摘要：Many scientists agree that the weight of the school bags is one of the most important factors that may affect the health and proper growth of the child, especially in elementary school. The aim of the research is to determine the effect of weight of school bags on the appearance of asymmetry of the lower extremities. Protocol research measured the vertical load Fz ground reaction upon contact with the ground at the foot simulated movements in the laboratory. Motions that child performes spontaneously in one school day were selected for simulation. The tests, involving the following movements, are: walking on a flat surface, walking up the stairs and walking down the stairs. Tests were carried out with and without the bag. For data collection, processing and analysis of signals, BTS was used, Elite system that contains a platform for measuring ground reaction force, manufacturers Kistler. To test statistically significant difference between limbs, Student's t-test for dependent variables with error inference of 0.05 (p As a right-handed, subject predominantly uses his right leg which is evident in the increased maximum force values in tests of walking on a flat surface and walking up the stairs. Conversely, in demanding test walking down the stairs maximum force is less than the maximum left, with and without bag. Research indicates that the application of external loads can lead to the asymmetry and differences between limbs, which can not be quantified by visual inspection. In particular, this difference between the right and left legs is visible in the most demanding test of a walk down the stairs with a bag, which recorded four differences that extend through all three main stages walk. In everyday life, these statistically significant differences may indicate a deficit of muscle strength, and with inadequate physical activity and reduced levels of physical activity, may be a potential cause of injury of the spine and musculoskeletal system of the child with the consequences that will follow him throughout life.
