Introduction. Physical activity is a minimum exercise necessary for the developement of the human body and to maintain relatively good health. Lack of exercise or its minimum may cause a metabolism disorder. It is the main factor of behavior, it strenghtens and developes health at every stage of life and keeps fitness and performance of the body at a high level. The number of youths exercising the minimum recommended 60 minutes of physical activity every day for 5 to 7 days a week is on decline. Aim. The aim of this thesis is to get to know and assess physical activity among youths in secondary school in Czechowice-Dziedzice and analysing its impact on the human body. Material and methods. A tool in the form of a questionnaire was used to analyse physical activity among student classess 1 to 3 in secondary school. 276 students were questioned, 142 boys and 134 girls. Results. 19% of girls and 14% of boys exercise everyday. 21% of girls and 11%of boys do not exercise at all during their free time. Most girls do areobic(31%) and jogging exercises(16%) while boys choose football (17%) and workout at the gym (16%). Almost 24% of girls and 4% of boys admit to exercising less than one hour per week. Conclusions. 1. Physical activity among youths is inadequate. 2. Time spent on exercising is inadequte especially among girls. 3. It is necessary to educate youths about the importance of physical activity and its imoportance for healh and well being.

Key words: physical activity, civilization disease, fitness.