Accurate determination of the push (propulsion) phase is essential to analyses of wheelchair propulsion. For studies that identify push phases through visual inspection of kinematic data, it is important to quantify the associated error. This study compared propulsion onset and cessation times determined with pushrim kinetic data (reference) to those calculated from visual inspection of hand trajectories (third metacarpal-phalangeal joint marker) and from sign changes in the angular velocity of the hand about the wheel axle. The average error of each kinematic method was less than 4 frames of data (collected at 60 Hz) and no significant differences between the average errors were found. Based on these limited results, the velocity-based approach was preferred, as it represents the most efficient and repeatable method.
wheelchair propulsion, pushrim kinetics, kinematics
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