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Physical Workload Analysis Among Small Industry Activities Using Postural Data.

Small industry workers are often involved in manual handling operations that require awkward body postures, therefore, musculoskeletal disorders and occupational injuries are a major problem. In this study, various types of tasks were recorded with a video camera to chart and analyze different postures by computerized OWAS (Ovako Working Posture Analysing System). Collected data showed that poor postures were adopted not only for lifting or hammering operation but also for other tasks; mostly with bent and twisted back. The main aim was to determine the physical workload by identifying harmful postures and to develop recommendations for improving the existing situation. Forty-eight male workers from eight different units (M age = 37 years) participated. The performed activities were then divided into 26 subtasks. Altogether, 1,534 postures were selected for analysis and then classified into different OAC (OWAS Action Categories). From all observations, unhealthy postures, for which corrective measures had to be considered immediately (i.e., 10.6% classified as OAC III, and 3.3% as OAC IV), were found. The applied method was useful in determining the physical workload by locating potential activities due to harmful postures, providing a detailed description with analysis, and suggesting successful means to reduce postural load.

OWAS↗

A Multilevel Approach to Manual Lifting in Manufacturing Industries.

Musculoskeletal injuries are often the consequences of wrong postural configurations used during Manual Materials Handling (MMH). This eventually leads to a large payout of worker's compensation and loss of production time. A simulated study of back injury risks has been carried out on seven selected manufacturing industries to identify and evaluate harmful working postures. For each MMH task, Ovako Working Posture Analyzing System (OWAS) codes have been identified with the help of motion study pictures. Also, Chaffin's biomechanical model was used to calculate L5/S1 load compression values on the spine during MMH activities. The multilevel approach adopted was a combination of OWAS and Chaffin's biomechanical model. The application of a digitizer enabled us to identify the coordinates and it made a subsequent evaluation of the angles of each body link possible.

OWAS↗

A survey of static and dynamic work postures of operating room staff.

Work in health care units is associated with considerable physical strain and many musculoskeletal complaints. Most investigations have concentrated on the work of general hospital nurses; little is known about the physical stress load on other health care workers. We therefore carried out an ergonomic study amongst operating room staff in order to (i) determine the work (posture) stress load on this particular group of health care workers and the effect of static posture on this stress, (ii) identify activities involving poor work postures, and (iii) determine differences between specialties in regard to work posture stress load. The work postures and related work activities of four different groups of staff in operating rooms (surgeons, assistant anaesthesists, instrumentation nurses and circulating nurses) were recorded and evaluated using the specified Ovako Working posture Analysing System (OWAS). Observation during the course of 18 daily surgical programmes (total number of observations: 3714) in the specialties general surgery and ear-nose-throat (ENT) surgery revealed that the work-load according to OWAS for circulating nurses and assistant anaesthesists was not harmful. Some work postures seen among instrumentation nurses and surgeons, however, need improvement. The work posture stress load in these groups is mainly due to the high prevalence of static work postures during the activities "surgery" (surgeons) and "assisting surgery" (instrumentation nurses). Significant differences in ergonomic stress load were observed between general surgeons and ENT surgeons. This survey in operating theatres relates work postures to basic activities and can be used as a starting point from which to improve work conditions in order to reduce or eliminate physical complaints among operating room staff.

Ergometry↗

Correcting working postures in industry: A practical method for analysis.

A practical method for identifying and evaluating poor working postures, ie, the Ovako Working Posture Analysing System (OWAS), is presented. The method consists of two parts. The first is an observational technique for evaluating working postures. It can be used by work-study engineers in their daily routine and it gives reliable results after a short training period. The second part of the method is a set of criteria for the redesign of working methods and places. The criteria are based on evaluations made by experienced workers and ergonomics experts. They take into consideration factors such as health and safety, but the main emphasis is placed on the discomfort caused by the working postures. The method has been extensively used in the steel company which participated in its development. Complete production lines have already been redesigned on the basis of information gathered from OWAS, the result being more comfortable workplaces as well as a positive effect on production quality.

Journal Article↗

Folding and unfolding manual wheelchairs: an ergonomic evaluation of health-care workers.

The objective of this study was to test the hypotheses (i) that health-care workers vary greatly in the methods used to fold and unfold selected manual wheelchairs, and (ii) that many of the methods used include bent and twisted back postures that are known to be associated with a high risk of injury. We studied 20 health-care workers in a rehabilitation center. Subjects folded and unfolded two wheelchairs of cross-brace design, one with and one without a sling seat. As outcome measures, we used a questionnaire, time taken, visual analog scales of perceived exertion and back strain, folded width, videotape and Ovako Working Posture Analysis System (OWAS) back scores (1-4). Subjects used up to 14 different combinations of approach, hand placement and back posture to accomplish the tasks. The mean OWAS scores were in the 2.4-3.1 range and 49 (42%) of the 118 scores recorded were class 4 (back simultaneously "bent and twisted", considered to be associated with the highest risk of injury). We also observed methods that appeared to be safe and effective. Age, gender, profession, experience and seat condition did not generally influence the outcome measures. We conclude that health-care workers use a variety of methods to fold and unfold wheelchairs, many of which include bent and twisted back postures that may carry a risk of injury. Further study is needed to confirm this risk, to identify more ergonomically sound wheelchair designs and to develop better methods of carrying out the common and important task of folding and unfolding wheelchairs.

Adult↗

Evaluation of low back pain risks in a beef skinning operation.

The low back pain risks in a beef skinning operation at a high stand kill floor workstation was evaluated. The increases in compressive forces at lower back (L5/S1) between normal slump (back angle 25 degrees, measured in the sagittal plane) and severe (45 degrees ) and between normal slump and very severe (70 degrees ) bent back postures were 387 N or 28% and 616 N or 45%, respectively. The high spine load coupled with high level of repetition can have a high probability of fatigue failure in the spine structural members. Non-neutral back posture for a large portion of the total work time can be a low back pain risk factor. The videotape analysis showed that the times involved during the task performance for the bent back (more than 25 degrees ) and severe bent back (more than 45 degrees ) were 48.4 and 33.5% of the total cycle time, respectively. The upper limit from OWAS (Ovako Working Posture Analysis System) for bent back posture is 30% of the total cycle time. The bent and twisted back posture (both more than 25 degrees ) time was 10.4% compared to OWAS limit of 5%. This indicated that actions are needed in the near future to alleviate the risk of low back pain. Ergonomics redesign of the workstation was recommended for the operation.

Biomechanical Phenomena↗

Objective assessment of aberrations induced by multifocal contact lenses in vivo.

PURPOSE: This study examined the effects of a soft multifocal progressive contact lens on individual Zernike coefficients describing the aberrations of the eye. METHODS: Ocular wavefront aberrations (OWA) of 10 subjects not wearing contact lenses were quantified using a Shack-Hartmann aberrometer and were repeated after lens insertion (two lenses,+2 diopters [D], and -2D distance power, order of insertion was randomized). All data were captured and stored on computer. Each coefficient of the Zernike polynomials representing, coma, spherical aberration (SA), and the fifth-order aberrations were evaluated for each OWA. Pupil size was monitored using an infrared device. RESULTS: After subjecting the data to various permutations, the following relationships and chief findings were detected: (1) Comparing coefficients with and without lenses, significant correlations for coma (Z(1)3 [rho,theta], P=0.0056; -2D and P=0.0399, +2D); SA (Z(0)4 [rho,theta], P=0.0006; -2D; and P=0.0061,+2D). Fifth-order aberration (Z(-1)5 [rho,theta], P= 0.0029,+2D). (2) With the -2D lens, the average root-mean-square (RMS) value for the SA coefficient Z(4)4 (rho,theta) and fifth-order Z(-3)5 (rho,theta) increased (P=0.045 and 0.0392, respectively). (3) With the +2D lens, the average RMS value for fifth-order coefficient Z(1)5(rho,theta) increased (P=0.0278). (4) Coma (Z(1)3 [rho,theta] coefficient) correlated with pupil size (P<0.05). Initial mean (+/-SD) pupil size (mm) was 3.05 (0.499), and this did not change significantly. CONCLUSIONS: Z(1)3(rho,theta) and Z(0)4(rho,theta) coefficients may be useful objective markers of success or failure for such contact lenses. The -2D lens had a more predictable effect on SA compared with the +2D lens design. The opposite occurs when considering the effects on the higher fifth-order order aberrations.

Contact Lenses, Hydrophilic↗

[Study on lifting-related musculoskeletal disorders among workers in metal processing].

OBJECTIVE: To investigate lifting-related musculoskeletal disorders in metal processing, to analyze the risk factors, and to study the validity and feasibility of using NIOSH lifting equation in China. METHODS: The questionnaires of semi-structured interview, the Ovako Working Posture Analysing System (OWAS) postural analysis and variables of the NIOSH equation were applied to the study. The study population consisted of 69 workers mainly involved in manual materials handling (MMH), categorized as Job A; and 51 machinery workers, served as controls, that were less MMH task involved, as Job B. RESULTS: The prevalence of low back pain (LBP), which was defined at least one episode lasting for more than 24 hours in the past 12 months, were 63.8% and 37.3% for Job A and Job B, respectively. However, the prevalence of LBP lasting for more than a week due to lifting were 26.09% and 5.88% for Job A and B, respectively. The proportion of awkward back postures were found higher in Job A than that of Job B (66% vs 63%, P < 0.05). The NIOSH Lifting Index (LI) was estimated to be 2.4 for Job A, and 0 < LI < 1 for Job B. The analysis of multiple regressions revealed that the repetitiveness of lifting and length of service had greatly attributed to the occurrence of LBP. The "composite load" (object weight x activity repetitiveness) had a significant adverse effect on lower back meaning that the objective weight remains an ingredient part of the risk. CONCLUSION: The occurrence of LBP is not only related to the force load, but the repetitiveness of lifting and awkward postures. The method of OWAS observation and US-NIOSH equation are important tools in assessing characteristics and risk factors of LBP for MMH tasks. Further study aimed at developing an integral scheme for the assessment system is needed.

Adult↗

Ergonomic analysis of working posture in nursing personnel: example of modified Ovako Working Analysis System application.

A postural analysis system was developed using a biomechanical approach to identify low back pain related working postures of nursing personnel. The Ovako Working Analysis System (OWAS) was modified for doing postural recording. Chaffin's biomechanical model was used to calculate the associated work stress on the L5/S1. The system was applied to examine the working postures of 64 nurses of 16 departments. The frequency distribution of the trunk showed 15.9% of the 8,629 observed postures were bending more than 15 degrees. Based on the calculated stress, 17.0% of the observed postures generated forces higher than the recommended action limit of the National Institute for Occupational Safety and Health (NIOSH). In addition to patient transfers, potentially health hazardous postures were identified in nursing tasks of inspection, nursing techniques, instrumentation, physical examination, taking inventory, and documentation.

Adult↗

The effects of an ergonomic-educational course. Postural load, perceived physical exertion, and biomechanical errors in nursing.

OBJECTIVES: To evaluate the results of an ergonomic-educational course for nurses we assessed the number and percentage of harmful postures and of ergonomic and biomechanical errors made before and after the course. We also studied the perceived physical exertion. MEANS AND METHODS: In all, 12 nurses who had participated in the course (trainees) and 12 who had not (controls) were recorded on video while performing standardized nursing tasks. The wards from which the two groups of nurses came were comparable, as were the patient populations. The nurses were also comparable in some personal characteristics. The tasks they performed included washing, lifting, and repositioning a patient as well as certain tasks other than patient handling. Video recordings were made once before (1-2 weeks) and twice after the course (after 3 months and after 15 months). The harmful postures, the errors made, and the ratings of perceived exertion were measured by means of the Ovako Working-posture Analysis System (OWAS), a checklist, and Borg scores, respectively. RESULTS: When the first and last measurements of all the above tasks taken as a whole were analyzed the trainees showed a significant improvement in the number and percentage of harmful postures and errors, whereas the controls did not. The same could be concluded for lifting alone. After the course the new work routine did not appear to have caused any extra perceived physical exertion. CONCLUSION: It can be concluded that the course was successful, although it should be carefully investigated as to whether nurses remain capable of working safely in daily practice. The work pressure that nurses experience during their normal duties could prevent them from working safely during everyday work.

Adult↗

Packing products for customers: an ergonomics evaluation of three supermarket checkouts.

The introduction of laser scanners at supermarket checkout areas has resulted in previous ergonomics studies focusing specifically on the scanning process and associated cumulative trauma disorders in the hands and arms. Few studies have evaluated the increased musculoskeletal load and exertion of checkout staff when they are also expected to pack the products into bags for the customers. This paper describes an ergonomics evaluation of three different designs of checkout workstation, which require the operator to stand when they scan the products, pack them into plastic bags and transfer the packed bags to the customer. Musculoskeletal load and exertion associated with the different checkouts were measured using OWAS, heart rate recordings and ratings of perceived exertion. In addition, subjective rankings of the workstations were obtained and the productivity associated with each design examined as part of the evaluation. Some of the variables measured showed significant differences in postural load between the workstations. The results of the evaluation formed the basis of recommendations for an improved workstation design. Some of the suggestions made to reduce postural load and increase productivity include positioning the weigh scale to the side and the bag frame beneath the scanner.

Journal Article↗

Reduction of farmers' postural load during occupationally oriented medical rehabilitation.

Farmers' back problems may be associated with the amount of back flexion and the handling of heavy loads. The aim of this study was to analyse the effects of occupationally oriented medical rehabilitation courses on female farmers' postural load. Twenty seven female farmers (aged from 32 to 52 years) took part in four rehabilitation courses at one rehabilitation centre in Finland. The subjects suffered from various musculoskeletal symptoms, which decreased their work ability. The rehabilitation courses included two periods: the first lasted for 3 weeks and the latter for 1 week, organized 6 months after the first period. The work postures and their load on the musculoskeletal system were classified by the computerized OWAS method in three daily work phases. During the 3-week periods new work techniques were learned, and simultaneous bent and twisted postures for the back decreased from 34 to 4% of all studied work postures. Similarly, postures with one or both arms above shoulder level were reduced from 44 to 24%. Rechecking after the 6-month period confirmed that the adoption of new work techniques was consistent. The study showed that female farmers could change their work techniques during this kind of intensive rehabilitation period, and the changes were seen 6 months later in the follow-up.

Journal Article↗

PATH: a work sampling-based approach to ergonomic job analysis for construction and other non-repetitive work.

A high prevalence and incidence of work-related musculoskeletal disorders have been reported in construction work. Unlike industrial production-line activity, construction work, as well as work in many other occupations (e.g. agriculture, mining), is non-repetitive in nature; job tasks are non-cyclic, or consist of long or irregular cycles. PATH (Posture, Activity, Tools and Handling), a work sampling-based approach, was developed to characterize the ergonomic hazards of construction and other non-repetitive work. The posture codes in the PATH method are based on the Ovako Work Posture Analysing System (OWAS), with other codes included for describing worker activity, tool use, loads handled and grasp type. For heavy highway construction, observations are stratified by construction stage and operation, using a taxonomy developed specifically for this purpose. Observers can code the physical characteristics of the job reliably after about 30 h of training. A pilot study of six construction laborers during four road construction operations suggests that laborers spend large proportions of time in nonneutral trunk postures and spend approximately 20% of their time performing manual material handling tasks. These results demonstrate how the PATH method can be used to identify specific construction operations and tasks that are ergonomically hazardous.

Journal Article↗

Postural analysis of nursing work.

Back pain in the nursing profession is an acknowledged wide spread occupational hazard. This study used OWAS (Ovako Working posture Analysis System) to measure the severity of the working postures adopted by nurses on Care of the Elderly wards when carrying out manual handling operations for animate and inanimate loads. Twenty-six nurses were observed on 31 occasions to obtain 4299 observations, these data were collected and processed using the OWASCO and OWASAN programs, and then analysed by grouping the results into defined patient (animate) handling and non-patient (inanimate) handling tasks. A statistical comparison was made between the two groups using the percentage of action categories two, three and four, to the total number of action categories. A significant difference (p < 0.05) was found, demonstrating that the percentage of harmful postures adopted during patient handling tasks was significantly higher than during non-patient handling tasks. This high level of postural stress and the poor track record of risk management within the Health Care Industry leads to the recommendation that an attitudinal change is needed to successfully address and reduce the manual handling burden which is currently being carried by the nursing staff.

Journal Article↗

Manual handling risks and controls in a soft drinks distribution centre.

This paper describes an investigation into manual handling risks and controls within a soft drinks distribution centre, presented as a case study regarding compliance with the requirements of the Manual Handling Operations Regulations 1992. Methods used included semi-structured interviews, document analysis, analysis of training, OWAS postural analysis and use of the NIOSH equation. Warehouse operators and delivery drivers were studied, and two methods of work compared involving pallets and cages. Significant differences were found between the two work methods with respect to harmful postures. Manual handling risks were found in both warehouse and delivery areas, some being classed as "excessive" using the NIOSH equation. As this company has a good safety record and considers itself proactive in the area of health and safety, the investigation raises concerns about how organisations have responded to the Manual Handling Operations Regulations.

Biomechanical Phenomena↗

Postural discomfort and perceived exertion in standardized box-holding postures.

To help in the design or redesign of workplaces it would be helpful to know in advance the postural stress consequences of a wide range of body postures. This experiment evaluated 168 postures chosen to represent those in the Ovako Working-posture Analysing System (OWAS) using Rated Perceived Exertion (RPE) and Body Part Discomfort (BPD) measures. The postures comprised all combinations of three arm postures, four back postures, seven leg postures and two forces (weights of held boxes). Twelve male subjects held each posture for a fixed duration (20 s) before providing RPE and BPD ratings. Analysis of the ratings gave highly significant main effects, with the major driver being the object weight. As each factor was varied, the largest effect was on the body region corresponding to that factor. A simple main-effects-only additive model explained 91% of the variance of RPE means for the postures.

Adult↗

Physical workload of ambulance assistants.

The physical workload of ambulance assistants was assessed by means of the Ovako Working posture Analysis System (OWAS) observation method and a Work and Health Questionnaire (WHQ) for measuring perceived workload. In addition, a biomechanical model was applied to several specifically strenuous conditions that were simulated in a laboratory situation. Bad postures were identified for a number of activities: 16% to 29% of a work shift was spent in harmful positions. Strenuous situations occur particularly during rides in emergency situations. The results of observed and perceived workload are generally in agreement. A number of practical recommendations are made. They concern, for example, the equipment in ambulance cars, training of ambulance assistants and adaptations in working procedures.

Ambulances↗

Assessment of Physical Load at Work Sites: A Finnish-German Concept.

The aim of this article is to introduce a set of work physiology methods for the assessment of physical load at the work site and to consider (a) their relevance for different types of muscular work, and (b) their feasibility for occupational health and safety practitioners. The results of an ergonomic intervention study for the reduction of workload associated with various manual materials handling tasks were used for the evaluation of the feasibility and sensitivity of the measurements of heart rate, the Edholm and OWAS methods, and the ratings of overall and local perceived exertion. The methods proved feasible, although time consuming, and their sensitivity for the quantification of small changes in physical workload was limited. Despite these shortcomings, these methods can be used by occupational health and safety practitioners when their strategy and data collection techniques are developed further. In conclusion, there are relevant and feasible methods fora reliable work-site assessment of cardiorespiratory and postural load related to the activation of large muscle masses. On the other hand, field methods for the quantification of local static workload and repetitive type of workload with small muscle masses are scarce.

ergonomics↗