Lower body bracing behaviours during externally supported tasks with extended reaches

In many jobs, objects in the task environment can restrict a worker's posture, by constraining how close their body is to the object being acted on. Although this provides an obstacle for the worker, these objects can be used to externally support their body by means of lower body bracing. The purpose of this study was to determine when participants would brace, and to quantify the amount of force used for bracing. At four task hand locations, participants performed six exertions, with all combinations of two forces and three directions, and participants chose whether they braced or not. Participants were twice as likely to brace when the task had a far reach. Average brace forces were 117 N for upwards and pulling exertions, and 67 N for downward exertions. These data can be used to guide the prediction of external forces during work simulation and proactive ergonomics assessments.