2016-07-01 12:00 - Messages

Evaluating the low back biomechanics of three different office workstations: Seated, standing, and perching

The objective of this study was to evaluate how different workstations may influence physical behavior in office work through motion and how that may affect spinal loads and discomfort. Twenty subjects performed a typing task in three different workstations (seated, standing, and perching) for one hour each. Measures of postural transitions, spinal loads, discomfort, and task performance were assessed in order to understand the effects of workstation interaction over time. Results indicated that standing had the most amount of motion (6–8 shifts/min), followed by perching (3–7 shifts/min), and then seating (<1 shift/min). Standing had the highest reports of discomfort and seating the least. However, spinal loads were highest in A/P shear during standing (190N posterior shear, 407N anterior shear) compared to perching (65N posterior shear, 288N anterior shear) and seating (106N posterior shear, 287 anterior shear). These loads are below the risk threshold for shear, but may still elicit a cumulative response. Perching may induce motion through supported mobility in the perching stool, whereas standing motion may be due to postural discomfort. Office workstation designs incorporating supported movement may represent a reasonable trade-off in the costs-benefits between seating and standing.

Source: Le, Peter, & Marras, William S. (2016). Applied Ergonomics, 56(9), 170-178.

Estimation of lumbar spinal loading and trunk muscle forces during asymmetric lifting tasks

Application of whole-body musculoskeletal modelling in OpenSim
Large spinal compressive force combined with axial torsional shear force during asymmetric lifting tasks is highly associated with lower back injury (LBI). The aim of this study was to estimate lumbar spinal loading and muscle forces during symmetric lifting (SL) and asymmetric lifting (AL) tasks using a whole-body musculoskeletal modelling approach. Thirteen healthy males lifted loads of 7 and 12 kg under two lifting conditions (SL and AL). Kinematic data and ground reaction force data were collected and then processed by a whole-body musculoskeletal model. The results show AL produced a significantly higher peak lateral shear force as well as greater peak force of psoas major, quadratus lumborum, multifidus, iliocostalis lumborum pars lumborum, longissimus thoracis pars lumborum and external oblique than SL. The greater lateral shear forces combined with higher muscle force and asymmetrical muscle contractions may have the biomechanical mechanism responsible for the increased risk of LBI during AL.

Source: Kim, Hyun-Kyung, & Zhang, Yanxin. (2016). Ergonomics.

Musculoskeletal Injury Prevention for New Nurses

Nurses continue to sustain musculoskeletal injuries even with increased emphasis on safe patient handling and mobility (SPHM) and organizational cultures of safety to protect health care workers. Analysis of data from 2011-2014 registered nurse graduates explored hospital safety culture, SPHM education/training, and incidence of new-nurse musculoskeletal injury. Results indicated hospitals provided some type of SPHM education and training, but 46% of study participants were not informed or aware of national SPHM standards or guidelines. Merely 13.9% of participants stated a written “no manual lifting policy” had been implemented; only 32.9% indicated staffing was adequate for SPHM tasks; and only 39.4% stated the hospital had all of the equipment needed to perform SPHM safely. Thirty-nine percent of participants had already sustained a musculoskeletal injury with an additional 35% sustaining but not reporting an injury. More actions are needed to ensure a decrease in musculoskeletal injuries for new nurses.

Source: Vendittelli, D., Penprase, Barbara, & Pittiglio, Laura. (2016). Workplace Health & Safety.

Influence of different stool types on muscle activity and lumbar posture among dentists during a simulated dental screening task

Whereas in the past dental stools typically facilitated a 90° hip angle, a number of currently available alternative designs allow for a more extended hip posture. The present study investigated the influence of different stool types on muscle activity and lumbar posture. Twenty five participants completed a simulated dental procedure on a standard stool, a saddle and the Ghopec. The latter stool comprises a seat pan consisting of a horizontal rear part for the pelvis and an inclinable sloping down front part for the upper legs, with a vertically and horizontally adjustable back rest. Lumbar posture was most close to neutral on the Ghopec, whereas sitting on a standard/saddle stool resulted in more flexed/extended postures respectively. Sitting with a 90° angle (standard stool) resulted in higher activation of back muscles while sitting with a 125° angle (saddle and Ghopec) activated abdominal muscles more, although less in the presence of a backrest (Ghopec). To maintain neutral posture during dental screening, the Ghopec is considered the most suitable design for the tasks undertaken.

Source: De Bruyne, Mieke A.A, Van Renterghemb, Benedikt, Baird, Andrew, Palmans, Tanneke, Danneels, Lieven, & Dolphens, Mieke. (2016). Applied Ergonomics, 56(9), 220-226.

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