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.

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.

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.

The Influence of Anthropometric Characteristics on Kinematic Parameters of Children's Sprinter's Running.

Children's sprinters running differs from the adults' one primarily in their motoric abilities, anthropometric characteristics, physiological and biochemical characteristics, as well as psychological and sociological characteristics. This research's aim was to examine the influence of anthropometric characteristics on kinematic parameters of children's sprinter's running. The sample of variables consisted of variables which determine anthropometric characteristics (14 anthropometric characteristics) and of 5 kinematic parameters'variables of sprinter's running. Kinematic parameters of sprinter's running in the phase of maximal speed have been collected by applying the Optojump technology (Microgate, Italy) and the sprinter's running times were measured every 5 meters on a 50 m lap. The results obtained from the multiple regression analysis between the group of anthropometric characteristics and the 50 m running results indicate that the percentage of fatty tissue is a statistically significant variable with boys, while the same variable with girls is near the limit of statistical significance. In the factor structure of anthropometric characteristics two factors have been set apart with boys and three with girls. The first factor set apart with both boys and girls is the factor of body voluminosity, the second factor with boys is the factor of longitudinal dimensionality, while with girls it is the factor of fatty tissue quantity. The factor of longitudinal dimensionality is the third girls' factor. For most variables a negative correlation has been determined with a higher percentage of fat or a higher quantity of subcutaneous fatty tissue with both boys and girls. Boys having a lower quantity of subcutaneous fatty tissue achieve better results in 50 m running, they have a shorter duration of contact with the pad, a longer duration of the flight phase and a longer step length when compared to boys with a higher quantity of subcutaneous fatty tissue. Boys with a bigger body muscular mass achieve a shorter duration of the contact, a longer duration of the flight and a longer step length. Girls who have a lower quantity of subcutaneous fatty tissue achieve a better 50 m running time, have a shorter duration of contact with the pad and a longer step length. It has been established that taller boys have a longer step length, and longer feet significantly influence the longer duration of contact with the pad and the lowering of the step frequency.