Purpose:
Previous research on intergenerational changes in body build has focused on body height and mass. The aim of this study was to determine both the direction and sexual dimorphism of secular changes in body build by using a sample population of students attending the University School of Physical Education (AWF) in Wrocław, Poland.

Methods:
The anthropometric data used in this study were collected every year from 1967 to 2008 and included a sample size of 4688 males and 3922 females. The subjects were analyzed for changes in somatotype by use of Sheldon’s method, as modified by Heath and Carter. Basic statistical analysis for significance and post-hoc tests were used to analyze the data with Statistica 9.0 software. The data were then converted in Excel 2003 into chart form to analyze the direction of changes.

Results:
Analysis of the successive classes of male and female subjects during the 40-year period under study revealed a number of different directional changes in the mean values of body height, mass and the level of body build components. Trend lines, calculated by the mean values of five-year intervals, indicated an increasing tendency in both body height and mass in the two genders. Mesomorphy was found to be the largest factor of body build composition of females and males. Throughout the entire analyzed period, the endomorphy of males was significantly lower in comparison to females. In women, the level of fatness was similar to their level of musculature, but during the last several years the observed level of muscle in the students exceeded their fatness level. Ectomorphy happened to be the most stable component of both sexes.

Conclusions:
Analysis on the male and female sample population revealed a constant increase in body mass and height in successive generations. In female subjects, intergenerational changes were found to be characterized by a decrease in endomorphy and an increase in ectomorphy, while the level of mesomorphy remained at a similar level. In men, a secular trend was visible with an increase in mesomorphy, while the levels of endomorphy and ectomorphy stayed constant.