###### Abstract  
Background: The issues raised in this study were inspired by the concern for the musculoskeletal status of school children. Carrying excess weight in the form of a school bag in this period of life affects the correct body posture of school children. The aim of the study was to analyze the influence of school bags on the feet force distribution on the ground and postural balance in children of both sexes between 11 and 15 years of age. Methods: The study investigated the distribution of pressure forces on the sole of the foot and its arch. The center of pressure for both feet and the whole body was also examined. The participants were 100 students from primary schools in Gdarsk, aged 11 to 15, including 54 girls and 46 boys. The research used a podobarographic platform that measures the distribution of foot pressure to the ground. The examinations included two measurements: in the first, the children stood on the platform in a natural position. Then, a 5 kg backpack was put on and they stood on the platform again. Results: Statistically significant differences were found in the distribution of the foot pressure on the ground in the left metatarasus (\(p\) = 0.000) and heel (\(p\) = 0.000) after putting on the backpack in both girls and boys. However, in the right foot, these differences concerned the metatararsal area (\(p\) = 0.001). The results of the balance tests were only statistically significant in the group of girls in the right foot sway area (\(p\) = 0.020). Conclusions: The school backpack load led to an increase in the values of the heel and metatararsal area measured in the students, causing its flattening.  
adolescent; teenagers; backpack; stability; overload; school Article  
Podiatric and Stabilographic Examinations of the Effects of School Bag Carrying in Children Aged 11 to 15 Years  
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groups, showed that despite different loads, there are statistically significant differences in the body posture in each group between the tests with and without loads [6]. There is ample evidence that wearing a backpack affects students' health. Research shows that the relationship between the student's body weight and the weight of his or her backpack is very often incorrect. It is not rare that the child's backpack is heavier than 10% of their body weight, which is the value recommended in the literature [5; 7; 8; 9]. As the load to the body increases, especially after exceeding the recommended backpack weight, significant kinematic changes in the ankle, knee, and hip joints are observed, both in children and adults. They affect both gait and pressure on the plantar side of the foot [10; 11]. The human foot is an important part of the musculoskeletal system that transfers both static and dynamic load. Its shape is different in every human being. Its structure and positioning have a great effect on gait quality and postural stability. A properly arched foot is flexible and prevents micro-injuries and shocks during locomotion. The correct shape of the foot depends on the efficiency of the muscles and ligaments and the structure of the osteoaircular system [12]. Wearing too heavy a backpack may cause increased strain on joints and problems with maintaining dynamic stability and balance [13]. Body balance is defined as the ability of the human body to maintain its position. Body balance is genetically determined and, at some stage of development, the ability to maintain balance is hampered by the fact that the brain already has a fully formed set of neurological connections. Similarly, motor skills are already shaped [14], for example, by developed movement patterns and habits developed in everyday life. The aim of this study was to analyze the influence of the backpack on the distribution of foot forces on the ground and body balance in children (boys and girls) aged 11 to 15 years.