Tadeusz Bielicki

Interrelationships among certain measures of growth and maturation rate in boys during adolescence

Relationships among ages at attaining 17 or 21 indices of maturity were considered in a longitudinal sample of 177 Polish boys examined at annual intervals from 1961 to 1972. Maturity indicators included ages at peak velocity for stature, sitting height, leg length and weight; ages at attaining 80%, 90%, 95% and 99% of adult stature; ages at attaining the median skeletal maturity scores (TW-2) characteristic of chronological ages 11, 12, 13, 14, and 15 years; and ages at attaining stages II and IV of genital and public hair development. Age at initiation of the stature spurt (take-off) and ages at eruption of 14, 20 and 26 permanent teeth were ascertained for only 111 boys. All intercorrelations among the developmental indicators were positive. Ordering the correlation matrix gave three clusters: (1) a large central group including age at take-off and ages at all peak velocities, at genital and pubic hair stages II and IV, at attaining 90%, 95% and 99% of adult stature, and at the later stages of skeletal maturity; (2) indices of the tempo of maturation during prepubertal and/or early pubertal stages; and (3) ages at attaining a given number of permanent teeth. Results of a principal components analysis of the ages indicated two principal components, the first accounting for about 77% of the sample variance and the second for about 12%. The first principal component is apparently a general maturity factor, while the second apparently relates to the rate of skeletal maturity during pre-adolescence.

Variation in Subcutaneous Adipose Tissue Distribution Associated With Age, Sex, and Maturation

Age-, sex-, and maturity-associated variation in subcutaneous adipose tissue (SAT) distribution is reviewed and then considered longitudinally in a sample of Polish youth. Current study of adipose tissue distribution places considerable emphasis on abdominal adiposity, specifically intra-abdominal or visceral adipose tissue (VAT). Most studies of children and adolescents do not include an abdominal skinfold, and when it is available, the skinfold is grouped with others as a sum of skinfolds. Correlations between abdominal VAT and SAT based on computerized tomography in non-obese children are moderate to high, and those between the suprailiac and abdominal skinfolds and abdominal VAT are moderately high. Changes in three individual skinfolds (triceps, subscapular, abdominal) and ratios of the skinfolds were considered by chronological age and relative to the timing of peak height velocity (PHV), and in children of contrasting maturity status in participants of the Wroclaw Growth Study, 193 boys and 197 girls, who were followed longitudinally from 8 to 18 years of age. Individual skinfolds behave differently during childhood and adolescence, and the changes are influenced by the timing of the adolescent growth spurt. Sex differences in estimated velocities are negligible up to about 2 years before PHV; then velocities tend to be higher in girls. The velocity of the triceps skinfold is negative in boys just before and after PHV; estimated velocities for the trunk skinfolds are positive through the growth spurt in both sexes, and are somewhat greater after PHV, especially in girls. The individuality of changes in individual skinfolds during the adolescent spurt contributes to changes in the relative distribution of SAT at this time. The timing of the adolescent growth spurt is an important factor influencing the distribution of SAT both in the total sample and in youth classified as early and late maturing. Am. J. Hum. Biol. 11:189-200, 1999. Copyright 1999 Wiley-Liss, Inc.

Social-class gradients in menarcheal age in Poland

In a sample of approx. 19 000 Polish schoolgirls from the three largest cities of the Upper Silesia conurbation, menarcheal age was studied in relation to parental education (four levels) and fathers occupation (12 groups). Menarcheal age tends to increase with decreasing parental education, although the gradient is not steep. When families below a certain level of economic standing are discarded from the best-educated and the least-well-educated groups, mean menarcheal age, surprisingly, decreases much more in the former than in the latter. Mean menarcheal ages for girls from different occupational groups range from 12.82 to 13.30 years and form the following sequence, in increasing order: managers--police--non-technical professionals--engineers, technicians and foremen--skilled industrial workers and small businessmen--unskilled workers--coal-miners. Mean menarcheal age for an occupational group is strongly dependent upon the groups socio-economic status, the latter being defined in terms of parental education, family income, family size, and dwelling conditions. However, daughters of men in the police force mature significantly earlier, and daughters of coal-miners significantly later, than would be expected from each groups rank in socio-economic status. The findings are compared with the results of other recent studies of social gradients in menarcheal age in Poland.

Retrospective longitudinal growth study of boys and girls active in sport

Longitudinal records from the Wroclaw Growth Study and the Wroclaw Longitudinal Twin Study were screened for individuals who were active in sport during childhood and adolescence and who were active in sport as young adults. The resulting sample was 25 boys and 13 girls. Heights and weights of the active boys indicated a growth pattern characteristic of early maturers. which was verified in advanced skeletal, sexual and somatic maturation during adolescence. The pubertal progress of active boys suggested no differences in tempo compared to nonathletic boys. In contrast, girls active in sport presented a pattern of growth and maturation characteristic of average maturing individuals, but were taller and heavier than local reference data. Skeletal and chronological ages of active girls did not differ, and the active girls did not differ from local reference data in sexual maturation. PHV, however, was reached later by about one‐half of a year. The pubertal progress of girls active in sport did not differ from that of nonathletic girls.

Stature, upward social mobility and the nature of statural differences between social classes

Stature and educational level achieved were studied in 10 groups of 19-year-old Polish men born in 1967 and examined in 1986. Each group consisted of subjects equated for (1) parental education and occupation, (2) urban-rural residence and (3) number of children in family. It was found that within each group subjects who were secondary school students or graduates were on average taller than their age-mates who by the time of examination had never moved beyond the level of elementary or basic trade school. This result is consistent with the long-debated hypothesis that in industrial societies upward social mobility tends to be selective with regard to body height. Theoretically, such social selection could be expected to inflate the magnitude of social-class differences in stature by adding to them a genetic component. However, a mechanism can be envisaged by which preferential recruitment of taller individuals to upper social strata might indeed be at work and yet produce no differential distribution of genotypes along the social scale.

Monitoring the dynamics of social stratification: Statural variation among polish conscripts in 1976 and 1986

The effects of three factors in the social environment on variation in stature were evaluated in two large samples of 19‐year‐old Polish conscripts, one examined in 1976 (birth cohort 1957) another in 1986 (birth cohort 1967). The factors were: A) population size of the locality of the conscripts habitation, B) occupational‐educational status (OES) of the father, and C) size of the conscripts sibship. In each cohort, stature decreased monotonically with decreasing population size, decreasing paternal OES and increasing sibship size, each factor exerting a significant influence on stature even after the influences of the other two were partialled‐out by analysis of variance (ANOVA) procedures. However, the order of the strenght of the influences has changed from B > C > A in 1976 to C > B = A in 1986. The most notable change was the decline in the importance of factor B. The condition of being a peasants son depressed stature less in 1986 than in 1976, but the stature‐depressing effect of the condition of being a rural dweller, as well as that of coming from a large family, has not diminished. Overall, secular gains in stature among groups lowest on the statural and social scale in 1976 have been more intense than among those highest on these scales, which resulted in an attenuation of some social contrasts in stature from 1976 to 1986.

Body height and upward social mobility

Stature and education in 214 pairs of adult brothers and 188 pairs of adult sisters were analysed in order to test the hypothesis that in modern stratified societies upward and downward social mobility is selective with respect to body height. Among the 116 male pairs in which the sibs differed in both education and stature, the proportion of pairs in which the taller sib was the better educated (BE) was significantly higher than the proportion of pairs in which the taller sib was the less well educated (LE) of the two. Mean intra-pair difference in stature between the BE and LE brothers was 1.26 cm, and significantly different from zero. In female pairs similar tendencies were noted but deviations from the null hypothesis were not significant. Implications of these findings are discussed.

Changing patterns of social variation in stature in Poland: effects of transition from a command economy to the free-market system?

The aim of this analysis was to examine the effects on stature in two nationally representative samples of Polish 19-year-old conscripts of maternal and paternal education level, and of degree of urbanization, before and after the economic transition of 1990. Data were from two national surveys of 19-year-old Polish conscripts: 27,236 in 1986 and 28,151 in 2001. In addition to taking height measurements, each subject was asked about the socioeconomic background of their families, including paternal and maternal education, and the name of the locality of residence. The net effect of each of these social factors on stature was determined using four-factor analysis of variance. The secular trend towards increased stature of Polish conscripts has slowed down from a rate 2.1 cm per decade across the period 1965-1986 to 1.5 cm per decade between 1986 and 2001. In both cohorts, mean statures increase with increasing size of locality of residence, paternal education and maternal education. The effect of each of these three social factors on conscript height is highly significant in both cohorts. However, the effect of maternal education has increased substantially while that of size of locality of residence and paternal education diminished between 1986 and 2001. These results imply that the influence of parental education on child growth cannot be due solely to a relationship between education and income, but is also perhaps a reflection of household financial management which benefits child health and growth by better educated parents, regardless of level of income. In addition they suggest that, irrespective of whether there are one or two breadwinners in the family, it is the mother, more so than the father, who is principally responsible for the extent to which such management best favours child health and growth. The asymmetry between the importance of maternal as against paternal education for child growth, clearly seen in the 1986 cohort, became more accentuated in 2001, after the abrupt transition from a command to a free-market economy in the early 1990s.

Genetic variance in the pattern of the growth curve for height: a longitudinal analysis of male twins.

Genetic aspects of the pattern of growth and of short-term variations in growth velocity for height were studied in a sample of 44 MZ and 42 DZ twin pairs from the Wroclaw Longitudinal Twin Study. The data consists of serial measurements of height, taken between 8.5 years of age and adulthood. The intra-pair resemblance of the pattern of attained height was quantified by means of the average Euclidean distance coefficient and the coefficient of shape difference, calculated on the raw height-for-age data. Comparison of these resemblance coefficients between the two types of twins indicated that the growth curves of MZ twins are closer to each other, and more similar in shape, than those of DZ twins. The shape of the growth curve was further characterized by a set of biological parameters, derived from Preece Baines model I (PB) fitted to each subjects serial growth data. Genetic analysis of these parameters, according to the model of Christian, Won Kang and Norton (1974), revealed a strong genetic component in the variance of size at particular milestones in the growth process (height at take-off, at peak velocity and at adulthood), and also in the timing of the growth process (age at take-off and at peak velocity). Height velocity at take-off and peak height velocity were also strongly genetically determined. Finally, short-term variations in growth velocity were analysed on the basis of the profiles of the residuals, obtained by the PB fits to each subjects serial measurements of height. Resemblance coefficients were calculated for the profiles of residuals. The results revealed a significantly greater similarity of profile shapes of the residuals in MZ twins than in DZ twins, strongly suggesting that there is a genetic component in the short-term variations of growth velocity.

Changes in the BMI of Polish conscripts between 1965 and 2001: secular and socio-occupational variation.

Objective:To describe changes in the body mass index (BMI) of nationally representative samples of young adult Polish males between 1965 and 2001, and to investigate variation in the incidence of underweight, overweight and obesity between 1965 and 2001 in the young adult males in the context of the socio-political transformation that occurred in Poland since 1989.Subjects:Four 10% nationwide random samples of 29-year-old Polish conscripts examined in 1965, 1986, 1995 and 2001. The conscripts were divided into four socio-occupational groups based on paternal education, occupation and degree of urbanization.Measurements:Height, weight and BMI (weight (kg)/height (m2)).Results:The proportion of overweight and underweight young adult males in the population increased between 1965 and 2001. The fraction of underweight decreased only among sons of farmers and entrepreneurs between 1986 and 1995 and then increased in all socio-occupational groups between 1995 and 2001. On the other hand, the proportion of overweight young adults gradually increased in all groups between 1965 and 2001.Conclusion:Socio-occupational position of the family is an important factor influencing underweight and overweight in young adult males. This factor apparently operates through a differential distribution of income, which influences components of lifestyle most likely associated with level of habitual physical activity and/or diet.