ABSTRACT
BACKGROUND: Problems associated with pain in several body regions due to work-related musculoskeletal disorders (WRMDs), repetitive movement and negative stress at work are quite common in many manufacturing industries of Latvia, int.al. clothing industry. The aim of this study was to evaluate efficiency of the psychotherapeutic intervention using medical hypnotherapy (MH) program for mind-body relaxation with pain-blocking imagery, cognitive restructuring of unpleasant physical and emotional experience. METHODS: 300 sewers and 50 cutters with chronic pain were involved in the study. Self-rated WRMDs symptoms, pain intensity and interference were assessed using the extended version of Nordic Musculoskeletal Questionnaire and Brief Pain Inventory Scale. Assessment of the functional state of muscles was carried out using myotonometric (MYO) measurements. Work heaviness degree was estimated via heart rate monitoring (HRM). The MH program was composed of cognitive hypnotherapy and self-hypnosis training. Sunnen Trance Scale was used to determine person's hypnotic susceptibility. Life quality assessment before and after MH program was carried out using Quality of Life Scale. RESULTS: At the beginning of MH program sessions both sewers and cutters reported on pain interference with general activities, mood, sleep, normal work, etc., but after MH the interference of pain significantly decreased. HRM data confirmed that work heaviness degree of sewers and cutters can be referred to as light and moderate work (energy expenditure for their tasks varies from 3.4 till 4.7 kcal/min). Using MYO measurements it was stated that before MH 22% of workers involved in the study fell under III MYO category indices, consequently, their muscle tone was increased, which is associated with muscular fatigue. After MH muscle tone remained within the normal range meaning that they were able to adapt to the existing workload (II MYO category) or fully relax (I MYO category). CONCLUSIONS: MH program including exercises-workouts, cognitive hypnotherapy and self-hypnosis training sessions is an effective method to decrease composite chronic pain intensity for sewers and cutters, as well as to decrease psychogenic tension and muscle fatigue (proved by objective measurements of muscles tone) and to increase the life quality.
ABSTRACT
OBJECTIVE: This research work is dedicated to occupational health problems caused by ergonomic risks. The research object was road building industry, where workers have to work very intensively, have long work hours, are working in forced/constrained work postures and overstrain during the work specific parts of their bodies. The aim of this study was to evaluate the work heaviness degree and to estimate the muscle fatigue of workers after one week work cycle. The study group consisted of 10 road construction and maintenance workers and 10 pavers aged between 20 and 60 years. METHODS: Physical load were analyzed by measuring heart rate (HR), work postures (OWAS) and perceived exertion (RPE). Assessments of the muscles strain and functional state (tone) were carried out using myotonometric (MYO) measurements. The reliability of the statistical processing of heart rate monitoring and myotonometry data was determined using correlating analysis. RESULTS: This study showed that that road construction and repairing works should be considered as a hard work according to average metabolic energy consumption 8.1 +/- 1.5 kcal/min; paving, in its turn, was a moderately hard work according to 7.2 +/- 1.1 kcal/min. Several muscle tone levels were identified allowing subdivision of workers into three conditional categories basing on muscle tone and fatigue: I--absolute muscle relaxation and ability to relax; II--a state of equilibrium, when muscles are able to adapt to the work load and are partly able to relax; and III--muscle fatigue and increased tone. It was also found out that the increase of muscle tone and fatigue mainly depend on workers physical preparedness and length of service, and less on their age. CONCLUSION: We have concluded that a complex ergonomic analysis consisting of heart rate monitoring, assessment of compulsive working postures and myotonometry is appropriate to assess the work heaviness degree and can provide prognosis of occupational pathology or work-related musculoskeletal disorders for the workers under different workload conditions. These results can also be used when deciding on necessary rest time and its periodicity.
