Children's Postures While Playing at Computer Workstations

There has been a significant increase in the incidence of musculoskeletal disorders (MSD) and the costs associated with these are predicted to increase as the popularity of computer use increases at home, school and work. Risk factors have been identified in the adult population but little is known about the risk factors for children and youth. Research has demonstrated that they are not immune to this risk and that they are self reporting the same pain as adults. The purpose of the study was to examine children’s postures while working at computer workstations under two conditions. One was at an ergonomically adjusted children’s workstation while the second was at an average adult workstation. A Polhemus Fastrak™ system was used to record the children’s postures and joint and segment angles were quantified. Results of the study showed that children reported more discomfort and effort at the adult workstation. Segment and joint angles showed significant differences through the upper limb at the adult workstation. Of significance was the strategy of shoulder abduction and flexion that the children used in order to place their hand on the mouse. Ulnar deviation was also greater at the adult workstation as was neck extension. All of these factors have been identified in the literature as increasing the risk for injury. A comparison of the children’s posture while playing at the children’s workstation verses the adult workstation, showed that the postural angles assumed by the children at an adult workstation exceeded the Occupational Safety and Health Association (OSHA) recommendations. Further investigation is needed to increase our knowledge of MSD in children as their potential for long term damage has yet to be determined.

An Ergonomic Evaluation of a Wrist Brace for Canadian Tree Planters

Tree planting is one of the most physically demanding occupations in Canada and as a result, tree planters are at an elevated risk of injury, specifically at the wrist. Wrist injuries develop on account of the highly repetitive nature of the job, as well as other musculoskeletal risk factors including non-neutral wrist postures and high impact forces sustained at the wrist during shovel-ground impact. As a result, wrist brace use has become common among planters, in an effort to limit deviated wrist postures while also providing enhanced stability at the wrist. The external stability provided by a wrist brace is thought to reduce the muscular effort required to provide stiffness at the wrist during shovel-ground impact. Since these prospective benefits have not been formally investigated, the purpose of this study was to determine the effect of a wrist brace on wrist posture, muscle activity, and joint rotational stiffness about the wrist joint (for two degrees of freedom: flexion/extension and ulnar/radial deviation). We hypothesized that the brace would promote more neutrally aligned wrist angles, and that muscle activity and joint rotational stiffness would also decrease when participants wore the brace. Fourteen tree planters with at least one season of experience were recruited to complete two planting conditions in a laboratory setting: one condition while wearing the brace (with brace, WB) and one condition without the brace (no brace, NB). The results from this study showed that at shovel-ground impact muscle activity trended towards increasing in three muscles when participants wore the brace. Additionally, wrist angles improved about the flexion/extension axis of rotation while increasing in deviation about the ulnar/radial axis of rotation when participants wore the brace. Joint rotational stiffness increased when participants wore the wrist brace. Participants from this study indicated difficulty gripping the shovel due to the bulk of the wrist brace, and this feature is discussed with possible suggestions for future iterations of design. In addition to grip diameter this analysis also prompts the suggestion that hand length and experience should also be considered in the design of tree planting tools, specifically an ergonomic aid such as a wrist brace.