Cross-sectional investigation of task demands and musculoskeletal discomfort among restaurant wait staff

A cross-sectional study of task demands and musculoskeletal discomfort among a sample of 100 wait staff in ten casual dining restaurants was conducted. In addition to answering a questionnaire about musculoskeletal discomfort and symptoms experienced in the past 12 months and attributed to work, subjects were asked about various aspects of their jobs, such as shift length, number of shifts per week and safety training. The managers of the restaurants were also interviewed to gather basic information on factors such as work hours, alternative duty availability and safety practices. When asked to rank the three most important causes of injuries, the responses of both managers and wait staff were congruent with Bureau of Labor Statistics (USA) data for 1999 on the nature of injuries and attributed exposures, with slips and falls, musculoskeletal disorders and acute injuries (e.g. burns, cuts) highlighted. Of the 100 subjects, 42% reported experiencing musculoskeletal symptoms in the past year, with the lower back area (18%) and shoulder (11%) with the most frequent symptoms reported in the responses. Although many of the materials handling tasks were not excessive, the heavier tray lifts and carries are a cause for concern. There are also slip and fall issues that influence the risks of these tasks. Future research needs, including addressing the mismatch between more common materials handling assessment tools and the nature of food serving tasks, are discussed.     

The effect of a resistance-training program on muscle strength, physical workload, muscle fatigue and musculoskeletal discomfort: An experiment

The aim of the study was to investigate the effectiveness of a resistance-training program on muscle strength of the back and neck/shoulder muscles, relative physical workload, muscle fatigue and musculoskeletal discomfort during a simulated assembly and lifting task. Twenty-two workers were randomized over an 8-week resistance-training group, and a control group. Isokinetic muscle strength was assessed using the Cybex dynamometer, muscle fatigue was measured using EMG, and perceived discomfort was measured using a 10-point scale. At the follow-up, we found no effect of the resistance-training program on isokinetic muscle strength of the back and shoulder muscles. Furthermore, we did not find any effect on EMG data, nor on musculoskeletal discomfort during the simulated work tasks. However, trained workers performed the lifting tasks for a longer time before reporting considerable discomfort than those in the control group.     

Perceived demands and musculoskeletal symptoms among employees of an Iranian petrochemical industry

As a part of a comprehensive ergonomics program, this study was conducted among employees of an Iranian petrochemical industry to determine the prevalence of musculoskeletal symptoms and to examine the relationship between perceived demands and reported symptoms. In this cross-sectional study, 928 randomly selected employees, corresponding to nearly 40% of all employees participated. Nordic Musculoskeletal Disorder Questionnaire and Job Content Questionnaire were used as collecting data tools. The results showed that 73% of the study population had experienced some form of symptoms from the musculoskeletal system during the last 12 months. Knees and lower back symptoms were the most prevalent problem among the employees studied. The results revealed that perceived physical demands were significantly associated with musculoskeletal symptoms (OR ranged from 1.45 to 2.33). Among the perceived physical demands, awkward working postures were most frequently associated with reported musculoskeletal symptoms. Association was also found between perceived psychological demands and reported symptoms. Conflicting demands, waiting on work from other people or departments, interruption that other make, working very fast and time pressure were psychological factors retained in the regression models with OR ≥ 1.49. Based on the findings, it could be concluded that any interventional program for preventing or reducing musculoskeletal symptoms among the petrochemical employees studied had to focus on reducing physical demands, particularly awkward working postures as well as psychological aspect of working environment.

Relevance to industry

In petrochemical industry where employees are involved in both static and dynamic activities, determination of musculoskeletal symptoms contributing factors can be considered as a basis for planning and implementing interventional ergonomics program for preventing musculoskeletal symptoms and improving working conditions.     

Flexible workspace design and ergonomics training: impacts on the psychosocial work environment, musculoskeletal health, and work effectiveness among knowledge workers

A macroergonomics intervention consisting of flexible workspace design and ergonomics training was conducted to examine the effects on psychosocial work environment, musculoskeletal health, and work effectiveness in a computer-based office setting. Knowledge workers were assigned to one of four conditions: flexible workspace (n=121), ergonomics training (n=92), flexible workspace+ergonomics training (n=31), and a no-intervention control (n=45). Outcome measures were collected 2 months prior to the intervention and 3 and 6 months post-intervention. Overall, the study results indicated positive, significant effects on the outcome variables for the two intervention groups compared to the control group, including work-related musculoskeletal discomfort, job control, environmental satisfaction, sense of community, ergonomic climate, communication and collaboration, and business process efficiency (time and costs). However, attrition of workers in the ergonomics training condition precluded an evaluation of the effects of this intervention. This study suggests that a macroergonomics intervention is effective among knowledge workers in office settings.     

An investigation of ergonomic interventions in dental hygiene work

Alternative methods for viewing teeth while performing simulated dental procedures were investigated. The methods allowed participants to assume postures requiring less neck flexion than the standard direct view. One alternative used a video camera and monitor to view the mouth, the other incorporated 90 degrees prism glasses. The study was conducted in two parts: (1) novice participants performing a targeting task; (2) dental hygienists performing a scaling task on a mouth model. Posture and subjective perceptions were assessed in Parts 1 and 2. Muscle activity and performance were also assessed in Part 1. The alternative methods significantly reduced muscle activity, neck flexion, and discomfort, compared to the direct view. Preferences were a function of criteria (general, comfort, productivity, or accuracy). Previously, recommendations for reducing ergonomic risk factor exposure of dental professionals emphasized reducing time spent performing dental procedures. This study shows ergonomic interventions offer alternative means of risk exposure reduction.     

Perceived physical stress at work and musculoskeletal discomfort in X-ray technologists

A structured questionnaire/interview was designed to explore demographic, personal, occupational and occupational health factors as well as recreational physical activities which can affect X-ray technologists' musculoskeletal symptoms. This questionnaire was piloted for clarity and validity. Subsequently, a random sample of 20 volunteer participants (18 female, 2 male) from two University hospitals were administered the questionnaire in the presence of the investigators to ensure that questions were correctly understood. The data obtained were analysed for magnitude, duration and frequency of activities and for severity, duration and recurrence of morbidity. The X-ray technologists in the sample were found to be a young group of professionals ranging from between 20?–?54 years of age. Eighty-nine per cent of the technologists were physically active and 44% indulged in physical recreational activities. Despite the young age and active life style, the X-ray technologists had significant and diverse musculoskeletal problems; 83% of technologists had backache and 39% of the female technologists had neck pain and 28% shoulder pain. The majority of technologists had suffered multiple episodes of pain. Fifty per cent of the female sample and both male volunteers suffered from upper extremity pain.     

A computerized method for assessment of musculoskeletal discomfort in the workforce: a tool for surveillance

A musculoskeletal discomfort survey was conducted to assess musculoskeletal discomforts among rural mail carriers in two post offices. Perceived musculoskeletal discomfort was collected directly from the workforce by means of a computerized discomfort assessment system (DAS). This investigation aimed at: (1)assessing the rural mail carrier's perception of DAS; and (2) assessing the rural mail carrier's musculoskeletal discomforts resulting from work. Most participants in the study found the computer tool easy to learn and easy to use. The information collected by DAS was used: (1) to determine the number of participating employees who were experiencing some kind of musculoskeletal problem; (2)to determine subtasks associated with discomfort; (3) to determine the body areas most affected by different subtasks; and (4) to investigate the patterns of discomfort that occurred with time.     

The prevalence of musculoskeletal symptoms among British Columbia sonographers

A survey (n = 211, 92% response rate) was carried out to determine baseline prevalence of musculoskeletal symptoms and identify related biomechanical, psychosocial, work organization and demographic factors among the population of sonographers in British Columbia, Canada. Ninety-one percent of respondents reported musculoskeletal pain or discomfort that they associated with the work tasks of scanning. Almost half reported frequent and severe symptoms. The neck, shoulder, and upper back were the main symptomatic body sites. A very small minority were absent from work due to the symptoms, with more than two thirds of respondents reporting working in pain. Bivariate analyses found significant associations between scanning time, static postures, psychosocial factors, and degree of musculoskeletal symptoms.     

Computer use and musculoskeletal symptoms among undergraduate university students

The use of computers has been shown to have the potential for detrimental effects on the musculoskeletal system. Previous research has identified risk factors for computer-related musculoskeletal symptoms (MSS) in the workforce, but the focus of investigation on university students is comparatively recent. There appears to be a relative paucity of research into computer-related MSS in European universities and none to date in Ireland. The primary aim of this study was to determine the prevalence of computer-related MSS in a cohort of undergraduate university students in Ireland. The cross-sectional study design involved a questionnaire of two parts. Part A was a questionnaire adapted from previously used questionnaires and included questions relating to demographic information regarding age, gender, year of study, hand dominance and details of computer use. Part B was a modified (to include only computer-related symptoms) Nordic Musculoskeletal Questionnaire. A total of 312 Health Sciences students were surveyed and 241 responded, giving an overall response rate of 76.9%. All students used a computer, with 95.4% using a laptop. Although the reported duration of computer use was quite low, the prevalence of computer-related MSS was high (52.8%). Increased prevalence of MSS was significantly associated with year of college, average daily laptop use and right hand dominance. A considerable proportion of students reported that MSS impacted on their work (18.3%) and leisure activities (23.6%) and furthermore 17.1% sought medical attention. The current study suggests that further research should be carried out on students from other disciplines and on students in other European universities to facilitate a greater understanding of the risk factors for computer-related MSS in undergraduate students.     

Ergonomic analysis of musculoskeletal discomforts among conversational VDT operators

VDT tasks are rapidly increasing as the office automation prevails. Despite its numerous benefits, occupational hazards such as visual fatigue, eye strain, radiation and musculoskeletal stresses have emerged as an important issue. This study was designed to investigate the effects of work postures and anthropometric differences upon the musculoskeletal stresses experience by operators involved in conversational VDT tasks. Evaluation of the level of muscoloskeletal discomfort was performed for 297 VDT operators from three divisions of telecommunication company in Korea. The ergonomic variables of the VDT tasks and the operators' anthropometric variables were evaluated for 70 out of the 297 VDT operators. Factor analysis is used for identifying underlying pattern of discomfort and multiple regression analysis were performed to examine the relationship between the measured ergonomic variables and the musculoskeletal discomfort. This study indicates that the ergonomic variables have influences on the musculoskeletal discomfort. It is important to provide the workers with fully adjustable workstations so that they can maintain their work postures most suitable for the sustained VDT work. Furthermore, in order to achieve the best working conditions, VDT operators should be given a proper training for the adjustment of their workstations.     

Effect of sports bra type and gait speed on breast discomfort,bra discomfort and perceived breast movement in Chinese women

This study investigated the effect of sports bra type (encapsulation versus compression) and gait speed on perceptions of breast discomfort, bra discomfort and breast movement reported by Chinese women. Visual analogue scales were used to evaluate breast discomfort, bra component discomfort and perceived breast movement of 21 Chinese participants when they wore an encapsulation or a compression sports bra, while static and while exercising at three different gait speeds. Participants perceived less breast discomfort and breast movement when wearing a compression bra compared to an encapsulation bra at a high gait speed, suggesting that compression bras are likely to provide the most effective support for Chinese women. However, significantly higher bra discomfort was perceived in the compression bra compared to the encapsulation bra when static and at the lower gait speed, implying that ways to modify the design of sports bras, particularly the straps, should be investigated to provide adequate and comfortable breast support.     

Analysis of the musculoskeletal system of the hand and forearm during a cylinder grasping task

Musculoskeletal disorders of the hand are mostly due to repeated or awkward manual tasks in the work environment and are considered a public health issue. To prevent their development, it is necessary to understand and investigate the biomechanical behavior of the musculoskeletal system during the movement. In this study a biomechanical analysis of the upper extremity during a cylinder grasping task is conducted by using a parameterized musculoskeletal model of the hand and forearm. The proposed model is composed of 21 segments, 28 musculotendon units, and 20 joints providing 24 degrees of freedom. Boundary conditions of the model are defined by the three-dimensional coordinates of 43 external markers fixed to bony landmarks of the hand and forearm and tracked with an optoelectronic motion capture system. External marker positions from five healthy participants were used to test the model. A task consisting of closing and opening fingers around a cylinder 25 mm in diameter was investigated. Based on experimental kinematic data, an inverse dynamics process was performed to calculate output data of the model (joint angles, musculotendon unit shortening and lengthening patterns). Finally, based on an optimization procedure, joint loads and musculotendon forces were computed in a forward dynamics simulation. Results of this study assessed reproducibility and consistency of the biomechanical behavior of the musculoskeletal hand system.     

Risk of neck musculoskeletal disorders among males and females in lifting exertions

Work-related neck disorders are common among various occupational groups. Despite clear epidemiological evidence for the association of these disorders with forceful arm exertions, the effect of such exertions on the biomechanical behavior of the neck muscles is currently not well understood. In this study, the effect of lifting tasks on the biomechanical loading of neck muscles was investigated for males and females. Twenty-six participants (13 males and 13 females) performed bi-manual isometric lifting tasks at knuckle, elbow, shoulder, and overhead heights by exerting 25%, 50%, and 75% of their maximum strength. The activity of the cervical trapezius and sternocleidomastoid muscles was recorded bilaterally using surface electromyography. Higher activity of the cervical trapezius muscle (10% MVC–43% MVC) compared to the sternocleidomastoid muscle (4% MVC–18% MVC) was observed. Females tend to use the sternocleidomastoid muscle to a greater extent than males, whereas, higher cervical trapezius muscle activation was observed for males than females. The main effect of weight and height, and weight by height interaction on the activity of neck muscles was statistically significant (all p < 0.001). The results of this study demonstrate that the neck muscles play an active role during lifting activities and may influence development of musculoskeletal disorders due to resulting physiological changes.     

The effect of work-rest schedules and type of task on the discomfort and performance of VDT users

Consideration of the literature survey indicates that video display terminal (VDT) operators tend to have a high incidence of musculoskeletal problems, visual fatigue, and job stress. Although a number of ergonomic improvements in workstation design and work environment can help to reduce these problems, a proper work-rest schedule deserves consideration since it is easily applicable and inexpensive. The objective of this study was to compare the work-rest schedules for VDT operators considering data entry and mental arithmetic tasks. An experiment was conducted with 10 male college students as participants. The methodology included a discomfort questionnaire and performance measures. The independent variables were the work-rest schedule (60-minute work/10-minute rest, 30-minute work/5-minute rest, and 15-minute work/micro breaks) and the type of task (data entry and a mental arithmetic task). The results were analysed using multiple analysis of variance followed by separate analyses. The 15/micro schedule resulted in significantly lower discomfort in the neck, lower back, and chest than the other schedules for data entry task. The 30/5 schedule followed by 15/micro schedule resulted in the lowest eyestrain and blurred vision. Discomfort in the elbow and arm was the lowest with the 15/micro schedule for the mental arithmetic task. The 15/micro schedule resulted in the highest speed, accuracy, and performance for both of the tasks, compared with the 60/10 and 30/5 schedules. The data entry task resulted in significantly increased speed, accuracy, and performance, and lower shoulder and chest discomfort than the mental arithmetic task.     

Musculoskeletal and visual symptoms among undergraduate students: Individual and computer-use-related risk factors and interference with academic performance

This study explored the prevalence and academic performance interference (API) of musculoskeletal symptoms (MS) and visual discomfort (VD), and investigated the associations of individual and computer-use-related risk factors with MS and VD among a group of university undergraduate students. The study involved first application of Student-Specific Cornell Musculoskeletal Questionnaire (SS-CMDQ) as a new tool to collect symptom data among student population. MS was found to prevail and interfere with ability to perform academic activities mostly in the neck, upper back and lower back with prevalence rates of 69.8%, 61.8% and 55.1%, respectively; and with API rates of 20.2%, 20.2% and 16.9%, respectively. The prevalence and API rates of VD were 62.9% and 33.7%, respectively. Among the investigated factors, being female, non-engineering academic concentration, years of computer use, daily computer use more than 4 h and experiencing visual discomfort during computer use were the significant risk factors.Relevance to industryStudents are prospective members of the computer work force. Taking proactive measures against musculoskeletal symptoms and visual discomfort will ensure a healthy and productive workforce in the future.     

State of science: occupational slips,trips and falls on the same level*

Occupational slips, trips and falls on the same level (STFL) result in substantial injuries worldwide. This paper summarises the state of science regarding STFL, outlining relevant aspects of epidemiology, biomechanics, psychophysics, tribology, organisational influences and injury prevention. This review reaffirms that STFL remain a major cause of workplace injury and STFL prevention is a complex problem, requiring multi-disciplinary, multi-faceted approaches. Despite progress in recent decades in understanding the mechanisms involved in STFL, especially slipping, research leading to evidence-based prevention practices remains insufficient, given the problem scale. It is concluded that there is a pressing need to develop better fall prevention strategies using systems approaches conceptualising and addressing the factors involved in STFL, with considerations of the full range of factors and their interactions. There is also an urgent need for field trials of various fall prevention strategies to assess the effectiveness of different intervention components and their interactions.

Practitioner Summary: Work-related slipping, tripping and falls on the same level are a major source of occupational injury. The causes are broadly understood, although more attention is needed from a systems perspective. Research has shown preventative action to be effective, but further studies are required to understand which aspects are most beneficial.     

Effects of combined wrist flexion/extension and forearm rotation and two levels of relative force on discomfort

This study investigated perceived discomfort in an isometric wrist flexion task. Independent variables were wrist flexion/extension (55%, 35% flexion, neutral, 35% and 55% extension ranges of motion (ROM)), forearm rotation (60%, 30% prone, neutral, 30% and 60% supine ROM) and two levels of flexion force (10% and 20% maximum voluntary contraction (MVC)). Discomfort was significantly affected by flexion force, forearm rotation and a two-way interaction of force with forearm rotation (each p < 0.05). High force for 60%ROM forearm pronation and supination resulted in increasingly higher discomfort for these combinations. Flexion forces were set relative to the MVC in each wrist posture and this appears to be important in explaining a lack of significant effect (p = 0.34) for flexion/extension on discomfort. Regression equations predicting discomfort were developed and used to generate iso-discomfort contours, which indicate regions where the risk of injury should be low and others where it is likely to be high. Regression equations predicting discomfort and iso-discomfort contours are presented, which indicate combinations of upper limb postures for which discomfort is predicted to be low, and others where it is likely to be high. These are helpful in the study of limits for risk factors associated with upper limb musculoskeletal injury in industry.     

Association of subjective ratings of slipperiness to heel displacement following contact with the floor

Falls precipitated by slipping are listed among the leading causes of occupational injuries. Several factors may influence the risk of slips and falls, including perception of surface conditions. The current research examined the relationship between perceptions of slipperiness and slip distance at heel strike. The investigation compared objective and subjective measures for 31 participants ranging in age from 19 to 67 years old. Subjective slipperiness ratings for several floor surface and walking velocity conditions were obtained. Small slips were not generally perceived, but a uniform slip distance threshold could not be identified due to the large variability in ratings. The Pearson correlation coefficient between slip distance and subjective ratings for slides (30-100mm) was r=-0.17. Results indicate that subjective ratings should be used cautiously as a measure of slipperiness, partially due to possible underestimation of slipperiness and the variability in perceptions.     

Feet kinematics upon slipping discriminate between recoveries and three types of slip-induced falls

This study investigated the relationship between feet kinematics upon slipping while walking and the outcome of the slip. Seventy-one slips (induced by walking over an unexpectedly slippery surface) were analysed, which included 37 recoveries, 16 feet-split falls, 11 feet-forward falls and seven lateral falls. Feet kinematics differed between recoveries and three types of slip-induced falls, and a discriminant model including six measures of feet kinematics correctly predicted 87% of slip outcomes. Two potentially modifiable characteristics of the feet kinematics upon slipping that can improve the likelihood of successfully averting a fall were identified: (1) quickly arresting the motion of the slipping foot and (2) a recovery step that places the trailing toe approximately 0–10% body height anterior to the sacrum. These results may inform the development of task-specific balance training interventions that promote favourable recovery responses to slipping.

Practitioner Summary: This study investigated the relationship between feet movements upon slipping and outcomes of the slip. Potentially modifiable characteristics that can reduce the likelihood of falling were: (1) quickly arresting slipping foot motion and (2) a recovery step that places the trailing toe approximately 0–10% body height anterior to the sacrum.     

Slipping of the foot on the floor when pulling a pallet truck

Workers pulling pallet trucks are likely to slip when pulling and stepping on a low-friction floor. This study investigated the slipping of male participants when pulling a pallet truck, walking backward, and stepping on either a dry, wet, or glycerol-contaminated vinyl surface. The weight of the load on the truck was either low (0 kg), medium (295 kg), or high (568 kg). A motion-tracking system was used to collect the three-dimensional coordinates of the markers on the shoes. It was found that subjects might slip either upon landing of the leading foot on the toe (slip I) or before taking off of the lagging foot on the heel (slip II). The results indicated that the slip distances for both types of slip were significantly affected by the load and surface conditions and their interactions. Micro-slips (slips between 0.1 and 3 cm) and midi-slips (slips between 3 and 10 cm) were more common in slip I than in slip II. On glycerol-contaminated surfaces, the probabilities of a slide, or a slip more than 10 cm, for both slips I and II were over 40%. The implications of the results were discussed.