The purpose of this study was to determine whether the phenomenon of bilateral deficit in muscular force production observed in healthy subjects and mildly impaired stroke patients also exists in patients with more chronic and greater levels of stroke impairment. Ten patients with chronic hemiparesis resulting from stroke performed unilateral and bilateral maximal voluntary isometric contractions of the elbow flexors. When the total force produced by both arms was compared, 12% less force was produced in the bilateral compared with unilateral condition (p = 0.01). However, studying the effect of task conditions on each arm separately revealed a significant decline in nonparetic (p = 0.01) but not paretic elbow flexor force in the bilateral compared with unilateral condition. Results suggest that a significant bilateral force deficit exists in the nonparetic but not the paretic arm in individuals with chronic stroke. Bilateral task conditions do not seem to benefit or impair paretic arm maximal isometric force production in individuals with moderate-severity chronic stroke.
Kevin McQuade, Michelle L. Harris-Love and Jill Whitall
Kevin J. McQuade, Margaret A. Finley, Michelle Harris-Love and Sandra McCombe-Waller
The use of magnetic tracking technology has become increasingly popular in recent years for human motion studies. However, there have been few independent evaluations of how these systems perform. The purpose of this study was to develop a dynamic pendulum calibration method to test the performance of magnetic tracking sensors. A nonmetallic pendulum was constructed and instrumented with a rotary potentiometer. A cube was attached to the distal end of the pendulum so that sensors could be mounted orthogonally. In this manner, it was possible to obtain simultaneous recordings of azimuth, elevation, and roll depending on the sensor mounting orientation relative to the axis of rotation of the pendulum. Sensor data, using Flock of Birds™ sensors, and potentiometer data were collected simultaneously during dynamic pendulum motion at two transmitter distances and then were compared. The results showed excellent trial-to-trial repeatability of 2% or better for the sensors, and high correlations between the sensor and potentiometer data. RMS errors range from about 3 to 10 mm depending on the angular velocity of the pendulum. Angular errors were less than 1 degree RMS for all speeds.