Comparison of motor unit action potential characteristics and hand dominance using monopolar needle electrodes in the abductor pollicis brevis and abductor digiti minimi muscles.

This study examined specific electrical characteristics of voluntary single motor unit action potentials (SMUAPs): amplitude, duration, phase change, and rate of rise. These characteristics, which were detected from two intrinsic muscles of the hand--the abductor pollicis brevis and the abductor digiti minimi--were compared to hand dominance. Forty subjects participated in the study. Five characteristics were detected from each muscle using the quadrant technique while the subject produced a minimal isometric contraction. Based on results of an ANOVA [two-factor with replication] test, our study revealed no significant difference between muscles in the dominant and non-dominant hands. Descriptive statistics for each muscle characteristic are presented. This study has identified parameters for SMUAP characteristics detected in non-impaired individuals ranging in age from 20 to 43 years. The normative parameters serve as a valuable base from which one may examine potential neuronal damage from cumulative trauma disorders.