Occupational Ergonomics - Volume 13, issue 3-4

Authors: McKinnon, Colin D. | Dickerson, Clark R. | Laing, Andrew C.T. | Callaghan, Jack P.

Article Type: Research Article

Abstract: BACKGROUND: Static postures and heavy helmets elicit neck pain in many aircraft personnel during or after flight. Helmet-mounted equipment can further increase neck loading and injury risk. OBJECTIVE: To quantify neck muscle activity changes as a function of helmet configuration and static neck postures. METHODS: Eight male participants participated. Neck surface EMG was measured bilaterally in each combination of 7 neck postures (neutral, flexed, extended, twisted, laterally flexed, and two combination postures) and 5 helmet-mounted equipment configurations (combinations of a helicopter helmet, night-vision goggles (NVG), and a 600 g counterweight (CW)). …RESULTS: Helmet configuration alone did not influence activity for any muscle. Peak muscle activity was less than 5% of maximum voluntary exertion for most trials. The highest neck extensor activity occurred when wearing the helmet with CW and NVG engaged, while the lowest activity occurred in the same setup but NVG in a disengaged position, and helmet configuration effects varied by target posture. Muscle activity tended to be greatest in extension and combination movements for the lateral muscles and in flexion and flexion with rotation for the neck extensors. CONCLUSION: Neck posture influenced neck muscular demands more than the configuration of helmet-mounted equipment. As such, cockpit layout may play a primary role in mitigating neck injury risk factors. Show more

Keywords: Neck load, helicopter helmet, static posture, night-vision goggles

DOI: 10.3233/OER-170245

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 119-130, 2016

Authors: Eddy, McKayla | Moore, Christopher | Nimbarte, Ashish

Article Type: Research Article

Abstract: BACKGROUND: Forceful exertions of the arm/shoulder are common during material handling and many other industrial tasks. Determination of how the risk of shoulder injury changes in conjunction with direction of force exertion could provide useful guidance on the design of workplaces and tasks. OBJECTIVE: This research was conducted to determine how direction of force exertion and muscle recruitment algorithm effect shoulder strain computed by musculoskeletal modeling. METHODS: Musculoskeletal modeling software was used to perform simulations of static force exertions of the right upper limb. A series of 36 force exertions in directions at …30° intervals in the transverse, sagital, and frontal planes were performed using three muscle recruitment optimization algorithms. A previously validated strain index equation was used to calculate risk injury for each force exertion based on the magnitude and direction of the resultant glenohumeral force. RESULTS: Generally, highest strain values were found in the downward, backward, and leftward direction and lowest strain values were found in the upward, forward, and rightward direction, or, in other words, during force exertions opposing forces in those directions. CONCLUSIONS: When designing workplace tasks that involve forceful exertions of the shoulder, pulling and downward pushing exertions should be given preference over pushing and lifting exertions. Show more

Keywords: Musculoskeletal modeling, static force exertions, shoulder strain

DOI: 10.3233/OER-170248

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 131-138, 2016

Authors: Sengupta, Arijit K. | Jiang, Xiaopeng

Article Type: Research Article

Abstract: BACKGROUND: Asymmetric and dynamic lifting is known to be one of the leading causes of occupational lower back disorders (LBDs). Biomechanical modeling has been utilized to investigate lifting task characteristics so that the task demands can be kept within a limit, and internal muscles and joints are not injured. OBJECTIVE: This study implemented AnyBodyTM to analyze internal torso loading in asymmetric and dynamic lifting tasks. METHODS: A six-camera motion capture (mocap) system collected dynamic motion data of lifting 30 lb (13.6 kg) weight at 0°, 30° and 60° asymmetry. The mocap data …drove the AnyBodyTM model, and the study investigated the effect of the asymmetry. RESULTS: Erector spinae was the most activated muscle for both symmetric and asymmetric lifting. When lifting origin became more asymmetric toward right, erector spinae activity was reduced, but oblique muscles increased their share of activity to counter the external moment. Most muscle tensions peaked at the lift initiation phase except left external oblique and right internal oblique. Left external oblique played a minor role in the right asymmetric lifting task, and the difference of activation for right internal oblique may be due to variance of the motion. Surprisingly the lift asymmetry decreased both compression and shear forces at the L5/S1 joint. CONCLUSIONS: This finding contradicted the results obtained from other research studies. The reduction in spine forces is postulated to have resulted from the increased oblique muscles' share in the production of back extensor moment. Since these muscles have longer moment arms, they generated lesser spine force to counteract the external moment. The subject also tended to squat as lifting origin became asymmetric, which effectively reduced the load moment on the spine. Show more

Keywords: Biomechanical evaluation, asymmetric lifting, AnyBodyTM modeling, spinal forces

DOI: 10.3233/OER-170247

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 139-146, 2016

Authors: Spratford, Wayne | Vu, Vy | Ball, Nick | Walker, Anthony

Article Type: Review Article

Abstract: BACKGROUND: Firefighting is a physically demanding occupation where workers are exposed to a significantly increased risk of injuries. OBJECTIVE: The purpose of this narrative review was to examine the literature surrounding protective firefighting boots and their relationship to lower body and lumbar biomechanics and potential injury. METHODS: An exhaustive search of peer reviewed firefighting literature was undertaken across 300 databases with 12 articles fitting the inclusion criteria and subsequently synthesised for the purposes of this review. RESULTS: The evidence suggested that protective firefighting boots restricted the range of motion at …both the ankle and the metatarsophalangeal joints, with changes subsequently observed for centre of pressure traces as well as at the knee and hip joints. These changes influenced gait characteristics during the stance and swing phases, with the potential to alter landing strategies adopted during occupational specific activities, all of which place firefighters at an increased risk of lower body and lumbar injuries. CONCLUSIONS: As a majority of the research was conducted with firefighters wearing personal protective equipment in conjunction with standard issue boots, to date, it remains unclear as to how protective firefighting boots in isolation or design differences influence lower body movement and injury. Show more

Keywords: Landing forces, biomechanics, firefighters, protective boots, centre of pressure, velocity of centre of pressure, boot design, injury prevention

DOI: 10.3233/OER-170246

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 147-155, 2016

Authors: Hoque, Mojahidul | Halder, Pobitra Kumar | Fouzder, Pushpendu Kumar | Iqbal, Zafor

Article Type: Research Article

Abstract: BACKGROUND: Passenger seats need to be designed according to ergonomic guidelines for long hour sitting travel. In Bangladesh, passenger seats are designed and fabricated by the local manufacturers who have no knowledge about anthropometry. As a result, passenger has to face stress, fatigue, headache and other disorders. OBJECTIVE: To compare passengers' anthropometric measurements and relevant existing seat dimensions for identifying possible discrepancy and recommending an optimum design. METHODS: In this study the passengers' anthropometric measurements and relevant existing seat dimensions were compared to identify possible discrepancy. RESULTS: The result represented …a considerable mismatch between body dimensions of passengers and the existing seat dimensions. The recommended new seat dimensions would enhance match percentage. CONCLUSIONS: The design and allocation of passenger seats were given on the basis of passenger's anthropometry. The proposed seat dimensions would ensure a safe and comfortable journey for the passengers. Show more

Keywords: Anthropometry, passenger seat, long haul bus, discrepancy, Bangladesh

DOI: 10.3233/OER-170249

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 157-172, 2016

Article Type: Other

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 173-175, 2016

Article Type: Other

Citation: Occupational Ergonomics, vol. 13, no. 3-4, pp. 177-, 2016