The effect of individually adjusted workstations on upper quadrant posture and muscle activity in school children

Evidence suggests there is increasing use of computers by children and poor workstation designs for children. This laboratory study investigated the effect of adjusting computer display height and desk height on upper quadrant posture and muscle activity. Thirty three children aged 4-17 years worked on a desktop computer at a standard school workstation and at a workstation adjusted to the individual, typically consisting of a lower display and desk height. The adjustments resulted in increased head tilt, neck flexion, gaze angle, cervical erector spinae activity and a trend for lower right upper trapezius activity. The recent evidence that suggests more head and neck flexion is not necessarily worse is discussed and normative values for children's head tilt and neck flexion presented. The role of forearm support in decreasing trapezius activity is also discussed.     

Postural assessment of school children: an input for the design of furniture

During the last decades of the previous century, school desks with a tilt top have disappeared. The chairs have been designed for sitting upright, with the hip, knees and ankles all at right angles. However, the erect posture cannot be maintained for more than one or two minutes, after which it will result in fatigue, discomfort or poor posture. The main aim of project is to identify the type of furniture that most effectively contribute to adequate neck and back postures of the school children, by carrying out a postural analysis of a sample of school pupils when using three different types of furniture. The postures adopted by school pupils were monitored by video during several activities, such as reading, writing and painting tasks, copying from a blackboard and listening the teacher. Additionally, the characteristics of the adopted postures were assessed by registering the head tilt, flexion of the neck, trunk and hips position. All these aspects were classified and the results were recorded for future analysis. The obtained results seem to point out that the use of a school desk with a tilted table surface resulted in a reduction in trunk and neck flexion, preserving the natural lordosis in the lumbar and cervical regions. Accordingly, it can be concluded that there are alternatives to consider in the furniture design in order to eliminate tensions and, consequently, to improve children's wellbeing.     

Eye- and neck/shoulder-discomfort during visually demanding experimental near work

Frequent use of digital information technology has an impact on eye- and neck/shoulder-discomfort. Studies with cross sectional and intervention design indicate an association between the two symptom categories. Still, whether visually demanding near work, per se, contributes to increased neck/shoulder discomfort remains a question of debate. The aim of this laboratory study was to assess if visually demanding experimental near work affects eye- and neck/shoulder-discomfort when the posture was adjusted for comfort and no movements were allowed. Thirty-three healthy subjects performed a visually demanding computer screen task (viewing task) under four different optical lens conditions: binocular -3.5 D and monocular -3.5 D, +3.5 D and ± 0 D. During the experiment subjects were seated in an office chair (with neck support) that was individually adjusted for comfort. At baseline and after each viewing task, subjects reported their perceived eye- and neck/shoulder discomfort on Borg's CR-10 scale. Results show a significant increase of eye discomfort between baseline and the first viewing task, and a significant increase in neck/shoulder discomfort from baseline throughout the first three viewing tasks. Further analysis is required to determent whether the neck/shoulder discomfort was induced by the demanding near work or the static posture, or a combination.     

Quantitative posture analysis of 2D, 3D, and optical microscope visualization methods for microsurgery tasks

The purpose of this paper is to present a quantitative posture analysis of microsurgery tasks performed with different visualization methods. Microsurgery is traditionally performed using a binocular microscope; however surgeons are constrained by the optical eyepieces and are forced to assume joint angles that deviate away from neutral postures. This may be especially problematic for the neck and can increase surgeon discomfort and fatigue. Alternative visualization methods may improve surgeon posture by eliminating the constraints imposed by the microscope. This study examines both 2D and 3D heads-up displays as possible alternatives. Six subjects performed microsurgical tasks with each visualization methods for four hours. Quantitative posture analysis was done using Maxtraq software that tracks reflective markers on the subjects. The initial analysis of neck, upper arm, and elbow angles found significant differences between each display. A biomechanical analysis found that the differences in angles can result in loads on the neck joint that are twice as high in the microscope than the headsup displays. Although the alternative displays can result in better postures, improvements the display technology is needed to improve microsurgical task performance.     

Evaluation of a personal device in reducing the risk of low back disorders during stooped work

Adoption of the stooped posture in the workplace is widespread throughout the world in agriculture, construction, and mining. This type of posture has been established as a risk factor for developing low back disorders (LBDs). The purpose of this study is to evaluate a personal weight transfer device as a possible intervention to reduce the load on the lumbar spine, thereby reducing the risk of developing LBDs. Eighteen healthy subjects performed stooped posture tasks in a laboratory study designed to simulate harvesting of low-growing crops. Results showed that when wearing the device in the static stooped posture, biceps femoris activity was reduced by 17%, lumbar flexion was reduced by 12%, ankle plantar-flexion increased by 5%, and the lumbar erector spinae of those subjects who did not experience flexion-relaxation of the erector spinae was reduced by 26%. Hip and knee flexion were not significantly altered. Therefore, the device may be beneficial for those with existing LBDs, and who use the stooped posture routinely.     

Long-term effects of forearm support: computer users working at conventional desks

Recent research has demonstrated that forearm support might be preferable to working in the traditional "floating" posture for computer users. A previous field study in a call centre reported a significant decrease in discomfort following 12 weeks of using a conventional desk for forearm support. The aim of this follow up study was to determine the long-term effect (21 months post intervention) of forearm support on reported musculoskeletal discomfort in the previous sample of intensive computer users. METHODS: The follow-up sample consisted of 33 females and 2 males (59% of original group). Data were collected via self-report questionnaires and workstation assessments. RESULTS: Despite a significant reduction in discomfort for most body regions following the initial intervention, the only significant decrease in discomfort over 21 months was for the neck. Reported discomfort for all other body regions had decreased, apart from the shoulder in which there was a reported increase in discomfort. The results of this follow up study indicate that forearm support has a positive effect on the reduction of neck discomfort. The increase in shoulder discomfort indicates that a concave desk may be preferable to the conventional desk if the forearm support posture is to be adopted.     

Back pack injuries in Indian school children: risk factors and clinical presentations

The use of backpack increased substantially among the school children. Studies have shown that carrying a backpack cause to develop different symptoms of musculoskeletal disorders among the carrier of the backpack. In India there are fewer studies available in literature which explains the musculoskeletal discomfort among the school children. This study aimed at to find out the prevalence of different musculoskeletal problems among the school children. In a retrospective study data were collected for twenty two students. The main diagnostic criteria were pressure mark (redness or swelling) over neck and shoulder corresponding to the straps of the backpack, stooping posture while carrying the back pack, pain or stiffness in the neck, upper back and shoulders predominantly while carrying the back pack and absence of these symptoms during school holidays. Results revealed that pain in the upper back (40%), neck (27%) and shoulder (20%) were most prevalent body regions followed by forearm and wrist pain (7%) and low back (6%). Results further revealed that all the students participated in this study have a pressure mark over shoulder. 54.55% of the children were diagnosed with myofascial pain and rest with thoracic outlet syndrome.     

The effect of ergonomic intervention on neck/shoulder and low back pain

The aim of this study was to examine the effect of two types of ergonomic intervention on pain and pain-related disability in the neck/shoulder and low back regions. A cohort of 492 subjects of various occupations with non-specific neck/shoulder or low back pain was followed over a five to six year period. The study subjects were classified into four intervention groups: no ergonomic intervention, educational worksite intervention, workplace intervention, and combined workplace and educational worksite intervention. The group with no ergonomic intervention was used as the reference group. The changes in pain intensity and pain-related disability from baseline to follow-up in each of the three groups with intervention were compared to the changes in the reference group. During the follow-up, 39% of the subjects had received ergonomic intervention. The average change in pain intensity and pain-related disability was smaller in the educational worksite intervention group than in the reference group. The average reduction of pain intensity and pain-related disability did not differ between the two other intervention groups and the reference group. Thus, for subjects still at work, ergonomic intervention seemed to be ineffective for reducing neck/shoulder and low back pain and pain-related disability.     

Ergonomic evaluation of conventional and improved methods of aonla pricking with women workers

Conventional and improved methods of aonla pricking were evaluated ergonomically on an experiment conducted for 20 minute with women workers. The working heart rate, energy expenditure rate, total cardiac cost of work and physiological cost of work with conventional tools varied from 93-102 beats.min-1, 6-7.5 kJ.min-1, 285-470 beats, 14 -23 beats.min-1 while with machine varied from 96-105 beats.min-1, 6.5-8 kJ.min-1 , 336-540 beats, 16-27 beats.min-1 respectively. OWAS score for conventional method was 2 indicating corrective measures in near future while with machine was 1 indicating no corrective measures. Result of Nordic Musculoskeletal Questionnaire revealed that subjects complaint of pain in back, neck, right shoulder and right hand due to unnatural body posture and repetitive movement with hand tool. Moreover pricking was carried out in improper lighting conditions (200-300 lux) resulting into finger injuries from sharp edges of hand tool, whereas with machine no such problems were observed. Output with machine increased thrice than hand pricking in a given time. Machine was found useful in terms of saving time, increased productivity, enhanced safety and comfort as involved improved posture, was easy to handle and operate, thus increasing efficiency of the worker leading to better quality of life.     

Ergonomic evaluation of novel tool for snap-off the neck of ampoule

Needlestick and Sharps Injuries (NSI) represent an important workplace issue in contemporary health care. Present study provided the new method to snap-off the neck of sealed ampoule. The idea of novel opener tool is prepare the grinding slice inside rubber ring, so users could put the ampoule inside the rubber ring and then rotated the rubber ring to snap-off the neck of ampoule. The purpose of present study was evaluated the methods of snap-off and sizes of ampoule on forearm muscle activities, wrist postures and performance. The pronator teres muscle were heavier load as increased the sizes of ampoule. For performance analysis, Duncan's multiple range tests indicated that time of snap-off were longer in 10 ml and 20 ml of ampoule. The EMG of pronator teres muscle was significantly affected by methods of snap-off. Duncan's multiple range tests indicated that lower load was experienced on forearm muscles while using grinding slice with glove. For wrist posture, the ranges of motion for wrist were significant lower while using the novel tool. Present study provided the novel tool effectively to snap-off the ampoule to decrease forearm workload and sharp injuries.     

Musculoskeletal symptoms among dentists in relation to work posture

OBJECTIVE: To determine the effect of work posture on musculosketal complaints in Israeli dentists. METHODS: The population included 60 male dentists mean age was 46.0 (+/- SD 8.66), 30 worked in sitting position and 30 were altering positions. Study population completed the standardized Nordic questionnaire and informative form concerning recipient's practice of dentistry, bio-demographic variables and questions about workloads. RESULTS: Musculoskeletal symptoms in the last 12 months were localized primarily in the lower back and in the neck (55% and 38.3% respectively). There was a significant correlation between the time spent sitting and the severity of low back pain (r = 0.41, p = 0.01). On the other hand there was no significant correlation between time spent sitting and other musculoskeletal complaints (r = - 0.16). CONCLUSIONS: Dentists who work in the sitting position have more severe low back pain than do those who alternate between sitting and standing despite the fact that those who sat at least 80% of the time worked less hours and had less of a workload during their working hours. This suggests that altering position should be recommended to dentists. An intervention study, however, is needed to demonstrate that changing posture will decrease the prevalence of low back pain in dentists.     

Cost-efficient observation of working postures from video recordings--more videos, more observers or more views per observer?

In ergonomics, assessing the working postures of an individual by observation is a very common practice. The present study investigated whether monetary resources devoted to an observational study should preferably be invested in collecting many video recordings of the work, or in having several observers estimate postures from available videos multiple times. On the basis of a data set of observed working postures among hairdressers, necessary information in terms of posture variability, observer variability, and costs for recording and observing videos was entered into equations providing the total cost of data collection and the precision (informative value) of the resulting estimates of two variables: percentages time with the arm elevated <15 degrees and >90 degrees. In all 160 data collection strategies, differing with respect to the number of video recordings and the number of repeated observations of each recording, were simulated and compared for cost and precision. For both posture variables, the most cost-efficient strategy for a given budget was to engage 4 observers to look at available video recordings, rather than to have one observer look at more recordings. Since the latter strategy is the more common in ergonomics practice, we recommend reconsidering standard practice in observational posture assessment.     

Effectiveness of an educational intervention to increase knowledge and reduce use of risky behaviors associated with cumulative trauma in office workers

OBJECTIVE: This pilot project assessed the effectiveness of an intervention to increase knowledge and reduce risky behaviors related to cumulative trauma disorders (CTD) in office workers. STUDY DESIGN: All 124 employees from the administrative offices of a health maintenance organization were invited to participate. Subjects were followed across time using an identification number. Data were collected via questionnaire in June 1994 (pretest1) (N=84), August 1994 (pretest II) (N= 63) and September 1995 (posttest) (N=40). The yearlong intervention focused on functional activities to prevent CTD. RESULTS: of chi-square analyses for the 40 subjects who completed all surveys indicated this intervention significantly increased overall knowledge of CTD (p =.002). Significant changes in self-reported hand/wrist (p =.016) and neck/shoulder (p =.003) posture were also found. CONCLUSIONS: This study is a first step in identifying effective educational interventions to increase knowledge and reduce risk factors related to CTD in office workers.     

Effects of pushing height on trunk posture and trunk muscle activity when a cart suddenly starts or stops moving

Unexpected sudden (un)loading of the trunk may induce inadequate responses of trunk muscles and uncontrolled trunk motion. These unexpected perturbations may occur in pushing tasks, when the cart suddenly starts moving (unloading) or is blocked by an obstacle (loading). In pushing, handle height affects the user's working posture, which may influence trunk muscle activity and trunk movement in response to the perturbation. Eleven healthy male subjects pushed a 200 kg cart with handles at shoulder and hip height in a start condition (sudden release of brakes) and a stop condition (bumping into an obstacle). Before the perturbation, the baseline of the trunk inclination, internal moment and trunk extensor muscle activity were significantly higher when pushing at hip height than at shoulder height. After the perturbation, the changes in trunk inclination and internal moment were significantly larger when pushing at shoulder height than at hip height in both conditions. The opposite directions of changes in trunk inclination and internal moment suggest that the unexpected perturbations caused uncontrolled trunk motion. Pushing at shoulder height may impose a high risk of low-back injury due to the low trunk stiffness and large involuntary trunk motion occurring after carts suddenly move or stop.     

Adoption of ergonomic features in a new reach truck cabin design--a usability study

The task of handling reach trucks frequently involves poor working postures. The location of the steering wheel in most reach trucks is in front of the operator which requires the drivers to bend forward and stretch their hands for holding onto the steering wheel. To overcome visibility restrictions, this posture is aggravated by twisting and bending their torso sideways. This paper presents a usability study which was conducted to compare adoption of ergonomic features in a new reach truck cabin with the way they were intended to be employed for improving physical working conditions. Participants drove the reach truck on a test track performing tasks of varying complexity. Video recordings were utilized to facilitate the observations. The results indicate that improved ergonomics features of the reach truck are not used as intended. The test subjects instead adopted postures that they were accustomed to when driving common reach trucks. The possible contributing factors to this posture regression are discussed. The procedure used in this study is recommended for the companies to determine the effectiveness and adoption of ergonomics solutions.     

Prevalence of musculoskeletal disorders among staffs in specialized healthcare centre

This study was conducted to investigate pervasiveness of the musculoskeletal disorder (MSD) among staffs in a specialized healthcare centre. Sixty-eight staffs from three departments namely Cardiovascular Lab (CVL), Nuclear Radiology, and General Radiography were recruited in this study. A modified Nordic Musculoskeletal Questionnaire (NMQ) was distributed among study population. The result shows that the prevalence of MSD was highest in lower back (88.2%), neck (76.5%) and shoulder (60.3%) for the past 12 months followed by lower back and elbow (44.1%), and wrist (39.1%) correspondingly, for the past 7 days. Present results suggest that healthcare professionals - radiographers, patient assistants and nurses incurs MSD risks through work tasks as well as psychosocial factors. These include awkward posture during patient handling, workload, work stress and time pressure. Therefore, an ergonomics improvement on the job design and workspace are needed in order to reduce the MSD risks.     

Factors contributing to work related low back pain among personal care workers in old age

This study aims to preliminary explore the work related and individual factors that contributed to the occurrence of low back pain (LBP) that affected work activities of Personal Care Workers (PCWs). A cross-sectional study was conducted to 36 PCWs in an old age home of Hong Kong. The study is divided into three parts: 1) a questionnaire to document the workload exposure factors and the musculoskeletal symptoms survey of the PCWs, 2) work posture evaluation; and 3) an evaluation of the physical fitness and lifting capacity of the PCWs. Univariate analyses were used to explore the risk factors associated with LBP that affected work activities. The results indicated that individual physical profile and lifting capacities did not contribute to occurrence of low back pain at work. For the work demand factors, the perceived physical demands in lifting and lowering heavy objects, awkward sustain neck and back postures, loading on the back, and perceived effort of cleaning task contributed to the occurrence of LBP. For the physical environment factors, thermal stress and improper ventilation were associated with the occurrence of LBP cases. For the individual factor, LBP cases were associated with workers' self perceived muscular effort, and perceived risk of mental illness in response to work requirements.     

Ergonomic evaluation in a values transportation company in Venezuela

The objective was to analyze the work activity and identify risk factors that could account for musculoskeletal disorders in the upper extremities, shoulder and neck of workers of a transport values company in Venezuela. The methods used were: collective interview, tasks observation, evaluation of posture with RULA method and evaluation of repetitive motions with the OCRA method. Five workstations were evaluated. Main problem perceived by workers was: exposure to chemical and biological hazards when handling paper money and coins; inadequate chairs and close supervision. The postures level risk was 1 or 2 for the RULA scale. Only two workstations showed ligth and medium risk level by OCRA method. Conclusion: The factors identified that could explain the musculoskeletal changes were: wrist repetitive flexion and extension, shoulder elevation, lifting weight above shoulder height, elbow repetitive flexion and extension, neck flexion, extended work journey, work overload, high responsibility and strict supervision by a video camera.     

An analysis of VDT monitor placement and daily hours of use for female bifocal users

A population of 72 bifocal wearers was studied to determine the relationship between VDT (video display terminal) placement for those who reported musculoskeletal pain and those who did not. The mean hours worked was 50.4 minutes (p=0.003) greater for those who reported head/neck pain versus those who did not and 48.6 minutes (p=0.004) greater for those who reported shoulder/arm pain that those who did not. There was no statistically significant difference between the means of monitor height, distance, or angle for those who reported pain symptoms versus those who did not. This study indicates that, self reported pain symptoms are correlated with hours of VDT work and that there appears to be a threshold at approximately five hours for pain symptoms among bifocal wearers. No such correlation can be made for monitor placement