The Basic Ergonomic Principles Health And Social Care Essay

CHAPTER 2

LITERATURE REVIEW

INTRODUCTION

This chapter represents the work of previous researchers and studies that have been carried out concerning to the area of ergonomic intervention. Other than that, this chapter also covers the previous research on the overview of Musculoskeletal Disorders.

OVERVIEW OF ERGONOMICS

The word Ergonomic is a word that derived from the Greek which are "ergo" means work and "nomos" means laws. Therefore, ergonomics are exactly means laws of work (Sluchak 1992). Other country like United States, usually called it as Human Factors. A previous studied by to Mustafa, Kamaruddin et al., 2009 as mention in their journal, the term ergonomics was initially introduced into the literature by the Polish natural scientist Jastrzebowski in 1857 (Bridger 2003). Based on the basic understanding of the author, ergonomic is defined as a rule that required in considering the users of the product. In other words, a designer should design a product that fit the users other than letting the users force to fit their product. Product here includes machines, tools, tasks or jobs, environments, and workplaces.

As the environment of the global economy nowadays is very competitive, it is necessary for each company to increase their worker’s productivity in order to stand still to compete with the others. It is because, the worker’s productivity is much affected by the stress that they experienced due to the working environments (Jian Ai, Khong Sin et al. 2012). When the workers’ stress level is lower, they can produce higher productivity.

For further understanding several definition is derived by the previous research will be highlighted. Ergonomics deals with the human behavior, capabilities, and their limitations to the design of systems, machines, tools, tasks, as well as environments (Mustafa, Kamaruddin et al. 2009).

It is a science focused on the study of human fit, and decreased fatigue and discomfort through product design. Ergonomics applied in designing any products that people used. In designing a product, it is required to consider how the products fit the people that are using them. As a result, when the product fit well with the users, it will be more comfort, safe, effective, less stress, as well as can produce higher productivity (Openshaw and Taylor 2006).

Ergonomic principles are generally used to solve or prevent problems. It is the most effective ways that can be implemented in the industries. Sometimes, with the minor ergonomic changes is not required any cost but it is really efficient to make significant improvements in working environment, health and safety.

Based on the previous study, there are varieties of view on ergonomics depends on individual perspective. According to Susan M. Moore et al., 2011 stated that ergonomic is the discipline of proper workplace situations and jobs demands to the abilities of workers to perform the tasks for the purpose of efficiency and safety (Moore, Krajewski et al. 2011).

Similarly, other researcher mentioned that ergonomic is multidisciplinary science involved with the relations between human and their working environment, as well as the tools and equipment that they used (Evelyn 1996).

OBJECTIVES IN ERGONOMICS

The main objectives in ergonomics were to improve the effectiveness and efficiency of the work performed in the certain industries. This includes increase the load of work to the efficiency of workers. However, the workers capacities as well as the limitations of workers are taken into major consideration by the employer. For that reason, the machines, equipments and tools as well as the working environment are properly designed so that they can be operated with greater efficiency, accuracy, reduced errors, and increased productivity (Evelyn 1996).

Other objectives are to improve the workers performance together with safety improvements, reduce fatigue and stress, better tools design for more comfort, and to make sure correct body postures, minimization of unnecessary load and excessive effort, increased job satisfaction and improved quality of life (Groover 2007).

Based on the research by Nihal Kemer (2011), mentioned that the goals of ergonomic were to maximize the productivity by reducing the worker’s fatigue and discomfort, as well as to make sure that ergonomic intervention can give continuous improvements to their productivity (Kemer 2011).

In addition, according to Siguencia, (2002) stated that the goal of ergonomics is to fit the task to human in order to eliminate or minimize hazards and consequently enhancing the effectiveness of human interaction with the working environment (Siguencia 2002).

For other researcher, different aims has been provided in application of ergonomic program, which are; eliminating or minimize injuries, fatigue and overexertion, improving quality and quantity, reducing lost time and costs associated with injuries and accidents, and finally improving safety, efficiency, comfort, and productivity (Mital 1995).

BASIC ERGONOMIC PRINCIPLES

The basics of ergonomics do not have to be difficult or expensive. Most of the ergonomics applications are to look at the routine activities from a new perspective (Macleod 2008). Many studies have been proved that, the positive effects of applying ergonomic principles in the workplace. Thus, several ergonomics principles will be discussed.

Workstations

A workstation is the place where the workers are occupy when performing their job. Work areas need to be comfortable and safe for the workers. Therefore, the work areas need to be set up so that the workers have a sufficient space to move around (Macleod 2008). A guideline is required in order to design ergonomic workstations. Well designed workstations is significant for preventing syndromes related to poor working conditions, as well as for ensuring that the workers are comfortable which will result in reducing stress which will lead to increase the productivity (Jian Ai, Khong Sin et al. 2012).

A study conducted by International Labor Organization (2000) found that the workstation should be designed with both the worker and the job are the main factors need to be focused so that work can be performed comfortably, smoothly, and efficiently (Dul and Weerdmeester 2001). If the workstation is properly designed, the worker should be able to sustain a correct and comfortable body posture to avoid from many diseases such as Repetitive Strain Injuries (RSIs).

Based on a study by Siguencia, (2002) the design of workstation should allow adjustability to fit every workers, maintain the workers neutral body posture while performing the job by avoid awkward of extended reaches, provide variety of working positions, provide adequate space for access the tools and equipments and make sure that the frequently used items are within easy arm’s reach (Siguencia 2002).

Good workstations must be adjustable so that every worker is comfortable. According to one of the previous research, the workers are preferred the fully adjustable ergonomically designed smart assembly workstation. It is because, it allow the workers to adjust and organize the workstation to their comfort (Garbie 2011).

In another study, there was evidence on the effective application of ergonomic in work system design. It would not only improve worker comfort ability, safety, and work quality, but it would also reduce cycle time. The reduction in mean cycle time was 27% when using the ergonomically designed workstation. This ergonomically designed workstation was concentrate on the sit-stand workstation concept for the repetitive assembly tasks. This study also concluded that the workers satisfaction has improved 41% on the newly designed which are fully adjustable system was applied (Shikdar and Al-Hadhrami 2005).

Standing Position

Standing is basically an ordinary human posture. Generally in industrial workplaces, most of the workers especially in the assembly lines are performing their processes jobs in standing positions. It is mainly because, when the workers perform their job in standing position, it will be more effective as compared with sitting positions. According to a study carried out by Isa H. and Abdul Rahman O. (2011), the significant rationales to perform this jobs in standing positions are: 1) the workers are requires large degree of freedom of working orientation; and 2) the design of workstation does not allowed the workers to perform the jobs in sitting position. As a result, this position encourages workers to be more efficient and productive (Halim and Omar 2011).

However, standing in a long period of time can lead to discomfort, muscle fatigue and occupational injuries to the workers. Standing in a long duration is tiring for the body. The workers will have a problem such as aching feet, low back pain, swollen ankles and calves, as well as leg and hip pain (Annki, Roland et al. 2008).

A workers can be considered to be exposed to prolong standing if they spent over fifty percent of the total working hours during a full work shift in standing position (Tomei, Baccolo et al. 1999).

Furthermore, a study also have stated that this prolong standing can decreased the workers’ performance in the industry, which lead to reduce the productivity, as well as increasing the number of treatment and medical cost due to this problems (Krijnen, Boer et al. 1998). Besides that, the employers will also have the impact regarding this matter whereby when the worker’s performance are decreased, this will lead to reduction of revenue due to lower productivity, worker’s compensation as well as higher medical costs (J. E. Zander, King et al. 2004).

On the other hand, according to a research by Whistance R. S. et al. (1995), stated that even the industrial workers are required to perform their jobs with a standing position, but a seat or a chair should be provided to allow the worker sit when needed. So that it can give workers more flexibility as well as having a variety of body positions. With the variety of body positions, really help in improving the blood supply to the working muscle which lead to reduce muscle strain (Whistance, Adams et al. 1995).

Hand Tools

Many processes jobs in manufacturing industries required the use of hand tools. However, the regularly used of these tools lead to discomfort during work. This kind of feeling can cause the decrease of work efficiency and job satisfaction to the workers (Fellows and Freivalds 1991). In addition, a long term of hand tools usage can also cause more serious illness such as Musculoskeletal Disorders (Aghazadeh and Mital 1987; Chao, A.J.Kumar et al. 2000). It is basically due to the used of improper tools, using the tools incorrectly or using poorly designed hand tools (East and Soo 2005). Therefore, several guidelines of ergonomics hand tools will be discussed.

Tool Weight

Weight of tool is needed to be consider because it affect the way of the worker hold the tools which can lead to awkward postures. The workers will hold the tools either with one or both hands depends on the jobs or tasks itself. Other factor that also needs to consider in designing hand tools was the duration of tools usage. Therefore, a study has found that the best weight for a tool that operated with one hand should be 1.4kg or less while for precision operations, the tools should be 0.5kg or less (East and Soo 2005).

Handle

The handle of hand tools is the most part that directly contact with the user’s hands. Consequently, the designs of handles are directly influence the usability and comfort level of the tool during operation. The design of handle should allow the workers to easily hold the tools using a power grip. The handle should also be designed to fit the workers hand which can help in reducing the uncomfortable pressure on the palm. A good handle design will finally results in neutral wrist postures and eliminates stresses to the worker’s hands (Skogsberg 2005).

Materials

For safety reason, hand tools should be made of non-slip, and non-conductive. In order to achieve these points, the selection of materials is important in order to ensure the tools are good grip on a handle. Hence, most probably, the suitable material is rubber. It is because rubber can provide good grip, as well as reduce the effort to hold the tools (Kuijt-Eversa, L.Groenesteijn et al. 2004).

BENEFITS OF ERGONOMIC

Ergonomic intervention gives positive effects both to the workers and the company. It is due to the new improvement or changes to the tools, job scopes, working environment, and body posture. Even with the small changes or improvement sometimes can give high impact to the productivity. There are many ways that can be implemented in order to increase the worker’s performance. As long as it involved in reducing worker’s stress, increased the job satisfaction, variety of body posture, automation which reduce repetitive movement, as well as having rest time in between to relieve the tension muscle.

Since ergonomic has proved that it can gives positive effect, there are more research has been conducted recently. Based on a study by Oesman et al. (2008) stated that the intervention or ergonomic in the stamping industry gives optimistic impact to the industry. This study involved in redesign a new push button stand for the stamping machine operator. The previous push button stand was poorly design where it cause the operator to control the machine in awkward body postures. With the new designed, it proved that this ergonomic design has improved in term of work quality, work satisfaction, increase in time efficiency and productivity, reduced in processing time and as a result it increased the company profit by 3.95% (Oesman, Manuaba et al. 2008).

In addition, with the positive impact of ergonomic involvement in the production, it is also linked to the reduction of occupational injuries, improvement of worker’s health conditions, and motivation of human resources (Kemer 2011).

Furthermore, ergonomics intervention in every job may solve all the musculoskeletal problems generated by the occupational activities (Chandra, Ghosh et al. 2007). It has been proved by the ergonomists as well as scientists from other fields. Major concern is on the workers’ strength. Strength test is required to obtain the worker’s ability and a specific job is then designed according to workers’ needs (Ridgley and Wilkins 2007).

Other study also has proved that the business who implemented the ergonomic programs reported that there are significant reductions in accidents, injuries, illness and health-care costs along with the improvement of productivity, product quality as well as workers’ morale (Simonton 2005).

VIOLATIONS OF ERGONOMIC

Many studies have proved that ergonomic involvement gives improvement in many aspects. It was clearly shown by the study that compared the result of using the old design of tools, and workstation with the new ergonomic environment. Application of ergonomic principles increased the work satisfaction, improved body postures, and increased the productivity and company profits as well. Therefore, the violations of ergonomic can lead to serious injuries.

Based on a study that have been done previously, stated that the job associated with poor working environment can lead to musculoskeletal disorders and high sick leave especially among the assembly workers. Other than that, it is resulted in impaired product quality and in decreasing productivity (Simonton 2005).

Musculoskeletal Disorders (MSDs)

Musculoskeletal Disorders (MSDs) are common health problems in a manufacturing industry throughout the world. All the soft tissue and bones in the human body are categorized under musculoskeletal system. The part of the musculoskeletal system are muscle (tissue that create motions); bones (the load-bearing structure of the body); tendons (tissue that attach muscle to bones); ligaments (tissue that attach bones to bones); cartilage (tissue that help to reduce friction between bones); nerves (connect tendon, muscles, and other tissue with the brain); and blood vessels (tube that circulate nutrients all over the body) (Simonton 2005).

MSDs involved with a variety of disorders of the muscle, tendon, or nerve which caused by irritated work (Armstrong, Buckle et al. 1993; Hagberg, Silverstein et al. 1995). According to Hagberg et al., (1995), musculoskeletal disorders affect the workers not only in a manufacturing industry, but also in a wide variety of occupations and it take some period of time to develop.

Musculoskeletal disorders influence a huge number of workers across most industries and occupations. It has the possibility to lead to permanent disability, and require high costs on employers and on society (Shahnavaz 1987; Vanwonterghem 1996; Buckle 2005). At a present time, MSDs is one of the major problems that ergonomists came across all the time in the workplace (Vanwonterghem 1996). A study has found that the prevention of musculoskeletal disorders has been considered as a national priority due to the high impact of this disorder to the workers, to the organization and to the country as well (Speilholz, Silverstain et al. 2001).

There are also other term that describe MSDs, which are: Cumulative Trauma Disorders (CTDs), Repetitive Strains Injuries (RSIs), Occupational Overuse Syndrome (OOS), Repetitive Trauma Disorders, and Repetitive Motion Disorders (Simonton 2005).

Risk Factors to MSDs

Risk factors of musculoskeletal disorders are known in previous study to comprise with the workplace activities such as repetitive movements, awkward postures, involved with an excessive force and vibration exposures (Linton and Kamwendo 1989; Carter and Banister 1994; Chandra, Ghosh et al. 2007; Nordander, Ohlsson et al. 2008).

Each risk factors will cause an injuries and the potential of injuries is depends on the duration of workers’ exposure. The risk factors are most likely combined with each other which can allow higher possibility to obtain MSDs.

Repetitive Movement

Repetitions are defined as a movements or motions made by a major joint such as arm, and shoulder. It is happened when the amount of repetitive movements are exceed the body limit. Many jobs involved with repetition tasks for example assembly, packing and typing (Evelyn 1996). Generally, after each task, an adequate recovery time is required to rest the muscles.

Repetitive movements is basically the used of muscle to perform assembly tasks without sufficient time to rest between the repetitions. Therefore, muscle will become tired and cramp and finally will injure. This repetitive tasks has already known as a main cause of muscle fatigue (Santy and Dawal 2010). A study conducted by Rempel (1992) and Takala (2002) also stated that muscle fatigue is caused instantly by repetitive work and might be a factor that contributed to the neck and shoulder muscle disorders or also known as musculoskeletal disorders (Rempel, Harrison et al. 1992; Takala 2002).

The severity of risk is depends on the speed of the movements, the number of muscles involved, frequency of repetition, and the required forces. Repetitive motions are also influenced by the machine or tools, higher productivity in the limited time, and improper working schedule or improper job division (Simonton 2005).

Awkward Postures

Awkward body postures has been widely accepted in musculoskeletal problems (Li, Haslegrave et al. 1995) and based on the previous study, awkward body posture is the major factor in development of musculoskeletal disorders (Wall, Riel et al. 1991; Das and Sengupta 1996; Li and Buckle 1999).

Poor postures have also been found to relate with the reduction of performance efficiency where it was generally identified that it can cause discomfort to the workers (Haslegrave 1994). Typically, awkward postures consist of working overhead, extend shoulder, reaching behind, kneeling, twisting, and squatting (Simonton 2005).

Basically, awkward body postures occurred in the manufacturing industries because this industry involved with manufactured and assembled work in a long working hours and in static position (Choobineh, Hamidreza et al. 2007). According to Choobineh et al., (2007) the result from rapid upper limb assessment (RULA) was found that 11.7% of the workers score 3 and 4 (investigate further), 75.2% score 5 and 6 (investigate further and change soon) and 13.1% score 7 (investigate and change immediately). These conclude that the workers are not in the suitable working environment and most of them are not satisfied with their job.

More comfortable and suitable working postures are required in order to improve the worker’s musculoskeletal systems and allow more effective control of work performance and reduction in the number of occupational injuries (Mattila and M.Vilkki 1999).

Excessive Force

Force is basically an effort that is required to accomplish a specific job or to control tools and equipments. The job or task that required higher force can cause the placement of higher mechanical loads on the muscles, tendons, ligaments, as well as joints. High forces also can lead to irritation, inflammation, and strains to the muscles, tendons and other tissues (Daley and Ames 1995).

Force is divided into two categories which are internal force and external force. Internal force is when the force is developed through tension within the muscles, ligaments and tendons during movements. While, external force involve with the force that is applied to the body by the used of hand tools or a movement of heavy loads, lifting and delivering packages.

There are a lot of manners in which operating hand tools can expose the workers to high forces. First, when the tool is heavy and the workers need to hold and control the tool. This may cause the muscle to fatigue quickly due to the higher force exposure. Second, hand tool do not have weight distribution which can cause the workers cannot hold the tools properly due to the tool is not balance. Third, when the handles of tools are not in suitable shape which require workers to grip the handle in order to hold and operate the tools (Daley and Ames 1995).

Vibration Exposure

Vibration is categorized as one of the physical occupational hazard in the workplace (Benshea 2009). Vibration is generally separated into two categories; Hand-Arm Vibration (HAV) and Whole-Body Vibration (WBV). This research is basically focused on the HAV. HAV is commonly associated with the use of vibrating hand tools. This tool can cause vibration exposure to the workers where it affects hands and arms. Normally, it can be arises when using powered hand tools due to the impact by the electrical or pneumatic power (Dul and Weerdmeester 2001). Or else, the vibration will arise due to external and internal forces.

Hand-arm vibration is a condition where the blood flow in the fingers is reduced which can affect the circulation, sensory and motor nerves that may lead to musculoskeletal disorders (MSDs) (Smith 2009).

According to Smith (2009), the major cause of HAVs is by the increase of vibration magnitude during the job performance as well as the duration that the workers expose to. Other factor that also include in developing HAVs are (1) the grip force that is use to guide the tools, (2) pattern of exposure, and (3) how much of vibration exposure to the hand. All of these factors squeeze the blood vessels which will then restricts the blood to flow smoothly to the body part (Smith 2009).

TRAPEZIUS MUSCLES

The existences of musculoskeletal disorders are involved with the injuries of upper extremities, lower extremities, back, and trunk. It was basically occurred among industrial workers (Dawal, Soin et al. 2008). According to Dawal (2008), a study conducted by Salvendy G. (1997) has proved that the most chronic body parts that lead to work-related musculoskeletal disorders are upper extremities. It is due to the manual jobs that are perform by the workers are actively used hands, arms and shoulders (Salvendy 1997).

Therefore, the muscle that normally involved with the upper extremities is trapezius muscles. The trapezius muscle is large, basically in triangle shape which is located from the back of scull until the lower thoracic region (Rosendal 2004). Trapezius muscle is divided into three parts; (1) upper part, (2) middle part and (3) lower part (refer Figure 2.1).

Figure 2.1: Schematic drawing of the trapezius muscle. Source: Lars Rosendal, Interstitial Changes in Trapezius Muscle during Repetitive Low-Force Work, (2004).

Since one of the research objectives is to study the vibration effects on the upper trapezius muscle, therefore, only this muscle will be discussed. It is because, upper trapezius is probably the most common muscle affected by the vibration exposure due to assembly work. Assembly work is mainly relate with the used of vibrating hand tools that involved with repetitive tasks (Moussavi 1997). Upper trapezius muscle main functions are; (1) to raise the shoulder, (2) as lateral flexion of the neck, (3) to rotate the head and (4) for neck hyper extension.