Physiological aspects of peripheral neuromuscular apparatus fatigue development and its diagnostics

Introduction. Diseases of the musculoskeletal system from functional overexertion in response to prolonged intense workload at the workplace, have so far occupied one of the leading places in occupational pathology. However, a number of questions regarding the diagnosis of fatigue of the peripheral neuromuscular apparatus, the conditions for its transition to overwork and overstrain require further study. In connection with the development of the concept of viscoelastic properties of skeletal muscles, it became possible to objectively assess the state of the peripheral link of the neuromuscular apparatus at different levels of fatigue, which makes it possible to clarify the mechanisms of the development of diseases of the musculoskeletal system from functional overstrain. The study aims to explore the dynamics of indicators of biomechanical and viscoelastic properties of skeletal muscles during the development of local muscle fatigue and to find out the possibility of using these indicators for an objective assessment of the state of fatigue of the musculoskeletal system. Results. A myotonometric study revealed an increase in the biomechanical properties of the muscles of the forearm — tone and stiffness and a decrease in the viscoelastic properties of creep and relaxation time, more pronounced during overwork. Changes in elasticity are less significant, since its parameters depend on the anatomical and structural properties of the muscle. A positive relationship was established between muscle strength measured by dynamometry and the tone and stiffness of wrist flexors obtained by myotonometry. Limitations. Limitations relate to the small sample of subjects. Conclusion. It was found that for the most objective assessment of muscle fatigue, a set of indicators was used, including the determination of muscle strength by the dynamometric method, tone, rigidity, creep and relaxation time according to myotonometry. The identified changes in the properties of muscle tissue not only expand our ideas about the development of fatigue but also clarify the mechanisms of the formation of diseases of the musculoskeletal system from functional overstrain. Ethics. This human subject study was conducted in compliance with the ethical principles presented in the latest version of the Declaration of Helsinki developed by the World Medical Association.