THE USE OF LOWER BODY BRACING DURING ONE-HANDED SUBMAXIMAL EXERTIONS WITH EXTENDED REACHES

Abstract

<p>In many occupational tasks, environmental constraints limit how close a worker can place their body to a desired element of the task. Although this provides an obstacle when performing the task, workplace obstructions can often be used by a worker to externally support their body by means of bracing. The purpose of this thesis was to identify how a worker’s posture would differ when the task must be performed with a constrained reach, compared to having the option to externally support against the thighs. At 4 different task hand Locations, subjects performed 6 exertions, comprised of 2 Loads (27.5 N and 55 N) and 3 Directions (Up, Down, and Pull). Subjects were able to choose if bracing would be used when performing the first 24 trial exertions. After the choice conditions had been collected, trials were performed again with a forced brace or unbraced. The most important finding of this study was that participants were twice as likely to brace when performing a task with a far reach. In addition, average brace forces were approximately 117 N for Up and Pull exertions, and were nearly half that (67 N) for Down exertions. Participants would brace at a lower height at low versus high locations. Flexing the trunk forward and twisting the right shoulder forward, combined with a more flexed task arm and reduced shoulder rotation, allowed participants to adopt a posture where their shoulder was closer to the point of exertion during braced exertions, thereby increasing their functional arm length.</p>