Relationships between physical activity, motor performance and body composition in school-age children

Introduction: Physical activity (PA) performed at recommended levels is associated with mul-tiple health benefits. However, as indicated by the available studies, the volume of habitual physical activity of children continuously decreases. Aim: The aim of the study was to assess the relationships between physical activity per-formed by school-age population and indicators of motor performance and body composition. Methods: The research group consisted of 144 students of the primary school assigned into groups according to the years of study (first, fifth and eighth-year students). The amount of physical activity was examined through a non-direct method, using Fels PAQ, recording four scores, namely sport index, leisure index, work (chore) index and total score. Body composition was tested using a direct segmental multi-frequency bioelectric impedance analysis (DSM-BIA). Motor performance was assessed in four categories. Endurance and strength endurance were assessed using Jacik’s motor test; strength abilities were measured using a hand grip test; speed abilities were tested in linear sprints at 5 and 10 meters and in the test of speed with changes of direction at 4 x 10 m and, finally, explosive strength was assessed from results of the countermovement jump (CMJ), squat jump (SJ) and 10-second repeated jumps tests. The strength of association between the selected factors was determined from the results using the Spearman’s rank correlation analysis. Results: The amount of physical activity was mainly associated with the indicators of active body mass (fat free mass, skeletal muscle mass) in all age categories. Low association was found in the parameters of adipose tissue (body fat percentage, visceral fat level). When assessing the strength of association between the characteristics of motor performance and physical activity performed, we observed various courses of associations, based on which it is not possible to determine the tendency. When assessing the relationship between the amount of physical activity and motor performance of students regardless of age, we found medium association only with indicators of strength abilities (hand grip test) and characteris-tics of speed abilities. Conclusions: The results are not explicit but they point to some tendencies in relationships between habitual physical performance and body composition indicators. With respect to mo-tor performance, it is not possible to consider these results decisive; therefore, further data collection and more accurate assessment of relationships are necessary.