Body height and weight increments: their variability and interrelation

Abstract

Body height and weight were measured twice in 1200 boys and the same number of girls aged 6 - 17 years (so each of 12 age groups had 100 individuals of either sex measured). On grounds of these measurements arithmetic means of annual increments of studied characters were calculated as well as correlation between rates of growth in body height and weight observed. For every age group correlation between. body height and its annual increment was examined. Without taking age into account the same problem was analyzed by studying by means of analysis of variance relation between body height and its increments in classes of stature. Examined group: comprised individuals from both urban and rural environment living at the area of previous Złotów County. Both males and females were higher (see tab. 1, 3) and heavier (tab. 2, 4) than averages for Polish urban population in 1966. Taking into account. that the group in question was examined in 1973 - 1974, one may assume that the said discrepancy is due to the continuing secular trend (data in tables 1-4 relate to measurements taken in 1973, the second standard deviation labelled with asterisk informs. about spread of distributions of characters measured in 1974). Dynamics of body height and weight growth was both in boys (tab. 5) and girls (tab. 6) similar to that: found in longitudinal studies (Bielicki & Waliszko 1976, Waliszko & Jedlińska 1976) of Wrocław sample (tab. 7). On grounds of this analogy it was concluded that adolescent growth spurt in body height occured in the majority of girls at age 11 - 12 yrs. and in boys mostly at the age 13 - 14 yrs. Interrelation between rates of growth of’ height and weight changes with age it is the strongest around adolescent growth spurt in height (tab. 5 and 6). It may be suggested that high correlation is present. at adolescence between rates of growth of most body dimensions. In relation to that. it can be assumed that high values of correlation coefficients could result from increased activity of „coordinating genes” that force maximal cooperation between genes responsible for further growth of the organism. Correlations between rate of growth of height and asbolute body height did not give clearly interpretable results relating to the question whether certain categories of body height are related to particular increments in stature (see correlation coefficients compared in the text). That the existence of such a relationship is probable may be seen from the analysis of ‘variance performed for the whole material. Values of correlation quotient (eta) are: 70 for girls and .62 for boys. In this context should be also noted that in some classes of body height averages of increments are particularly high (tab. 8).