Secular changes of body height and mass in the children and adolescents of Lódź.

The report illustrates secular changes in the development of body height and mass in Lódź school children and youths in a period of time covering 65 years between 1930-1994. The lowest values of both traits were found in the early post-war period (1948-1949) increasing gradually until the end of the seventies. From that time the secular trend diminished successively, restraining completely in the last years (1992-1994). This seems to be connected with the economic crisis of the eighties in Poland, and the deep transformation of socio-economic relations in the last several years. According to the secular changeability values, the rate of that process in relation to younger groups of children increases considerably from the 12th year of life. The biggest changes (in centimeters and kilograms per decade) can be observed in the age of 15 and 16 years. Usually more distinctive variableness is apparent in boys than in girls.