Physical Activity Levels During Physical Education Classes and Their Impact on Physical Fitness in 10-Year-Old School Children: A Comparative Study.

: The aim of this research was to determine the differences in physical fitness according to the level of physical activity (PA) during physical education classes in 10-year-old school children. : The research included 315 primary school children (age 10 ± 1.3 years), divided into three groups by level of PA: low, moderate and high. A Eurofit test battery was used to evaluate the physical fitness of children. Physical activity (volume (number of steps) and intensity) was measured using a Coach Gear pedometer and a Suunto Memory Belt heart rate monitor. : Presented results indicate that there are significant differences between groups of children of both genders in relation to the level of PA. Group of boys with low PA showed lower values in sit and reach ( = 0.01), standing long jump ( = 0.02), bent arm hang ( = 0.04) and polygon backwards ( = 0.01) compared to the remaining two groups. Girls with low physical activity showed significant differences in sit and reach ( = 0.01) and bent arm hang ( = 0.01) compared to the other two groups, while in hand tapping, the high PA group showed better results compared to the other two groups ( = 0.03). : The results reported in this research support the significant effects of PA level on physical fitness in school children. Less active children generally showed poorer physical fitness in both genders.