Reliability of a simple method for determining muscle fiber conduction velocity

Abstract

This study evaluated the reliability of muscle fiber conduction velocity (MFCV) measurement. Forty healthy, young participants performed isometric dorsiflexion of the foot on 3 non-consecutive days. The reliability of force, root-mean-square (RMS) amplitude of the surface electromyographic (sEMG) signal, and MFCV were evaluated using the intraclass correlational analysis of variance technique. The means across test days for all measures exhibited slight changes (<5%) and were considered stable. All measures exhibited remarkable consistency within subjects as indicated by high intraclass correlation coefficients (0.83-0.98). The procedures resulted in highly reliable MFCV values, and included: (1) electric identification of motor points prior to electrode placement; (2) twitch identification of muscle fiber orientation to guide initial electrode placement; (3) rotation of electrodes clockwise or counter-clockwise to maximize the similarity and delay of compound muscle action potentials across all detection surfaces; and (4) minimization of synergistic activity during voluntary contractions.