Vladimir Živanović

Background/Objectives: The aim of this study is to investigate the relationship between CRF (cardiorespiratory fitness) and body composition, specifically obesity indicators, in a sample of schoolchildren from the continental and Adriatic regions of the Republic of Croatia. Given that Croatia ranks among the leading countries in Europe in terms of obesity, it is believed that there is a need to combat this condition starting from school age. The usefulness of cardiorespiratory fitness (CRF) lies in the fact that it is one of the indicators of children’s overall health and is considered a measure of general health status. The findings will emphasize the need to determine CRF and BMI as important factors that should be addressed from early school years in order to prevent future cardiovascular diseases. Methods: The total sample consisted of 423 students, including 212 girls and 211 boys, from the continental and Adriatic regions of the Republic of Croatia, with an average age of 10.32 years. Body height was measured using a portable stadiometer, while body weight, body mass index (BMI), and body fat percentage were measured using a dual-frequency body composition analyzer (TANITA DC-360P) based on the principles of bioelectrical impedance. The WHR index was calculated as the ratio of waist to hips, while the WHtR index was calculated as the ratio of waist circumference to height. Cardiorespiratory fitness was assessed using the 20-meter multistage shuttle run test. Results: The results show that 25% of the participants were overweight, and 9% were obese. The ANOVA results indicate that the boys had significantly higher values for BMI, WC, HC, WHtR, and WHR, while the girls had a significantly higher body fat percentage (BF%). Additionally, the boys had better CRF, as they ran more meters in the 20-meter shuttle run test. The variance analysis revealed that the participants with normal body weight had significantly higher cardiorespiratory capacity values compared to overweight or obese students. Regression analysis showed statistical significance for the set of predictor variables, which were BMI indicators, on the criterion variable predicting cardiorespiratory fitness (CRF) in both genders. The coefficient of determination (R2) explained almost 22% of the shared variability in boys and 19% in girls. Statistically significant beta coefficients were found for body fat percentage (−0.60) in boys and (−0.98) in girls. Conclusions: Body fat percentage (BF%) was shown to be a significant and useful predictor of cardiorespiratory fitness in school-aged boys and girls. Maintaining an optimal body weight along with high levels of CRF should be an important goal in promoting health among children and adolescents.

Background: The primary goal of this study was to investigate the relationship between body composition and motor coordination performance, and the secondary goal was to determine sex differences in body composition and motor coordination of preschool children. Methods: Forty-eight children (23 boys and 25 girls) underwent assessments for body composition and motor coordination using the Köperkoordinationstest für Kinder (KTK). Results: Linear regression analysis revealed significant associations between body composition and motor coordination in boys (p < 0.05) but not in girls. In boys, Body height (p = 0.01), Total muscle mass (p = 0.03), Total fat (p = 0.03), and Total water (p = 0.02) show statistically significant influence on single-leg jumps. Similar results were obtained for lateral jumps where there was a statistically significant influence of Body height (p = 0.01), Total muscle mass (p = 0.03), and Total water (p = 0.02). Interestingly, predictive variables showed no statistically significant influence on KTK overall score in boys (p = 0.42) nor in girls (p = 0.90). Conclusions: The predictive system of morphological variables demonstrated significance only among boys in this age group and sample. Girls outperformed boys due to early maturation, resulting in better average KTK scores.

As cardiorespiratory capacity is an important factor of an overall quality of life and a significant indicator of physical fitness, its development should begin from early childhood. The goal of the research is to determine the differences in the quality of life and cardiorespiratory abilities of primary education students. A total of 651 fourth-grade primary school students from the Republic of Croatia participated in the research. The average age of the subjects was 10.38±0.50 years, and the sample was divided in two subsamples according to gender, 316 girls (10.30±0.47 years) and 335 boys (10.34±0.49 years). Body height was measured with a portable altimeter, while body mass, body mass index-BMI, percentage of fat, level of obesity, and muscle mass were measured with a two-frequency body composition analyser (TANITA DC-360P). Waist circumference and hip circumference were measured with a centimeter tape, while the ratio of the waist and hip circumference (WHR index) was calculated based on their ratio. Cardiorespiratory capacity was assessed with a multi-stage 20m-running test (20MSRT Shuttle run test). For assessing the qualty of life, the researchers used a Croatian version of the KIDSCREEN-10 Questionnaire. The research results show a high mean value of the overall life quality assessment (4.33). The identification of individual differences between the researched groups demonstrated that students with a high level of cardiorespiratory capacity rate their quality of life significantly higher than students with a low or moderate cardiorespiratory capacity. According to the results, 41.01% of students have an unsatisfactory level of cardiorespiratory ability. There are statistically significant differences in morphological characteristics and cardiorespiraory capacity among the groups classified according to their level of cardiorespiratory capacity. Children with a higher level of cardiorespiratory capacity report a better quality of life and have better indeces of physical nutrition. Physical exercises used to boost the development of the cardiorespiratory capacity of children indirectly impact the prevention of obesity and can diminish other factors of cardiovascular risk.

The aim of the research was to determine the state of nutrition of children of the older and preschool education group who attend kindergartens in the municipality of Belgrade. The measurement of anthropometric measures was carried out in the physical education halls at the beginning of February 2023. The research used the probability sampling method. The subjects of the research were children of the older and preschool age groups of the kindergarten "Čukarica" from Belgrade. The research determined possible statistical differences between age groups, as well as statistical differences between both sexes of both age groups. The results of the research indicate that there are no statistically significant differences in the nutritional status of children from Belgrade in PU "Čukarica". When gender is taken as a parameter, it can also be concluded that children do not differ significantly in the state of their nutrition. In relation to the educational group to which they belong, it can be concluded that the nutritional indices of children of the older preschool group are significantly lower compared to the preschool group. This indicates that the anthropometric measurements of children correspond to their age and natural factors that influence physical development. The equality of the nutrition index between children from different groups is also observed, which indicates that their nutrition is in accordance with the age and specifics of physical development. The authors recommend further monitoring of children's growth and development before entering school.

The aim of this research is related to the influence of swimming on the development of motor abilities of students of younger school age, as well as defining the skills that are most developed under the influence of swimming. Differences in anthropometric characteristics and motor abilities between the two groups of students were analysed. One group consisted of students who, in addition to physical and health education classes, practice swimming (students/swimmers), and the second group consisted of students who do not engage in any additional organised physical activities (students). The sample of the respondents included 18 students, members of the Belgrade swimming club "Mornar" and 17 students of "Branko Radičević" primary school from Pančevo, all aged 10 years ± 6 months. In addition to basic anthropometry, an assessment of motor abilities was also carried out, with the help of the tests of strength, speed, endurance, flexibility, agility, balance, and coordination. By analysing the differences using the t-test for independent samples, the group of students/swimmers showed generally better results, and a statistically significant difference between the groups at the level of significance (p<.005) was found in five motor tests: Standing long jump, Stick twist, Lying-sitting for 30 sec., Seated forward bend, and Bent arm hang. The obtained research results indicate that swimming, as a basic physical activity, has a positive effect on the development of the motor abilities of the students of younger school age, especially on strength and flexibility. The authors' recommendations go in the direction of paying more attention to swimming as a physical activity that has a positive impact on the development of students' motor abilities.

The study aimed to comprehensively investigate associations between anthropometric features and motor abilities in young school-age children. The sample included 285 students (140 boys and 145 girls, aged 10.44 ± 0.33 years). Sex differences in the anthropometric and motor variables were determined by an independent t-test, while multiple linear regression was used to examine whether anthropometric characteristics could predict motor test scores. Girls were significantly taller, with greater sitting height, leg and arm length, as well as hip width. Also, greater body mass and skinfold thickness, as well as better scores on flexibility tests were observed in girls compared to boys (t=1.384-3.290, p<0.05). Conversely, boys demonstrated better scores on tests to evaluate coordination, agility, aerobic endurance, and strength. Except for movement frequency and flexibility, all motor items showed small-to-large correlations with anthropometric measures. Skinfold thickness, body mass index, arm girth, together with leg length and wrist diameter, explained 44% of the explosive strength variance, while 32% of aerobic endurance was explained by leg girth, BMI, and skinfold thickness. These results indicate that anthropometric measures have a significant influence on several motor abilities, especially explosive strength and aerobic endurance, while the role of anthropometry on flexibility, frequency of movement, and coordination seem to be negligible.