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.

Introduction

Definition and standards

Musculoskeletal disorders (MSD) extend to almost all occupations and sectors, bearing critical physical and economic consequences for the sufferer: workers, families, businesses, and governments. These ailments are considered the most common labour medical problems among workers in the European Union. The continual exposure of workers to different labour risks leads to these disorders and despite their varied forms of appearance, they can be classified into two broad groups: accumulative (upper and lower limbs) and dorsolumbar injuries1, 2, 3).

The Finnish Institute of Occupational Health (FIOH) identified musculoskeletal disorders as one of the most common work-related infirmity, emphasizing that despite numerous parts of the body being involved, the back accounts for most of the discomfort4).

According to the Occupational Safety & Health Administration5) of the Department of Labour of the United States of America, musculoskeletal disorders cause great losses of work hours. Each year, a high number of American workers suffer work-related MSD in the back and shoulders, tendinitis, and carpal tunnel syndrome.

The Canadian Centre for Occupational Health and Safety6) affirms that MSD constitute a grave problem. Therefore, risk evaluation needs to be established to reduce risk, as these complaints cause many absences, heavy economic losses, and reductions in productivity.

The World Health Organization defines MSD as “health problems of the locomotor apparatus, i.e. muscles, tendons, bone skeleton, cartilage, ligaments, and nerves. This includes any type of complaint, from slight transitory discomforts to irreversible and incapacitating injuries”7).

EU-OSHA2) defines them as “alterations suffered by body structures such as muscles, joints, tendons, ligaments, nerves, bones, and the circulatory system, caused or aggravated mainly by work and the effects of the surroundings in which this is undertaken”. These disorders can arise in any part of the body, although they are more frequent in some zones.

The International Labour Organization8) defines the musculoskeletal system as being made up of “two components, the muscular system and the skeletal system”. It establishes musculoskeletal disorders as “acute, chronic, and those that can impair the function of different body parts”. It states that the work itself triggers the musculoskeletal disorders, depending on the workplace and the worker.

The prevention of MSD involves the analysis of the work to be done and to determine the risk factors in order to apply a series of preventive measures1, 2). In this sense, the factors that increase the risk of MSD9) can be grouped into two types, i.e. those based on physical aspects of the work (loads, bad postures, repetitive movements, physical exertion, mechanical pressure on bodily tissues, cold working conditions, body vibrations) and those based on the work environment and work organization (pace of work, repetition of tasks, work timetable, remuneration systems, job monotony, fatigue, worker perception of job organization, and psychosocial factors). In turn, the European Agency for Safety and Health at Work2, 3), classifies these factors into physical, biomechanical, organizational, and psychosocial, individual, and personal categories.

Musculoskeletal disorders

Evaluation methods

Methods for analysing work vary depending on the means available in each company, from checklists (with all the possible factors) to sophisticated methods of movement analysis (infrared, ultrasound, etc.). For the study and evaluation of MSD, it is possible to use different methods for which classification could be simplified into direct, semi-direct, or indirect methods.

Direct methods

These consist of using certain electronic devices on the human body to measure work postures. Specifically, these sensors record the angles, distances, and the velocities of elements to be analysed. Precision, exactitude, practically automatic data gathering, and the possibility of monitoring the different variables over time are the most notable advantages. The main drawbacks include the high economic cost and the difficulty of using these methods in real time for many work environments due to the discomfort of working with the sensors operating. This is exacerbated when the sensors require cords.

Semi-direct methods

These are based on the use of computer programs that enable the evaluation of postures and therefore of musculoskeletal risks. The use of the software requires prior examination of the postures adopted by the workers, normally by video recording or photography.

In these cases, precision is lower than in the direct methods. However, the indirect methods are more economical although they usually require licences of computer programs. The evaluation with these methods takes more work time with respect to the direct methods, primarily because of the subsequent interpretation of the videos and/or photographs.

Table 1 shows a partial classification of the semi-direct methods according to the type of cause of the MSD.

Table 1.

Classification of the semidirect methods according to the cause of the MSD

Repetitive Movements	Strained Postures	Handling of Loads
RULA method10)“Job Strain Index” method11)Posture and Repetition Risk Factor Index (PRRI)12)IBV method13)OCRA method14)PLIBEL method15)	REBA method16)OWAS method17)Corlett method18)Vira method19)PATH method20)	INSHT method21)NIOSH equation22)Snook and Ciriello tables23)KIM method24)MAC method25)Liberty Mutual tables26)

Indirect methods

Indirect methods are based on the use of questions that are complemented by the worker and/or evaluator. These methods have been developed and tested by research centres or specialized researchers. The advantages of these methods are principally their low cost and more or less confirmed reliability. However, the complexity on occasions, the statistical treatment of the data and the need to administer questionnaires to a representative portion of the workers under study are the main disadvantages.

Some of the best-known questionnaires include those of Michigan27), the famous Standardised Nordic Questionnaires for the Analysis of Musculoskeletal Symptoms28), the questionnaire of Keyserling, Brouwer, and Silverstein29), that of Keyserling30), and the Quick Exposure Check31). Also, in this section, the scale of Borg32) could be included since it is not properly a questionnaire but is not a direct or semi-direct method, either.

The OWAS method

Inception of the OWAS

The Ovako Working Posture Assessment System (OWAS) was formulated in Finland, specifically in the OVAKO OY company, a leading European producer of steel bars and profiles. This system was used to evaluate the work load in the repair process of smelting furnaces33).

The OWAS was initially created with the identification of 72 postures established by photographing the work postures used in different working areas in OVAKO OY. It reliability was confirmed by the analysis of several tasks by a group of engineers (national and international) previously trained in the method. For this, the observations were made by two engineers on two workers during two different work shifts (morning and afternoon). The results found by both groups were roughly similar. Afterwards, they established four risk categories, the first being related to normal postures without recommendations of any type for corrective activity. The second and third categories concerned postures with some risk with recommendations for corrective actions to be taken over the middle term. The fourth category referred to unacceptable postures with recommendations for immediate corrective measures17).

The method

The OWAS method was intended to identify the frequency and time spent in the postures adopted in a given task, to study and evaluate the situation, and thus, recommends corrective actions17). The OWAS identifies the most habitual back postures in workers (4 postures), arms (3 postures), legs (7 postures) and weight of the load handled (3 categories). All this implies up to 252 possible combinations. Therefore, each posture assumed by a worker was assigned a 4-digit code that depended on the classification within the previous postures for each part of the body and the load33).

The procedure to apply the OWAS consisted of making observations of the work tasks, codifying the postures, assigning risk categories and proposing corrective actions (Fig. 1).

Fig. 1.

Flow diagram of the OWAS-application process.

There are different computer programs which have able to apply this method, allowing saving time of work, and which have been already used in several studies34, 35, 36, 37).

Advantages

It is a simple and useful method, can be used by personnel of different spheres, such as health, engineering, industry, etc., without specialized training17) and is well documented33).

Limitations

Several authors neither differentiated the right from left upper limbs, nor evaluated the parts of the body such as the neck, elbows, and wrists, posture coding crude for shoulders, excessive time for its application, and did not take into account repetition or duration of the sequential postures33).

Objective

The objective of the present work is to review the literature on the applications of the OWAS method17) in the diverse sectors or fields of knowledge and countries from December 1977 to March 2017.

Subjects and Methods

A great number of methods are known, as well as their advantages and disadvantages, for evaluating the load posture of workers during a given task, but one of the most commonly used and widely endorsed methods in different studies for multiple work environments such as medicine, the oil industry, and agriculture is the OWAS17). This studies have been made by researchers with varied profiles, from doctors to engineers33, 38, 39, 40).

For the purposes of the present work, the literature was thoroughly reviewed. The data were gathered through electronic access that the Library of the University of Almería, offer through the Spanish Foundation for Science and Technology (FECYT), which in turn manages the Spanish licensing of the “Web of Science” (Wos) provided by Thomson Reuters41). 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. Of these 166 results, the relevant articles according to the title and abstract were initially selected, excluding those that, despite including the term OWAS, did not concern work health and safety. The final material centred on the period of 1981 to March 2017, dates for the first and last document related to this method.

As limitations of the literature search, some citations might have been overlooked with the search procedure used (only TS=OWAS). Also, the search was made first in the main collection of the Wos without considering other complementary data bases. Also, on considering only articles from conferences and scientific journals, work from books, book chapters, or other formats were disregarded.

As incidents during the search, documents with the same content were detected, these being reprints or papers from conferences later published in scientific journals. Therefore, only the original article was considered. Also, some articles found did not concern the application or the use of the OWAS method in a given sector or with a specific purpose, but subjects related to labour health and safety, and therefore were eliminated for not being a direct application. Finally, other articles have applied the OWAS method to different fields involving several types of workers. In these few cases, they were assigned to the field of knowledge with the highest number of workers studied.

Results and Discussion

By categories of knowledge

Works published in different fields of knowledge42) are based on analyses of work postures during different tasks and identify the discomfort or injuries provoked by incorrect posture.

A total of 12 work environments have been identified. The fields of knowledge in which the OWAS has been applied go from “Manufacturing industries”, with a total of 34 published articles, to “Administrative and support services activities” or “Accommodation and catering activities”, with just one study each (Fig. 2).

Fig. 2.

Publications by field of knowledge.

Healthcare and social assistance activities

Several health disciplines in which the OWAS was applied are summarized in Table 2.

Table 2.

Healthcare and social assistance activities

References	Location	Date	Objective	Section
43)	Netherlands	1992	Application of the OWAS in surgery personnel.	3.1.1.1
50)	England	1994	Application of the OWAS by computer in nurses.	3.1.1.3
49)	Netherlands	1994	Application of the OWAS in nurses in orthopaedics and urology.	3.1.1.3
60)	Netherlands	1995	Application of the OWAS and other ergonomic tool in ambulance workers.	3.1.1.5
51)	England	1996	Application of the OWAS in nurses caring for the aged.	3.1.1.3
52)	Australia	1997	Application of the OWAS in an evaluation of the training received by nurses and caretakers.	3.1.1.3
53)	Netherlands	1998	Application of the OWAS, monitoring list to measure errors committed and Borg scores in the evaluation of an ergonomic source for nurses.	3.1.1.3
54)	Netherlands	1998	Evaluation of the reliability of the OWAS observations concerning postures adopted by nurse.	3.1.1.3
58)	England	1998	Application of the OWAS, questionnaire and the Borg scale RPE in nursery-school staff.	3.1.1.4
61)	Canada	2003	Application of the OWAS and other techniques in workers at a rehabilitation centre.	3.1.1.5
44)	Poland	2008	Application of the OWAS in nurses working in anaesthesia.	3.1.1.1
45)	Poland	2009	Application of the OWAS in nurses during surgery.	3.1.1.1
55)	Slovenia	2009	Application of the OWAS in a study examining the advantages of using ergonomic equipment in nursing.	3.1.1.3
46)	Germany	2009	Development of a positioning system of a surgery table and evaluation of postures with the OWAS and RULA.	3.1.1.1
56)	Poland	2012	Application of several ergonomic tools, including the OWAS, for midwives.	3.1.1.3
62)	Brazil	2012	Application of the OWAS and RULA, Corlett poll and questionnaire in radiologists.	3.1.1.5
59)	Brazil	2012	Application of the OWAS in nursery-school workers.	3.1.1.4
63)	Spain	2013	Application of the OWAS in workers with mental disabilities.	3.1.1.5
57)	Slovenia	2014	Application of the OWAS and computer simulation in nurses in ophthalmology.	3.1.1.3
47)	Poland	2015	Application of several methods, including the OWAS, in surgery personnel (nurses and surgeons).	3.1.1.1
64)	Italy	2015	Application of the OWAS and other techniques to design the e-Health station.	3.1.1.5
48)	Slovenia	2015	Application of the OWAS in ophthalmology staff.	3.1.1.2

Surgery

Several authors used the OWAS model for surgery personnel (nurse’s aids, nurses, and surgeons), belonging to general surgery and the ear-nose-and-throat specialty. These authors concluded that surgeons and nurses assume harmful postures43). Kulagowska44) also studied the postures adopted by nurses administering anaesthetics, concluding that the musculoskeletal problems were determined by the organization of the tasks. One year later, Kulagowska45) found similar results for nurses in surgery, leading to the same conclusions. Other authors46) applied the OWAS together with the RULA method10) to evaluate the postures required by the new surgical table for hips, knees, and spinal column. Finally, Bartnicka47) analysed the tasks of nurses and surgeons through a number of methods, including the OWAS, enabling comparisons between methodologies.

Ophthalmology

Different authors48) assessed the postures carried out by ophthalmology staff using OWAS method, making suggestions to improve the taken postures.

Nursing

This is the health field where the OWAS method has most widely been used. For example, Engels et al.49) applied it to nurses belong to the field of orthopaedics and urology, discovering that the postures adopted over a large part of the work day were harmful. In this same year, Hignett50) used the same method with the help of computer software, thereby reducing the analysis time of the results.

In nurses specialized in geriatrics the method was also used, reflecting that the tasks of moving the patients resulted in the greatest percentage of strained postures51). Several authors52, 53) evaluated the postures adopted by nurses before and after receiving training courses. These authors concluded that the training had helped to diminish the amount of strained postures assumed during the work day.

Other authors54) used the OWAS to verify the reliability of the observations based on this method, using a compilation of the postures observed in nursing. Stricevic et al.55) evaluated the postures of nurses working without the use of mechanical equipment to aid in the tasks, and compared these postures to those adopted when using mechanical equipment. These authors concluded that the use of mechanical equipment diminished the number of strained postures.

The OWAS has also been used with midwives while assisting in childbirth, together with other methods and support questionnaires. It was concluded that the midwives suffered back pain from adopting incorrect postures56).

Finally, the method has also been applied to nurses working in the area of ophthalmology with the help of computer software. Certain incorrect postures were found and short-term corrective actions were proposed57).

Nursery schools

Crawford and Lane58) used the OWAS together with an MSD questionnaire and the Borg scale to evaluate the staff of a nursery school. The strained postures were found primarily during the play activities and meal supervision.

Also, several authors59) evaluated a group of nursery teachers using the OWAS and a questionnaire. These authors demonstrated that, even though the teachers were mostly standing, they adopted strained postures of bending, leaning laterally, and rotating the trunk.

Other fields

Doormaal et al.60) using the OWAS, studied the physical load in ambulance workers by a biomechanical analysis and a questionnaire on work and health. Different harmful postures were detected, the most serious occurring during emergencies.

The OWAS was also used in combination with other methods in workers at a rehabilitation centre. In this case, only the tasks of the staff were evaluated, these consisting of folding and unfolding wheelchairs. It was concluded that in many cases the postures adopted could be harmful and generate musculoskeletal injuries61).

Other authors62) used the OWAS together with RULA and the Corlett questionnaire in radiologists of a hospital in Rio de Janeiro. One of the main conclusions was that the staff suffered MSD due to the adoption of strained postures during the work day.

Diniz-Baptista63) evaluated tasks of gardening, ironing, etc. among workers with mental disabilities. These authors used the OWAS, RULA, and the NIOSH equation (Table 1). The great presence of MSD was evidenced as a consequence of strained postures, especially of the back.

Finally, OWAS was applied together with other methods into a study to design an eHealth technology station (a virtual interactive tool about health), which was going to be available on pharmacies. For this, the postures that patients should be taking in this place were analysed. The goal of this technology was to improve some issues like management, organization, etc64).

In all these cases, the study within the sphere of health has found strained postures. This fact suggests that the method is overly sensitive in detecting risk or that work related to the field of health requires short- to medium-term improvement. These improvements could be made from innovation in the auxiliary mechanical equipment adapted to each task of health workers.

Housework activities as employers; non differed housework activities as good and services producers for their own use

In Table 3 there is a summary of the existing studies in this field.

Table 3.

Housework activities as employers; non differed housework activities as good and services producers for their own use

References	Location	Date	Objective	Section
65)	Finland	1998	Application of the OWAS in women caring for patients at home.	3.1.2
66)	Turkey	2008	Application of the OWAS to evaluate postures of mothers of disabled children.	3.1.2

Only two researches related to this field have been carried out in the period of time analysed.

Pohjonen et al.65) used the method to evaluate women who cared for disabled persons in private homes. The results helped to propose corrective action that diminished the adoption of strained postures.

Similarly, Tonga and Duger66) applied the OWAS and another auxiliary method to improve the positions adopted by mothers who assisted their disabled children. Furthermore, they detected the lack of training among such mothers.

Manufacturing industries

Table 4 shows the studies in industry where the OWAS was used.

Table 4.

Manufacturing industries

References	Location	Date	Objective	Section
67)	Finland	1981	Application of the OWAS in steel workers.	3.1.3.1
70)	Finland	1992	Application of the OWAS by computer for workers in the paper industry.	3.1.3.2
68)	Netherlands	1992	Analysis of several working bending at the trunk, by applying the OWAS and a measuring device placed on an area of the body.	3.1.3.1
71)	Netherlands	1993	Application of the OWAS method in workers in the wood industry.	3.1.3.2
74)	Finland	1994	Application of the OWAS in maintenance workers at two chemical plants.	3.1.3.3
89)	Netherlands	1997	Application of the OWAS in male workers in ship maintenance.	3.1.3.7
75)	Germany	1998	Application of the OWAS in workers at a chemical plant.	3.1.3.3
90)	United States	2001	Application of the OWAS, for RPE and BPD measurements in workers carrying boxes.	3.1.3.7
83)	Slovenia	2003	Experimental design of the workplace for sewing designed ergonomically, using several methods, including the OWAS.	3.1.3.5
91)	South Korea	2007	Application and comparison of the OWAS, RULA, and REBA in workers in several industries a hospital.	3.1.3.7
69)	Slovenia	2007	Analysis by the OWAS and other methods in soldiers.	3.1.3.1
72)	United States	2007	Application of the OWAS and the software ErgoMaster (TM)2D to investigate lumbago in carpenters.	3.1.3.2
92)	United States	2009	Application of the OWAS in obese maintenance workers.	3.1.3.7
94)	Cuba	2011	Use of several methods, including the OWAS, for an ergonomic analysis in several sectors of industry and tourism.	3.1.3.7
93)	South Korea	2011	Study of the introduction of safety and health regulations in the workplace in the motor industry by ergonomic evaluations.	3.1.3.7
96)	Thailand	2012	The OWAS, REBA, and RULA applied in workers producing rubber sheets.	3.1.3.7
81)	India	2012	Application of several tools, including the OWAS, to investigate the workers of the jute industry.	3.1.3.4
77)	Brazil	2012	Application of the OWAS in workers of the pig industry.	3.1.3.4
79)	India	2012	Measurement of parameters, the OWAS and Nordic methods in women who dice and grind fruit (Aonla).	3.1.3.4
80)	India	2012	Application of the OWAS, RULA, and a scale of perceived effort in workers who dice and grind fruit (Aonla).	3.1.3.4
84)	India	2014	Application of the OWAS and questionnaires of weavers using handlooms.	3.1.3.5
78)	Brazil	2015	Application of the OWAS in workers of the pig industry.	3.1.3.4
37)	Indonesia	2015	Questionnaire NBM and software WinOWAS in workers of a corn-chip factory.	3.1.3.4
76)	India	2015	Use of several tools, including the OWAS in furniture builders.	3.1.3.3
97)	Portugal	2015	Application of QEC, REBA, and the OWAS in workers in tasks related to electric and electronic equipment.	3.1.3.7
98)	Germany	2015	Use of body sensors to ergonomic analysis on industry, allowing OWAS and EAWS assessments.	3.1.3.7
85)	Turkey	2015	Application of the OWAS in workers producing materials for tyres.	3.1.3.6
95)	Taiwan	2016	Application of the OWAS method and other ergonomic tools in workers of the TFT-LCD manufacturing industry.	3.1.3.7
86)	Turkey	2016	Application of the OWAS in workers producing materials for tyres.	3.1.3.6
82)	Iran	2016	Application of the OWAS and other methods in food industry workers.	3.1.3.4
87)	Poland	2016	Application of the OWAS in automobile industry workers.	3.1.3.6
73)	England	2016	Application of the OWAS and REBA in a furniture factory workers.	3.1.3.2
99)	Iran	2017	Application of the OWAS, RULA, REBA, PATH, QEC and Nordic Musculoskeletal Questionnaire, in industry workers.	3.1.3.7
88)	Germany	2017	Application of the OWAS in workers assembling semi-trailers.	3.1.3.6

Steel

Several authors17, 67), in the steel industry, proposed a new evaluation method (OWAS) and afterwards implemented corrective actions in different jobs. Later, Burdorf et al.68) evaluated two groups of workers. The larger group worked in maintenance and the other in transport. The researchers evaluated the bending of the torso with two methods to make comparisons. One was by the OWAS and the other by a sensor on the back. Major differences were found between the two methods, and the results of the evaluation.

Finally, in the works of welding, Horvat et al.69) investigated the conditions to which the welders were exposed, in a study with the OWAS and the Corlett method18). These authors concluded that welders suffer discomfort and pain as a consequence of strained postures, proposing corrective measures.

Paper and wood

Several researchers70, 71) used the OWAS to evaluate the postures of workers in the paper and wood industries, respectively. In the former case, the method was applied by a computer in workers in charge of multiple tasks. In the second case, after the OWAS was applied, modifications were made in the workplace and the ways of approaching the tasks.

Gilkey et al.72) investigated lumbago in carpenters and their risk factors. These authors used the OWAS with the support of computer tools. The results showed that more than half of the tasks studied surpassed the load limit for the lumbar established by NIOSH22).

On the last available study, Hussain et al.73) studied how the workers abilities influenced in a furnishing factory on their tasks, and made an evaluation of the postures using OWAS y REBA16). This showed that a 33% of the postures were grave and an immediate correction was suggested.

Chemistry

Vayrynen et al.74) studied workers in charge of maintenance in two chemical plants. The OWAS identified a large number of strained postures. These facts account for the musculoskeletal problems in several areas of the body of the workers. Vedder75) applied the OWAS in a chemical plant, using videos of the tasks performed by workers, identifying incorrect postures for the back and head. Finally, in the furniture-manufacturing industry using plastic injection, located in India, Sanjog et al.76) analysed the postures of the worker in relation to musculoskeletal ailments in those workers. These researchers used photograph, the OWAS, REBA16), and the standardized Nordic questionnaire28) and concluded that the production staff suffered more MSD than did the other workers.

Agrofood

Evangelista et al.77) applied the OWAS to workers performing different meat-processing tasks in Brazil. These authors concluded that in the canning tasks correct short-term actions were necessary. Afterwards, in the same agrofood industry, focusing on cutting up meat, Evangelista and Borges78) detected strained postures and proposed corrective actions over the short and long term.

Several authors79, 80) studied problematic posture for workers that diced fruit in the cultivations of Aonla (Phyllanthus emblica L.) in India. These researchers sought to verify whether the introduction of mechanical equipment for dicing the fruit improved the traditional labour done by hand. For this, in the first study, using the OWAS together with the standardized Nordic questionnaire28), the heart rate was measured and evaluated, but only in women. In the second study, the OWAS, RULA10), and a questionnaire of perceived effort (scale) was used without distinguishing between sexes. In both cases, it was concluded that the mechanical equipment diminished the adoption of strained postures.

Sett and Sahu81) used the method in the jute industry, considering only male workers. They concluded that there was a direct relation between strained postures adopted and the MSD suffered by the workers.

Other authors37) used OWAS, using computer tools and additional questionnaires, in an industry of corn-chip production. It was found that the four risk categories of the OWAS (from the lowest to the highest) occurred during the analysis of postures adopted in each task.

Finally, Naeini et al.82) assessed a food industry workers using OWAS. They deduced that the design of a wheelbarrow which could improve the ergonomic conditions was convenient.

Textiles

Two sewing workshops were analysed by Polajnar and Caks83) using the OWAS and other complementary methods. These researchers concluded that workplaces previously designed for textile work result in the least number of strained postures by the workers. On the other hand, Durlov et al.84) investigated lumbago among workers using handlooms in India. The authors used a series of questionnaires in addition to the OWAS. The results showed that over half of the workers suffered lumbago with different degrees of severity.

Vehicles

In two studies85, 86), OWAS method was used to evaluate the postures of workers in charge of producing materials for tyres manufacture. Also, they suggested measures to correct injuring postures.

Other authors87), also used it to evaluate staff working with spot welding machines on the automobile industry. The study focused on 45 workers, men and women, proposing some improvements. As well, Brandl et al.88) applied the method to assess postures of workers in charge of assembling semi-trailers, and suggested new prevention programs.

Others

The first study in this section is based on the posture analysis, using the OWAS, of workers (only males) in the maintenance of ships belonging to two companies. Harmful postures were detected and excessive effort in some tasks89).

Olendorf and Drury90) used the method to evaluate workers carrying boxes. In addition, these authors used biomechanical methods to complement OWAs. The results showed strained postures as a consequence of the weight of the boxes.

Kee and Karwowski91) applied the OWAS in several industries (electronics, automotive, steel and chemicals) as well as in a hospital. They also used the methods RULA10) and REBA16) to compare the three methods in different work environments. It was concluded that the OWAS and REBA gave similar results whereas RULA gave overestimations with respect to the other two.

Park et al.92) using the OWAS and a biomechanical evaluation method, investigated the influence of obesity in static maintenance tasks. These researchers concluded that obesity was a more limiting factor in the adoption of strained postures.

Other authors93) undertook a study seeking to diminish the MSD of workers in the automotive industry of South Korea (complying with the regulations of the country on work health and safety). A similar study was made in Cuba, in the tourist sector, tobacco industry, pharmaceutical industry, and biotechnology94). In turn, Lu et al.95) made a comparable study in Taiwan in the industrial electronics sector (manufacture of liquid-crystal displays). All of these researchers used the OWAS and other complementary methods, proposing corrective measures.

In the rubber industry, the OWAS was applied together with RULA10) and REBA16). The results of the three methods established that the postures adopted by the workers were harmful96).

Other authors97) applied the OWAS together with the QEC method (Table 1) to workers related to the use of electric and electronic equipment. Injuring postures were detected and some measures were suggested.

Also in the industrial sector, Di Valentin et al.98) developed a system to make ergonomic evaluations to workers by using sensors on their bodies, so that, they got immediate results about the performed postures. With this system, evaluations of methods like OWAS and EAWS were possible.

Finally, Yousefi et al.99) studied musculoskeletal disorders on Iranian workers of the industrial field. They used information from different studies and reports. They used OWAS method together with other methods like RULA10), REBA16), PATH20), QEC (Quick Exposure Check) and Nordic Musculoskeletal Questionnaire28). Disorders on knees and back were the main disorders detected.

As in the health field, each time that the OWAS was applied, strained postures were found to a greater or lesser degree. Also, many authors have used the OWAS together with other semi-direct methods (e.g. RULA and REBA; Table 1) and indirect ones (standardized Nordic questionnaire). This finding suggests that the OWAS alone might not be sufficient for the evaluation of strained postures and needs complementary data, mainly for its limitations.

Since the 1990s, computer tools began to be used to interpret the images taken of different tasks of the workers evaluated, and this substantially shortened the evaluation times.

Mining and quarrying

Table 5 shows studies available about mining and quarrying.

Table 5.

Mining and quarrying

References	Location	Date	Objective	Section
100)	Italy	2009	Application of the OWAS in quarry workers.	3.1.4
101)	India	2010	Application of the OWAS in quarry workers.	3.1.4

Several authors100, 101) applied the OWAS to quarrying. The former authors observed the postures adopted by the workers on including two mechanical pieces of equipment in their tasks. The conclusion was that the use of the auxiliary equipment resulted in better work postures. The latter research team demonstrated that the strained postures detected during the tasks affected primarily the lumbar zone, the knees, and the shoulders.

Agriculture, livestock, forestry, and fishing.

Table 6 shows the different works related to agriculture, livestock, forestry, and fishing.

Table 6.

Agriculture, livestock, forestry, and fishing

References	Location	Date	Objective	Section
102)	Netherlands	1989	Choice of the OWAS to evaluate work postures in agriculture.	3.1.5.1
103)	Finland	1995	Application of the OWAS to evaluate work postures after rehabilitation courses in women farmers, as well as to conclude whether the procedure was favourable.	3.1.5.1
120)	Scotland	1996	Application of the OWAS in the poultry industry.	3.1.5.2
104)	Finland	1996	Application of the OWAS and other techniques to evaluate rehabilitation for farmers.	3.1.5.1
116)	Finland	1996	Application of the OWAS, and measurements of certain parameters in workers in milking sheds.	3.1.5.2
117)	Sweden	1999	Application of the OWAS in workers milking cows.	3.1.5.2
118)	Finland	2005	Application of the OWAS and measurement of other parameters for workers in stanchions and in free-ranging dairy cows.	3.1.5.2
119)	Poland	2011	Application of the OWAS in dairy farmers.	3.1.5.2
112)	Brazil	2012	Application of the OWAS workers producing charcoal.	3.1.5.1
107)	Brazil	2012	Application of the OWAS in workers in a eucalyptus nursery.	3.1.5.1
108)	Brazil	2012	Application of EAW methodology y use of WinOWAS in sugar-cane cutters.	3.1.5.1
106)	Brazil	2012	Application of several methods, including the OWAS, in workers raising organic vegetables.	3.1.5.1
105)	Japan	2012	Application of the OWAS in vineyard workers.	3.1.5.1
110)	India	2013	Application of REBA, the OWAS, the standardized Nordic questionnaire, and measurement of other parameters of children doing farm work.	3.1.5.1
111)	Austria	2014	Application of the OWAS, interview and measurement of parameters of workers picking apples.	3.1.5.1
113)	Malaysia	2015	Application of the OWAS in harvesters of oil-palm fruit.	3.1.5.1
36)	Brazil	2015	Application of a software of the OWAS method and another technique in workers raising meat chickens.	3.1.5.2
114)	Colombia	2016	Application of the OWAS in workers of rubber harvesting and rubber industry.	3.1.5.1
115)	Japan	2017	Application of the OWAS in harvesters of asparagus.	3.1.5.1

Agriculture

Vanderschilden102) of the Netherlands selected the OWAS, among other semi-direct methods (Table 1), as the most favourable to evaluate the postures of farmers, above all for its simple application.

NevalaPuranen103, 104) used the OWAS with the help of computer tools in a group of farmers who had previously received training (rehabilitation course). In the first study (in 1995) it was applied only to female workers, while in the second (in 1996), it was used with males and females in addition to using other semi-direct evaluation methods (Table 1). In both cases, a reduction was found in strained postures and therefore a reduction in MSD. Furthermore, new ways of completing the tasks were recommended.

Another study was made in Japan, in vineyards. The postures of workers were evaluated by the OWAS with and without robotic machinery. It was found that the pruning work gave rise to greater workloads than did fruit thinning, regardless of the terrain (sloped or level). Nevertheless, in both cases, the posture load was greater when the land was sloped. It was concluded that fewer strained postures resulted with robotic machinery105).

In horticultural crops, Abrahao et al.106) used the OWAS together with an adaptation of the PATH method20), the Corlett method18), the Borg scale32), and heart-rate measurements, concluding that the strained postures adopted were more harmful than the pulse rate. Similarly, several researchers107), using the OWAS, evaluated the workers in a eucalyptus nursery in Bahia (Brazil) and concluded that the postures adopted in the tasks of preparing cuts should be corrected rapidly and those of mini-cuts, on the other hand were established as correct. In another nursery in Brazil, growing sugar cane, Messias and Okuno108) used the OWAS and the general method known as “Ergonomic Workplace Analysis”109) with the help of computer tools. The results indicated that several of the postures adopted were harmful and corrective measures were proposed.

Although it may appear surprising, not only has research been done on adult agricultural workers, both male and female, but also on children working in agriculture in India. Das et al.110) applied the OWAS, REBA16), and the standardized Nordic questionnaire28) together with the measurement of heart rate and blood pressure. The results showed that the parts of the body most affected in children during farm labour were the lumbar area, the knees, hands, shoulders, and neck.

For the apple harvest, other authors111) used the OWAS and selected a group of fruit pickers, both male and female, whom he also interviewed, analysing their oxygen consumption and heart rate. The results were conclusive, indicating the need to adopt short-term corrective action.

Maia and de Francisco112) applied the OWAS together with a questionnaire on MSD in the charcoal industry. This study demonstrated that inappropriate postures performed at work caused musculoskeletal disorders.

Ng et al.113) investigated the MSD in the tasks carried out by pickers of oil-palm fruit. The OWAS was used together with a questionnaire. It was demonstrated that the strained postures detected were directly related to MSD that the workers suffered.

Velasquez et al.114) also used this method with rubber agro industry workers. They suggested some improvements as very forced back postures were detected.

Finally, Sakamoto et al.115), did research with OWAS on postures performed by asparagus harvest workers who were using adapted scissors and others traditional ones. They showed that adapted scissors decreased the risk of suffering from musculoskeletal disorders.

Livestock

The milking of cows has been widely analysed by several authors by OWAS and other complementary parameters. For Nevala Puranen et al.116), the work of milking was light for the musculoskeletal and cardiorespiratory system, both in males as well as in females, according not only to the OWAS but also measurements of cardiac frequency. Pinzke et al.117) using the OWAS as well as surface electomyography, studied the time spent and the work load in milking cows that were tied up and those that were loose. Also, Perkio-Makela and Hentila118) evaluated workers in charge of open-range cattle. They measured the workers’ heart rate, the perceived effort by questionnaires and the work postures by the OWAS. The images showed that most of the tasks required strained postures for the back. Several authors119) also analysed two dairymen during the milking of cows. The manual transport of the milk and a mechanized system were evaluated. It was deduced, surprisingly, but the use of the OWAS that the automation did not alleviate the posture load.

In poultry, Scott and Lambe120) recorded videos of tasks carried out by workers collecting the eggs of penned chickens and concluded that the postures adopted to collect the eggs were not the most suitable, proposing corrective measures. Finally, on a chicken farm, Carvalho et al.36) used the OWAS and the Michigan test27) with the help of computer evaluation tools to warn of strained postures with possible MSD consequences.

In the agriculture and livestock sector, differences can be distinguished between workers from developed countries (Finland and Sweden, mainly) and other less developed countries (e.g. Brazil and India). In the former case, better work postures are adopted and more automation is used, whereas in the latter case the situations are more precarious, and even child labour is used. This could be due to the fact that agriculture and livestock are primary-production sectors and therefore of extreme necessity.

Also, the analysis of strained postures was made in organic farming. This may be important within the concept of sustainability of any company or process, which is based on economic, ecological, and social development maintained over time121).

As in other fields of knowledge, the use of the OWAS is almost always complemented with other semi-direct and indirect methods (Table 1), presumably for its limitations.

Information and communications

Table 7 shows works on the implementation of software tools that have been developed to use the OWAS by means of computers.

Table 7.

Information and communications

References	Location	Date	Objective	Section
122)	Finland	1988	Development of a computer application for the OWAS method.	3.1.6
123)	Finland	1992	Development of a data collection and analysis system for the OWAS.	3.1.6
124)	Sweden	1997	Use of a PC together with a video camera to record data and make evaluations. Ergonomic evaluation by the OWAS.	3.1.6
125)	Sweden	2001	Development of the way to use the OWAS automatically.	3.1.6
126)	Spain	2007	Use of simulation for the ergonomic analysis and evaluation of postures according to the OWAS.	3.1.6
128)	Japan	2008	Use of virtual reality and posture evaluation with the OWAS.	3.1.6
129)	Italy	2008	Use of simulation and modelling together with the OWAS method for the ergonomic design of a job.	3.1.6
127)	South Korea	2008	Use of the OWAS to analyse postures represented by the digital human model.	3.1.6
130)	Italy	2009	Development of a methodology for the ergonomic design of work places of an industry.	3.1.6
131)	Japan	2010	Use of virtual reality and posture evaluation with the OWAS.	3.1.6
134)	Sweden	2011	Development of a platform for storing data and information on movements, analysed according to the OWAS.	3.1.6
132)	Japan	2012	Development of a system that, with the use of virtual reality, enables the evaluation of work postures, using the OWAS for their evaluation.	3.1.6
136)	Germany	2012	Ergonomic evaluation with software that uses the OWAS method.	3.1.6
133)	China	2014	Ergonomic simulation using the OWAS and BSHA.	3.1.6
137)	Spain	2014	Development of software for the OWAS, in which data are acquired by the sensor Kinect I.	3.1.6
35)	Turkey	2015	Development of the software I-OWAS.	3.1.6
139)	Japan	2016	Use of Kinect sensor to evaluate postures.	3.1.6
140)	Portugal	2016	Application of surface electromyography (sEMG) and 3D cameras to evaluate postures.	3.1.6
141)	United States	2016	Application of computer vision to evaluate postures.	3.1.6

The first researchers to facilitate the analysis of images by computer applications were Vayrynen122) and Long123). Both succeeded in integrating the data gathering of the OWAS (photographic and video camera) together with a computer to enable its subsequent evaluation. Some years later, Engsrom and Medbo124) did the same but provided examples of application in the automobile industry. Pinzke and Kopp125) attempted to advance a bit more and studied the possibility of applying the OWAS automatically using computer and video techniques.

Santos et al.126) used 3D videos (eM-Workplace) in a task of furniture manufacturing for the application of the OWAS by a digital human model in real time that also included the work area. This same model was used by several authors127) in an assembly task in the automobile industry, with the difference that in addition to the OWAS, they used RULA and REBA. Similarly, but with other computer programs of human/digital-space modelling, the OWAS was applied in industrial activities128, 129, 130, 131, 132, 133). The tool enables the subsequent evaluation to correct the worker by the mouse or keyboard.

Seeking the fastest use, Keyvani et al.134) developed a storage system for images/data of movements using MATLAB135) to be subsequently analysed according to the OWAS. Klippert et al.136) evaluated strained postures using software for the analysis according to the OWAS. These authors compared the traditional evaluation (without software) with the computerized evaluation and concluded that the work time of the operator had been optimised. Diego-Mas and Alcaide-Marzal137) developed a software for the application of the OWAS based on a wireless sensorial/virtual computer system connected between the individual and the computer, called Kinect138). Figlali et al.35) have developed the software tool I-OWAS that permits the analysis of images of work tasks and evaluates them at the same time.

Finally, several authors139, 140, 141) used new technologies allowing information compilation to apply OWAS method.

The evolution from the analysis by photos, videos, digital/spatial human modelling towards Kinect138) technology appears clear.

Although the OWAS was conceived as a semi-direct evaluation method (Table 1) the development of new technologies has enabled the OWAS to be applied as a direct method. This has also been extended to the rest of the semi-direct methods (Table 1). Also, these technologies have palliated one of the drawbacks of the method based on the factor “evaluation time”. Perhaps companies have not yet developed computer systems of the latest generation that allow the control of strained postures in real time.

Construction

Table 8 lists the studies related to the construction sector that have applied the OWAS.

Table 8.

Construction

References	Location	Date	Objective	Section
142)	Finland	1991	Application of the OWAS in building construction, with the development of a computer application for the OWAS.	3.1.7
143)	Finland	1993	Application of the OWAS by computer in workers undertaking hammering tasks.	3.1.7
145)	Taiwan	1999	Application of the OWAS in construction workers; design of the program CCOWAS.	3.1.7
144)	Finland	1999	Comparison of physical load caused in young workers and those of advanced age, by the OWAS and other techniques.	3.1.7
146)	Germany	2003	Various methods and techniques, including the OWAS are applied in workers in charge of flooring.	3.1.7
147)	Brazil	2006	Application of the OWAS and other evaluation tools in suspended scaffolding.	3.1.7
150)	China	2009	Application of methods including the OWAS, in workers installing electrical lines in China.	3.1.7
148)	Portugal	2012	Application of the OWAS and other ergonomic tools in construction workers.	3.1.7
149)	Taiwan	2013	Application of the OWAS in construction workers of the foundation of a cabin.	3.1.7

Kivi and Mattila142) used the OWAS with the help of computer tools in construction workers. The results identified the strained postures and facilitated the adoption of corrective measures. Also, for hammering in construction, other authors143) applied the OWAS with the help of a computer, concluding that 7.8% of the postures analysed should be urgently corrected. Afterwards, Louhevaara144) used the OWAS to make a biomechanical comparison between male workers, young as well as advanced in age. For this the author evaluated the dynamic load, static load, and the perceived effort. The results showed that age was not an influential factor in the physical load of these workers.

In Taiwan, Li and Lee145), on applying the OWAS in construction workers, with the help of computer software, discovered harmful postures that should be immediately corrected. Also, the use of other methods was necessary to evaluate the positions of the hands.

In the same way, the OWAS together with other methods was used to evaluate workers dedicated to flooring146). The authors concluded that the most important MSD were provoked by the adoption of strained postures due to the weight of the rolls used for flooring.

Saurin and Guimaraes147) used the OWAS to evaluate workers on suspended scaffolding (lightweight and heavy). These authors used other methods, deducing that in both types of scaffolding the workers exceeded the thresholds of strained posture, and therefore required corrective actions.

Bolonha et al.148) evaluated construction workers of houses, applying the OWAS and RULA. These researchers observed a high number of strained postures in different phases of execution of a dwelling, the most harmful being adopted in the execution of the foundation. Lee and Han149) used the OWAS in the construction sector with the support of videos. These authors detected incorrect postures, notably the bent, twisted trunk.

Finally, several researchers150) used the OWAS in workers related to the maintenance of electric lines in Chinas. In this case, strained postures were detected and corrective measures were proposed.

Transportation and storage

Table 9 represents all the studies using the OWAS in transport and storage.

Table 9.

Transportation and Storage

References	Location	Date	Objective	Section
151)	Netherlands	1990	Application of the OWAS in auto-repair workers.	3.1.8
152)	England	1998	Application of the OWAS and the NIOSH equation in workers handling soft drinks in a distribution centre.	3.1.8
153)	England	1999	Application of the OWAS and other tools in workers in a soft-drink distribution centre.	3.1.8
154)	Scotland	2005	Application of the OWAS and RULA in forklift drivers.	3.1.8
155)	Malaysia	2007	Application of different techniques, such as the OWAS, to study lumbar pain in drivers of commercial vehicles.	3.1.8
156)	Slovenia	2008	Application of the OWAS and other techniques to analyse the discomfort of automobile drivers.	3.1.8
157)	Brazil	2010	Application of the OWAS in workers who load and unload lorries.	3.1.8
158)	Taiwan	2010	Application of the OWAS in toll-booth workers.	3.1.8
159)	Italy	2014	Use of six methods, including the OWAS in workers who load and unload airplanes.	3.1.8
160)	Italy	2016	Application of the OWAS and other tools in workers handling cargo in pallets.	3.1.8

Kant et al.151), using the OWAS to evaluate auto-repair workers, recommended corrective actions.

Wright and Haslam152, 153) investigated the MSD risks in a soft-drink distribution centre, specifically in manual handling tasks. The use of the OWAS was complemented by other evaluation methods. In both studies the results showed that there are strained postures in areas of storage and delivery.

Forklift drivers154) and drivers of commercial vehicles155) were studied by means of the OWAS and RULA. In addition, several authors154) analysed vibrations during the work. In both cases, the lumbar pain was related to the strained postures adopted during the tasks. Also, in the case of the forklift drivers, certain harmful vibrations were detected. Ravnik et al.156) studying a group of automobile drivers, used the OWAS, RULA, the Corlett method, auxiliary questionnaires, and goniometry to identify the strained postures and their relation to MSD that the workers suffered. Farias et al.157) used this approach for tasks of loading and unloading lorries with the aid of photographs and videos. In addition to using the OWAS, they used complementary evaluation methods. According to the observations, there was at least one very harmful posture that required immediate corrective actions.

Li158), with the OWAS, evaluated toll-booth workers and found numerous postures to be harmful both for the workers in the booths located in the car lanes as well as those in the lorry and bus lanes. Short-term corrective actions were advised.

Cattaneo et al.159) evaluated the tasks of loading and unloading airplanes for an airline transport company. These researchers used the OWAS, KIM, MAC, and NIOSH (Table 1) for the loading and KIM, Snook, and Ciriello (Table 1) for unloading. The results indicated that none of the methods are 100% efficient to evaluate MSD risks.

Finally, Calzavara et al.160), used OWAS and other methods with workers handling loads (pallets).

As in other studies, the OWAS is not normally used alone when evaluating the tasks in this field of knowledge, to offset its limitations especially in the actions of loading and unloading. The OWAS is a good method to evaluate strained postures but it is not ideal for evaluating the handling of cargo and thus is combined with other methods more suitable for tasks of transport and logistics.

Teaching

Only four studies are available in this field of knowledge (Table 10).

Table 10.

Teaching

References	Location	Date	Objective	Section
161)	Slovenia	2010	Temporary Observation Method and the OWAS to investigate school work.	3.1.9
162)	Brazil	2013	Application of the OWAS and RULA in odontology students.	3.1.9
163)	Turkey	2016	Application of the OWAS and other methods in teachers.	3.1.9
164)	Belgium	2016	Application of the OWAS in secondary school teachers.	3.1.9

Fosnaric and Planinsec161) using the OWAS and the multimoment method, evaluated a group of students during the practice session of a subject. The researchers concluded that it was possible to improve the performance of the students without changing the postures adopted.

García et al.162) applied the OWAS and RULA in odontology students. The OWAS method warned of a moderate risk while the RULA indicated very high risk. Both methods recommended corrective actions.

Apaydin et al.163), related factors like body-mass index, age and time performing forced postures, using OWAS and suggesting correcting measures.

As well, other authors164) applied OWAS to evaluate secondary school teachers who used electronic school boards and conventional chalkboards. In both cases, they concluded there was not an important risk of suffering from musculoskeletal disorders.

Normally, teaching professionals are exposed to psychophysical and physical tension. However, the use of the OWAS in this field has been scant. This may be because it does not involve tasks of heavy physical loads and perhaps psychosocial factors are predominant.

Wholesale and retail trade; motorcycles and motor vehicles reparation.

Table 11 presents the use of the OWAS in the trade field, as there is no evidence of any study about motorcycles and motor vehicles reparation.

Table 11.

Wholesale and retail trade; motorcycles and motor vehicles reparation

References	Location	Date	Objective	Section
165)	Australia	1995	Application of the OWAS, recordings of the heart rate and perception of effort in supermarket personnel.	3.1.10
166)	India	2016	Application of the OWAS and other methods in workers of a central market.	3.1.10

Carrasco et al.165) used the OWAS and other support methods to evaluate supermarket workers while they worked at the cash register. Improvement actions were recommended.

Sarkar et al.166) used it to evaluated postures performed by workers handling goods in a central market. The concluded that 83% of the postures were injuring and should be urgently corrected. As well, they used the Standardized Nordic Questionnaire28) to measure the frequency of these workers suffering from musculoskeletal disorders.

Accommodation and catering activities

Table 12 includes only one activity in this field.

Table 12.

Accommodation and catering activities

References	Location	Date	Objective	Section
167)	China	2014	Application of the OWAS, RULA, and NIOSH in Chinese restaurant cooks.	3.1.11

Xu and Cheng167) using the OWAS, RULA, and the NIOSH equation to evaluate restaurant cooks in Hong Kong, warned of very repetitive tasks and recommended corrective measures.

Administrative and support services activities

Table 13 also includes only one study referring this field.

Table 13.

Administrative and support services activities

References	Location	Date	Objective	Section
168)	Taiwan	2016	Application of the OWAS in a University cleaning staff.	3.1.12

Several authors168) applied OWAS method to evaluate postures of workers performing cleaning activities in the university. Forced postured were detected and the adaptation or modifications of cleaning tools was recommended.

By country

For each study presented above, the countries of origin of the authors were considered (Fig. 3).

Fig. 3.

Publications by country.

In total, the OWAS was applied in 125 studies, and the country with the highest number of works was Finland, with a total of 13, followed by Brazil with 12, Netherlands with 10, India and United Kingdom with 8, Slovenia with 7, Poland, Japan, Italy, and Germany with 6, Taiwan and Turkey with 5, Sweden and USA with 4, China, South Korea, Portugal, and Spain with 3, Iran, Malaysia, and Australia with 2, and Austria, Canada, Cuba, Indonesia, Colombia, Belgium and Thailand with one each (Fig. 3).

Figure 4 presents the studies made by field of knowledge in each country. Of these the country that has most applied the OWAS in different sectors is Brazil, with 6, followed by Finland with 5; Germany, Slovenia, India, Italy Netherlands, Taiwan, Turkey, and United Kingdom with 4; China, Portugal and Poland with 3; Australia, South Korea, Spain, Malaysia, Sweden, and USA with 2; and Belgium, Colombia, Iran, Thailand, Indonesia, Cuba, Canada, and Austria with one.

Fig. 4.

Number of publications in each field of knowledge by country.

It is not surprising that the country with the most studies applying the OWAS was Finland, since this is the country of origin of the authors of method. In this country, the OWAS has been applied in almost all the sectors, particularly “agriculture, livestock, forestry, and fishing” with 4 and “construction” and “manufacturing industries” with 3 studies published. A similar case in the sector “agriculture, livestock, forestry, and fishing” occurs in Brazil, with 5 studies. In turn, India is notable with 5 studies in the last 6 yr of a total of 8 in the “manufacturing industries” field, perhaps for being an emerging economy.

In the Netherlands, of a total of 10 studies, half were conducted in the sector of “healthcare and social assistance activities”. Similarly in Poland, of a total of 6 studies, 4 were in the “healthcare and social assistance activities area”.

In the category of information and communications, Japan stand out with 4 studies. This country has economy associated with new technologies.

Finally, United Kingdom focus it investigations on the transportation and storage field, and in the healthcare and social assistance activities with 3 each one, out of a total of 8.

By year

Figure 5 shows the number of publications by year as well as by the number of fields studied each year.

Fig. 5.

Number of publications in each field of knowledge by year.

The year having the greatest number of publications was 2012, with 16 publications in 5 fields of knowledge, followed by 2016 with 14 publications in 7 fields of knowledge. On the contrary, for the years 1981, 1988, 1989, 1990, 1991, 2006 only one study published. Furthermore, there is a total 9 yr (1982, 1983, 1984, 1985, 1986, 1987, 2000, 2002, and 2004) with no evidence of the application of the OWAS. Finally, the last 10 yr account for the greatest number of works.

Because of the massive access to Internet worldwide, the dissemination of scientific studies has grown exponentially with respect to the 1980s, especially in the last 10 yr. This fact has influenced the greater application of the OWAS in recent years. In addition, the technological development mixed with mathematical methodologies of optimising processes have encouraged the appearance of new computer tools to greatly facilitate the use of semi-direct methods (Table 1).

In the future, research may continue with this method, not only in the fields of knowledge analysed here but also in others still to be explored (sports activities, recreation, artistic endeavours, entertainment, hotels, aviation, etc.).

Conclusions

The OWAS has been applied mainly in three sectors: industry, health, and agriculture and livestock. It is one of the most widely used and tested semi-direct methods of MSD evaluation in the world, but needs to be complemented with other indirect or direct methods.

The application of the OWAS has been digitalized/computerized, based on the development of new technologies of information and communication, which has greatly shortened the application time since its appearance.

The forced postures detected by OWAS will depend on the physical conditions and the perception and interpretations of the tasks made by the workers in the different working environments.

Finally, whenever the OWAS has been used, whether individually or together with other methods, MSD risks have been detected, this perhaps being an indicator to review the evaluation parameters because overestimating the risk.