Working practices in a perchery system, using the OVAKO Working posture Analysing System (OWAS)

Forces: A Motion Capture-Based Ergonomic Method for the Today's World

Approximately three of every five workers are affected by musculoskeletal disorders, especially in production environments. In this regard, workstation ergonomic evaluations are especially beneficial for conducting preventive actions. Nevertheless, today's context demonstrates that traditional ergonomic methods should lead to smart ergonomic methods. This document introduces the Forces ergonomic method, designed considering the possibilities of inertial motion capture technology and its applicability to evaluating actual workstations. This method calculates the joint risks for each posture and provides the total risk for the assessed workstation. In this calculation, Forces uses postural measurement and a kinetic estimation of all forces and torques that the joints support during movement. This paper details the method's fundamentals to achieve structural validity, demonstrating that all parts that compose it are logical and well-founded. This method aims to aid prevention technicians in focusing on what matters: making decisions to improve workers' health. Likewise, it aims to answer the current industry needs and reduce musculoskeletal disorders caused by repetitive tasks and lower the social, economic, and productivity losses that such disorders entail.

Classification of Whole-Body Postural Discomfort Using Cluster Analysis

The objectives of this study were to evaluate the effect of gender and postures of the neck, trunk, and knee on overall postural discomfort, and to classify combined postures into different postural discomfort groups. A total of 95 participants (42 males and 53 females) performed 45 different static postures, which were a combination of 3 neck angles, 5 trunk angles, and 3 knee angles, and rated the perceived postural discomfort. Non-hierarchical K-means cluster analysis was employed to classify the 45 different combined postures into several postural discomfort groups. Postural discomfort was significantly affected by gender and postures of the neck, trunk, and knee (p < 0.001). Three clusters (high, medium, and low discomfort) were identified and the postural discomfort was significantly different between clusters (p < 0.001). The high discomfort group consisted of mostly males with high knee and trunk flexion angles and a moderate neck flexion angle. The low discomfort group was female-dominant with low neck and trunk flexion angles and a moderate knee flexion angle. The different flexibility (stiffness) of the joint motions between genders may affect the gender difference in postural discomfort. The knee and trunk postures were critical to the postural balance, which may affect the perception of whole-body discomfort. This result will be useful for developing and improving postural observation tools.

Preventive factors against work-related musculoskeletal disorders: narrative review

Musculoskeletal disorders (MSDs) are major causes of morbidity among workers. They comprise several signs and symptoms, as e.g. pain, paresthesia, fatigue and limited range of motion, which can be related to work tasks. Workplace-related factors include physical, psychological, social and biomechanical hazards. The main kinetic factors associated with MSDs include repetitive movements, exerting excessive force, awkward postures, compression and mechanical vibration. Accurate knowledge of epidemiological aspects, evaluation of ergonomic hazards and musculoskeletal symptoms, and workplace exercise may help reduce the occurrence of MSDs. The aim of the present review is to analyze the applicability of preventive strategies against MSDs among workers. We performed a narrative review based on a survey of databases PubMed and BIREME and included studies published in English, Spanish or Portuguese. We found that workplace exercise is beneficial for both employers and workers. Risk analysis of MSDs is essential for early identification of occupational hazards and to prevent health consequences and costs associated with absenteeism.

Musculoskeletal disorders: OWAS review

The prevention of musculoskeletal disorders (MSD) is very important in the world. Governments and companies are the most interested. The objective of the present work is to review the literature on the applications of the OWAS method in the diverse sectors or fields of knowledge and countries from its publication to March 2017. The use of OWAS method has been classified by categories of knowledge, by country and by year. The search was made by selecting only the main collection of the Web of Science. This was selected by the option "Advanced search" using the term OWAS (ts=OWAS) for the time period of 1900 to 2017. A total of 166 results were found, consisting of conference papers and articles in scientific journals. In conclusion, the OWAS has been applied mainly in two sectors: "Manufacturing industries" and "Healthcare and Social assistance activities". This method needs to be complemented with other indirect or direct methods. Also, whenever the OWAS has been used, whether individually or together with other methods, musculoskeletal disorders risks have been detected, this perhaps being an indicator to review the evaluation parameters because overestimating the risk.

Identification of awkward postures that cause discomfort to Liquid Petroleum Gas workers in Mumbai, India

Background:

Awkward, extreme and repetitive postures have been associated with work related musculoskeletal discomfort and injury to the lower back. Liquid Petroleum Gas (LPG) workers in India; that is the delivery men carry heavy cylinders on their shoulders and back. The cylinders come in commercial and residential form which range in weight from 14.2kgs, 16.2kgs, 19.2kgs, 32kgs, 40 kgs etc. They have a tedious schedule of 8 h/day and mostly associated with loading and unloading of the cylinders. Their job demands a high intensity of strength and power. They are exposed to high level of physical demands and relatively lesser amount of rest which makes them vulnerable to various injuries over a period of time.

Materials and Methods:

100 LPG workers (delivery men) were interviewed using the Ovako work assessment system OWAS posture code and action category system developed by ISMAIL et al.[10] was used. A battery of questions with specific stress was constructed and validated in the Department of Physiotherapy, Padmashree Dr D.Y Patil University, Nerul, Navi Mumbai, India.

Results:

This study presented an ergonomic assessment of LPG workers. The results show that the workers work in awkward postures. They transfer the cylinders in poor postures with high velocity and motion repetitiveness thus subjecting their spine to greater amounts of compressive forces. Regarding to work discomfort survey questionnaire, the postures cause ill effects on their various body segments. Among them 90% fall in category 4 while loading the cylinder, that is the load by those postures have a very harmful effect on musculoskeletal, system-corrective action for improvement required immediately. And while unloading 70% fall in category 3, which are postures that have harmful effect on musculoskeletal system. Corrective actions should be done as soon as possible. Majority of workers also complained of severe injury to back-34%, shoulder-20%, knee-20%, neck-16%, and toes-10%.

Conclusion:

These findings provide a prima facie evidence of higher occupational stresses among the LPG workers because of identified specific stressors prevalent in their jobs and explore the possible intervention strategies for its reduction.

Evaluation of upper-limb body postures based on the effects of back and shoulder flexion angles on subjective discomfort ratings, heart rates and muscle activities

A possible limitation of many ergonomics checklists that evaluate postures is an independent evaluation of each body segment without considering the coordination between body segments and resulting in the under-/over-estimation of body postures. A total of 20 men were selected to evaluate the effects of shoulder and back flexion angles on the upper-limb muscle activities, subjective discomforts and heart rates. Interesting findings were obtained from the coordination between back flexion angles and shoulder flexion angles. At a back flexion angle of 45°, the discomfort and heart rates were the least at a shoulder flexion angle of 45°. The %MVC also showed a similar trend. It could be inferred that the 0° shoulder flexion angle would be a natural posture, when the back flexion angle is 0°, whereas 45° shoulder flexion might be a more natural posture when the back flexion angle is 45°. STATEMENT OF RELEVANCE: This study evaluated the effects of back and shoulder flexion angles on subjective as well as objective measures. The findings of this study considered the coordination between two body flexion angles and could be used to improve the accuracy of existing ergonomics evaluation methods for body postures.

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.

Current techniques for assessing physical exposure to work-related musculoskeletal risks, with emphasis on posture-based methods

Physical exposure to risks for potential work-related musculoskeletal injuries has been assessed using a variety of methods, including pen and paper based observation methods, videotaping and computer-aided analysis, direct or instrumental techniques, and various approaches to self-report assessment. These methods are critically reviewed in this paper. The applications of these techniques in ergonomic and epidemiologic studies are considered, and their advantages and shortcomings are highlighted. Finally, a strategy that considers both the ergonomics experts' view and the practitioners' needs for developing a practical exposure assessment tool is then discussed.