Work - Volume 47, issue 1

Authors: David M. Andrews,

Article Type: Other

DOI: 10.3233/WOR-131759

Citation: Work, vol. 47, no. 1, pp. 1-3, 2014

Authors: Costigan, Patrick A. | Morin, Evelyn L. | Reid, Susan A.

Article Type: Research Article

Abstract: OBJECTIVE: In this paper, Dr. Joan Stevenson's work on assessment of the effects of lifting, supporting and transporting loads is reviewed. A defining attribute of this work is the use of objective, biomechanical measures as the basis from which a fuller understanding of all factors affecting worker performance can be obtained, and how such performance should be measured and evaluated. METHODS: The central objectives and conclusions of Dr. Stevenson's research programs spanning the years …from 1985 through 2012 are summarized and discussed in terms of an overall research trajectory. CONCLUSIONS: The guiding principle of Dr. Stevenson's work is to reduce the potential harm to which workers are exposed through the development of bona fide occupational standards, a better understanding of risk factors leading to low back pain, and the establishment of an enhanced objective design process for functional load-bearing clothing and equipment. Show more

Keywords: Occupational standards, low back pain, load bearing, biomechanical measures, ergonomic design, objective quantitative assessment

DOI: 10.3233/WOR-131688

Citation: Work, vol. 47, no. 1, pp. 5-13, 2014

Authors: Abdoli-E, Mohammad | Damecour, Caroline | Petersen, Anne | Potvin, Jim

Article Type: Research Article

Abstract: BACKGROUND: In industrial supply companies, the pressure for productivity can conflict with the ergonomic safety of material handling on the loading dock, with workers tending to rush through the lifting tasks at the expense of higher biomechanical loads. OBJECTIVE: The purpose of this investigation was to determine: a) the potential benefit of introducing an ergonomic safety initiative, which slows the speed of lifting, and b) the need to use more complex biomechanical models in …work assessments. PARTICIPANTS: One experienced worker and nine university male students between the ages of 22 and 42 participated in this study; all reported no recent history of musculoskeletal injuries. METHODS: The investigation involved stacking empty propane cylinders, one on top of the other, while using a single-handed lift at a self-selected slow and fast pace, and lifting small, weighted beverage bottles at a slow, medium and fast pace, this time using a metronome to set the pace. RESULTS: The results demonstrated a significant main effect for lift pace for both peak static and dynamic external moments at the shoulder and at L4/L5, with a larger effect occurring with the lighter loads. A reduction in peak acceleration with heavier weights partially explained the confounding influence from load. Significant differences occurred between the peak static moments according to load, suggesting an accommodation in the lift strategy. There were also significant differences between the static and dynamic external moments, which became meaningful when the lift pace was medium or fast, suggesting that a dynamic analysis is not necessary if the pace is slow. CONCLUSION: This investigation further supports that the pace of lifting is an important work factor in safe lifting and material handling. Show more

Keywords: Low back, shoulder, biomechanics, lift pace

DOI: 10.3233/WOR-131682

Citation: Work, vol. 47, no. 1, pp. 15-22, 2014

Authors: Godwin, Alison A. | Eger, Tammy R.

Article Type: Research Article

Abstract: BACKGROUND: Anecdotal evidence from industry suggests that those working as arborists prefer to use minimal brim style, climbing helmets rather than traditional forestry helmets. In the mining industry, workers prefer wireless, LED cap lamps. Workers cite better comfort, better ability to see their work and better ventilation as reasons to use those helmets and cap lamps. Safety personnel in the industry would like to base future helmet decisions and requirements on a complete understanding of the …ergonomic and safety issues of all available head-borne equipment. OBJECTIVE: Previous research has found that helmet design, head load and head/neck posture can influence the amount of neck discomfort experienced by users. Specific features of helmets and head-mounted personal protective equipment (PPE) in various industries have been changing to reflect ergonomic design principles. A series of three studies were conducted to evaluate usability and preference of new style cap lamps and helmet brims. Participants: Participants (n=10–16) were recruited primarily from undergraduate students, and each study represents a different group of novice participants. METHODS: Two different courses that included a tunnel were used in the first two studies to evaluate cap lamp styles and wireless cap lamps, while a simulated arborist task was used in the final study to evaluate helmet brim. Measures of ergonomic and discomfort questionnaires were analysed for this paper. RESULTS: The first cap lamp study was able to conclude that LED lamps are preferred over incandescent lamps, while the second study demonstrated that users prefer a multi-directional beam, and adjustability features of the cap lamp. In the final study, participants who must perform extreme overhead tasks prefer a helmet with a minimal brim. CONCLUSIONS: Additional research is warranted to determine whether actual, industry workers demonstrate the same preferences for these PPE items. Show more

Keywords: Discomfort, safety gear, cap lamps, mining, arborist

DOI: 10.3233/WOR-131687

Citation: Work, vol. 47, no. 1, pp. 23-31, 2014

Authors: Albert, Wayne J. | Everson, Donald | Rae, Michelle | Callaghan, Jack P. | Croll, Jim | Kuruganti, Usha

Article Type: Research Article

Abstract: BACKGROUND: The prevalence of neck and low back musculoskeletal injuries in transit operators has been shown to be high; with work absences exceeding double the National average. There is a lack of biomechanical data generated from field researches to inform on musculoskeletal risk associated with transportation and driving occupations. Instead there has been a reliance on simulated driving and questionnaire-based research. OBJECTIVES: This study was designed to examine the musculoskeletal and biomechanical stresses experienced …by urban bus drivers. The main objective was to obtain a baseline understanding of sitting posture, muscle activiation and subjective ratings of stress during regular driving tasks. PARTICIPANTS: Fifteen urban city bus drivers were recruited for this study. METHODS: Bus drivers drove the same 65-minute bus route once, at the same time of day, in the same preselected bus. Wireless surface electromyography monitored muscular activity of the drivers' neck, upper trapezius, and erector spinae and video analysis and seat pressure mapping was used to monitor changes in driving posture. A health and lifestyle questionnaire was administered to record specific neck and back pain experienced by drivers as well as to provide lifestyle habits. RESULTS: Drivers were found to exhibit non-neutral postures for less than 30% of the time while conducting routine tasks of turning and stopping for passenger loading and unloading. The neck posture was the greatest concern in terms of non-neutral posture and this was supported by the higher muscle activation to the neck musculature. There was significant posture adjustment made during the one-hour driving period with the adjustments increasing with driving time. CONCLUSION: Activities associated with bus driving appear to require the use of non-neutral postures an increase in muscle activation. Significant postural adjustments were needed over the one-hour observation period suggesting that the musculoskeletal demands may increase over a regular 12-hour shift. Show more

Keywords: Ergonomics, electromyography, muscle activity, bus driving

DOI: 10.3233/WOR-131683

Citation: Work, vol. 47, no. 1, pp. 33-44, 2014

Authors: Moser, Daniel J. | Graham, Ryan B. | Stevenson, Joan M. | Costigan, Patrick A.

Article Type: Research Article

Abstract: BACKGROUND: The Mark 3 (M3) water power pump is an integral piece of wildfire fighting equipment. However, it is provided to fire stations without a carrying harness. The currently-used carrying harness is very uncomfortable, especially when carrying the pumps considerable distance in a forest to reach a water source. OBJECTIVE: The purpose of this study was to advise the Ontario Ministry of Natural Resources on the selection of a new M3 load carriage system. …PARTICIPANTS: Twenty Fire Rangers wore the three systems (Original, Prototype, and Modified) through a circuit of tasks representative of their working environment. METHODS: Subjective and objective approaches were combined to assess and rank the M3 carriage systems. Subjective visual analogue scale ratings were obtained for ease of loading/unloading, comfort, system stability, and overall performance. Tri-axial accelerometers were mounted on each pump and at the sternum of each participant to determine relative pump-carrier accelerations. RESULTS: Overall, the Prototype was ranked as the best system; it resulted in the lowest relative pump-carrier accelerations on 10 out of 15 objective measures, and also received a first place ranking on all subjective measures. CONCLUSION: It was recommended that the Prototype be implemented as the M3 carriage system for fire suppression teams. Show more

Keywords: Load carriage, ergonomics, fire fighting equipment, performance assessment, accelerometry

DOI: 10.3233/WOR-131690

Citation: Work, vol. 47, no. 1, pp. 45-53, 2014

Authors: Doan, Jon B. | Copeland, Jennifer L. | Brown, Lesley A. | Newman, Jeff T. | Hudson, D. Shane

Article Type: Research Article

Abstract: BACKGROUND: Bridge employment (scheduled paid work after retirement age) may promote successful aging and continued health, as work can be an important component of daily physical activity. Appropriate work demands for older adults are neither well-established nor well-applied, however, and excessive loading or increased perceptions of discomfort may negate the health benefits of work activity. OBJECTIVE: This study examined work status and musculoskeletal discomfort (MSD) amongst older Albertans. METHODS: 1044 Albertans aged …55 years and older participating in an organized 'Games' received a research package. Enclosed in the package were an introductory letter, a return envelope, and modified versions of validated questionnaires examining leisure and work activities, activity frequency, and perceptions of musculoskeletal health. RESULTS: 228 respondents were classified into one of three employment trajectory groups: fully retired, fully employed, or bridge employed. Groups differed in age, and both employed groups more frequently reported MSDs in all body areas. Bridge employed reported increased 'occasional' frequency of musculoskeletal injury risk factors, while both groups reported similar overall ratings of work-related exertion. CONCLUSIONS: The increased MSDs reported by bridge employed adults may be the result of irregularity of work activity and soft tissue loading. Detailed examination of work demands and musculoskeletal injuries amongst bridge employed adults could help define safer levels for less regular work activity. Show more

Keywords: Retirement, aged worker, career, bridge employment, activity

DOI: 10.3233/WOR-131685

Citation: Work, vol. 47, no. 1, pp. 55-62, 2014

Authors: Dumas, G.A. | Preston, D. | Beaucage-Gauvreau, E. | Lawani, M.

Article Type: Research Article

Abstract: BACKGROUND: In Western Africa, women continue performing heavy physical work that includes carrying loads on their heads during pregnancy. Women may adapt to pregnancy related body changes by modifying their postures to perform such tasks. OBJECTIVE: The objectives of this biomechanical task analysis study were to 1) determine sagittal plane postures of the trunk and upper extremities at specific events during the task of lifting and lowering a load to be carried on the …head, 2) compare postures of pregnant and non-pregnant participants, 3) evaluate risk for musculo-skeletal disorders (MSD) with the rapid entire body assessment (REBA) criteria. PARTICIPANTS: Twenty-six pregnant (26 ± 5 years, 159 ± 9 cm, 63 ± 15 kg, 25 ± 9 weeks of pregnancy) and 25 paired non-pregnant retail merchants were recruited in Porto-Novo (Benin). METHODS: Participants were recorded on video in a laboratory setting while they lifted a tray (20% body weight) from a stool to their head and then put it back down. Trunk inclination and knee, shoulder and elbow flexion angles were determined using Dartfish® software. RESULTS: The trunk was bent by more than 80° at pick-up and set-down and knees were moderately flexed, significantly less (< 11°) for pregnant women, possibly because it was harder to lift the trunk, or for stability. For all postures analysed, the majority of trials were classified as "high" risk or "very high risk" for MSD. CONCLUSIONS: Future research should investigate prevalence of MSDs in this population to confirm the results of this study. Show more

Keywords: Musculoskeletal disorders, pregnancy, Africa

DOI: 10.3233/WOR-131686

Citation: Work, vol. 47, no. 1, pp. 63-72, 2014

Authors: Azar, Nadia R. | Iley, Tara | Godin, Christina A. | Callaghan, Jack P. | Andrews, David M.

Article Type: Research Article

Abstract: BACKGROUND: In order to obtain a complete understanding of the etiology of upper extremity musculoskeletal disorders, a spectrum of risk factors needs to be evaluated, within and external to the workplace. To date, cumulative shoulder loads (forces and moments) have only been documented during automotive assembly tasks. No information on shoulder loads during non-occupational tasks has been reported. OBJECTIVE: To document 3D peak and cumulative shoulder loads and postures associated with non-occupational tasks. …METHODS: Seven male (35.8 ± 15.7 years) and six female (44.0 ± 14.3 years) healthy working-aged individuals volunteered for this study. A video-based 3D posture sampling approach was used to document shoulder joint postures while participants performed non-repetitive tasks in and around their own homes over a 2-hour period. A 3D rigid link segment model was used to calculate reaction forces and moments at the shoulder. RESULTS: Peak shoulder moments approached, and in some cases exceeded, published maximum isometric strength measurements, particularly in female participants. When extrapolated to a 7-hour shift, cumulative shoulder flexion and abduction moments, cumulative reaction caudal shear forces, and the time spent in non-neutral flexion and abduction were comparable in magnitude to those reported for light automotive assembly tasks. CONCLUSIONS: Non-occupational tasks should be evaluated more widely if a complete picture of the risk of musculoskeletal injury associated with shoulder loading is to be established. More work is needed to develop threshold limits for both peak and cumulative shoulder loads to improve injury prevention strategies. Show more

Keywords: Video, posture sampling, biomechanical model

DOI: 10.3233/WOR-131684

Citation: Work, vol. 47, no. 1, pp. 73-86, 2014

Authors: Hubley-Kozey, Cheryl | Moreside, Janice M. | Quirk, D. Adam

Article Type: Research Article

Abstract: BACKGROUND: Trunk neuromuscular alterations have been found in those with chronic low back pain, but less well studied are whether responses are altered in those deemed recovered following an injury. Furthermore, coordinated trunk muscle responses are deemed important for normal spinal function, but there are no studies of temporal patterns early after a low back injury. Determining whether altered trunk muscle patterns exist early after injury could improve our understanding of recovery by providing an objective …assessment of functional recovery and risk of re-injury. OBJECTIVE: To determine if amplitude and temporal characteristics of trunk neuromuscular patterns differ during a dynamic functional task in a group of participants with recent (within 12 weeks) low back injury (LBI), but deemed ready to resume normal activities, when compared to those with no similar history of injury (ASYM). PARTICIPANTS: 35 participants in each group (17 females) were matched for age and body mass index (BMI); (ASYM 36 yrs, BMI 26, LBI 39 yrs, BMI 27). METHODS: Participants performed a controlled lifting task (2.9 kg) in a standing maximum reach position, which altered frontal and sagittal plane moments of force. Electromyographic activity of 24 trunk muscle sites, as well as thoracic and pelvis position via an electromagnetic sensor was collected. Principal component analyses extracted the temporal and amplitude waveform patterns. Mixed model ANOVAs tested for effects (p< 0.05) in the main patterns. Preliminary data regarding re-injury status after 1 year was included. RESULTS: Three principal patterns explained 97% of the variance, with the LBI group demonstrating increased amplitude and a more constant level of activity compared to the ASYM group. The LBI group also demonstrated more thoracic motion in all 3 axes during this highly constrained task. The no re-injury group had lower activation than the re-injury group, but similar temporal patterns. CONCLUSIONS: Despite the perception of readiness to return to work and low pain scores, the temporal and amplitude muscle activation patterns were altered in this LBI group indicating that differences exist compared to a non-low back injured group. The differences are not just relative amplitude differences among muscles but include differences in the temporal response to the flexion moment. Show more

Keywords: Low back injury, neuromuscular patterns, principal component analysis, electromyography, temporal waveform patterns

DOI: 10.3233/WOR-131689

Citation: Work, vol. 47, no. 1, pp. 87-100, 2014

Authors: Eger, Tammy | Thompson, Aaron | Leduc, Mallorie | Krajnak, Kristine | Goggins, Katie | Godwin, Alison | House, Ron

Article Type: Research Article

Abstract: BACKGROUND: Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. OBJECTIVES: The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk …of vibration-induced injury. PARTICIPANTS: Workers who operated locomotives (n=3), bolting platforms (n=10), jumbo drills (n=7), raise drilling platforms (n=4), and crushers (n=3), participated. METHODS: A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. RESULTS: Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. CONCLUSIONS: Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury. Show more

Keywords: Occupational vibration, Raynaud's, white-foot, standing, vibration white-toes

DOI: 10.3233/WOR-131692

Citation: Work, vol. 47, no. 1, pp. 101-110, 2014

Authors: Hunt, S. | Boyle, C. | Wells, R.

Article Type: Research Article

Abstract: BACKGROUND: Electrical utility workers wear thick rubber gloves and often work in the cold. OBJECTIVE: To document the challenge of working in the cold and the effectiveness of different glove/liner combinations in keeping workers' hands warm. METHODS: Ten experienced male electrical utility employees worked in a controlled temperature walk-in chamber at −20°C for 45 minutes for each of five glove conditions: standard five-finger rubber gloves with cotton liners and gauntlets, mitten style …gloves, a prototype wool liner, and two heating options; glove or torso. Dependent measures were maximum grip force, skin temperatures, finger dexterity and sensitivity to touch, ratings of perceived effort and a rating of thermal sensation. RESULTS: Participants' hand skin temperatures decreased, they perceived their hands to be much colder, their finger sensitivity decreased and their ratings of perceived exertion increased, however their performance did not degrade over the 45 minute trials. The mitten-style gloves showed a smaller drop in skin temperature for the 3rd and 5th digits (p< 0.05) than the other glove conditions. CONCLUSIONS: Mitten style gloves kept workers' hands warmer than the standard five finger glove. Show more

Keywords: Grip, strength, temperature, dexterity, heating

DOI: 10.3233/WOR-131754

Citation: Work, vol. 47, no. 1, pp. 111-121, 2014

Authors: Conrad, Leanne F. | Oliver, Michele L. | Jack, Robert J. | Dickey, James P. | Eger, Tammy R.

Article Type: Research Article

Abstract: OBJECTIVE: The purpose of this work was to help a steel industry partner select the most appropriate of three high end heavy equipment seats to retrofit a number of their heavy mobile machines used in the steel making process. PARTICIPANTS: The participants included 8 males (22.3 ± 2.0 yrs.) and 8 females (23.5 ± 1.8 yrs.) with no experience operating heavy mobile equipment. METHODS: Previously recorded 6-DOF chassis acceleration data from a …Pot Hauler (a machine which picks up and transports pots of slag) were used to extract six, 20 second representative profiles for implementation on a lab-based heavy machine simulator (6-DOF Parallel Robotics System Corporation robot). Subjects sat on three heavy equipment seats (BeGe7150, Grammar MSG 95G1721, and a 6801 Isringhausen with the seat pan cushion retrofitted with a Skydex™ cushion) mounted on the simulator. Each subject completed three trials for each combination of seat (n=3) and vibration profile (n=6). Chassis and operator/seat interface vibration were measured by 2, 6-DOF vibration transducers. Variables included Seat Effective Amplitude Transmissibility (SEAT) (X,Y,Z,Roll,Pitch,Yaw,6DOF Vector Sum) to determine if the seat was attenuating or amplifying the vibration, 6-degree of freedom (DOF) vibration total value weighted predicted comfort (A_{vc} ) (according to ISO 2631-1) and operator reported comfort (ORC). RESULTS: Factorial ANOVAs revealed significant differences (p⩽ 0.05) between seats for all SEAT variables but different seats performed better than others depending on the axis. Significant differences between males and females were observed for SEAT in X,Y, and Pitch as well as for A_{vc} . As expected there were significant differences between vibration profiles for all assessed variables. A number of interaction effects were observed, the most frequently occurring of which was between seat and vibration profile. CONCLUSIONS: Based upon the number of seat and vibration profile interactions, results suggest that a single seat is not suited for all tested conditions. However, SEAT values for all of the seats tested were extremely low (e.g., 6-DOF SEAT < 30%) indicating that all of the seats were capable of providing good vibration attenuation. Show more

Keywords: Whole-body vibration, operator reported comfort, seat selection, ISO 2631-1(1997)

DOI: 10.3233/WOR-131758

Citation: Work, vol. 47, no. 1, pp. 123-136, 2014

Authors: Stevenson, Joan M.

Article Type: Research Article

Abstract: Over my career I have been involved in research covering three different strategies to reduce workplace injuries, namely: (a) developing bona fide occupational requirements for physically demanding jobs, (b) conducting training programs and a case-control study of low back pain in industry, and (c) developing ergonomically-designed equipment and tools. The purpose of this paper is to identify some areas where I believe research is needed to reduce the risks of musculoskeletal disorders. Hopefully, new researchers will …pick up the torch on some of these topics and continue to enhance the impact of occupational biomechanics and ergonomics on improving jobs for workers. Show more

Keywords: Employee selection, biomechanical, ergonomics, manual materials handling, low back disability

DOI: 10.3233/WOR-131691

Citation: Work, vol. 47, no. 1, pp. 137-141, 2014