Abstract
The major objective of this study was to evaluate the effects of mild trunk flexion on localized muscle discomfort in a realistic light assembly task. Secondary objectives included evaluating two instruments commonly used to measure muscular discomfort, determining the level of erector spinae muscle activity during mild trunk flexion, and determining how well low back discomfort predicted loss of torso extension muscle strength. Participants performed a light assembly tasks for 20 minutes while in mild trunk flexion for periods of either 30 or 60 seconds, followed by recovery periods, in which participants stood erect, for periods of either 15, 30, 60 or 120 seconds. Duration of recovery period had a statistically significant effect on localized muscle discomfort of the lower back, upper back and shoulders. Duration of trunk flexion and recovery time had an interactive effect on loss of torso extension strength. Differences in performance between the two discomfort ratings scales were found.
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