Kinematic characteristics and energy expenditure during manual wheelchair propulsion: a comparison of two stroking techniques in non-experienced users

Manual wheelchair propulsion is a physiologically stressful and biomechanically inefficient form of locomotion. The repetitious nature of propulsion puts wheelchair uses at high risk for developing upper extremity overuse injuries. Previous kinematic analysis has revealed that wheelchair users employ several distinct stroking techniques. One of the techniques, circular pattern (CP), may be recommended to prevent injuries in the upper extremity because of lower cadence, greater ratio of push time to recovery time, and lower joint accelerations. However, another technique, single-loop over pattern (SLP) is most commonly used among actual wheelchair users. A possible reason for this was that SLP may be related to lower energy expenditure required for propulsion. Organisms have a natural tendency, which is self-optimization process of motor performance. A movement pattern is adapted to minimize metabolic energy expenditure. SLP may result from this process. The purpose of this study was to examine the kinematics and energy expenditure of two stroking techniques (CP and SLP) after training non-experienced wheelchair users. Sixteen participants completed a three-week training session for each stroking technique, CP and SLP, and were tested on their kinematics and energy expenditure after each training session. They performed six-minutes of propulsion at a velocity of O.9mIs. Three-dimensional motion capture data were collected at three and a half minutes to compute the kinematic variables: cadence (cycles/s), ratio of push time to recovery time, joint motion in the shoulder, elbow and trunk. Metabolic data were collected during the second three minutes of each trial, using a metabolic cart system. Repeated measures MANOVA revealed a significantly lower cadence (F(2,14) = 4.74, p<.05) and greater ratio of push time (F(2,14) = 18.47, p<.01) in CP than in SLP. No significant differences were found in the joint motion except a greater peak acceleration of elbow flexion in SLP (F(2,14) = 6.82, p<.02). Energy expenditure showed no differences between CP and SLP. No significant correlations were found between the joint motion and energy expenditure. This study confirmed that CP may be beneficial propulsion technique for manual wheelchair users in terms of stroke cadence. CP had the same amount level of energy expenditure as SLP, but CP had a lower task frequency that is related to a reduction in the risk of overuse injuries. Further studies should examine mechanical efficiency in order to identify a more efficient technique. Also, more investigations are needed to reveal associations between physical function and stroking techniques. Reasons why more wheelchair users employ SLP were not answered in this study

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