The numbers and relative sizes of motor units estimated by Computer

AbstractA fully automated system is described for estimating the numbers and relative sizes of functioning motor units in proximal and distal muscles of the arm and leg. In this system, a computer controls the motor nerve stimulation, and analyzes the potentials evoked from the muscles; a subprogram searches for instances of “alternation.” In 33 healthy volunteers, aged 21 to 56 years, the median‐innervated thenar muscles of one hand were tested 2 to 3 times; the mean motor unit estimate was 228 ± 93 SD. For similar numbers of biceps brachii, extensor digitorum brevis, and vastus medialis muscles, the respective mean values were 113 ± 40, 131 ± 45, and 229 ± 108 units. The reproducibility of the method was such that the overall coefficient of variation, for the normalized results from the 121 muscles studied, was 22%. The reliability of the automated method was doubled if 3 estimates, rather than one, were performed on each muscle. Comparisons of the results obtained by automated and “manual” methods indicated that the computer‐derived values tended to be lower by approximately 33%.

The numbers and relative sizes of motor units estimated by Computer Journal Articles