Associate Professor, PhD Adam Wilczewski^1
1Józef Piłsudski University of Physical Education in Warsaw, Faculty of Physical Education and Health, Biała Podlaska, Poland

The objective of the study was to analyze the changes taking place in the physical development, the rate of reaching sexual maturity, and the physical fitness level of girls from southern Podlasie between the years 1980 and 2015 against the background of peers from Eastern Poland and nationwide research.
Methods and structure of the study. In order to implement the subject of the presented report, the results of studies from 1980 (9 074 girls), 1985 (8 182 girls), 2005 (1 907 girls), and 2015 (2 583 girls) were selected. The results of studies from southern Podlasie and the entire eastern region were compared with the results of nationwide studies. Using Martin’s measurement technique of height and weight, the results from individual stages of the research were normalized to the results of research from 1980. Using the "status quo" method, counting the fraction of already menstruating girls in relation to all respondents, the mean age of menarche was calculated using the probit method according to Finney. The level of physical fitness at individual stages of the researches was determined by the results of the International Physical Fitness Test.
Results and conclusions. Among the examined girls from southern Podlasie there were clear secular trends in increasing height and weight (2.28 cm and 1.27 kg per decade). A similar tendency occurred in the case of lowering the mean menarche age. Girls from southern Podlasie lowered the menarche age from 13.333 years in 1985 to 12.580 years in 2015. There was a clear decrease trend in the general physical fitness level in all analyzed environments. Particularly unfavorable changes occurred among the examined girls and their peers from the eastern region. While in the studies carried out in 1985 both groups obtained results exceeding the nationwide standards, in the following stages of the research they lost this advantage.

Keywords: girls, body height and weight, menarche age, physical fitness level, secular trends, environmental conditions.

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