Background
The motor unit number index (MUNIX) and motor unit size index (MUSIX) refer to the electrophysiological measurement of the motor units using the surface electromyographic interference pattern (SIP) recorded during graded muscle contraction. In order to improve the reliability and reproducibility of MUNIX by the systematization of the graded muscle contractions, we applied a digital hand instrument to the procedure of recording SIP signals.
Methods
We tested the applicability of the digital instrument in the MUNIX technique by assessing the mean values and the reproducibility of the MUNIX involving the abductor pollicis brevis (APB) and the abductor digiti minimi (ADM) muscles in 30 healthy adults.
Results
The digital dynamometer was successfully applied to the MUNIX measurements of the APB and ADM muscles, and showed high reproducibility across trials.
Conclusions
Application of the digital instrument would be useful in improving the reliability and reproducibility of MUNIX.
