RELATIONSHIP BETWEEN LONG LATENCY ACTIVITIES FROM WRIST FLEXOR AND PERFORMANCE DURING TARGET MATCH TASK OF THE WRIST JOINT

Abstract

A study was conducted to investigate the relationship between long latency activities evoked by a sudden muscle stretch of the right wrist flexor and a peformance during a target match task accompanying wrist movement. The index of performance was the target match time (TMT) from onset of a handle displacement untill the handle position output was matched with a traget line. The standard deviation of TMT (TMT-S.D.) was calculated. Sixteen healthy men, ranging in age from 20 to 27 yr., participated in the study. A DC torque motor was used to generate an angular displacement at the right wrist joint. Analysis of the surface electromyogram recorded from the wrist flexor showed that the short and long latency reflex components (Ml, M 2 and M3) were evoked by muscle stretching. In the target match task, the amplitude of the M 2 and M 3 components for all subjects were significantly smaller than the M 1 component (p<0.01) . In some subjects the M 3 component was not identifiable, since its amplitude was very small in the target match movement. There were significant correlations between the M 2 amplitude and performances (TMT : r=0.857, p<0.01 and TMT-S. D. ; r=0.651, p<0.01) during the target match task. In shoat, the smaller the M 2 amplitude was, the shorter the TMT became and the smaller the TMT-S. D, became. These results suggest that the change in the M 2 component is related to motor control for the target match task.