SHOULDER AND ELBOW MOTION DURING 2 SPEEDS OF WHEELCHAIR PROPULSION - A DESCRIPTION USING A LOCAL COORDINATE SYSTEM

Individuals who propel wheelchairs have a high prevalence of upper ext remity injuries. To better understand the mechanism behind these injur ies this study investigates the motion of the shoulder and elbow durin g wheelchair propulsion. The objectives of this study are: (1) To desc ribe the motion occurring at the shoulder and elbow in anatomical term s during wheelchair propulsion; (2) to obtain variables that character ize shoulder and elbow motion and are statistically stable; (3) to det ermine how these variables change with speed, The participants in the study were a convenience sample of Paralympic athletes who use manual wheelchairs for mobility and have unimpaired arm function. Each subjec t propelled an ultralight wheelchair on a dynamometer at 1.3 and 2.2 m eters per second (m/s). Biomechanical data was obtained using a force and moment sensing pushrim and a motion analysis system. The main outc ome measures investigated were: maximum and minimum angles while in co ntact with the pushrim, range of motion during the entire stroke and p eak accelerations. All of the measures were found to be stable at both speeds (Cronbach's alpha >0.8). The following measures were found to differ with speed (data format: measure at 1.3 m/s+/-SD measure at 2.2 m/s+/-SD): minimum shoulder abduction angle during propulsion (34.5 d egrees+/-6.7, 21.6 degrees+/-7.2), range of motion during the entire s troke in elbow flexion/extension (54.0 degrees+/-9.9, 58.1 degrees+/-1 0.4) and shoulder sagittal flexion/extension (74.8 degrees+/-9.4, 82.6 degrees+/-8.5), and peak acceleration in shoulder sagittal flexion/ex tension (4044 degrees/s(2)+/-946, 7146 degrees/s(2)+/-1705), abduction /adduction (2678 degrees/s(2)+/-767, 4928 degrees/s(2)+/-1311), and el bow flexion/extension (9355 degrees/s(2)+/-4120, 12889 degrees/s(2)+/- 5572). This study described the motion occurring at the shoulder and e lbow using a local coordinate system. Stable parameters that character ize the propulsive stroke and differed with speed were found. In the f uture these same parameters may provide insight into the cause and pre vention of shoulder and elbow injuries in manual wheelchair.