Effort Perception of Workers with Spinal Cord Injury or Low Back Pain in Manual Transfer Tasks K. Han Kim and Bernard J. Martin Proceedings of the International Ergonomics Association Conference, Seoul, Korea 2003. Objectives: Understanding differences in effort perception between controls, low back pain (LBP) patients and Spinal cord injured (SCI) persons is necessary to adapt work requirements and workplace design in manual material handling tasks. The objective of this study was to develop statistical models of perceived effort at the shoulder and torso levels in one or two handed manipulation tasks for these three groups. These models can then be included in CAD design software to predict effort in simulated task and determine limitations in a proactive manner. Methods: The participants (10/group) performed loaded reach movements to spatially distributed targets [4 elevations, 3 azimuths (0, 45 and 90 degrees and 2 distances (close and far)] while seated. The loads were a light box (12.5 % shoulder MVC) or a heavy box (25% MVC) manipulated with both hands, and a vertical or horizontal cylinder (25% MVC) manipulated with the right hand. After completing each loaded transfer, the subjects were asked to rate their perception of effort for the right shoulder and the torso using a 10-point visual analog scale with 0 and 10 corresponding to minimal and maximum effort, respectively. Results: The results show that the torso and shoulder effort ratings were significantly higher for LBP and SCI than control subjects. LBP subjects tend to report higher torso and shoulder effort ratings when compared to SCI subjects. SCI and/or LBP subjects did not reach some of the targets. For example, more than 90% of the SCI subjects did not reach the lowest shelf at 90° of azimuth. The number of unreachable target, mostly to the right side, was smaller for the LBP than the SCI subjects. Perception of effort tends to increase as a function of the linear distance between the body and the target shelf. It also increases as a function of elevation above and below the horizontal plane of the home shelf. This tendency was more pronounced in SCI and LBP than control subjects. Torso effort rating was similar for SCI and control subjects for some targets near the home shelf. However, torso effort ratings were higher for the LBP than control subjects for all targets. Discussion: These results suggest that motion kinematics and envelope, and biomechanical analysis should be complemented by effort perception rating to adequately adapt the workplace for different populations. abs2003_07