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Physical and psychological work demands as potential risk factors for musculoskeletal disorders among workers in weaving operations Abstract Aim: The study was undertaken to examine the relationship between perceived physical and psychological work demands and self reported musculoskeletal disorders (MSDs) among workers involved in weaving operations. Method: The Nordic Musculoskeletal Disorders Questionnaire and Work Demands Scale, developed and standardized for the present investigation were the tools for data collection. Chi square test was used to assess univariate associations between work demands and reported MSDs. Multiple logistic regression analysis was performed for each of the outcome MSD retaining the variables in the model to adjust for potential confounding. Results: Women were significantly more affected than men in shoulders, wrists/hands, upper back, lower back, and ankle/feet. Perceived physical and psychological demands were significantly associated with MSDs of different body regions. Pulling, pushing, moving, lifting and lowering heavy objects, working while bent or twisted at the waist, and repetitive motions with hands/wrists were the main physical factors retained in the regression models with odds ratios greater than 2. Conflicting demands, work is not remunerative, and no sufficient time to get the job done were the main psychological factors retained in the regression models with odds ratios greater than 1.68. Gender was found to be a significant factor for shoulders, wrists/hands, lower back, and ankles/feet with odds ratios ranging from 1.71 to 2.14. MSDs occurrence was more probable in the mentioned regions among women as compared to men. Both physical and psychological work demands in the work environment were contributing factors for developing MSDs among workers involved in weaving operations. INTRODUCTION Indian weaving industry has traditionally been one of India's thriving sectors of mass employment. The weaving industry of India provides employment to approximately 12.5 million people, thereby, making this industry the largest provider of rural workforce.[1] Over 3,800,000 weaving industries have been built throughout India, Andhra Pradesh houses some 3,20000 weaving industries. Abundant raw materials and an unlimited supply of cheap labor have contributed to the success of weaving industry.[2] The weaving industry is supporting some 32 other sectors that include marketing, financial, transportation, hotels, and even maintenance.[3] The weaving industry in India has self-depending mechanism that includes training the young weavers, abundance of resources and capacities, thereby, helping the industry not to be dependent on the government. The manufacturing of the weaving products makes a remarkable contribution to the national GDP and even in the exports revenue. It is estimated that the Indian weaving industry would grow by 25% to over 35 million tons by the year 2013.[1] The total weaving process encompass a wide range of tasks such as manual sorting of raw materials, carding and spinning in cord machine, dyeing by acid, and chrome dyes proceeding the actual weaving. In weaving operations, workers are exposed to dust. The job demands high attention in making designs. Fibers are boiled in a vat containing acetic acid and dye solution, washed in running water and dried, and spindles are made out of fibers. The post-weaving operations involve materials woven to clipped, embossed and carved into art designs, mending, edge bending, and finally a chemical wash being given to get finished product. Due to repetitive movements, awkward postures involved, and the nature of work demands; pre- and post-weaving activities and the actual weaving are high risk operations for developing musculoskeletal disorders (MSDs). In the weaving industry, the weavers do the main job of weaving. Apart from weavers; majority of men, women, and children are involved in post- and pre-weaving operations. Weaving is one of the most tedious profession requiring long hours of static work.[4] In spite of national importance of weaving industry, and its impact on overall economy of the country, there have been few ergonomic studies of weavers work. Research has not focused on understanding the occupational risk factors in pre- and post-weaving operations. The present study was therefore conducted among workers involved in pre- and post-weaving operations. The main aim of the study was to elicit the role of physical and psychological work demands as risk factors for developing musculoskeletal symptoms in workers involved in weaving operations. The objectives of the study are to (i) determine the prevalence rate of musculoskeletal symptoms among workers involved in weaving operations, (ii) identify major factors associated with musculoskeletal symptoms in the study population, and (iii) examine the relationship between perceived physical and psychological work demands and musculoskeletal symptoms experienced in nine anatomical body regions viz., neck, shoulder, elbow, wrist/hand, upper back, lower back, hips/thighs, knees, and ankles/feet taking into consideration the impact of other potential confounding variables. MATERIALS AND METHODS The descriptive research design and interview method of data collection were adopted. Three hundred and seventy-five male and female members involved in various weaving operations with weaving as the only main occupation were selected as the sample for the investigation. Variables and their measurement Musculoskeletal symptoms in nine anatomical body regions were the dependent variable of the study. Work-related MSDs occur when there is a mismatch between the physical requirements of work and the physical capacity of human body. These are a group of painful disorders of muscles, tendons, and nerves.[5] Physical work demands like bending, lifting heavy loads, gripping, twisting, kneeling, pushing and pulling heavy objects, and working in awkward postures form a part of weaving activities. When these kinds of operations are involved in the work and the workers carry out the work for a long period, the chances of developing MSDs are more. Nordic Questionnaire of Musculoskeletal Symptoms was used to examine the reported cases of MSDs among the study population.[6] The independent variables of the study were grouped as personal variables and perceived physical and psychological work demands. The personal variables consisted of age, gender, weight, height, body mass index (BMI), marital status, having children, years of employment, daily working time, and work schedule. BMI is calculated by using the Quetelet's BMI formula.[7] BMI = person's weight in kilograms (kg) divided by his or her height in meters squared (kg/m2 ). The physical and psychological work demands of workers involved in weaving operations were identified through focus group discussion, in-depth interviews, and observation by researcher; while the workers are on job. The 12 physical work demands identified were demands for physical effort, continuous physical activity throughout the day, moving or lifting heavy loads, working for long hours with the head or arms in awkward positions, working for long period with the body in awkward positions, lifting or lowering objects to or from floor, lifting or lowering objects to or from height, working while bent or twisted at waist, pushing or pulling heavy objects, standing in one place or static position for more than 30 min, performing repetitive motions with hands or wrist continuously for more than 30 min, and applying pressure with arms or hands or fingers. The eight psychological work demands identified were work is strenuous, work is monotonous, excessive amount of work, long periods of intensive concentration on the task, not sufficient time to get the work done, conflicting demands on self, work takes long time to complete, and work is not remunerative. A scale was developed to measure the perceived physical and psychological work demands. Twelve physical work demands identified were adopted to measure the physical work demands. Each item was scored based on a four-point scale from strongly agree to strongly disagree. The scores on physical work demands scale ranged between 12 and 48. The responses were categorized as low (12-24), medium (24-36), and high (36-48) physical demands at work. Eight psychological work demands identified were considered to measure psychological work demands. Each item was scored based on a four-point scale from strongly agree to strongly disagree. The scores on psychological work demands scale ranged between 8 and 32. The responses were categorized as low (8-20) and high (20-32) psychological demands at work. The reliability of the scale (0.92) was established by test-retest methodology. Data analysis Statistical analyses were performed. Chi-square tests were used to assess univariate association between independent variables and reported musculoskeletal symptoms. Multiple logistic regression analysis was performed for each of outcome retaining the variables (individual and perceived physical and psychological work demands) in the models to adjust for potential confounding. In the regression analysis, if the P value of Chi-square test for assessing association between the variables and reported symptoms was ≤0.25, the variable was included in the regression model of that region (inclusion criteria).[8] For each body region, this procedure was performed for all individual and perceived physical and psychological work demands variables. RESULTS General profile of study sample Gender The sample consisted of 126 male and 249 female workers involved in weaving-related activities. Age The age of the sample ranged between 19 and 62 years with a mean of 31.54 and standard deviation (SD) of 8.46. The mean age of female respondents was 30.20 and male respondents was 34.16. Comparatively women at an younger age were found involved in weaving operations. Weight The mean body weight of the sample was 63.09 kg with a SD of 11.81. Men were heavier with a mean body weight of 72.79 kg than women (58.08 kg). The body weight of men and women ranged between 51 and 95 kg and 40 and 98 kg, respectively. Height The mean height of the sample was 165.94 cm with a SD of 8.48. Mean height of the women (161.93 cm) was slightly less than the sample average and in case of men (173.57 cm) it was slightly more than the sample average. BMI The mean BMI of the study sample (men 24.18 kg/m2 and women 22.11 kg/m2 ) was 22.83 kg/m2 with a SD of 3.35. The BMI scores can be interpreted as underweight (≤18.5), normal weight (18.50-24.90), overweight (25.0-29.9), and obese (≥30.0).[9] The men and women working in weaving industry were in the category of normal weight. Marital status Majority of men were married (80.2%) and only 51% of women were married. Majority of women before marriage at a young age were involved in weaving operations. Having children Thirty percent of women and 58% of men were having children. From the distribution of sample based on age, marital status, and having children; it was understood that compared to men, women at an younger age before marriage were taking up works related to weaving. Duration of employment The duration of employment ranged from 1 to 35 years. The mean duration of employment for women was 7.41 years (SD 7.03) and in case of men it was 11.19 years (SD 8.36). Daily working time Mean number of daily working hours was 10.4 hours. Working hours in a day was more in case of men (11.33 hours) than women (9.90 hours). Men and women in weaving industry start the work very early and continue to work till late hours. Women were found taking breaks in between for attending household work. Working schedule A gap of more than 20 min while on work was considered as a break. Rest periods below 20 min were not considered as breaks. The workers were working continuously from morning 8 am to 10 pm in the night. Out of the total sample, majority (85.5%) were working continuously with less than 30 min break. Only 14.5% were taking 2 hours break in two to three spells in a day. Prevalence of musculoskeletal symptoms in different body regions The prevalence of MSD symptoms in different body regions of the workers in weaving operations during the last 12 months are presented in Table 1. The most commonly affected regions among workers in weaving operations were lower back (60.6%), ankles/feet (59.0%), knee (58.1%), and upper back (54.6%). Women were significantly more affected than men in shoulders, wrists/hands, upper back, lower back, and ankles/feet (P < 0.05). During the preceding year, due to musculoskeletal problems, 38.5% of the respondents had to visit a physician, 25.1%of the workers took medical rest, and 18.8% of them needed to use medicines continuously. Table 1 Frequency of prevalence of musculoskeletal symptoms in different body regions of male and female workers in weaving during the 12 months prior to the study Factors associated with musculoskeletal symptoms for each body region The significant factors for each body region are the result of a multiple logistic regression analysis performed to adjust for potential confounding. Some items of perceived physical as well as psychological demands were significantly associated with reported musculoskeletal symptoms of different body regions [Table 2]. Pulling, pushing, moving, lifting and lowering heavy objects, working while bent or twisted at the waist, and repetitive motions with hands/wrists were the main physical factors retained in the regression models with odds ratios generally greater than 2. Conflicting demands, work is not remunerative, and not sufficient time to get the job done were the main psychological factors retained in the regression models with odds ratios generally greater than 1.68. Table 2 Models indicating factors with the strongest influence on musculoskeletal symptoms in different body regions of workers in weaving operations Among all factors included in the regression models, the mentioned physical and psychological work demands had noticeable association with reported symptoms in different body regions. Gender and BMI were the only demographic factors retained in the regression models. Gender was found to be a significant factor for shoulders, wrists/hands, lower back and ankles/feet with odds ratios ranging from 1.71 to 2.14. It meant that musculoskeletal symptoms occurrence was more probable in the mentioned regions among women (66.4%) as compared to men (33.6%). BMI was a significant factor for lower back problems with odds ratio equal to 2.12. Continuous working was also found to be associated with musculoskeletal problems in neck, upper back, and knee regions with odds ratio ranging from 2.29 to 3.38. Physical and psychological work demands as risk factors for MSDs The association between the level of perceived physical and psychological work demands and perceived musculoskeletal symptoms in different body regions of the sample are presented in Table 3. Since the number of respondents categorized in low perceived physical demands level was small, to perform meaningful statistical analysis, the low and the medium physical demands levels were combined to form a low-medium physical demands level. In total population, the prevalence of symptoms in all body regions except the lower back and the neck were significantly higher in the group who perceived high level physical demands (P < 0.05), indicating the association between high perceived physical demands and the prevalence of musculoskeletal symptoms. Regarding psychological demands, the same result was obtained, showing that in all body regions; except for the neck, the prevalence of musculoskeletal symptoms were significantly higher in the group who perceived high psychological demands (P < 0.05). This indicated association between high perceived psychological demands and the prevalence of musculoskeletal symptoms. Similar results were obtained for female workers. This meant that in most body regions the prevalence of musculoskeletal symptoms were more among the respondents who perceived high physical and psychological work demands as compared to that of the other group. Among male workers, although in some body regions the prevalence of musculoskeletal symptoms was significantly higher among the group who perceived high work demands, but it was not the case for most regions. Table 3 Frequency of reported symptoms in different body regions of the male and female workers in weaving operations during the last 12 months prior to the study DISCUSSION Prevalence of musculoskeletal symptoms A vast majority of the study population had experienced some form of MSDs during the past 12 months. Lower back symptoms (60.6%), symptoms in ankle/feet (59.0%), knees (58.1%), and upper back (54.6%) were the most prevalent problem. Reports from Thailand[10] and India[1112] confirm the prevalence of MSDs among weavers. Forced back bent sitting work posture due to workspace constraints and informal workstation, high muscle exertion, and repetitive movement of body parts might be attributed to high prevalence of musculoskeletal symptoms in the present study. Females reported higher incidence of back pain in comparison to males in the study and the same has been reported by other researchers.[1314] Weaving activities involve repetitive work, causing strain on the musculoskeletal system increasing the likelihood of fatigue and decreasing the opportunity for tissue to recover leading to pain and discomfort.[15] Standing for long hours influence center of pressure points of the body and lumbar extensor muscle fatigue.[16] Demographic factors and musculoskeletal symptoms Gender was a significant factor retained in the models for shoulders, wrists/hands, lower back, and ankles/feet with odds ratios ranging from 1.71 to 2.14. This indicated that the chance of MSDs occurring in the above mentioned regions among females was more likely than males. This is in agreement with the findings of Choobineh et al.[17] BMI was also a significant factor for lower back problems with odds ratio equaled to 2.12. This meant that among those with abnormal BMI (BMI < 18.5 or BMI > 26), the chance of musculoskeletal problems occurring in the lower back region was nearly twice more likely than among the subjects with a normal BMI. Although age was found to be a significant factor for wrists/hands symptoms in χ2 test, but it was not retained in the regression model of this region. It could be inferred that age was a confounding variable for this region which was omitted from the model in regression analysis. There was no association between working hours or job tenure and prevalence of MSDs. This is in accord with Bos et al.[18] Continuous working was also a significant factor retained in the regression models of neck, upper back, and knees regions; which increased the chance of MSD occurrence nearly two to three times higher among workers in weaving operations. Physical and psychological work demands as associated factors for musculoskeletal symptoms Among the perceived physical demands investigated in this study, activities including pulling/pushing heavy objects, moving/lifting/lowering heavy loads, repetitive motions with hands/wrists, and bent or twisted posture of the trunk, were significantly associated with musculoskeletal symptoms in different body regions. The results revealed that the level of perceived physical demands had significant influence on MSD symptoms occurrence among both men and women; however, the body regions influenced were not the same in both genders (i.e. hip/thigh, knees, and ankles/feet among men and shoulders, elbows, wrists/hands, and knees among women). Women were more susceptible to psychological demands than men. The psychological factors including conflicting demands, the work is not remunerative and not sufficient time to get the job done were significantly associated with musculoskeletal symptoms in different body regions and retained in the regression models. Bongers et al.,[19] in an extensive review on the role of psychosocial factors in the development of musculoskeletal symptoms found that in the majority of the studies reviewed an association between psychosocial factors and upper extremity symptoms had been reported. High perceived workload, time pressure, low control on the job, and poor social support was among those factors consistently associated with these disorders in many studies.[19] In the present study, no psychological factor was retained in the neck and the elbows regression models, but for shoulders and wrists/hands, conflicting demands, and work is not remunerative remained in the regression models, respectively, with noticeable odds ratios showing the influence of these psychological factors on adverse symptoms of these two body regions, which was in agreement with the report of Bongers et al.[19] In the hip/thigh, knees, and ankles/feet regression models the psychological factor work is not remunerative remained in the regression model. In case of upper back regression model, the psychological factor not sufficient time to get the job done remained in the regression model. The results are also similar to those of Italian X-ray technologists study in which psychological workload was found to be associated with occurrence of MSD.[20] In conclusion, the results of this study highlighted the importance of perceived, physical, and psychological demands in relation to reported musculoskeletal symptoms in different body regions. Among the perceived physical demands studied here, those involving manual material handling, were most frequently and strongly associated with reported musculoskeletal symptoms in nearly all body regions. Any interventional program for preventing or reducing musculoskeletal problems should focus particularly on reducing excessive manual material handling demands as well as the psychological aspects of the working environment. Source of Support: Office of Consortia Principle Investigator, National Innovation Project on Value Chain in Natural dyes funded by Indian Council of Agricultural Research, New Delhi Conflict of Interest: None declared.