The aim of the study was to measure the causal effect of selected socio-economic factors and anthropometrical characteristics on the menarche occurrence. Methods:The sample consisted of 2195 Bengali girls (aged 7-21) from middleclass families, from Kolkata city, India. The age at menarche was recorded from the retrospective data and status quo method. The causal effect of anthropometric and socio-economic variables on menarche occurrence was estimated by the nonparametrical analysis of survival probability (survival random forest).Results: In the examined cohort menarche occurred, on average, at 11.8 years of age. The probability of menarche occurrence amplified with the increasing values of factors such as body mass index, height-for-age z-scores, number of family members, household rooms, and toilets, but decreased when expenditures increased. The relation maintained a similar pattern of causal effect with girls' age.Conclusions: A complex pattern of relationship among sexual development, physique, and socio-economic characteristics was defined. The tendency toward early menarche, along with the observed causal relationships indicate that the analyzed sample is nearing the characteristics and standards of living noted in other middle and even high-income countries in the world.

The objective of the study was to analyse selected anthropometric features of children, adolescents and young adults from middle-class families in Kolkata, India, by BMI and adiposity categories. Standardized anthropometric measurements of 4194 individuals (1999 male and 2195 female) aged 7–21 were carried out between the years 2005 and 2011. The results were compared by BMI and adiposity categories. Statistical significance was assessed using two-way-ANOVA and linear regression analysis was performed. The study population could be differentiated in terms of BMI and adiposity categories for all examined anthropometric characteristics (p ≤ 0.001). After taking age into consideration, differences were observed for males in the case of body height and humerus breadth in BMI and adiposity categories, and for femur breadth in the case of adiposity categories. For females, differences were noted in body height measurements in BMI and adiposity categories, a sum of skinfold thicknesses in BMI categories, and upper-arm and calf circumferences in adiposity categories. The patterns of differences in the BMI categories were found to be similar to those in adiposity categories. The linear regression analysis results showed that there was a significant relationship between BMI and body fat ratio in the examined population. Underweight individuals, and those with low adiposity, were characterized by lower extremity circumferences and skeletal breadths. These features reached highest values in overweight/obese persons, characterized by high body fat. However, the differences observed between each BMI and adiposity category, in most cases, were only present in early childhood.

Socioeconomic changes occurring over time influence the lifestyle choices of a population, and these can significantly affect children’s body weight and composition. The aim of this study was to assess the changes in prevalence of overweight, obesity and adiposity in pre-school children in Poland between 2008 and 2018. Body height, body weight and subscapular and triceps skinfolds were measured in 2167 children aged 3–7 years from Kraków. Body mass index and adiposity (percentage body fat, %BF) were calculated for the children, who were then categorized as underweight, normal weight, overweight or obese according to Cole’s cut-off points. Adiposity was categorized according to the z-scores for %BF as low (<−1), normal (−1 to 1) or high (>1). Differences between cohorts were analysed using the chi-squared test. Only the decrease in the prevalence of obesity in 5-year-old girls was found to be statistically significant. However, some overall tendencies were noted. Decreases in the prevalence of underweight, overweight and obesity were observed for both sexes, as well as in the incidence of high adiposity in boys and low adiposity in girls. Increases in the prevalence of high adiposity in girls and low adiposity in boys were also noted. There was no significant change in the prevalence of overweight and obesity among pre-school children over the study decade, and the visible tendencies included decreases in the prevalence of excess body weight and adiposity as well as underweight and low body fat. Also, the visible trends in adiposity were mostly negative. Further studies should, however, also consider the levels of physical fitness and activity of children, as these have a crucial influence on the measured characteristics.

The study aim was determining gender-related differences of underwater undulatory swimming (UUS) kinematic indicators and their impact on UUS velocity. Methods: The study included 18 girls (F: age 16.71 ± 0.64 years, FINA points 551 ± 68) and 23 boys (M: age 16.79 ± 0.57 years, FINA points 533 ± 66) training swimming. After marking characteristic anatomical points, subjects performed approximately 7 meters of UUS. A filming device placed behind the underwater window registered the trial. Recordings were analysed using the SkillSpector programme.

In the light of changes in the living conditions of populations, excess adiposity is currently a serious public health problem worldwide. The aim of this study was to assess the changes in the body fat ratio among preschool children aged 3–7 years from Kraków, Poland, between 2008 and 2018. The study group consisted of children examined in two cross-sectional studies. Analysed characteristics included triceps, calf, subscapular, abdominal and suprailiac skinfold thicknesses, and adiposity calculated according to Slaughter’s equations. The trunk adiposity index and limbs-to-trunk fat ratio were also calculated. Statistical significance was obtained using two-way ANOVA and Tukey’s tests. Lower-limb adiposity was largest in the 2008 cohort and trunk adiposity was greater in the 2018 cohort. The mean values of the trunk adiposity index and limbs-to-trunk fat ratio were lower in the 2018 cohort than in the 2008 cohort. The 2018 cohort was also characterized by a lower overall adiposity. Regardless of the lower body adiposity percentage, in 2018 there was a tendency towards the central allocation of fat tissue. This is a negative phenomenon because, especially when co-existing with reduced lower-limb adiposity, it is associated with an increased risk of metabolic and cardiovascular diseases, even in young children.

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Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.

Objectives The aim of the study was to analyze the changes of the motor skills of children and adolescents from Kraków between 2010 and 2020. Methods The group included 4106 children and adolescents (8–18 years of age). The analysis of changes included results of the following fitness tests: backwards overhead medicine ball throw, standing broad jump, dynamometric strength of the hand, flexibility test, as well as shuttle run (10 × 5 m). Results A negative trend in both sexes was observed in the results of overhead medicine ball throw. The girls also had a negative intergenerational changes in the results of the shuttle run and the flexibility test. A positive secular trend was also observed in both sexes in relations to the dynamometric force of the right and left hand. In addition, the boys studied in more contemporary times showed better results in the shuttle run, compared to their peers in 2010. Conclusion The study reported a decline in overall motor performance in children and adolescents. The observed results may be related to a decrease in the level of physical activity, as well as a higher incidence of overweight and high levels of body fat in the modern population.