Wrist biomechanics during two speeds of wheelchair propulsion: an analysis using a local coordinate system.
ABSTRACT To describe motion, forces, and moments occurring at the wrist in anatomic terms during wheelchair propulsion; to obtain variables that characterize wrist function during propulsion and are statistically stable; and to determine how these variables change with speed.
Convenience sample of Paralympic athletes (n = 6) who use manual wheelchairs for mobility and have unimpaired arm function.
Subjects propelled a standard wheelchair on a dynamometer at 1.3m/sec and 2.2m/sec. Biomechanical data were obtained using a force and moment sensing pushrim and a motion analysis system.
Maximum angles, forces, and moments in a local, wrist coordinate system. Each variable was evaluated for stability using Cronbach's alpha. Measures found to be stable (infinity > .8) at each speed were then compared to look for differences associated with speed.
The following measures were stable at both speeds: maximum wrist flexion, ulnar deviation, and radial deviation angles, peak moments acting to cause wrist flexion, extension, and ulnar deviation, peak shear forces acting between the radial and ulnar styloids, and peak axial force acting at the wrist. Of these measures, the following measures differed (p < .05) between speeds (+/-SD): maximum radial deviation (1.3m/sec, 25.1 degrees +/- 9.0; 2.2m/sec, 21.4 degrees +/- 6.9), peak flexion moment (1.3m/ sec, 3.4N.m +/- 3.0; 2.2m/sec, 5.2N.m +/- 3.7), peak extension moment (1.3m/sec, 10.4N.m +/- 4.8; 2.2m/sec, 13.6N.m +/- 5.1), peak shear acting from the ulnar styloid to the radial styloid (1.3m/sec, 2.3N +/- 2.7, 2.2m/sec, 8.3N +/- 7.5) and maximum axial force (1.3m/sec, 50.9N +/- 18.2; 2.2m/sec, 65.9N +/- 27.6).
This study found stable parameters that characterize wrist biomechanics during wheelchair propulsion and varied with speed. Ultimately these parameters may provide insight into the cause and prevention of wrist injuries in manual wheelchair users.
- SourceAvailable from: Lan-Yuen Guo[Show abstract] [Hide abstract]
ABSTRACT: Researchers of wheelchair propulsion have usually suggested that a wheelchair can be properly designed using anthropometrics to reduce high mechanical load and thus reduce pain and damage to joints. A model based on physiological features and biomechanical principles can be used to determine anthropometric relationships for wheelchair fitting. To improve the understanding of man-machine interaction and the mechanism through which propulsion performance been enhanced, this study develops and validates an energy model for wheelchair propulsion. Kinematic data obtained from ten able-bodied and ten wheelchair-dependent users during level propulsion at an average velocity of 1m/s were used as the input of a planar model with the criteria of increasing efficiency and reducing joint load. Results demonstrate that for both experienced and inexperienced users, predicted handrim contact forces agree with experimental data through an extensive range of the push. Significant deviations that were mostly observed in the early stage of the push phase might result from the lack of consideration of muscle dynamics and wrist joint biomechanics. The proposed model effectively verified the handrim contact force patterns during dynamic propulsion. Users do not aim to generate mechanically most effective forces to avoid high loadings on the joints.Journal of biomechanics 10/2010; 44(3):455-60. · 2.66 Impact Factor
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ABSTRACT: The aim of this study was to propose a new index called Postural Force Production Index (PFPI) for evaluating the force production during handcycling. For a given posture, it assesses the force generation capacity in all Cartesian directions by linking the joint configuration to the effective force applied on the handgrips. Its purpose is to give insight into the force pattern of handcycling users and maybe used as ergonomic index. PFPI is based on the force ellipsoid which belongs to the class of manipulability indices and represents the overall force production capabilities at the hand in all Cartesian directions from unit joint torques. The kinematics and kinetics of the arm were recorded during a 1-min exercise test on a hand-cycle at 70 revolutions per minute performed by one paraplegic expert in handcycling. The PFPI values were compared to the Fraction Effective Force (FEF) which is classically associated with the effectiveness of force application. The results showed a correspondence in the propulsion cycle between FEF peaks and the most favorable postures to produce a force tangential to the crank rotation (PFPI). This preliminary study opens a promising way to study patterns of force production in the framework of handcycling movement analysis.Journal of applied biomechanics 02/2013; · 1.26 Impact Factor
- 21st Annual meeting of ESMAC; 09/2011