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Background. The study deals with the mathematical modeling of the stress-strain state of the lumbar motion segments in the case of intervertebral disc herniations under different loads. Objective: to develop and analyze a mathematical model of the stress-strain state of the lumbar motion segments in the case of intervertebral disc herniations under different loads, to determine the patterns of stress and deformation distribution in the fibrous ring and the nucleus pulposus. Materials and methods. A basic mathematical finite element model of the human lumbar spine was developed, which contained the lumbar vertebrae, the sacrum, intervertebral discs and cartilages in the facet joints. Intervertebral discs were modeled from two elements — the annulus fibrosus and the nucleus pulposus. The stress-strain state after discectomy was studied: 1 — discs without damage (normal): 2 — damage to the L4-L5 disc; 3 — damage to the L5-S1 disc; 4 — combined damage to the L4-L5 and L5-S1 discs. The stress-strain state of the models was studied under the influence of a vertical compressive load of 350 N, as well as under the influence of an additional load of 250 N, which simulates the presence of a bulletproof vest, and 500 N, which simulates the full equipment of a fighter. On the caudal surface of the L5 disc, the model had a rigid fixation. Results. Defects in the annulus fibrosus of the intervertebral disc lead to a local increase in stresses in the nucleus pulposus of the damaged segment, regardless of the magnitude of the external load, localization or number of affected discs. Stresses in the nucleus pulposus may exceed physiological values by ≥ 20 times, which explains the mechanism of disc herniation. This allows us to highlight several key aspects. Localized defects in the annulus fibrosus cause critical increases in stresses in the nucleus pulposus, which is the main mechanism of herniation. Accurate mathematical modeling allows us to quantitatively assess the risks and effectively plan the choice of surgical intervention, including decompression and stabilization of segments. Further studies combining clinical observations and numerical modeling are necessary to clarify the mechanisms of load distribution in pathological conditions of the spine and to increase the safety of surgical techniques. Conclusions. Defects of the annulus fibrosus of the intervertebral disc lead to local changes in the stress-strain state, limited to the damaged segments. Even with increased load, the nature of stress distribution between the vertebrae remains stable and does not depend on the localization of the defects. Damage to the annulus fibrosus causes a moderate increase in stresses in the annulus (10–20 % depending on the area) and a significant increase in stresses in the nucleus pulposus — up to 20 times compared to physiological values. In multiple injuries of the intervertebral discs, the intersegmental effect remains minimal, and stresses are concentrated mainly in the area of the immediate defect.