Normative values of cardiorespiratory fitness in Croatian children and adolescents.

Although defining normative values of cardiorespiratory fitness have been the topic of many Western societies, little evidence has been provided for less developed countries like Croatia. Since cardiorespiratory fitness rapidly declines in Croatian children and adolescents, the newly established normative values would help health-related professionals and physical education teachers to detect 'talented' groups and direct them towards sport and 'risky' groups for planning special interventions. Therefore, the main purpose of the study was to determine normative reference values of cardiorespiratory fitness. A total of 1,612 children and adolescents aged 7-14 years (mean±SD; age 9.7±2.4 years; stature 151.0±17.6 cm; body mass 45.1±19.1 kg; 52.5% girls) participated in this cross-sectional study. Cardiorespiratory fitness was assessed by the Maximal multistage 20-m shuttle run test and the performance was expressed as the number of stages. Maximal oxygen uptake (VO2max) was estimated by equations. Smoothed percentile curves were calculated. Boys outperformed girls in the maximal number of levels achieved after the 20-m shuttle run test and in the VO2max values at each age category. In boys, a gradually higher level of performance between ages 11 and 14 was observed, while in girls the values started to rise after the age of 8. Our study provides one of the first sex- and age-specific normative values for cardiorespiratory fitness assessed by the 20-m shuttle run test in Croatian children and adolescents.

Corrigendum: Effect of neuromuscular training program on quality of life after COVID-19 lockdown among young healthy participants: A randomized controlled trial.

[This corrects the article DOI: 10.3389/fpsyg.2022.844678.].

Effect of Neuromuscular Training Program on Quality of Life After COVID-19 Lockdown Among Young Healthy Participants: A Randomized Controlled Trial.

Study in the period of coronavirus disease 2019 (COVID-19) lockdown and the effect of different exercise training programs on the quality of life (QoL) dimension are limited. This randomized control study as a part of which the impact of an 8-week neuromuscular training program on the 90 healthy young individuals' QoL after COVID-19 lockdown was assessed using a short form of the WHOQOL-BREF questionnaire comprising of four domains (physical health, psychological health, social relations, and the environment). The intervention group (NT) (n = 47) took part in a neuromuscular training program consisting of dynamic neuromuscular stabilization and whole-body vibration training. In contrast, the control group (CG) (n = 43) did not participate in any programmed physical activity. From pre- to post-intervention test, the NT group significantly and substantially improved [mean change (95% CI)] all the QoL domains, physical for 12.78 scores (8.89, 16.64), psychological for 13.12 scores (9.51, 16.74), social relationships for 20.57 scores (16.12, 25.02), and environmental for 24.40 scores (21.45, 27.35). These results suggest that the NT program could enhance QoL in young and healthy participants following COVID-19 lockdown.

Defining Optimal Cut-Points for Cardiorespiratory Fitness Associated With Overweight/Obesity in Children: A School-Based Study.

The main purpose of the study was to define optimal criterion-referenced cut-points for cardiorespiratory fitness (CRF) associated with overweight/obesity. In this cross-sectional study, participants were 1,612 children aged 7-14 years (mean age ± SD = 9.7 ± 2.4 years; 52.5% girls). CRF was assessed by the Maximal multistage 20-m shuttle run test, from which maximal oxygen uptake (VO2max) was estimated. Anthropometric indices included body-mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR). Receiver operating characteristic (ROC) curves were performed to determine cut-off points. In boys, the optimal cut-off points of CRF in defining overweight/obesity for BMI, WC, and WHtR were 44.6, 46.4, and 46.9 mlO2/kg/min. The areas under the curves (AUC) were 0.83 (95% CI 0.78-0.88, p < 0.001), 0.77 (95% CI 0.71-0.83, p < 0.001), and 0.90 (95% CI 0.86-0.93, p < 0.001). In girls, the optimal cut-off points were 41.0, 40.8, and 40.7 mlO2/kg/min for BMI, WC, and WHtR, with the AUCs of 0.86 (95% CI 0.82-0.90, p < 0.001), 0.83 (95% CI 0.79-0.88), and 0.88 (95% CI 0.84-0.93, p < 0.001). In conclusion, our newly developed cut-off points for CRF assessed by the Maximal multistage 20-m shuttle run test may adequately detect primary school-aged boys and girls with general and abdominal obesity.

Normative Data for Musculoskeletal Fitness in 13,217 Children and Adolescents: The Croatian Fitness (CROFIT) Study.

Purpose: The main purpose of the study was to establish normative data for health-related musculoskeletal fitness. Method: We recruited 13,217 children and adolescents aged 11-18 years (6,181 boys and 7,036 girls; 57% of girls). To evaluate musculoskeletal fitness, the following field tests were applied: standing broad jump (cm), sprint 20 m (sec), medicine-ball throw (dm), sit-ups in one minute (#), sit-ups in one minute (short, #), and squats in one minute (#). Curves for the 10th, 20th, 30th, 40th, 50th (median), 60th, 70th, 80th, and 90th percentiles were calculated using the Lambda (L), Mu (M), and Sigma (S) method. The LMS method assumes that the data can be normalized by using a power transformation and removing the skewness. Results: Median scores for standing broad jump, sprint 20 m, medicine-ball throw, sit-ups in one minute, sit-ups in one minute (short) and squats in one minute were 185.00 cm, 3.66 sec, 80.00 dm, 46.00 x, 56.00 x and 49 x in boys and 160.00 cm, 4.01 sec, 60.00 dm, 40.00 x, 49.00 and 43 x in girls. Effect sizes (ES) showed that boys performed better in all physical fitness tests (ES = 0.50-1.05), compared to girls. In general, age-related physical fitness changes showed the plateau between ages 15 and 16 in boys, while in girls, the plateau was reached at the age of 14. Conclusions: This study shows standards for musculoskeletal tests in youth.

Normative data for the 6-min walk test in 11-14 year-olds: a population-based study.

BACKGROUND: The 6-min walk test (6MWT) has become an established measure for assessing exercise capacity in children with chronic diseases. However, little evidence has been provided regarding population-based normal data in healthy children. The main purpose of the study was to provide normative data in a large sample of children. METHODS: In this cross-sectional study, 4352 children between 11 and 14 years were recruited (66% girls). The main outcome measure was the distance walked for six minutes. Sex- and age-specific percentile values (5th, 15th, 25th, 50th, 75th, 85th and 95th) for the 6MWT were created and the differences and correlations were examined by the analysis of variance and Pearson's coefficient of correlation. RESULTS: The mean distance walked in 6 min was 576 ± 93 m in boys and 545 ± 92 m in girls, respectively. The mean walking speed for boys and girls was 98 ± 5 m/min and 91 ± 6 m/min. Older boys and girls performed better, compared to their younger counterparts (p for age < 0.001). The 6MWT was significantly correlated with age (r = 0.24, p < 0.001), height (r = 0.09, p < 0.001), weight (r = - 0.13, p < 0.001) and body-mass index (r = - 0.26, p < 0.001). CONCLUSIONS: This is the first population-based study aiming to provide normative data for the 6MWT in healthy children between 11 to 14 years. Children in lower percentiles are 'target groups' for special intervention aiming to enhance the performance.

Reference Data for Fat Mass and Fat-Free Mass Measured by Bioelectrical Impedance in Croatian Youth.

Fat mass and fat-free mass have become useful clinical indices in determining healthy growth and physical development during critical periods of childhood and adolescence; however, despite a wide range of nutritional surveillance its study is limited by a lack of reference data. The purpose of this study was to establish sex-specific and age-specific standards for fat mass and fat-free mass in a large sample of Croatian children and adolescents. In this cross-sectional study, we collected data from 12,678 participants aged 11 to 18 years old (mean age ± standard deviation (SD): 14.17 ± 2.25 years; height 164.56 ± 11.31 cm; weight: 57.45 ± 13.73 kg; body mass index: 21.24 ± 3.67 kg/m2; 53% girls). Fat mass and fat-free mass were measured three times by bioelectrical impedance. The Lambda, Mu and Sigma methods were used to create percentile charts for fat mass index (FMI) and fat-free mass index (FFMI; fat mass and fat-free mass divided by height2). Sex and age differences were calculated using an analysis of variance (ANOVA) with post hoc comparisons. Boys had lower FMI (from 2.66 to 3.89) and higher FFMI values (from 16.90 to 17.80) in all age groups, compared to girls (for FMI from 2.79 to 5.17 and for FFMI from 14.50 to 14.90, p < 0.001). In boys, FMI slightly declined until the age of 14, after which an increase from the age of 15 to 18 was observed. In girls, FMI gradually increased from the age of 11 to 18 (p < 0.001). In general, FFMI increased by age in boys [F(7,5440) = 52.674, p < 0.001], while girls had more stable FFMI across all age groups [F(7,7222) = 2.728, p = 0.057]. The newly established sex-specific and age-specific reference data could be used for national surveillance and to screen for children and adolescents with high FMI and low FFMI.

Secular trends in health-related physical fitness among 11-14-year-old Croatian children and adolescents from 1999 to 2014.

The main purpose of the study was to analyze secular trends of health-related physical fitness in 7-14-year-old Croatian children and adolescents from 1999 and 2014. In this observational cross-sectional study, we recruited 5077 children and adolescents between ages 11 and 14 (50.8% girls) from five primary schools located in the capital city of Zagreb. Physical fitness performance was tested from 1999 until 2014. Physical fitness performance included: (1) body-mass index (measure of body size), (2) standing broad jump (measure of lower-body power), (3) polygon backwards (measure of general coordination and agility), (4) sit-ups in 60 s (measure of upper-body strength), (5) sit-and-reach test (measure of flexibility) and (6) 6-min run test (measure of cardiorespiratory fitness). Boys performed better in all physical fitness tests, except for sit-and-reach test (p < 0.001). In boys, between 1999 and 2014, body size, upper-body strength and coordination/agility increased, while flexibility, lower-body power and cardiorespiratory fitness decreased. During the same period, girls experienced an increase in body size, lower-body power, upper-body strength, coordination/agility and flexibility, while cardiorespiratory fitness decreased. This study shows that cardiorespiratory fitness, flexibility and coordination/agility decrease, while upper-body strength increases in both sexes. These findings should serve as an avenue for national monitoring system to screen and track biological development in children and adolescents.

Functional endurance capacity is associated with multiple other physical fitness components in 7-14-year-olds: a cross-sectional study.

BACKGROUND: Although evidence suggests that functional endurance capacity is the most important component associated with future health, little is known of how it is associated with multiple other physical fitness components. Since various physical fitness aspects do not change the same as functional endurance capacity during childhood, it is necessary to establish possible associations between functional endurance capacity and other physical fitness components in children. Therefore, the main purpose of the study was to test the associations between functional endurance capacity with other physical fitness components in 7-14-year-old children, stratified by gender. METHODS: In this cross-sectional study, we recruited 1612 children [mean age ± standard deviation (SD) = 9.72 ± 2.37 years; 52.5% girls). Health-related physical fitness components included: 1) body-mass index (kg/m2) calculated from height and weight (measure of body size), 2) sit-and-reach test (measure of flexibility), 3) standing broad jump (measure of explosive strength of lower extremities), 4) sit-ups in 30 s (measure of repetitive strength of the trunk), 5) 10 × 5 shuttle run test (measure of agility) and 6) 20-m shuttle run test (measure of functional endurance capacity). The associations were performed using generalized estimating equations with beta (ß) coefficients. RESULTS: After adjusting for age, functional endurance capacity was associated with sit-and-reach test (ß = 0.13, p < 0.001), standing broad jump (ß = 0.59, p < 0.001), sit-ups in 30 s (ß = 0.53, p < 0.001) and 10 × 5 shuttle run test (ß = - 0.56, p < 0.001) in boys. In girls, functional endurance capacity was associated with body-mass index (ß = - 0.12, p < 0.001), sit-and-reach test (ß = 0.21, p < 0.001), standing broad jump (ß = 0.25, p < 0.001), sit-ups in 30 s (ß = 0.36, p < 0.001) and 10 × 5 shuttle run test (ß = - 0.40, p < 0.001). No significant associations between functional endurance capacity and body-mass index in boys were observed. CONCLUSIONS: Although significant, functional endurance capacity is weakly to moderately associated with other physical fitness components, pointing out that such measure should be tested separately from other aspects of physical fitness in school-aged children.

One-year changes in physical activity and sedentary behavior among adolescents: the Croatian Physical Activity in Adolescence Longitudinal Study (CRO-PALS).

Background Little is known about the concurrent change in physical activity (PA), sedentary behavior (SB) and sport participation (SP) during adolescence. The main purpose of this prospective and partly objective study was to simultaneously investigate PA, SBs and SP changes between the 1st and 2nd grades of high school in urban adolescents. Methods In this 1-year follow-up study, the participants were 81 secondary-school students (28 boys and 53 girls) aged 15.5 years at the baseline. PA was assessed with the SenseWear Armband multi-sensor activity monitor, while SBs were assessed by using School Health Action, Planning and Evaluation System (SHAPES) PA questionnaire. The SHAPES questionnaire was supplemented with two questions inquiring about SP in organized sports in school and outside of school. Results PA decreased markedly in both genders between the 1st and 2nd grades of high school. Total energy expenditure (TEE) was reduced by 13 kcal/kg/day on average in boys and by 10 kcal/kg/day in girls (p for both <0.001), while mean daily active energy expenditure (AEE) decreased by 7 kcal/kg/day (p < 0.001) and 3 kcal/kg/day (p = 0.04) in boys and girls, respectively. Similarly, the amount of moderate PA declined by 49 min/day in boys and 21 min/day in girls (p for both <0.001). At the same time vigorous PA was cut by 14 min/day (p < 0.001) and 3 min/day (p = 0.003) in boys and girls, respectively. Conversely, time spent in SBs did not show any change. Conclusion In conclusion, a decline in PA between the 1st and 2nd grades of high school was marked but was not accompanied with an increase in SBs. Policies aimed at increasing PA should be targeting the period of entering secondary school to offset the observed drop in PA.