Ten normal adults and forty-two post stroke hemiplegic patients were evaluated by our balance test using Dynamic Posture Analyzing System (DPAS), which we had developed in our laboratory. All hemiplegic subjects were able to ambulate with or without walking aids and lower limb orthoses.
DPAS can generate horizontally displacing stimulation of moving platform under following various stimulation conditions.
Condition 1: displacement; 2.5cm, velocity ;10cm/sec. Condition 2: displacement; 3cm, velocity; 12cm/sec. Condition 3: displacement; 5cm, velocity; 20cm/sec. Directions of displacement were backward (BW) and forward (FW). In all, 6 conditions were performed to each subject.
Subjects were instructed to keep standing position on the force plates with eyes open. Postural sway after platform displacing stimulation was measured by split force plates on the platform and COP (center of pressure) movement of each foot was recorded.
Range of COP displacement during body sway was 24.1 (posterior) to 65.1 (anterior)% of individual's foot length for normal subjects in Condition 1. As for hemiplegic subjects, the range was wider (about 20 to 70%) than normal subjects for unaffected side in same condition. COP displacement and foot torque for postural adjustment of affected side were much smaller than unaffected side, and weight load was deviated to unaffected foot, especially among the patients with orthoses.
Response time for postural adjustment after BW displacement was 0.28 to 0.31 sec for normal subjects and 0.31 to 0.36 sec for hemiplegic patients.
As platform displacement increased, hemiplegic subjects became to react with hip pattern as well as ankle pattern. This pattern was obvious in Condition 3 of FW displacement.

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The purpose of this study was to determine whether the direction of the trunk rotation and severity and side of the hemiplegia would have an effect on the isokinetic rotatory muscle strength of the trunk. We evaluated the muscle strength of the trunk of 55 hemiplegic patients by an isokinetic dynamometer at a 60 degree/second angular velocity. There were no significant differences in percentages of muscle peak torque per body weight between the right and left directions of the trunk rotation, the left and right side hemiplegia, or the severity of hemiplegia. The results suggested that the bilateral innervation of the nerves to the trunk muscles and the coordinated trunk muscle contractions on both sides might keep the trunk muscle strength in the hemiplegic patients from decreasing.

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