The influence of speed and grade on wheelchair propulsion hand pattern

Abstract

Background: The hand pattern used during manual wheelchair propulsion (i.e., full-cycle hand path) can provide insight into an individual's propulsion technique. However, previous analyses of hand patterns have been limited by their focus on a single propulsion condition and reliance on subjective qualitative characterization methods. The purpose of this study was to develop a set of objective quantitative parameters to characterize hand patterns and determine the influence of propulsion speed and grade of incline on the patterns preferred by manual wheelchair users.

Methods: Kinematic and kinetic data were collected from 170 experienced manual wheelchair users on an ergometer during three conditions: level propulsion at their self-selected speed, level propulsion at their fastest comfortable speed and graded propulsion (8%) at their level self-selected speed. Hand patterns were quantified using a set of objective parameters, and differences across conditions were identified.

Findings: Increased propulsion speed resulted in a shift away from under-rim hand patterns. Increased grade of incline resulted in the hand remaining near the handrim throughout the cycle.

Interpretation: Manual wheelchair users change their hand pattern based on task-specific constraints and goals. Further work is needed to investigate how differences between hand patterns influence upper extremity demand and potentially lead to the development of overuse injuries and pain.

Keywords: Incline; Manual wheelchair; Propulsion pattern; Propulsion technique; Speed.

Fig. 1

Hand pattern and variable definitions. The four hand pattern types are arcing (AR), single loop (SL), double loop (DL) and semi-circular (SC). The solid line denotes the contact phase, while the dashed line denotes the recovery phase. Also depicted is the radius of the handrim (r) and angle of handrim contact (θ). The mathematical signs denote whether the signed area enclosed by each loop is positive (+) or negative (−).

Fig. 2

Experimental setup used to collect propulsion mechanics on a custom-built wheelchair ergometer. A CODA motion analysis system (Charnwood Dynamics Ltd., Leicestershire, UK) was used to collect kinematic data, while a SmartWheel (Three Rivers Holdings, Mesa, AZ, USA) was used to measure handrim kinetics.

Fig. 3

Comparison of objective and subjective hand pattern classification results. The vertical axis corresponds to TRT and the horizontal axis corresponds to the ratio NRT/TRT. Thresholds for the objective classification are depicted with the dashed lines at TRT = 0.03m, NRT/TRT = −0.95 and NRT/TRT = 0.95. Regions corresponding to each pattern type are labeled with the objective classification. Subjective classification is indicated with the following symbols: AR (), DL (), SC () and SL (). For figure clarity, NRT/TRT was selected as the horizontal axis variable instead of NRT.

Fig. 4

Hand pattern parameter values across conditions. The vertical axis corresponds to TRT and the horizontal axis corresponds to NRT. Thresholds for the objective classification are depicted with the dashed lines at TRT = 0.03m, NRT/TRT = −0.95 and NRT/TRT = 0.95. Regions corresponding with each pattern type are labeled with the objective classification. Propulsion condition is indicated as follows: free (), fast () and graded (). The across-subject mean values are indicated with a larger version of the same symbols. For comparisons across conditions, NRT was selected as the horizontal axis variable instead of NRT/TRT.