was accompanied by an increase in spontaneous arterial baroreflex sensitivity and a decrease in the relative power of the LF range in the variability spectrum of systolic BP. The changes were assumed to reflect the adaptive response to changes in educational environment.

Predictive Analysis of Health/Physical Fitness in Health-Promoting Lifestyle of Adolescents

Objective: Explore the correlation and predictive power of health physical fitness on health-promoting lifestyle of adolescents to provide an important reference for reform in middle school physical education classroom teaching. Methods: Taking some junior and senior high school students in Nanchong City of Sichuan Province as survey objects, a stratified random sampling method was used to carry out a health/fitness test and conduct a questionnaire survey. SPSS17.0, amos 21.0, and other statistical analysis software were used to process the relevant data. Results: (1) Male adolescents had 14.4% predictive power for their overall health-promoting lifestyle through the combined effects of cardiopulmonary endurance, muscle strength, and explosive strength, while female adolescents had 16.8% predictive power for their overall health-promoting lifestyle through the combined effects of cardiopulmonary endurance, flexibility, and body mass index (BMI). (2) Ten percent of the variation in the health-promoting lifestyle of men under 14 years old was caused by the combined effects of muscle endurance and muscle strength, while 14.4% of the variation in the health-promoting lifestyle of female adolescents was caused by the combined effects of muscle endurance, muscle strength, flexibility, and cardiopulmonary endurance. (3) Some 10.9 and 17.6% of the variation in health-promoting lifestyle of male and female adolescents aged between 14 and 17 was caused by the combined effects of cardiopulmonary endurance, muscle strength, and flexibility, respectively. (4) Some 20.7% of the variation in health promoting lifestyle of male adolescents aged 17 years or above was caused by cardiopulmonary endurance, explosive force, and muscle endurance, while 16.8% of the variation in health-promoting lifestyle of female adolescents was caused by the combined effect of cardiopulmonary endurance, BMI, and muscle endurance. Conclusion: Health and physical fitness of adolescents can significantly predict their health-promoting lifestyle, and the predictive power and typical correlation between them are affected by demographic factors.

Association between physical fitness components and fluid intelligence according to body mass index in schoolchildren

Physical fitness is considered a protective factor for children's general health and has been related to enhanced cognitive functioning. However, it appears that cognition could be affected in children with overweight or obesity. The present study aimed to determine the relationship between physical fitness components and fluid intelligence in normal-weight and overweight/obese children. In this cross-sectional study, a total of 317 schoolchildren participated (165 boys, 52.05%), aged between six and 11 years old (1st to 5th grade), belonging to a public school in the south of Brazil. Psychologists evaluated fluid intelligence through the Raven's Colored Progressive Matrix Test. The physical fitness evaluation followed the procedures of the "Brazil Sports Project". Weight and height were measured to determine body mass index and generalized linear regression analyses were used with a 95% confidence interval. Our results showed that agility was inversely associated with fluid intelligence only in the overweight/obese group (β = -1.506; p = 0.01). Cardiorespiratory and muscular fitness were not associated with fluid intelligence. In conclusion, agility was the only physical fitness component related to fluid intelligence, and this relationship was found exclusively in overweight/obese schoolchildren.

Neck circumference and cardiometabolic risk in children and adolescents: the moderator role of cardiorespiratory fitness

BACKGROUND

The increased incidence of cardiometabolic risk factors has become a public health issue, especially in childhood and adolescence. Thus, early identification is essential to avoid or reduce future complications in adulthood. In this sense, the present study aimed to verify the influence of cardiorespiratory fitness (CRF) as a moderator in the association between neck circumference (NC) and cardiometabolic risk in children and adolescents.

METHODS

Cross-sectional study that included 2418 randomly selected children and adolescents (52.5% girls), aged 6 to 17 years old. Anthropometric measurements, such as NC and body mass index (BMI), and CRF was measured by the six-minute running/walking test, as well as cardiometabolic risk (systolic blood pressure, glucose, HDL-C, and triglycerides), were assessed.

RESULTS

For all age groups, NC showed a negative relationship with CRF. A significant interaction term was found for CRF x NC with cardiometabolic risk for children (6 to 9 years old), early adolescents (10 to 12 years old), and middle adolescents (13 to 17 years old). It was found that children who accomplished more than 1092.49 m in CRF test were protected against cardiometabolic risk when considering NC. In adolescents, protection against cardiometabolic risk was found when the CRF test was completed above 1424.14 m and 1471.87 m (early and middle stage, respectively).

CONCLUSIONS

CRF is inversely associated with NC and acts as a moderator in the relationship between NC and cardiometabolic risk in children and adolescents. Therefore, this detrimental health impact linked to fatness might be attenuated by improving CRF levels.

Fitness and executive function as mediators between physical activity and academic achievement

Physical activity is related with academic achievement in children. This cross-sectional study aimed to assess whether cardiorespiratory fitness (CRF) and executive function act as mediators of the association between moderate to vigorous physical activity (MVPA) and academic achievement. This study included 186 schoolchildren (9-11 years) from Cuenca, Spain. Sociodemographic variables, anthropometric variables, academic achievement, executive function (inhibition, cognitive flexibility and working memory), CRF (20-m shuttle run) and physical activity (by accelerometry) were measured. Serial mediation models were estimated using the Hayes´ PROCESS macro. The significant paths in the model mediating this relationship between MVPA and academic achievement were as follows: MVPA → CRF → academic achievement (IE = 0.068, 95% CI: [0.018; 0.127]; IE = 0.079, 95% CI: [0.029; 0.144]; and IE = 0.090, 95% CI: [0.032; 0.165], controlling for inhibition, cognitive flexibility and working memory, respectively), MVPA → CRF → inhibition → academic achievement (0.018, 95% CI: [0.001; 0.047]) and MVPA → cognitive flexibility → academic achievement (0.087, 95% CI: [0.012; 0.169]). The relationship between MVPA and academic achievement may not be direct but mediated by CRF, cognitive flexibility, and inhibition via CRF. Physical activity interventions to improve AA should be focused on improvements in CRF and executive function.

Physical activity and fitness: The feasibility and preliminary effectiveness of wearable activity tracker technology incorporating altruistic motivation in youth

PURPOSE

The purpose of this study was to examine the feasibility and preliminary effectiveness of using wearable activity tracker technology, integrated with altruistic motivation in children to increase physical activity (PA), fitness, and prosocial behavior.

DESIGN AND METHODS

A quasiexperimental design was employed in two 4th grade classrooms in a rural southern state. The intervention was a wearable PA tracker and a web-based curriculum with activities to earn power points redeemable to provide life-saving food to undernourished kids internationally. Seventeen children in the intervention group participated in the 10-week PA program and 18 children were in the wait listed control group. Three measures were assessed in both groups at baseline and postintervention: (a) PA measured with accelerometers, (b) fitness levels measured with shuttle run, and (c) prosocial behavior measured with Strengths and Difficulties questionnaire.

RESULTS

Of the 35 children enrolled, the majority were nine years old (n = 28), black (n = 31) and female (n = 23). An overall enrollment rate of 88%, attrition rate of 9%, and an accelerometer noncompliance rate of 25% was determined to assess feasibility. There was no statistical significance between the control and intervention group outcome variables. The average minutes of PA in the control group decreased 8 min from baseline to postintervention (p = .05). In the intervention group, PA decreased by 10 min from baseline to postintervention (p = .12). In both the control and intervention groups, prosocial behavior scores decreased (p = .09 control; p = .62 intervention). The fitness scores, VO₂ max, did not significantly change (intervention p = .21; control p = .35).

PRACTICE IMPLICATIONS

Developing effective interventions that foster PA and dissuade sedentary behaviors are essential to enhancing PA and fitness levels. The recruitment, retention, and accelerometer wear adherence suggest this setting, with this population is feasible. The intervention is deliverable, however, the potential of wearable activity trackers and the effect of prosocial behavior that benefits others in increasing PA and improving cardiorespiratory fitness, should be further researched by building on the successful elements of this study.

Adiposity Mediates the Association of Objectively Measured Physical Activity with Cardiorespiratory Fitness in Children

Background: The relationship of physical activity (PA) to cardiorespiratory fitness (CRF) is well established in children. However, the extent to which adiposity affects this association remains unclear. Objective: The study aimed to explore whether the relationships of different PA intensities to CRF are explained by adiposity. Methods: Cross-sectional data were collected from 374 children (51.87% boys) aged 7-12 years. The time spent (min/day) in vigorous PA (VPA), moderate PA (MPA), light PA (LPA), and sedentary behavior was objectively measured using triaxial accelerometry. Height, weight, and waist circumference (WC) were objectively measured, from which the BMI was derived. The 20-meter shuttle run test was conducted to estimate maximal oxygen consumption [VO_2max, mL/(kg·min)]. Linear mixed models and mediation analysis with bootstrapping were used to analyze data. Results: VO_2max was positively associated with VPA [β = 0.143, 95% confidence interval (95% CI): 0.091 to 0.194], MPA (β = 0.051, 95% CI: 0.016 to 0.086), and moderate-to-vigorous PA (MVPA) (β = 0.052, 95% CI: 0.029 to 0.075), but not LPA or sedentary time. Both BMI and WC partially mediated the relationships of VPA and MVPA to VO_2max, with the percentage of the total effect mediated by adiposity ranging from 18.0% to 19.6%. Similar results were also observed among boys but not among girls. Conclusions: Only moderate or vigorous intensity of PA is favorably correlated with CRF in children. BMI and WC play a pivotal mediating role in these associations, especially in boys, suggesting that promoting higher intensity of PA might benefit children's CRF through reducing adiposity.

Comparison of the effects of treadmill and vibration training in children with attention deficit hyperactivity disorder: A randomized controlled trial

OBJECTIVE

The aim of this study was to compare the effects of treadmill training (TT) and whole body vibration training (WBVT) on attention, severity of attention deficit hyperactivity disorder (ADHD) symptoms and impairment of executive function behaviors, and quality of life in children with ADHD.

METHODS

Thirty children (7-11 years of age) with ADHD were randomly assigned to either the 'TT' group or the 'WBVT in addition to TT' group (TT + WBVT). Both groups received TT for 8 weeks (3 days/week). The TT + WBWT group also received WBVT for 15 minutes. Stroop Test TBAG form, Behavior Rating Inventory of Executive Function (BRIEF), Conners' Rating Scale (CRS) and Pediatric Quality of Life Inventory (PedsQL) were applied at baseline and after 8 weeks of training.

RESULTS

All assessment results significantly improved in both groups at the end of the program compared to baseline values (p < 0,05). There were significant differences between groups regarding improvements in CTRS-R/L and BRIEF-Teacher form in favor of the TT + WBVT group.

CONCLUSIONS

The findings suggest that exercise training including TT and WBVT might be used in the treatment of ADHD but further research is required to provide evidence of the effectiveness of the whole body vibration training in the management of ADHD.

Reference values and secular trends for cardiorespiratory fitness in children and adolescents with obesity

AIM

To present specific reference values for cardiorespiratory fitness (CRF) in children with obesity and to analyse secular trends of CRF in the studied population.

METHODS

Cardiorespiratory fitness, the maximal oxygen uptake (VO₂ max), was estimated with the Åstrand-Rhyming submaximal bicycle test, in 705 Swedish children (356 girls, 8-20 years) with obesity according to the International Obesity Task Force (IOTF). Data were collected from 1999 to 2013. Secular trends, analysed with multiple linear regression, were adjusted for age, height and body mass index standard deviation score (BMI SDS).

RESULTS

All children had low CRF compared with normal weight standards but there was a marked variability of CRF in children with obesity, which was possible to quantify with the developed obesity specific CRF reference values. The mean value of absolute VO₂ max (L/min) increased with age and relative VO₂ max (mL/kg/min) decreased with age in both boys and girls. There was a negative secular trend in both sexes (P < .001).

CONCLUSION

These are the first obesity specific reference values of CRF in children enabling clinical evaluation in childhood obesity treatment. Cardiorespiratory fitness in children with obesity has declined the last decades, indicating that also within this vulnerable group physical activity has gone down.

Children's Physical Activity, Academic Performance, and Cognitive Functioning: A Systematic Review and Meta-Analysis

Researching the relationship between physical activity and academic performance is becoming an important research topic due to increasing evidence about the positive effect of physical activity on cognitive functioning. The present systematic review and meta-analysis (PROSPERO registration number: CDR132118) is a unique contribution to the recently published reviews since it only includes interventions longer than 6 weeks and acknowledges the influence of the qualifications of practitioners who deliver interventions. After identifying 14,245 records in five databases and selecting 247 full-text articles assessed for eligibility, 44 interventions passed all eligibility criteria. This meta-analysis uses validity generalization in a random effects model, which shows that academic performance itself is not solely caused by increased physical activity. The weighted mean population effect of all included interventions was r_w = 0.181. Most of the studies had serious limitations since they did not report physical activity intensity, which is an essential component to achieving positive exercise effects on cognition. In addition, the qualifications of the staff who administer the interventions were largely ignored in existing literature. It was found that 13 out of 20 physical activity interventions with significant positive effects on academic performance were performed by practitioners who held higher qualifications in the field of physical education and exercise science, who could mediate higher physical activity intensities of the given interventions. The population effect in studies where interventions were administered by practitioners with lower qualifications in the field (r_w = 0.14) was lower compared to interventions performed by staff with higher qualifications (r_w = 0.22). There was also a significant difference in academic performance with regard to staff qualification level (χ = 4.464; p = 0.035). In addition to activity duration, future physical activity intervention studies including those investigating academic performance should focus on the importance of physical activity intensity and include measures of physical fitness as objective indicators to enable more reliable analyses to establish physical activity influence on academic performance.

Relationship between Adherence to the Mediterranean Diet and Body Composition with Physical Fitness Parameters in a Young Active Population

The current study aimed at analyzing the relationship between body composition, adherence to the Mediterranean diet (MD), and physical fitness (PF) in a young active population. A total of 1198 athletes (boys = 875; girls = 323) enrolled in different municipal sports schools participated in this study. Data on adherence to the MD (KIDMED questionnaire), anthropometric measurements, and PF (20 m shuttle run test, handgrip strength, vertical jump and forced spirometry) were collected. Results show that the pubertal boys had a higher score in the KIDMED test than the prepubertal ones (+0.38, p = 0.28). Moreover, boys with better adherence to the MD had significantly higher results in handgrip strength (+12.20 regarding low MD group and +9.13 regarding medium MD group, p < 0.05), as well as in forced vital capacity (FVC) (+0.66 regarding low MD group and 0.29 regarding medium MD group, p < 0.05). No differences were found in the girls. Finally, the result of the KIDMED test is a variable with a positive and significant relationship with cardiorespiratory fitness, along with the FVC, percentage of fat mass, and performance in the vertical jump (p < 0.05). It is concluded that adherence to the MD could show a relationship with various PF variables in boys and could be a predictor of cardiorespiratory fitness in both cases.

The Relationship between Physical Activity Levels, Cardiorespiratory Fitness and Academic Achievement School-Age Children from Southern Spain

The relationship between physical activity (PA), cardiorespiratory fitness (CRF) and academic achievement in young people is unclear. The aim of this study was to analyze the relationship between PA, CRF and academic achievement in 152 children according to sex (average age of 8.6 ± 0.3 years) in southern Spain. A tri-axial accelerometer was used to measure PA; the 20-m Shuttle Run Test was performed to assess the CRF; and to know the academic achievement, the official school records were considered. The results showed a weak correlation between moderate PA and moderate-to-vigorous PA (MVPA) with CRF in boys (all, 0.2 > r < 0.4; p < 0.05), whereas the vigorous PA showed a moderate and weak correlation with CRF (all, p < 0.05), in both boys (r = 0.537) and girls (r = 0.382), respectively. In addition, a weak inverse correlation between moderate PA and MVPA with academic achievement showed in girls (all, 0.2 > r < 0.4; p < 0.05). Finally, the CRF weakly correlated with academic achievement only in boys (all, 0.2 > r < 0.4; p < 0.05). Our study showed a relationship between PA and CRF in both sexes. Nonetheless, the PA was inversely related to academic achievement in girls, whereas the CRF was related to academic achievement in boys.

Bidirectional Associations between Objective Physical Activity and Sleep Patterns in Spanish School Children

Physical activity (PA) and sleep contribute to better children’s health. Nonetheless, the bidirectional relationship between both of these health-related factors is unclear when using objective measures. The aims of this study were (1) to describe the PA (light PA and moderate-to-vigorous PA (MVPA) and sleep (duration, latency, and efficiency) patterns of children and compare them with recommendations, and (2) to analyze the bidirectional association between PA levels and sleep patterns in 470 Spanish children according to sex (average age of 8.4 (0.4) years, 51.9% boys). A tri-axial accelerometer and sleep logs were used to measure PA (light PA and MVPA) and sleep patterns (duration, latency, and efficiency) in the children for seven consecutive days. Linear mixed models were conducted to analyze the bidirectional association (PA → sleep and sleep → PA) adjusted for the child, the sex, the school, and the day of observation. The results showed that, overall, the children did not meet the sleep duration recommendations per day. Regarding the bidirectional association, increased light PA and MVPA during the day was related to decreased sleep duration but an improvement in sleep efficiency that night. However, sleep duration and sleep efficiency were only related negatively and positively to light PA the following day, respectively. Regarding sex, light PA was associated with decreased sleep duration in both sexes, although the average value was lower in boys. In addition, light PA was also related only to an improvement in sleep efficiency the same night in both sexes, with girls generally having more efficient sleep. More studies in a representative sample of children that use objective measures to corroborate these results are needed.

Classroom-Based Micro-Sessions of Functional High-Intensity Circuit Training Enhances Functional Strength but Not Cardiorespiratory Fitness in School Children-A Feasibility Study

The present study assessed the short-term effect of 6 min classroom-based micro-sessions of multi-joint functional high-intensity circuit training (FunctionalHIIT) performed by students during regular classes on parameters related to functional strength and cardiorespiratory fitness. In this randomized controlled 4-week study, 17 students (11 male; 6 female; age: 11.6 ± 0.2 years) performed 6 min of FunctionalHIIT (targeting >17 on the Borg scale) 4 days per week during regular school classes and 18 students (11 male; 7 female; age: 11.7 ± 0.3 years) served as control group (CG) without any additional in-class physical activity. The FunctionalHIIT group completed 86% of all planned sessions (mean duration: 6.0 ± 1.5 min) with a mean RPE of 17.3 ± 2.1. Body height, mass and BMI did not differ between the groups at baseline or between pre- and post-testing (p > 0.05; eta2 ≤ 0.218). The performances in lateral jumping (p < 0.000; part eta2 = 0.382; Δ% 4.6 ± 8.6), sit-ups (p < 0.000; part eta2 = 0.485; Δ% 3.1 ± 8.6) and 20-m sprints (p < 0.000; part eta2 = 0.691; Δ% 15.8 ± 5.4) improved in both groups with greater increase following FunctionalHIIT. No baseline differences and no interaction effects occurred in performance of 6 min run, flexibility, push-ups, balance, and long jump. Classroom-based FunctionalHIIT sessions, performed 4 days per week during 4 weeks did not improve variables related to aerobic endurance performance but enhanced certain parameters of functional strength in schoolchildren. As time is limited in the educational system of schools, FunctionalHIIT during regular school classes could offer a new perspective for increasing functional strength in schoolchildren.

Improving Cognitive Performance of 9-12 Years Old Children: Just Dance? A Randomized Controlled Trial

Exercise is assumed to have positive effects on children's cognitive performance. However, given the inconclusive evidence for the long-term effects of exercise, it is difficult to advice schools on what specific exercise programs can improve children's cognitive performance. In particular, little is known about the effects of small exercise programs that may be feasible in daily school practice. Therefore, we assessed the effects of a 9-weeks program consisting of daily exercise breaks on children's cognitive performance, aerobic fitness and physical activity levels. We conducted a cluster-randomized controlled trial in 21 classes of eight Dutch primary schools. A total of 512 children aged 9-12 years participated. The exercise intervention had a duration of 9 weeks and consisted of a daily 10-min classroom-based exercise break of moderate to vigorous intensity. Before and after the intervention, we used four cognitive tasks (i.e., the Attention Network Test, Stroop test, d2 test of attention and Fluency task) to measure children's cognitive performance in domains of selective attention, inhibition and memory retrieval. In addition, we measured aerobic fitness with a Shuttle Run test and physical activity during school hours by accelerometers. We analyzed data using mixed models, adjusting for baseline scores, class and school. After 9 weeks, there were no intervention effects on children's cognitive performance or aerobic fitness. Children in the intervention group spent 2.9 min more of their school hours in moderate to vigorous physical activity as compared to the children in the control group. In conclusion, daily 10-min exercise breaks in the classroom did not improve, nor deteriorate cognitive performance in children. The exercise breaks had no effect on children's fitness, and resulted in 2.9 min more time spent in moderate to vigorous physical activity during school hours. Daily exercise breaks can be implemented in the classroom to promote children's physical activity during school time, without adverse effect on their cognitive performance.

Do Obese Children Achieve Maximal Heart Rate during Treadmill Running?

Objective: Maximal heart rate (HR) is commonly defined as the highest HR obtained during a progressive exercise test to exhaustion. Maximal HR is considered one of the criteria to assess maximum exertion in exercise tests, and is broadly used when prescribing exercise intensity. The aim of the present study was to compare peak HR measurements during maximal treadmill running and active play in obese children and adolescents. Design: Comparison of peak heart rate during active play vs. maximal treadmill running in 39 (7–17 years old, 18 males) obese children and adolescents. Methods: Heart rate was recorded during intensive active play sessions, as well as during a progressive running test on a treadmill until exhaustion. HR, respiratory exchange ratio (RER), and oxygen uptake were continuously measured during the test. The criteria for having reached maximal effort was a subjective assessment by the technician that the participants had reached his or her maximal effort, and a RER above 1.00 or reporting perceived exertion (RPE) above 17 using the Borg-RPE_6–20-Scale. Results: Thirty-four children had a RER ≥1.00, and 37 reported a RPE ≥ 17. Thirty-two children fulfilled both criteria. During active play, peak HR was significantly (p < 0.0001) increased (4%) (mean and 95% confidence intervals; 204 (201, 207) beats/min), compared to during maximal treadmill running (196 (194, 199) beats/min), respectively. Conclusion: The results of the present study indicate that peak heart rate measurements during progressive running to exhaustion in obese children and adolescents cannot necessarily be determined as maximal heart rate.

We12BFit!-Improving Physical Fitness in 7-12-Year-Old Children With Developmental Coordination Disorder: Protocol of a Multicenter Single-Arm Mixed-Method Study

Background: Children with developmental coordination disorder (DCD) are less physically fit than their typically developing peers. No substantiated treatments are available for children with DCD to address this issue. Aims: This study aims to describe 1. the design and rationale of We12BFit!-PF, a training to increase cardiorespiratory fitness, muscle strength and anaerobic power in 7-12-year-old children with DCD and 2. the methods to examine its preliminary effectiveness and feasibility. Methods: We12BFit!-PF was developed using the steps of defining a treatment theory as proposed by Whyte et al. This includes the definition of targets, mechanisms of action, and essential ingredients. We12BFit!-PF will be evaluated in children diagnosed with DCD according to the criteria of the Diagnostic and Statistical Manual of mental disorders (DSM-V) aged 7-12, recruited from rehabilitation centers and physical therapy clinics. Indication for participation will be a need related to enhancing PF, for example tiring quickly, being quickly out of breath or being unable to keep up with peers during PA. During the treatment the participants will be engaged in a group training (2 × 60 min/week, 10 weeks) targeting cardiorespiratory fitness using high intensity interval training, muscle strength using exercises without weights and anaerobic power using plyometrics. Training intensity during high intensity interval training will be monitored with heart rate monitors, if necessary the intensity will be adjusted. Using a single-arm mixed-method design, the preliminary effectiveness will be determined using the 20 meter Shuttle Run Test, hand held dynamometry (JAMAR and MicroFET) and the Muscle Power Sprint Test, which will be assessed in week 0, 11, and 23. Feasibility will be assessed by interviewing parents and children and by organizing a focus group session with the trainers at the end of We12BFit!-PF. Based on a 5% improvement in VO_2peak the minimum sample size is 19 children. Ethics and dissemination: The University of Groningen, University Medical Center Groningen medical ethics committee approved the study (METC 2015.216). Final results will be disseminated via scientific publications, presentations and congress proceedings. Funding organizations will receive a final study report. Trial Registration: This study was registered with Netherlands Trial Registry (NTR6334, www.trialregister.nl).