DYNAMICS OF ANTHROPOMETRIC INDICATORS OF THE LOWER LIMBS IN GIRLS AND BOYS OF EARLY CHILDHOOD

SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 25 DYNAMICS OF ANTHROPOMETRIC INDICATORS OF THE LOWER LIMBS IN GIRLS AND BOYS OF EARLY CHILDHOOD U.M. Mirsharapov1, A.O. Shermanov2 Tashkent Medical University, Uzbekistan, Tashkent, Farabi Street, 21,2 https://doi.org/10.5281/zenodo.17394091 Abstract. The aim of this study was to conduct a comparative analysis of the growth dynamics of the lower limbs in girls and boys aged 0–3 years and to determine the clinical significance of the identified features. Anthropometric measurements demonstrated that early childhood is characterized by intensive and harmonious growth of the lower limbs, contributing to the formation of body proportions and the functional readiness of the musculoskeletal system for independent locomotion. Linear parameters were more pronounced in boys, while circumferential measures were greater in girls. Increasing individual variability with age highlights the need for personalized assessment. The application of Z-score and centile charts confirmed that most indicators comply with WHO standards, whereas values outside the normal range require clinical monitoring. Keywords: early childhood, lower limbs, anthropometry, sexual dimorphism, Z-score, physical development. Introduction Early childhood (0–3 years) is a critical stage of postnatal ontogenesis during which body proportions are established and the musculoskeletal system is formed. The lower limbs play a key role at this stage, as they ensure verticalization, balance, and the development of independent walking. According to Tanner (1990) and Malina, Bouchard & Bar-Or (2004), the first years of life are characterized by the most rapid increase in limb length, which determines overall body proportions. Hermanussen (2016) reported that the most pronounced growth occurs in the foot, reflecting adaptation to vertical loading. Shapovalenko N.I. (2018) and Baranov A.A. (2019) emphasize that the harmonious growth of limb segments (thigh and lower leg) is an important indicator of a child’s somatic development. As noted by Yampolskaya M.A. (2020), the ratio of thigh to lower leg length remains stable during the first three years of life, indicating synchronized growth. Volkov V.M. et al. (2017) found that sexual dimorphism begins to manifest already at an early age: boys tend to exhibit higher linear growth indicators, while girls demonstrate greater circumferential measurements. International studies (WHO Multicentre Growth Reference Study Group, 2006; Cole, Flegal, Nicholls & Jackson, 2007; de Onis et al., 2010) have confirmed the importance of standardized assessment methods—such as percentile charts and Z-score analysis. These approaches allow for an objective evaluation of growth dynamics and help identify children with deviations from normative development. Thus, a review of the literature confirms that early childhood represents a foundational period for the establishment of body proportions and the functional readiness of the musculoskeletal system. A comparative study of the growth dynamics of the lower limbs in boys and girls from birth to three years of age is therefore of significant scientific and practical interest. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 26 The aim of the study was to conduct a comparative analysis of the growth dynamics of the lower limbs in girls and boys aged from birth to three years, as well as to determine the clinical significance of the identified characteristics. Materials and Methods The study was carried out on a sample of early childhood children (0–3 years), including newborns, as well as twoand three-year-old girls and boys (n = 616) residing in Tashkent city. Anthropometric measurements included: • length of the lower limb; • length of the thigh, lower leg, and foot; • thigh and lower leg circumference; • pelvic width. Measurements were performed using standard anthropometric techniques with determination of mean values (M), standard errors (m), and standard deviations (σ). To assess conformity with normative values, percentile charts and Z-score calculations were applied according to the standards of the World Health Organization (WHO). Results The conducted study of the anthropometric parameters of the lower limbs in girls aged from birth to three years revealed regular and statistically significant changes confirming the high rates of somatic growth during early childhood. This age period is critically important, as it is when the basic body proportions are established, and the foundations of vertical stability and functional activity of the musculoskeletal system are formed. Growth Dynamics in Girls Linear growth indicators demonstrated pronounced changes. The average length of the lower limb in newborns was 22.4 ± 0.29 cm (σ = 1.8). By the age of two, this value nearly doubled to 41.7 ± 0.44 cm (σ = 4.6), and by three years reached 44.55 ± 0.47 cm (σ = 5.4). Thus, the overall increase during the first three years of life exceeded 22 cm, emphasizing the leading role of the lower limbs in shaping the child’s body proportions. Segmental growth was both intense and harmonious: the length of the thigh increased from 10.7 cm in newborns to 21.65 cm at three years, while the length of the lower leg rose from 11.5 cm to 21.5 cm. The preservation of proportional relationships between these segments indicates balanced development of the musculoskeletal system without disharmony. Of particular interest is the growth dynamics of the foot: its length increased from 4.93 cm to 15.95 cm, more than tripling. This parameter reflects morphofunctional adaptation to increasing static and dynamic loads associated with verticalization and the acquisition of standing and walking skills. Circumferential and transverse dimensions also changed significantly. The thigh circumference grew from 16.7 cm in newborns to 28.1 cm at age three, reflecting not only bone growth but also the development of muscular and adipose components. The calf circumference nearly doubled—from 10.7 cm to 20.9 cm, confirming functional strengthening of the muscles responsible for locomotion and balance. The pelvic width remained relatively stable—from 18.0 cm in newborns to 20.03 cm by age three—due to age-related characteristics and the absence of marked sexual dimorphism at this stage. Noticeable pelvic changes occur later, during prepubertal and pubertal development. An important finding was the increase in variability (σ) with age: for the lower limb length, σ rose from 1.8 in newborns to 5.4 at age three. This indicates growing individual differences in growth rates and proportions, which must be considered when constructing normative charts. Z-score SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 27 analysis confirmed that the mean values of most parameters were within WHO reference ranges (–2 ≤ Z ≤ +2). However, some children had values beyond this range, indicating the need for clinical monitoring to rule out developmental abnormalities. Clinical and Physiological Interpretation (Girls) The obtained data have several important implications: 1. Limb elongation shapes age-appropriate body proportions, characterizing the “phase of intensive limb growth.” 2. The substantial increase in foot and lower leg dimensions reflects musculoskeletal adaptation to new functional demands—standing, walking, and running. 3. Growth in circumferential parameters reflects active development of the muscular and ligamentous apparatus ensuring stability and motor activity. 4. The relative stability of pelvic width confirms that major pelvic remodeling in girls occurs later in ontogenesis. Thus, early childhood in girls is characterized by intensive and harmonious growth of the lower limbs. The elongation of the thigh, lower leg, and foot ensures functional readiness for independent movement and shapes the body’s proportions. Increasing variability of anthropometric parameters emphasizes the need for individualized assessment of physical development. The use of Z-score and percentile scales in clinical practice enables objective evaluation of growth dynamics and timely detection of deviations, essential for early diagnosis and prevention of developmental disorders. Growth Dynamics in Boys The analysis of anthropometric data in boys during the first three years of life demonstrated intensive growth of the lower limbs, accompanied by increases in both linear and circumferential dimensions. These changes reflect general postnatal growth patterns and play a key role in shaping body proportions during early childhood. Linear growth parameters confirmed the rapid increase in size. The average length of the lower limb in newborns was 22.4 ± 0.29 cm (σ = 1.8), increasing to 40.4 ± 0.36 cm (σ = 3.8) by two years, and 45.7 ± 0.50 cm (σ = 5.5) by three years. Thus, from birth to age three, lower limb length more than doubled, highlighting the dominance of linear growth in body proportion formation. Segmental growth was equally intensive: the thigh length increased from 10.7 ± 0.20 cm in newborns to 19.3 ± 0.16 cm at two years and 22.1 ± 0.32 cm at three years. The lower leg length rose from 11.5 ± 0.27 cm to 21.6 ± 0.21 cm, indicating harmonious segmental growth. The foot length showed the highest growth rate—from 4.93 ± 0.30 cm at birth to 16.4 ± 0.11 cm at age three, more than tripling. This reflects morphofunctional adaptation of the foot to increasing load and active locomotion. Circumferential measurements changed similarly: the thigh circumference increased from 16.7 ± 0.54 cm in newborns to 27.4 ± 0.29 cm by age three, and the calf circumference rose from 10.7 ± 0.30 cm to 20.8 ± 0.20 cm, reflecting muscular development required for stability and movement. The pelvic width remained relatively constant (18.0 ± 0.53 cm → 20.0 ± 0.26 cm), consistent with the absence of marked sexual dimorphism in early childhood. As in girls, variability increased with age: σ for lower limb length rose from 1.8 in newborns to 5.5 by age three, confirming growing individual differences and the need for percentile and Z-score evaluation. Clinical and Physiological Interpretation (Boys) 1. Limb elongation reflects the critical role of early childhood in shaping male body proportions. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 28 2. Foot growth indicates morphofunctional preparation for increased mechanical loads due to standing and walking. 3. Circumferential growth demonstrates the development of the muscular system necessary for balance and movement. 4. Relative pelvic stability aligns with age-specific characteristics, with sexual dimorphism appearing later during puberty. Thus, early childhood in boys is characterized by intensive and harmonious growth of the lower limbs, with the most significant contributions from thigh, lower leg, and foot elongation, as well as circumferential increases. The rising individual variability emphasizes the importance of a personalized approach to evaluating physical development. Applying WHO standards, Z-score, and percentile methods allows for accurate assessment of growth rates and timely detection of potential developmental deviations. Comparative Analysis A comparative analysis of the anthropometric parameters of the lower limbs in girls and boys aged from birth to three years demonstrated intensive growth in both sexes, with shared trends as well as distinct sexual differences. At birth, both sexes showed identical average lower limb length (22.4 cm). However, the subsequent growth dynamics differed slightly: by two years, this parameter reached 41.7 cm in girls and 40.4 cm in boys, while by three years, it measured 44.55 cm in girls and 45.7 cm in boys. Thus, by age three, boys exhibited slightly higher values, indicating a more pronounced linear growth tendency. Segmental data confirmed this trend: by three years, thigh length reached 21.65 cm in girls and 22.1 cm in boys; lower leg length — 21.5 cm in girls and 21.6 cm in boys. Although differences were minimal, boys consistently showed slightly higher values. Particularly notable is the foot growth pattern: in girls, foot length increased from 4.93 cm to 15.95 cm, while in boys — from 4.93 cm to 16.4 cm, suggesting a more pronounced functional adaptation of the male foot due to greater motor activity. In summary, both sexes exhibit intensive and harmonious growth of the lower limbs in early childhood, with boys demonstrating slightly higher linear indicators, reflecting early manifestations of sexual dimorphism and functional adaptation to locomotion. Fig. 1. Dynamics of Anthropometric Indicators of the Lower Limbs in Children Aged from Birth to Three Years 0 1 2 3 4 5 6 Length of the lower limb Point of the superior anterior iliac spine Point of the superior margin of the pubic symphysis Thigh length Thigh circumferencePelvic width Lower leg length Lower leg circumference Foot length Newborns 2 years 2 years 3 years 3 years SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 29 The diagram clearly illustrates that the greatest increase in size is observed in such parameters as the length of the lower limb, the length of the foot, and the measurements of the thigh and lower leg. In newborns, all values are minimal, whereas by two years, and especially by three years of age, they increase significantly, forming a broader polygon on the diagram (Fig. 1). The most pronounced increase is seen in the indicators of linear growth (length of the limb, thigh, lower leg, foot), while the pelvic width remains relatively stable. This pattern corresponds to the physiological characteristics of this age period, when growth occurs predominantly in length, while transverse dimensions’ exhibit less dynamic changes. Thus, the figure demonstrates the harmonious growth of a child’s lower limbs during the first three years of life, characterized by a predominant increase in linear parameters and gradual development of circumferential ones. Circumferential and transverse parameters show somewhat different trends. By the age of three, the thigh circumference in girls reached 28.1 cm, whereas in boys it was 27.4 cm. Hence, despite boys having greater linear dimensions, girls display higher values reflecting the development of the muscle–fat component. The calf circumference reached 20.9 cm in girls and 20.8 cm in boys, indicating similar patterns of muscular formation at this age. Pelvic width was 20.03 cm in girls and 20.0 cm in boys, confirming the absence of significant sexual dimorphism in early childhood. Pronounced differences in this parameter appear only in the prepubertal and pubertal periods. An important aspect of the analysis is variability. The standard deviation (σ) increases in both sexes, reflecting greater individual differences in morphology. At the same time, in boys, the spread of values for the length of the lower limb at three years is slightly higher (σ = 5.5 versus σ = 5.4 in girls), indicating a wider range of individual growth trajectories and confirming the need to use percentile tables and Z-score analysis in clinical assessments. The clinical and physiological significance of this analysis is as follows. Girls are characterized by earlier development of circumferential parameters (thigh, calf), associated with a more pronounced fat component and specific anatomical-physiological features. Boys, on the other hand, show predominantly linear growth, expressed in higher values of the length of the lower limb, thigh, lower leg, and foot, reflecting functional preparation for more intensive physical activity. In both cases, a key feature is the high growth rate during the first two years of life, followed by a slowdown by the age of three, which corresponds to the physiological patterns of early childhood. Thus, a comparative analysis of the dynamics of lower-limb growth in girls and boys showed that in early childhood, girls exhibit more developed circumferential parameters, while boys are characterized by predominance of linear ones. Overall, the development of the lower limbs from birth to three years is harmonious and highlights the critical role of this period in shaping body proportions and ensuring the functional readiness of the musculoskeletal system for active motor activity. Discussion The analysis of the collected data showed that between birth and three years of age, children of both sexes exhibit a pronounced and statistically significant increase in the anthropometric parameters of the lower limbs. This process represents one of the key biological mechanisms that ensure the formation of body proportions and prepare the child for active motor activity. At birth, linear parameters in both girls and boys—specifically, the length of the lower limb—had identical baseline values (22.4 cm), indicating the absence of marked sexual dimorphism at the onset of postnatal development. However, by the age of three, some differences became apparent: in girls, the length of the lower limb reached 44.55 cm, whereas in boys it reached 45.7 cm. Although the difference is minimal, it reflects a trend toward more pronounced SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 30 linear growth in boys. Analysis of individual segments confirmed this pattern: the lengths of the thigh and lower leg were slightly greater in boys than in girls, consistent with the general biological tendency of the male body toward more intensive skeletal elongation. The most rapid increase was recorded in the foot: its length more than tripled in girls (to 15.95 cm) and reached 16.4 cm in boys. These changes are closely related to functional adaptation to vertical posture, walking, and increasingly complex motor activities. Circumferential and transverse parameters. Along with linear growth, a significant increase in circumferential measurements was observed, reflecting the development of the muscular, connective, and adipose components. By the age of three, the thigh circumference in girls reached 28.1 cm, which was greater than in boys (27.4 cm). A similar pattern was observed for the calf circumference—20.9 cm in girls versus 20.8 cm in boys. These findings suggest that early childhood girls have more pronounced circumferential characteristics, which can be explained by their morphofunctional features—greater fat accumulation and earlier establishment of the muscle–fat balance. The pelvic width at this age showed virtually no difference (20.03 cm in girls and 20.0 cm in boys), confirming the absence of sexual dimorphism at this stage. Significant changes in transverse pelvic dimensions appear later, during the prepubertal and pubertal periods. Variability. With age, the standard deviation (σ), reflecting individualization of morphological parameters, naturally increased. For lower limb length, σ rose from 1.8 in newborns to 5.4 in girls and 5.5 in boys by the age of three. This indicates that as children grow, wider individual growth trajectories are established, influenced by genetic factors, nutrition, physical activity, and overall health status. Taken together, the results demonstrate that early childhood is a period of intensive and harmonious growth of the lower limbs, accompanied by distinct sexrelated differences. In boys, linear parameters (lengths of the limb, thigh, lower leg, and foot) dominate, indicating the body’s orientation toward more pronounced longitudinal growth. In girls, by contrast, circumferential dimensions are more prominent, reflecting specific features of fat and muscle tissue development. Functional interpretation. The differences in growth patterns can be explained by distinct adaptive responses to physical load. Boys typically exhibit higher rates of linear growth, forming a foundation for future intense motor activity. Girls, on the other hand, show greater stability and earlier functional readiness of the musculo-fat system, expressed in larger circumferential measurements. Clinical significance. The use of Z-score analysis and percentile tables demonstrated that most obtained values fall within the World Health Organization (WHO) reference range (–2 ≤ Z ≤ +2). However, the presence of children with parameters beyond these limits highlights the need for clinical observation to detect possible developmental abnormalities at an early stage. Therefore, early diagnosis using standardized evaluation methods has significant practical importance for pediatrics and pediatric endocrinology. Conclusion 1. Early childhood in both girls and boys is characterized by intensive and harmonious growth of the lower limbs, manifested in the elongation of the thigh, lower leg, and foot, as well as in the increase of circumferential dimensions. 2. Boys predominantly exhibit linear growth parameters, whereas girls display more developed circumferential parameters, reflecting sexual differences in somatic development. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 10 OCTOBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 31 3. With age, individual variability of parameters increases, emphasizing the necessity of personalized assessment of physical development. 4. The application of international standards (WHO, Z-score, percentile charts) ensures the objectivity of analysis, allows for the detection of deviations from normal growth, and enables timely clinical monitoring. REFERENCES 1. Tanner, J. M. (1990). Foetus into Man: Physical Growth from Conception to Maturity. 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