The diploma thesis evaluates the morphology of the abdominal wall muscles focusing on the assessment of lateral symmetry in elite female floorball players and its relationship with the occurrence of back pain in these players. The theoretical part of the thesis includes an overview of the physiological mechanisms of postural stabilization in comparison with deviations in patients with back pain and describes the principles of sonographic examination and its use in physiotherapy. The theoretical part is also focused on the imagining of the abdominal muscles and the summary of specific findings in floorball players and other athletes, with a predominant one-sided load related to the biomechanics of movement in these sports. Methodology: A total of 20 female players of the highest floorball competition in the Czech Republic participated in this research. The linear parameters of the abdominal muscles (m. RA, m. TrA, m. OI and m. OE) and the whole lateral abdominal muscles were measured in players on both sides at rest using sonography. The participants also filled in an electronic questionnaire evaluating back pain. Results: Significant lateral asymmetry of linear parameters of abdominal muscles was demonstrated in the work (p = 0,017; d = 0,52). The relationship between the lateral asymmetry and the...