Modeling the mechanisms of readaptation of functional reserves in military personnel with musculoskeletal limb injuries during long-term rehabilitation

Purpose. To evaluate the effectiveness of experimental training models in promoting the readaptation of functional reserves in military personnel with musculoskeletal limb injuries after completing long-term rehabilitation under standard physical therapy protocols. Material & Methods. The study was conducted during the long-term rehabilitation of military personnel with musculoskeletal limb injuries from mine-blast trauma. A total of 64 individuals were examined. During both inpatient and outpatient 12-month rehabilitation, the study participants followed standard physical therapy protocols. Depending on their nosological profiles, study participants were divided into two groups: individuals with musculoskeletal injuries of the upper limbs (group 1) and of the lower limbs (group 2). These groups were further divided into subgroups based on the characteristics of their adaptive and compensatory responses to acute test loads. Heart rate variability (HRV) analysis was used to assess the baseline functional state of the study participants and to characterize readaptation processes across all stages of the study. HRV parameters were monitored at the beginning of the study and after three months of using the experimental training models aimed at readapting functional reserves. Results. After 12 months of long-term rehabilitation based on standard physical therapy protocols, 50% of the study participants exhibited an increase in central regulation of sinus rhythm at rest. At the same time, they showed the highest baseline tension within the cardiac rhythm regulation system. Furthermore, in response to test loads, 50% of the examined military personnel, regardless of nosology, showed an increase in the central regulatory contour of sinus rhythm accompanied by a simultaneous decrease in sympathetic and parasympathetic tone. Only 12.5% of military personnel with these nosologies, after completing long-term rehabilitation under standard protocols, demonstrated an increase in parasympathetic tone accompanied by a simultaneous reduction in VLF power in response to test load. The baseline tension of the cardiac rhythm regulation system decreased in 75% of participants after using three-month experimental training models for restoring functional reserves. In response to test loads, the autonomic balance of 50% of military personnel with musculoskeletal limb injuries shifted toward parasympathetic regulation, accompanied by a decrease in very low-frequency (VLF) power. Additionally, a weakening of vagal influence on the sinoatrial node was observed in 12.5% of the study participants, irrespective of their nosology, in response to the test load. However, this change did not enhance the central regulatory mechanisms. Conclusions. The majority of study participants with musculoskeletal limb injuries exhibited signs of adaptation failure in their resistance levels and functional reserves after 12 months of rehabilitation under standard protocols. In developing the rehabilitation models, a novel combination of core structural components was implemented, differing by approximately 90% from traditional physical therapy approaches. The findings revealed that after three months of using the experimental training models, 50% of study participants demonstrated increased parasympathetic activity in response to test loads, accompanied by a simultaneous weakening of the central regulatory contour. Such changes in HRV indices in response to the stimulus indicate the effective activation of mechanisms of short-term adaptation. The obtained results revealed one of the key factors underlying the low effectiveness of the neuromuscular system readaptation and functional reserves during long-term rehabilitation of military personnel with such nosologies