The effect of back injury and load on ability to replicate a novel posture.

The purpose of this study was to investigate the effect of back injury and load on the ability to replicate a target standing posture. Subjects included 16 back-injured males and 16 age-matched controls. Subjects were asked to reproduce a target standing posture and to repeat this task while holding a weight. Trunk inclination was measured using an electrogoniometer. Analysis of variance indicated that back-injured subjects were less accurate in reproducing the target posture than were control subjects. Back-injured subjects typically overestimated how much they had moved and therefore underestimated the target position. Both groups demonstrated a small but statistically significant difference between the load and no-load condition, with greater degrees of trunk inclination under the load condition. Analysis of covariance indicated that neither self-reported pain level nor maximum voluntary range of motion contributed to significant differences between the two groups. These data indicate that, following injury to the back, individuals may develop an inaccurate perception of body position. This study has implications for training the injured worker.