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Vol. 37 No. 3, May/June 2000
Pages 283 - 296

Influence of trunk flexion on biomechanics of wheelchair propulsion

Mary M. Rodgers, PhD, PT; Randall E. Keyser, PhD; Elizabeth R. Gardner, MS, PT; Pamela J. Russell, PhD; Peter H. Gorman, MD

University of Maryland School of Medicine, Departments of Physical Therapy and Neurology, Baltimore, MD; Veterans Affairs Maryland Health Care System, Research & Development and Physical Medicine and Rehabilitation Services, Baltimore, MD

Abstract — Propulsion styles that are characterized by high stresses may influence the susceptibility of manual wheelchair users (MWCU) to upper limb injury. An experimental, cross-sectional study was designed to compare physiological and biomechanical characteristics of wheelchair propulsion in two groups of MWCU--a trunk flexion propulsion style group (FG) and a non-trunk flexion propulsion style group (NFG)--across fresh and fatigued states. Data on joint kinetics and kinematics, handrim kinetics, propulsion temporal characteristics, and electromyography were collected at the fresh and fatigued states, and oxygen uptake was collected continuously, to characterize wheelchair propulsion performance of 19 MWCU during a submaximal exercise test to exhaustion. The FG was characterized by a more flexed trunk position accompanied by greater shoulder flexion and elbow extension (p<0.05), which was accentuated with fatigue when compared to the NFG. When fatigued, marked decreases (p<0.05) in key propulsion muscle activity were observed in the FG, but not in the NFG. Temporally, the FG decreased contact time on the handrim by 1 percent of the propulsion cycle when fatigued, in contrast to the NFG who increased contact time by 7 percent (p<0.05). Results suggest that a trunk flexion style of wheelchair propulsion may lead to potentially debilitating upper limb injury, since these individuals appear to be compensating for peripheral muscle fatigue.

Key Words: biomechanics, fatigue, kinematics, kinetics, propulsion style, wheelchair propulsion.

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