Reliability of a simple method for determining muscle fiber conduction velocity.

Introduction: This study evaluated the reliability of muscle fiber conduction velocity (MFCV) measurement.

Methods: 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.

Results: 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).

Conclusions: 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.