Variability in Wheelchair Propulsion: A New Window into an Old Problem

Abstract

Manual wheelchair users are at great risk for the development of upper extremity injury and pain. Any loss of upper limb function due to pain adversely impacts the independence and mobility of manual wheelchair users. There is growing theoretical and empirical evidence that fluctuations in movement (i.e., motor variability) are related to musculoskeletal pain. This perspectives paper discusses a local review on several investigations examining the association between variability in wheelchair propulsion and shoulder pain in manual wheelchair users. The experimental data reviewed highlights that the variability of wheelchair propulsion is impacted by shoulder pain in manual wheelchair users. We maintain that inclusion of these metrics in future research on wheelchair propulsion and upper limb pain may yield novel data. Several promising avenues for future research based on this collective work are discussed.

Keywords: complexity; injuries; kinematics; kinetics; motor variability; wheelchair biomechanics.

Figure 1

(A) Peak hand-rim resultant force profile as a function of time during steady state wheelchair propulsion. Inset illustrates subtle variations in peak force over four pushes. (B) Resultant shoulder force output during the push phase of ~300 pushes of steady state wheelchair propulsion. Dashed line depicts mean resultant force, while triangles depict individual cycle peak resultant shoulder force.

Figure 2

Wrist recovery trajectories during semi-circular pattern wheelchair propulsion. Wrist cycle-to-cycle recovery trajectories (“gray solid lines”). The mean wrist recovery trajectory is shown by the bold dashed line. The wrist positions orthogonal to mean recovery trajectory for which PCA was computed (0–100% at every 10% interval along the recovery path) is denoted by (“o”).