This study aimed to determine the prevalence of occupational-related LBP in a defined cohort of truck drivers and to ascertain if certain risk factors i.e. demographic factors of truck drivers, manual material handling (heavy physical work), static work posture, and perceived levels of whole-body vibration are associated with truck driving and LBP.
The study design chosen was descriptive, cross-sectional, and quantitative. For the study, the widely established “Standardized Nordic Questionnaire” (SNQ) was used to collect data. A total of 450 drivers participated in the study by completing the questionnaire.
Occupational driving has often been associated with a high prevalence of low-back pain. Truck drivers in the petrochemical industry in South Africa are vulnerable to work-related low back pain because of the very nature of their job, and this vulnerability has to date not been quantified. The individual and job factors that contribute to causing this pain are diverse and might include prolonged sitting, exposure to whole-body vibration, heavy physical work, smoking, and other psychosocial factors.
TABLE OF CONTENTS
Abstract
Acknowledgments
Definitions
List of tables
List of figures
CHAPTER 1: INTRODUCTION
1.1 Preamble
1.2 Background to the study
1.3 Motivation for the study
1.4 Problem statement
1.5 Aim
1.6 Objectives
1.7 Rational for the study
1.8 Structure of the study
1.9 Summary
CHAPTER 2: REVIEW OF LITERATURE LOW-BACK PAIN (LBP) AND TRUCK DRIVING
2.1 Introduction
2.2 The back
2.2.1 The causes of back pain
2.2.2 Prevalence of lower-back pain in truck drivers
2.3 Risk factors and truck driving
2.3.1 Material manual handling (heavy physical work)
2.3.2 Whole-body vibration
2.3.3 Static work posture
2.3.4 Anthropometry
2.3.5 Smoking
2.4 Summary
2.4 Summary
CHAPTER 3: MATERIALS AND METHODS
3.1 Introduction
3.2 Research design and methodology
3.3 The study environment
3.4 The study design
3.5 The sample
3.6 The research method
3.6.1 The questionnaire
3.6.1 The questionnaire
3.6.2 Structure of the questionnaire
3.6.3 Pre-testing of the questionnaire
3.6.4 Questionnaire administration
3.6.5 Computerization and coding of the data
3.7 Data analysis
3.7.1 Descriptive statistics
3.7.2 Inferential statistics
3.8 Bias and confounding factors
3.9 Validity and reliability
3.9.1 Validity
3.9.2 Reliability
3.10 Ethics
3.11 Summary
CHAPTER 4: RESULTS
4.1 Introduction
4.2 Demographic characteristics
4.2.1 Age characteristics
4.3 Questionnaire items
4.3.1 Point prevalence of low-back pain
4.3.2 Comparison between hospitalization and prevalence of low-back pain
4.3.3 Low- back pain severity
4.4 Correlational analysis
4.4.1 Smoking
4.4.2 Static work posture
4.4.3 Total years of driving and low-back pain
4.5 Summary
CHAPTER 5: DISCUSSIONS, CONCLUSIONS, AND RECOMMENDATIONS
5.1 Introduction
5.2 Response rate
5.3 Demographics
5.4 Point prevalence of low-back pain
5.5 Severity of low-back pain
5.6 Correlational analysis
5.6.1 Smoking
5.6.2 Static work posture
5.6.3 Total years of driving and low-back pain
5.6.4 Age
5.7 Limitations of the study
5.8 Recommendations
5.9 Areas for future research
5.10 Conclusions
5.11 Summary
REFERENCES
ABSTRACT
Motivation
Occupational driving has often been associated with a high prevalence of low-back pain. Truck drivers in the petrochemical industry in South Africa are vulnerable to work-related low back pain because of the very nature of their job, and this vulnerability has to date not been quantified. The individual and job factors that contribute to causing this pain are diverse and might include prolonged sitting, exposure to whole-body vibration, heavy physical work, smoking, and other psychosocial factors. Studies on the prevalence and knowledge of the risk factors associated with occupational-related LBP are important since they allow not only for the determination of the impact of the condition on society or a given social stratum but can also help to organize health services and channel investments necessary for the prevention and control of occupational-related LBP.
Aim
This study aimed to determine the prevalence of occupational-related LBP in a defined cohort of truck drivers and to ascertain if certain risk factors i.e. demographic factors of truck drivers, manual material handling (heavy physical work), static work posture, and perceived levels of whole-body vibration are associated with truck driving and LBP.
Methods
The study design chosen was descriptive, cross-sectional, and quantitative. For the study, the widely established “Standardized Nordic Questionnaire” (SNQ) was used to collect data. The questionnaire was divided into three sections, viz. biographical, low-back pain, and risk factors for ease of completion by the participants of this study. A total of 450 drivers participated in the study by completing the questionnaire. SPSS version 15.0 (SPSS Inc., Chicago, Illinois, USA) was used to analyze the data. Both descriptive and inferential statistics were used in the analysis of the data.
Results
Of the 450 drivers, 385 (86%) experience LBP, and 65 (14%) reported to have not experienced any form of LBP. On a scale of 0 to 10, 68 drivers (15%) indicated that they had pain as bad as it could be, whereas 32 drivers (7%) indicated that they suffered no back pain at all. When the severity of the pain was categorized, as low, medium, and high, 40.5 % of the LBP respondents indicated that they had a high severity of LBP. Smoking, static work posture, and total years of driving were all found to be significantly associated with LBP. Whole-body vibration, biomass index, and heavy physical work were found to have no association with LBP which was not expected.
Conclusion
The prevalence of occupational-related low-back pain in petrochemical truck drivers was 89%. Smoking, static work posture, and total years of driving were the only risk factors associated with LBP amongst the truck drivers.
ACKNOWLEDGEMENTS
I wish to express my sincere gratitude and appreciation to the following individuals and institutions for their assistance and contribution during this project:
- My employer Sasol Oil (Pty) Ltd partly funded my MPH studies.
- The Management of the Truck Stop in Gauteng, Sasolburg for allowing me the opportunity to administer the questionnaires at the facility.
- All truck drivers who participated in the study.
- Andrew Swanepoel my supervisor for his professional and academic guidance and support throughout the completion of this report.
- Professor Kerry Gardiner my co-supervisor from the United Kingdom for his expert advice on the challenging discipline of ergonomics and occupational hygiene.
- Ranitha my wife has always supported me throughout my academic endeavours.
Thank you all.
DEFINITIONS
Low-back pain (LBP): Any acute or chronic pain, ache, or stiffness experienced by the worker in the lower part or lumbar region of the back, lumbago, or chronic recurrent discomfort in the lower back/lumbar area excluding sciatic pain radiating into the legs (Kirkaldy-Willis & Bernard, 1999).
Risk factors: Characteristics (e.g. race, sex, age, obesity) or variables (e.g. smoking, occupational exposure level, whole-body vibration, material manual handling) associated with increased probability of a toxic or adverse health effect (Karwowski & Marras, 1999).
Ergonomics: The application of human biological sciences with the engineering sciences to achieve optimum mutual adjustment of people and their work, the benefits measured in terms of human efficiency and well-being (Karwowski & Marras, 1999).
Keywords: Lower-back pain and risk factors.
LIST OF TABLES
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LIST OF FIGURES
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CHAPTER 1
INTRODUCTION
1.1 PREAMBLE
Musculoskeletal disorders are among the most common cause of occupational morbidity. Epidemiologic studies have shown that 80% of the population has presented or will present an episode of lower back pain (LBP) during their active lives (Beurskens & Koke, 1995).
LBP corresponds to over 50% of all musculoskeletal dysfunctions that cause disabilities in industrialized countries, leading to expenses with treatments and absenteeism (Roland & Morris, 1983). Truck driving has often been widely associated with a high prevalence of LBP. This introductory chapter outlines the purpose and motivates why such a study is needed.
1.2 BACKGROUND TO THE STUDY
Truck drivers comprise a large category of workers that are exposed to many risks associated with LBP. Static work posture, whole-body vibration (WBV), and manual material handling (heavy physical work) are a few of the risk factors that have been associated with LBP amongst truck drivers (Karwowski & Marras, 2000).
Occupational-related LBP is related to mechanical causes, the onset of which normally occurs whilst a person is at work. The debate about work-related LBP reflects both confusions about epidemiologic principles and gaps in the scientific literature (Punnett & Wegman, 2004) which this study would attempt to clarify.
1.3 MOTIVATION FOR THE STUDY
Among the many occupations affected by work-related LBP is truck driving. Professional drivers present 3 times the risk for LBP when compared to workers involved in other types of work (Kelsey & Hardy, 1975). Thus, given the high incidence and prevalence of occupational-related LBP amongst truck drivers and the high costs of its consequences to industry and society, many studies have been conducted to establish the most effective measures to control the symptoms of LBP. However, preventing the onset of LBP can be much more effective and cost-effective, rather than focusing on the symptoms of this work-related occupational health problem. This requires knowledge of the predictors, triggering factors, and the profile of the workers who are most susceptible to the onset of LBP in the work environment.
Studies on the prevalence and knowledge of the risk factors associated with occupational-related LBP are important since such studies allow not only the determination of the impact of the disease on society or a given social stratum but can also help to organize health services in a country to deal with such problems. Furthermore, investments that are necessary for the prevention and control of occupational-related LBP can be correctly channelled.
1.4 PROBLEM STATEMENT
Occupational driving has often been associated with a high prevalence of LBP. The factors that contribute to the cause and the pain are many and might include factors such as prolonged sitting, poor postures, material manual handling (heavy physical work), WBV, and other non-driving related factors such as playing contact sports and smoking.
As a result, the current perception of truck driving is that it is a high-risk job that is associated with LBP, which needs to be validated.
1.5 AIM
This study will aim to determine the prevalence of occupational-related LBP in a defined cohort of truck drivers and to ascertain if certain risk factors i.e. demographic manual material handling (heavy physical work), static work posture, and perceived levels of whole-body vibration are associated with truck driving and LBP.
1.6 OBJECTIVES
The objectives of the study will be:
- To determine the point prevalence of LBP in truck drivers.
- To determine the severity of LBP in truck drivers.
- To determine if selected demographic factors, i.e. age, body mass index (BMI) of truck drivers will be associated with LBP.
- To determine if the risk factors of manual material handling (heavy physical work), static work posture, perceived levels of whole-body vibration (WBV), and smoking will be associated with LBP.
1.7 RATIONALE FOR THE STUDY
The study will contribute to the discipline of Occupational Hygiene i.e. Ergonomics in three specific ways:
- Data on the prevalence of occupational-related LBP in truck drivers from the petrochemical sector would become available in South Africa. Presently such data does not exist.
- It is envisaged that the findings of the study would further validate the existing “body of knowledge” on the risk factors and their association with truck driving and occupational-related LBP.
- Finally, it is envisaged that the study would prompt Occupational Hygienists, Ergonomists, and the drafters of Health and Safety Legislation and Policy in South Africa to categorize truck driving as an “at-risk” occupation. Currently, truck driving is categorized as a risky occupation in Europe.
1.8 STRUCTURE OF THE STUDY
The structure of this study is as follows:
Chapter 2 - Review of literature: LBP and truck driving
This chapter will provide a review of literature both international and local on occupational-related LBP and, the risk factors associated with LBP and truck driving.
Chapter 3 - Materials and methods
This chapter will provide the methodology and research design used for the study. The chapter also cites the ethics approval sought before the study could commence.
Chapter 4 - Results
This chapter provides the results from the statistical analysis of the questionnaire data.
Chapter 5 - Discussion, Conclusions, and Recommendations
This chapter will provide a discussion of the results, and culminate with conclusions and recommendations from the study.
1.9 SUMMARY
This first chapter of the study provided a very succinct introduction to occupational-related LBP. The risk factors and their association with LBP and truck driving were also introduced. The next chapter would provide a review of the literature on truck driving and LBP.
CHAPTER 2
REVIEW OF LITERATURE: LOW-BACK PAIN (LBP) AND TRUCK DRIVING
2.1 INTRODUCTION
LBP is one of the oldest occupational health problems in history. In 1713, Bernardino Ramazzini, the “founder” of occupational medicine, referred to ‘ ’certain violent and irregular motions and unnatural postures of the body by which the internal structure” is impaired. Ramazzini examined the harmful effects of unusual physical activities on the spine, such as sciatica caused by constantly turning the potter’s wheel, lumbago from sitting, and hernias among porters and bearers of heavy loads (Levy & Wegman, 2000).
LBP is now an epidemic of our times, and perhaps the most common orthopedic complaint that general medical practitioners will have to deal with (Papagerorgiou & Croft, 2000). LBP can generally be defined as chronic or acute pain of the lumbosacral, buttock, or upper leg region. Sciatic pain refers to pain symptoms that radiate from the back region down one or both legs whereas lumbago refers to an acute episode of LBP. In most cases of LBP, specific clinical signs are absent. Generally, low-back impairment is regarded as a loss of ability to perform physical activities; with low-back disability being defined as necessitating restricted duty or time away from the job (Bernard, 1997). The intermittent nature of LBP complicates prevalence studies. Furthermore, studies on disability due to LBP are also influenced by legal and socio-economic factors.
Several cross-sectional studies on LBP have been conducted in countries like the United States, Scandinavia, Israel, The Netherlands, and Belgium. The prevalence rates of LBP in these countries ranged from 30% to 92% (Karwowski & Marras, 2000). These studies were, however, conducted on the general population of these countries and not on any workers from specific occupations. There have, however, been specific studies on LBP in specific occupations such as truck drivers and nurses. These studies have produced varying prevalence rates from 13% to 85% (Uebel & Rae, 2009; Naude & Mudzi, 2009; Ramroop, 2006).
Truck drivers comprise a large population that is exposed to many risks in the workplace. Studies have found that high-mileage drivers have been associated with a high prevalence of musculoskeletal pain (Porter & Porter, 1992; Gyi & Porter, 1998; Porter & Gyi, 2002). Drivers who were exposed to whole-body vibration for extended periods have also been associated with LBP (Seidel & Heide, 1986; Hulshof & Van Zanten, 1997; Bovenzi & Hulshof, 1999; Mansfield, 2005). Poor ergonomic design in some models of trucks has been linked to neck and trunk pain (Massacesi & Pagnotta, 2003).
All of the above studies have indicated that there is an association between certain risk factors, driving a truck and LBP. However, most of these studies were conducted outside of South Africa or even Southern Africa. A review of literature on truck driving and LBP in South Africa resulted in only one study being found, which was conducted amongst Refuse Truck Drivers in Kwa-Zulu Natal (Ramroop, 2006). Therefore, the need for such a study is warranted at this juncture.
2.2 THE BACK
To appreciate why the back is so vulnerable to injury, it is necessary to have a basic understanding of its constituent parts and how it functions (see Figure 2.1 below). This brief explanation of the spinal column and the discs will assist in the understanding of the problem of LBP.
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Figure 2.1 The spinal column
Adapted from Kirkaldy-Willis & Bernard, 1999.
In brief, the back consists mainly of:
- Spinal cord - this is a thick cord or nerve tissue that is enclosed by the spine; and, together with the brain, it forms the central nervous system.
- Vertebrae - these are the bones that act as the building blocks of the spine and they can be damaged by impact injuries such as those resulting from heavy objects dropping directly on the back from a height.
- Intervertebral discs - these are the “shock absorbers’’ positioned between the vertebrae and they give the spine flexibility. The discs are made up of a fibrous outer band with a fluid-filled center. When a person stands or sits upright with an “S’’- shaped spine, downward pressure is exerted evenly over the surface of the discs. If a person bends over at the waist to pick up an object, the downward pressure will be exerted unevenly over the surface of the discs, with the loading being greater on the front edge of the disc than at the rear. To compound the stress, at the same time, the viscous fluid inside the disc will be squeezed towards the rear of the disc.
Over time, the fibres on the rear section of the outer band may begin to tear and a bulge may form. The tear and bulge will become bigger if pressure is applied repeatedly and eventually the fluid from the centre of the disc may be pushed out, pressing on nerves which will cause the individual to experience pain. This is called a prolapsed (or slipped) disc.
- Ligaments - these are gristly straps that stretch between bones, holding them together. In the main, they control the direction of motion, provide passive resistance, and limit movement towards the end of the normal range.
- Tendons - these are how the muscles are attached to bones.
- Muscles - these are found in pairs on either side of the spine. They provide the main stability of the vertebral column and provide passive resistance to spinal movement, the resistance increasing as they stretched.
The ligaments, tendons, and muscles are susceptible to injury as a result of twisting and stretching; particularly, if carried out repeatedly over a prolonged period.
Injuries to these soft tissues are probably responsible for the majority of back injuries reported (McKeown & Twiss, 2001).
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Figure 2.2 The discs
Adapted from Kirkaldy-Willis & Bernard, 1999.
2.2.1 The causes of back pain
Most back pain is due to simple mechanical problems in the spine. However, a small proportion arises as a consequence of other disorders. The causes of back pain can be classified as mechanical, fibromyalgia, inflammatory, infective, metabolic, neoplastic, and referred pain (Baxter & Adams, 2000). Mechanical problems dominate but in the majority of subjects, it is not possible to make a specific diagnosis. Such patients are commonly labelled as having non-specific back pain.
Back pain may be acute, recurrent, or chronic. Most acute episodes will resolve rapidly but there is always a risk of recurrence and in some patients, this occurs with relatively minor mechanical stresses. According to Baxter, et al., (2000) only a small proportion develops chronic pain and disability, but it is this group who are responsible for most of the costs associated with back disability and is a burden to the country's health systems. Most patients have simple backache and in these cases, the Medic generally does not make a specific diagnosis. Most of such cases will recover rapidly.
2.3 Prevalence of LBP in truck drivers
Four studies reviewed, have concluded that there is a high prevalence (59%, 50.3%, 60% and 79%) of LBP in truck drivers (respectively, Andrusaitis & Oliveira, 2006; Okunribido & Magnusson, 2006; Robb & Mansfield, 2007; Ramroop, 2006). From the findings of the critical appraisal of the literature on LBP and truck driving together with the conclusions from the abovementioned studies, it is hypothesized that the prevalence of LBP amongst petrochemical truck drivers in South Africa will also be high (> 60%). The findings from the above four studies would be briefly discussed below.
In the study by Andrusaitis, et.al., (2006), of the 410 truck drivers evaluated, 242 (59%) presented with LBP, while 168 (41%) did not have LBP. Of the 242 (59%) truck drivers with LBP, 31.2% had occasional pain, 18% had constant pain, and 9.8% had experienced LBP some time in their professional lives. Several hypotheses were considered in this study one of which was that the prevalence of LBP in truck drivers would be high and the study, did validate this hypothesis.
In a similar study by Okunribido, et al., (2006), it was established that LBP during the preceding 12 months was found to reach a prevalence of 50%, amongst the drivers investigated. Typically, this lasted between 1 and 6 days and in some cases was attributed to sciatica or prolapsed/degenerated vertebral discs. Other causes, such as muscle stiffness and stretched nerves were also identified. Similarly, Miyamoto & Shirai, (2000) reported a 50.3% prevalence of LBP, in the preceding month, although this data was collected from long-haul (inter-city) truck drivers, in a large chemical industry corporation, most of whom found their pain to be mild or moderate. Therefore, Okunribido, et al., (2006) and Miyamoto, et al., (2000) obtained lower prevalence results than Andrusaitis, et.al., (2006).
In a study by Robb & Mansfield (2007) which evaluated the prevalence of LBP amongst professional drivers, most participants (81%) reported musculoskeletal problems (‘ache, pain, discomfort’) in at least one area of their body in the past 12 months, with 2.83 problems reported on average per person. The greatest proportion of reported problems was from the low-back (60%), with high numbers reporting shoulder, knee, and neck trouble (39%, 35%, and 34%, respectively). Just under one-third of respondents reported prevention of normal work due to musculoskeletal trouble, and just over one-third reported having had trouble in the last 7 days. Low-back trouble at some point during their life was reported by 70% of the sample. Referring to the worst episode, this was rated as ‘mild’ by 36.5%, ‘severe’ by 38.3%, and ‘very, very severe’ by 25.2%. Those who reported more severe LBP had taken significantly more time off work during the previous year (p < 0.05, Chi-Square). The majority (86%) of those reporting LBP at some point during their lives claimed that the trouble had occurred in the past 12 months. For most respondents, the number of days that they had suffered from LBP was between 1 and 30.
Despite the high prevalence of LBP pain in this group, 71% stated that their work was unaffected in the previous 12 months. Work and leisure factors were blamed for LBP in approximately equal measures. Answers in a catch-all ‘other’ category pointed out factors such as posture, lifting, wear and tear, and old age. A quarter of respondents reported having visited a doctor, physiotherapist, or chiropractor during the last 12 months; a similar proportion to those whose reported pain was severe. About one quarter (26%) of respondents had injured their low-backs in an accident, most (79%) of which had occurred at work. Those who had ever had an accident reported significantly more musculoskeletal problems in the past 12 months than the non-accident group (independent samples t-test; p < 0.001, two-tailed).
In the study by Ramroop (2006) who evaluated the prevalence of LBP in refuse truck drivers from a Municipality, it was found that the prevalence of LBP amongst these drivers was 79%. The point prevalence of LBP after driving was 69%, 64% indicated that they experienced pain during the past week and 51% of the respondents indicated that they were experiencing pain at the time the questionnaires were administrated to them.
Of the 79% of the subjects who reported to have experienced LBP during the last 12 months, 58% indicated that the pain always spread to their legs to below their knees. A further 53% indicated that they had trouble putting on their socks due to the spread of the pain to their legs. Therefore, the latter two studies established considerably higher prevalence rates, 81%, and 79% respectively.
The above four studies that have been cited do provide considerable evidence that truck driving can be associated with LBP. The results from this study would therefore attempt to add to the body of knowledge derived from these studies. Furthermore establishing if driving a petrochemical tanker truck, can also be associated with a high prevalence of LBP. Therefore, one of the main hypotheses of this study is that the prevalence of LBP amongst the drivers of petrochemical tanker trucks would be high. The reasons for formulating this hypothesis are mainly since professional drivers spend much of their time in the seated position (static work posture) and frequently twist and bend their torsos. Also, the drivers are subjected to various risk factors, which are associated with LBP as concluded by various studies already cited.
2.4. RISK FACTORS AND TRUCK DRIVING
Risk factors may be individual and related to the person, bio-mechanical related to the job, and psychosocial. The common risk factors found to be associated with LBP are heavy physical work, static work postures, frequent bending and twisting, lifting pushing, and pulling, repetitive work, vibrations, and psychological and psychosocial risk factors (Karwowski & Marras, 2000).
However, there may be other risk factors associated with LBP that relate to the worker, which include a history of prior LBP, the poor physical condition of the drivers, obesity, smoking, length of time driving, and increased age (Bovenz & Battie, 1994 & Bovenz & Battie, 1998). For this study, the risk factors of material manual handling (heavy physical work), static work posture, perceived levels of WBV, and other risk factors associated with the demographics of the truck drivers, and their association with LBP would only be explored.
The relationship between occupational risk factors and LBP is difficult to determine because exposure is usually difficult and sometimes impossible to quantify. Using job titles alone such as “drivers” is not appropriate. Healthy workers may well stay in the same occupation and job, while workers with LBP may leave a job and move to a less taxing one. The result is a possible shift in prevalence of LBP from heavy to light jobs (Karwowski & Marras, 1999), which creates what is known as the “healthy worker effect”.
As outlined above, there are many risk factors associated with developing LBP in individuals. Davis and Heaney (2000) have developed a conceptual model of the potential relationships among psychosocial work characteristics, bio-mechanical work demands, and LBP. This conceptual model will form the basis for further discussions on occupational-related LBP and the relationship between these risk factors and truck driving. A schematic representation of this model is shown in Figure 2.3.
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Figure 2.3 Conceptual model of the relationship between psychosocial and bio-mechanical risk factors and LBP. Adapted from Davis & Heaney, 2000.
Regarding the above-mentioned model, psychosocial factors (see pathway A) and bio-mechanical factors (see pathway B) may contribute to the aetiology and progression of LBP independently. Psychosocial factors may also influence the relationship between bio-mechanical factors and LBP (see pathway C), such that bio-mechanical demands have a greater effect on LBP under poor psychosocial work conditions. Additionally, poor psychosocial characteristics and high bio-mechanical demands may covary (e.g. tend to concentrate on similar jobs and occupations such as truck driving). This co-variation (see pathway D) raises the possibility of confounding if both types of risk factors are present.
Therefore, the relationship between LBP and work can be very complex. Individuals may experience impairment or disability at work because of back disorders irrespective of whether the latter was directly caused by job-related factors or not. The degree to which the ability to work is impaired is often dependent on the physical demands of the job. Furthermore, when an individual experiences a back disorder at work, it may be a new occurrence or an exacerbation of an existing condition. Again, originally it may have been directly caused by work or by non-work-related factors.
Those suffering from LBP may modify their work activities to prevent or lessen the pain. Thus, the relationship between work exposure and LBP may be direct in some cases, but not in others. This relationship will also apply to LBP experienced by workers in the different industries and job categories i.e. truck driving in the petrochemical industry. The different types of risk factors will now be discussed.
2.3.1 Material manual handling (heavy physical work)
Heavy physical work is defined as work that has high energy demands or requires some measure of physical strength. Some bio-mechanical studies interpret heavy work as jobs that impose large compressive forces on the spine (Marras & Lavender, 1995). For this study, the definition of manual material handling (heavy physical work) includes activities, which range from heavy tiring tasks, covering loads on the trucks with tarpaulin, and heavy, dynamic, or intense work associated with driving activities in the petrochemical industry.
Petrochemical truck drivers are known to perform various activities which fall within the above definition of heavy work whilst on duty. Depending on the company the driver is employed in, drivers may perform the following tasks: changing truck tyres when the truck has a puncture, covering the load transported with tarpaulin, securing the load using ropes, assisting in loading, and offloading the trucks. It is hypothesized that such heavy physical work performed by the drivers is associated with LBP. The study will attempt to establish if this is indeed the case for petrochemical truck drivers.
Several studies support the above hypothesis by having concluded that heavy physical work was significantly associated with LBP amongst truck drivers (Okunribido, et al., 2006; Van der Beek and Frings-Dresen, 1995; Hedberg, 1985). The findings from these three studies are briefly discussed below.
In the study by Okunribido, et.al., (2006) and by Van der Beek & Frings-Dresen, (1995) it was established that lifting, pushing, and carrying tasks were performed by the majority of the drivers. These activities were part of their daily work and where the majority of the time performed immediately after long stints of driving. The tasks were performed frequently, but loading and unloading of goods generally involved handling of light and medium weight loads (10 kg) and/or exertion of low hand forces. As mentioned above drivers of petrochemical trucks do perform similar tasks in addition to driving activities and it is expected that this study will find similar associations.
In the study by Hedberg (1985), it was established that loading and unloading were the most strenuous tasks performed by the group of drivers that were being studied.
The physical workload varied over the workday, such that, the average heart rate ranged between 82 and 128 beats/min and the drivers tended to work at above 40% of their maximum oxygen capacity for 36% of the task time. Low physical effort was experienced by the drivers however; the high frequency of lifting immediately after driving was established as more of a problem. The high-frequency lifting immediately after driving provided conditions favourable for a back injury, due to reduced lumbar strength from vibration-induced muscle fatigue. Petrochemical truck drivers, however, do not perform any physical tasks that require high-frequency repetitive activities. Hence, the evidence supports the view that the risks of whole-body vibration and heavy physical work combined can increase the prevalence of LBP in truck drivers. The risk factor of WBV would now briefly be discussed.
2.3.2 Whole-body vibration (WBV)
WBV refers to mechanical energy oscillations which are transferred to the body as a whole (in contrast to specific body regions), usually through a supporting system such as a seat or platform. Typical exposures include driving automobiles and trucks and operating industrial vehicles such as tractors and forklifts. Most types of trucks produce some level of vibration which is transmitted via the vehicle's suspension to the driver’s seat and eventually to the driver’s body. Therefore, in this study, it is hypothesized that WBV will be associated with LBP amongst the petrochemical truck drivers.
Petrochemical trucks normally have a horse which consists of the driver's cab and engine, the tanker which varies in length, and a “pap” which is a smaller length tanker at the back of the truck. Carrying a load or empty, the truck normally produces a fair amount of vibration. In this study, the levels of vibration were not quantified i.e. measured formally. The perceived level of vibration was, however, established through question 18 of the study questionnaire. It must be noted that in all the studies reviewed as part of the literature review process for this study, vibration measurements were taken.
Various studies concluded have supported the hypothesis that WBV is associated with LBP, (Seidel & Hinz, 1986; Kelsey & Hardy, 1975; Gruber & Ziperman, 1974; Okunribido, et al., 2006; Massaccesi, et al., 2003; Bovenzi & Rui, 2006). These studies also suggested that LBP occurs at an earlier age in subjects exposed to vibration and that there is an increased risk of LBP in drivers of tractors, trucks, buses, and aeroplanes. In a critical review of musculoskeletal disorders and workplace factors, investigators at the National Institute of Occupational Safety and Health (NIOSH, 1997) judged that, after adjusting for potential confounders (e.g. age, smoking, physical and psychosocial work-related factors), there is strong evidence of a positive association between exposure to WBV and LBP. There is, therefore, already strong evidence of a positive association between exposure to WBV and LBP and it is envisaged that this study's findings would corroborate with this existing body of knowledge. However, the very big difference in this study is the fact that no vibration measurements will be taken which might produce a different result.
In support of most studies that have concluded that WBV is a significant risk factor associated with LBP, a review of laboratory studies has also demonstrated WBV effects on the vertebrae, intervertebral discs, and supporting musculature. Both experimental and epidemiologic evidence, therefore, suggests that WBV may act in combination with other work-related risk factors such as prolonged sitting, lifting, and awkward postures to cause an increased risk of back disorder (Bernard, 1997). The risk factor of static work posture (being in a sedentary position for a prolonged period) will now be discussed.
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- Shaun Ramroop (Autor), 2011, Occupational related low back pain in truck drivers, Múnich, GRIN Verlag, https://www.grin.com/document/1225451
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X. -
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¡Carge sus propios textos! Gane dinero y un iPhone X.