LIMITATIONS OF KINEMATICS IN THE ASSESSMENT OF WHEELCHAIR PROPULSION IN ADULTS AND CHILDREN WITH SPINAL-CORD INJURY

Background and Purpose. Recently, there has been a trend for designers to reduce the weight of wheelchairs. Wheelchair performance is freque ntly evaluated in clinical as well as laboratory settings by kinematic motion analysis. The purpose of this study was to examine the effect of weight on the kinematics of wheelchair propulsion in nonathletic ad ults and children with spinal cord injury. Subjects and Methods. The w eight of identical new low-weight test chairs (9.3 kg) was manipulated by adding weight (5 and 10 kg) in two matched groups (n= 20) of adult s and children with spinal cord injury. The three-dimensional coordina tes of reflective markers were obtained as the subjects performed leve l wheeling at a speed of 2 m/s. Results. The pediatric group was found to have significantly lower wheeling speeds than the adult group. The addition of weight, however, did not after the wheeling speeds in eit her group. Neither the proportions of the wheeling cycle spent in prop ulsion (24%) nor the angular (shoulder flexion-extension, elbow flexio n-extension, shoulder abduction, and trunk flexion-extension) kinemati cs of wheeling changed with additions of weight in either group. The a ngular kinematics of the pediatric group, however, were different than those of the adult group. Conclusion and Discussion. These results in dicate that adding weight in the range of 5 to 10 kg did not affect wh eeling style under the level-wheeling, low-speed conditions of the stu dy. It is possible that performance in wheelchair propulsion may be mo re appropriately determined by kinetic and energetic outcome measures than by kinematic measures. [Bednarczyk JH, Sanderson DJ. Limitations of kinematics in the assessment of wheelchair propulsion in adults and children with spinal cord injury. Phys Ther. 1995;75:281-289.]