Análise do sinal eletromiográfico, força e variabilidade da frequência cardíaca em cuidadores do SAD-HC/UFU, antes a após uma jornada de trabalho

Abstract

Introduction: The aging of the population along with the chronification of diseases has increased the demand for continued care, leading governments to rethink the health care model and thus reclaim the residence as a therapeutic environment for caring. Therefore, the caregiver has a fundamental role in the care process, becoming a link between the health team and the patient. The task of taking care of patients exposes the caregivers to physical, organizational and psychosocial risk factors that generate physical and mental overload, making them susceptible to the development of musculoskeletal disorders (low back pain), and/or diseases related to high levels of stress, which can lead to the inability of the caregiver and inability to keep taking care of the patients. Objectives: To analyze the electromyography signal and strength of the erector spinae muscles and the heart rate variability in caregivers of a Home Care Service, before and after a workday. Methods: Twenty-four caregivers (18 women and 6 men) with low back pain, who belong to a home care service at Hospital das Clínicas de Uberlândia, were selected for the study. Electromyographic data and erector spinae strength were collected from 3 maximal voluntary isometric contractions. For this, simple differential surface electrodes were used, with a gain of 20 times, and recorded by means of a computerized electromyography - EMG System do Brasil 830C. Heart Rate Variability (HRV) was collected using the POLAR® H10 strap with the caregiver at rest. All collections were performed in the morning and at the end of a working day, with an interval of 8 hours between them. For the normalization of electromyographic (RMS and F50) and strength (MVIC) data, the initial values (pre-workday) were considered as 100%. Two questionnaires, the Roland Morris Questionnaire (RMQ) and the Need for Rest Scale (ENEDE), were also used to assess, respectively, the caregiver's degree of disability and his/her need to recover from work. For data analysis, the computer program GraphPad Prism (version 8.4 – Graphpad Software, Inc) was used, and the level of significance was set at 5%. Results: Despite the significant increase in RMS after working hours, no significant declines were observed for the values of F50 and strength for the same moment (after working hours). The measurement of functional disability, based on the RMQ, revealed that only 20.8% of the individuals, all female, were classified as functionally disabled. Regarding HRV, a predominance of the sympathetic system (increased SNS and IEB) was observed to the detriment of the parasympathetic system, which confirmed physiological stress in this group. Finally, 45.83% of caregivers were identified with a greater number of symptoms of tiredness and a greater need to recover from work. Discussion: The fatigability of the spine muscles in isometric tests of women is lower when compared to men because the former has a relatively larger crosssectional area of type I fibers, resistant to fatigue (73.08% of the sample was composed of women). Also, the fact that caregivers are active in their work activities guarantees the preservation of their functional capacity and the maintenance of type I fibers. In addition, there may have been a redistribution of the activity of the posterior muscles of the spine, generating adaptive compensations at the time of the test, which could explain the results found for the F50 and strength. Finally, the numerous stressors related to the task of caring, and the accumulated fatigue experienced by caregivers due to repeated insufficient recoveries, increase the activity of the sympathetic system to the detriment of the parasympathetic system, which characterizes physiological stress, which, when maintained for a prolonged time, can be harmful to health, in addition to generating incapacity for work and compromising the quality of life. Conclusion: A significant increase in RMS values at the end of the workday was demonstrated, indicatingmuscular fatigue, despite the fact that the values of F50 and strength did not show a reduction in the same period. Furthermore, it was observed a significant increase in the stress index after the workday, followed by an increase in the SNS and a decrease in the PNS