Relationship between kinematic factors and muscle activity during wheelchair propulsion

The primary motivation for the study reported herein was to investigate the relationship between the kinematic factors and muscle activity during wheelchair propulsion under four speed conditions (90%, 70%, 50% and 30% of individual maximum speed) when using a recreational wheelchair. Ten wheelchair athletes were tested in which the IEMG muscle activity from five muscles (pectoralis major, anterior and posterior deltoid, biceps and triceps brachii) and 3-D kinematics were recorded. A computer software package was developed by the author for the analyses of the kinematic and IEMG data.It was determined from this study that: (1) As the speed condition increased, vertical motion increased and the maximum velocity of the hand, elbow and shoulder increased, (2) In a stroke, as speed increased, the percentage time in the recovery phase increased while it decreased in the drive phase, (3) The angle-angle diagrams can be used to identify the demarcation point between the drive and recovery phases, and to identify the maximum speed condition during wheelchair propulsion, (4) In the drive phase, as speed increased, the mean value of muscle activity from each of the five muscles increased, (5) As maximum speed was approached, muscle activity amplitude from the posterior deltoid in the recovery phase did not increase. This is due to the greater kinetic energy and momentum obtained at the beginning or middle part of the recovery phase which carried the upper extremity to its final position, (6) As the subject's maximum speed was achieved, short periods of cocontraction occurred between the antagonistic muscles at initial contact or during the first part of the drive phase. This cocontraction stiffens the joints allowing for the transfer of force to the pushrim.U of I OnlyETDs are only available to UIUC Users without author permissio