Work - Volume 39, issue 2

Article Type: Other

DOI: 10.3233/WOR-2011-1154

Citation: Work, vol. 39, no. 2, pp. 89-89, 2011

Article Type: Other

DOI: 10.3233/WOR-2011-1155

Citation: Work, vol. 39, no. 2, pp. 91-92, 2011

Authors: Nainzadeh, Nahid K. | Ilizarov, Svetlana | Piligian, George | Dropkin, Jonathan | Breyre, Amelia

Article Type: Research Article

Abstract: Objective: This case series sought to determine the prevalence of ulnar neuropathy at the elbow (UNE) by using electrophysiologic criteria among all computer keyboard operators (CKOs) referred over a four-year period (1995–1999) for electrodiagnosis (EDX) due to clinical suspicion of focal upper limb neuropathies. Participants: All CKOs referred to an EDX laboratory for suspicion of focal upper limb neuropathies primarily from private practice physicians, mostly hand surgeons, and an occupational medicine clinic. …Methods: All 148 CKOs underwent NCV studies of the upper limbs, which included segmental studies of the ulnar nerve and were questioned for the presence and distribution pattern of paresthesias in the symptomatic upper limb(s). The CKOs provided the electromyographer with subjective descriptions of their workstation configuration, layout, and basic office equipment. Results: Focal ulnar neuropathy at the elbow (UNE) was identified in 105 out of 148 CKOs referred to an EDX laboratory for clinical suspicion of upper limb focal neuropathies. Conclusions: Compared with the more prevalent diagnosis of carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow should also be considered among CKOs referred for EDX testing because of suspicion of focal upper limb neuropathies. Clinicians evaluating CKOs for suspicion of focal upper limb neuropathies should routinely ask about symptoms of ulnar neuropathy. Show more

Keywords: Ulnar neuropathy at the elbow, computer keyboard operators, cubital tunnel syndrome

DOI: 10.3233/WOR-2011-1156

Citation: Work, vol. 39, no. 2, pp. 93-101, 2011

Authors: Stone, Amy | Marklin, Richard | Seeley, Patricia | Mezei, Gabor

Article Type: Research Article

Abstract: As part of a collaborative approach involving electric utility companies, university researchers, individual contractors and a not-for-profit research institute, two ergonomics teams consisting of skilled utility workers and trained ergonomists, were assembled. These teams were to identify tasks with risk factors for musculoskeletal disorders (MSDs) among workers in fossil-fueled generating stations and and to propose ergonomic interventions for these tasks. One team focused on tasks of electricians and the other focused on …tasks of plant operators and mechanics. Several of the tasks were tested in an ergonomics laboratory and at one of the utility's generating stations. We present a sample of the recommended interventions in this paper. An anthropometric analysis of electrical box height recommended the appropriate height for electrical boxes. The results of a field experiment showed that low rolling resistance wheels decreased the forces to initiate and sustain pushing a cart. The same experiment also demonstrated that the forces required to turn a cart with six wheels were lower than the forces equired to turn a cart with four wheels. A collaborative approach to ergonomics proved to be an effective method to identify and assess tasks that are problematic for workers and to develop best practices for these tasks in the electric power industry. This method could be used by other industries in their attempt to decrease the incidence, cost and severity of workplace MSDs. Show more

Keywords: Alliance, collaboration, musculoskeletal disorders, partnership

DOI: 10.3233/WOR-2011-1157

Citation: Work, vol. 39, no. 2, pp. 103-111, 2011

Authors: Harbin, Gary L. | Shenoy, Catherine | Garcia, Amy | Olson, John C.

Article Type: Research Article

Abstract: Objective: This study is an interventional evaluation of a post-offer employment testing. The study is designed to determine if shoulder injury rates are lowered when employees are placed at jobs they demonstrate the physical ability to perform. Methods: A physical capacity evaluation based testing protocol was utilized to determine if each new employee had the physical work capacity to perform the job for which they were hired. Injuries to the shoulder were specifically scrutinized. …The interventional group was compared to a historical control. Results: The incidence of shoulder injuries was 0% in the tested group and 3.8% in the untested historical control. Over a 6 year study timeframe the utilization of physical capacity testing for work placement appeared to be the major factor in decreasing work related shoulder injuries. The annual cost of administering the tests for three years was $9,543, while the net annual cost savings was $124,451. This represented a 37% decrease in medical costs for shoulder and other work-related injuries. For every dollar spent on testing there was a $14 savings in medical costs secondary to injury prevention. Conclusion: The use of post-offer physical capacity testing resulted in a substantial and noticeable decrease in shoulder related non-accidental injuries. Furthermore, it is evident that a properly conceived and implemented post-offer testing program may help in the reduction of work-related injuries. Show more

Keywords: Occupational accidents, work capacity evaluation, workload, fitness to work

DOI: 10.3233/WOR-2011-1158

Citation: Work, vol. 39, no. 2, pp. 113-123, 2011

Authors: Marshall, Jennifer | Wells, Richard

Article Type: Research Article

Abstract: Objective: Tarping and untarping loads on flatbed trailers creates concerns related to falls as well as high musculoskeletal demands. The purpose of this study is to compare the demands and risks present when using three different tarping systems and to determine which system is preferred to reduce demand and injury risks. Participants: Nine male volunteers from a flatbed trucking company participated in the study. Methods: The truck drivers covered the load on the flatbed trailer using …three different tarping systems: manual tarps, sliders, and rack and tarp kits. Multiple measures were used to characterize the three tarping systems, including required forces, identifying injury risk by assessing peak, average and cumulative forces, moments and electromyography, heart rate, and exposure to fall hazards. Results: Manual tarping resulted in greater physical demands and safety risks than the two alternate systems, both of which all participants preferred. The slider method was preferred overall as it has numerous advantages. Conclusions: The slider and rack and tarp kit methods offered a wide range of benefits including reduced physical demands, reduced exposure to fall hazards as well as improved productivity due to the shorter execution times, but had the disadvantage of being less versatile. Show more

Keywords: Transportation industry, musculoskeletal disorders, fall hazards, ergonomic assessment, workplace intervention research

DOI: 10.3233/WOR-2011-1159

Citation: Work, vol. 39, no. 2, pp. 125-140, 2011

Authors: Lenker, James A. | Nasarwanji, Mahiyar | Paquet, Victor | Feathers, David

Article Type: Research Article

Abstract: Background: While there are many available tools and methods to evaluate product usability, few have been tested on user groups with disabilities and even fewer systematically consider universal design principles. Objective: This paper describes the development and preliminary psychometric testing of the Rapid Assessment of Product Usability & Universal Design (RAPUUD), a 12-item user-report tool based on the seven principles of universal design. Method: A preliminary set of items was created to …elicit ratings of diverse product characteristics (e.g., physical effort, cognitive effort, assistance required, safety). Data were gathered from 61 participants who rated the usability of products they use in their own environments. Results: Each item elicited a full range of responses, with no apparent floor or ceiling effects. Collectively, the 12 items achieved a high internal consistency (Cronbach's α = 0.80). The data indicate that the tool was sensitive to differences in functional abilities, as well as differences in product characteristics. The instrument was usable for a range of consumer products, though not all items were appropriate for each and every product. Conclusion: The results suggest that the instrument could become a pragmatic tool for designers to identify usability problems experienced by a diversity of user populations. Show more

Keywords: Universal design, usability, consumer products, measurement, special populations, disability

DOI: 10.3233/WOR-2011-1160

Citation: Work, vol. 39, no. 2, pp. 141-150, 2011

Authors: Asundi, Krishna | Odell, Dan

Article Type: Research Article

Abstract: Objective: This article aims to provide designers and researchers with a summary of the current literature regarding the effects of specific keyswitch design parameters on user preference, performance, and biomechanical outcomes. Methods: Studies which evaluated the effects of keyswitch make force, make travel and over travel on preference, typing speed, errors, keyboard reaction forces and upper extremity EMG are included in the review. Studies which examined possible control strategies employed during keyswitch …tapping are also covered. Results: General conclusions that can be drawn from these studies are: greater make forces result in increased keyboard reaction forces and EMG activity, users strike keys with forces 2–7 times the required make force and that they employ a ballistic finger motion to do so. Furthermore, typists tend to prefer kinesthetic and auditory feedback. Conclusions: Due to the ballistic nature of typing, new keyswitch designs should be aimed at reducing impact forces. Future studies should examine the role of breakaway force and over travel as limited research has been done on the role of these parameters. Show more

Keywords: Typing force, human computer interaction, biomechanics

DOI: 10.3233/WOR-2011-1161

Citation: Work, vol. 39, no. 2, pp. 151-159, 2011

Authors: Tsiros, Margarita D. | Grimshaw, Paul N. | Shield, Anthony J. | Buckley, Jonathan D.

Article Type: Research Article

Abstract: Objective: To critically appraise the Biodex System 4 isokinetic dynamometer for strength assessment of children. Methods: Appraisal was based on experiences from two independent laboratories involving testing of 213 children. Issues were recorded and the manufacturer was consulted regarding appropriate solutions. Results: The dynamometer had insufficient height adjustment for alignment of the knee for some children, requiring the construction of padding to better fit the child within the dynamometer. …Potential for entrapment of the non-testing leg was evident in the passive and eccentric modes and a leg bracket restraint was constructed. Automated gravity correction did not operate when protocols were linked or data was exported to an external device. Conclusions: Limitations were noted, some of which were applicable to knee strength testing in general and others which were specific to use with children. However, most of these obstacles could be overcome, making the Biodex System 4 suitable for assessment of knee strength in children. Show more

Keywords: Child, quadriceps, muscle strength, ergonomics, critical appraisal

DOI: 10.3233/WOR-2011-1162

Citation: Work, vol. 39, no. 2, pp. 161-167, 2011

Authors: Dale, Ann Marie | Rohn, A.E. | Burwell, A. | Shannon, W. | Standeven, J. | Patton, A. | Evanoff, B.

Article Type: Research Article

Abstract: Objective: Occupational use of vibrating hand tools contributes to the development of upper extremity disorders. While several types of vibration damping materials are commercially available, reductions in vibration exposure are usually tested in the laboratory rather than in actual work environments. This study evaluated reductions in hand vibration with different vibration damping interventions under actual work conditions. Methods: Three experienced sheet metal assemblers at a manufacturing facility installed sheet metal …fasteners with a pneumatic tool using no vibration damping (bare hand) and each of six anti-vibration interventions (five different gloves and a viscoelastic tool wrap). Vibration was measured with tri-axial accelerometers on the tool and the back of the hand. Results: Unweighted mean vibration measured at the hand showed reduced vibration (p< 0.001) for all six interventions (range = 3.07–5.56 m/s^{2} ) compared to the bare hand condition (12.91 m/s^{2} ). Conclusions: All of the interventions were effective at reducing vibration at the hand during testing under usual work conditions. Field testing beyond laboratory-based testing accounts for the influences of worker, tools, and materials on vibration transmission to the body from specific work operations. Show more

Keywords: Hand-arm vibration, ergonomic intervention, exposure reduction

DOI: 10.3233/WOR-2011-1163

Citation: Work, vol. 39, no. 2, pp. 169-176, 2011

Authors: Lichty, Monica G. | Janowitz, Ira L. | Rempel, David M.

Article Type: Research Article

Abstract: Repetitive pipetting is a task that is associated with work-related musculoskeletal disorders of the hand and arm. Objective: The purpose of this study was to evaluate the usability and ergonomic performance of commercially available pipettes as determined by user ratings and objective measurements. Participants: Participants were laboratory technicians and scientists at the Lawrence Berkeley National Laboratory with experience performing pipetting tasks. Methods: Twenty-one experienced pipette users …completed a standardized pipetting task with 5 manual and 5 electronic pipettes. After using each pipette, the user rated it for attributes of comfort and usability. Results: Although no single pipette was rated significantly better than all of the others for every attribute tested, some significant differences were found between pipettes. The Rainin Pipet-Lite received the highest overall quality score among manual pipettes, while the Thermo Scientific Finnpipette Novus was the top-ranked electronic pipette. Features correlated with greater hand and arm comfort were lower tip ejection force, lower blowout force, and pipette balance in the hand. Conclusions: The findings, when considered with participant comments, provide insights into desirable pipette features and emphasize the value of user testing and the importance of the interactions between task, workplace layout, and pipette design. Show more

Keywords: Laboratory, usability testing, tool design, biotechnology

DOI: 10.3233/WOR-2011-1164

Citation: Work, vol. 39, no. 2, pp. 177-185, 2011

Authors: Asundi, Krishna | Johnson, Peter W. | Dennerlein, Jack T.

Article Type: Research Article

Abstract: Objective: Compare wrist kinematics and typing force during computer work across two workstations, one configured according to recommended guidelines with the keyboard support surface flat and near resting elbow height, the other according to users' actual setup and preference, with an elevated, and positively tilted support surface. Participants: Twenty participants completed a standard computer task at the two workstation configurations. Methods: A thin profile force plate, placed under the …keyboard recorded keyboard reaction forces. Twin axis electro-goniometers (SG65 Biometrics Ltd, London, UK) affixed to the back of the right and left hand of each subject continuously measured wrist extension/flexion and ulnar/radial deviation. Results: Typing force and wrist kinematics were similar between the two configurations with only 10th percentile ulnar deviation for the right hand showing a borderline significant difference of 1° between the two configurations. Conclusion: Elevating and tilting the input device support surface does not necessarily affect typing force and kinematics of the wrist. The combination of the input device support surface and user upper extremities form a complex kinematic system with several degrees of freedom. Wrist postures during computer use are a function of multiple factors other than simply keyboard tilt. Show more

Keywords: Computer workstation, physical risk factors, musculoskeletal disorders

DOI: 10.3233/WOR-2011-1165

Citation: Work, vol. 39, no. 2, pp. 187-193, 2011

Authors: Rempel, Paul | Janowitz, Ira | Alexandre, Melanie | Lee, David L. | Rempel, David

Article Type: Research Article

Abstract: Objective: Pipetting involves static upper arm positions with the pipette held away from the body for sustained periods of time, putting increased musculoskeletal load on the shoulder and upper back. This study explores the effect of using two alternative arm supports while pipetting on muscle loading in the shoulder/neck region. Participants: 15 experienced pipette users participated in this study. Methods: In a repeated-measures design, participants performed simulated pipetting in a laboratory setting …under three arm support conditions: (1) a gel pad on the work surface, (2) a freely-moving counter-balanced forearm support, and (3) no support (control). Surface electromyography (EMG) of the anterior deltoid and upper trapezius muscles were recorded, as well as productivity and subjective usability. Results: Both arm support conditions resulted in significantly lower mean muscle activity of the anterior deltoid and upper trapezius muscles (p< 0.001) and significantly higher subjective comfort ratings (p< 0.001) compared to the control condition. The freely moving forearm support resulted in significantly lower peak muscle activity in the anterior deltoid compared to the control condition (p< 0.001). Productivity was not affected by the arm supports. These findings suggest that arm support may be beneficial in reducing muscle loading and improving comfort in the shoulder and upper back during pipetting. Future studies are needed to measure the impact of these arm supports in the workplace. Show more

Keywords: Electromyography (EMG), musculoskeletal disorders (MSD), ergonomics

DOI: 10.3233/WOR-2011-1166

Citation: Work, vol. 39, no. 2, pp. 195-200, 2011