Muscle velocity recovery cycles: Comparison between surface and needle recordings

Introduction: Recording of muscle velocity recovery cycles (MVRCs) has been developed as a technique to investigate the pathophysiology of muscle diseases. MVRCs have been measured by direct muscle stimulation and concentric electromyographic needle recording. This study was undertaken to determine whether recordings can be made with surface electrodes. Methods: MVRCs with 1 and 2 conditioning stimuli were recorded simultaneously with concentric needle and surface electrodes from the brachioradialis muscle in 12 healthy volunteers. Muscle relative refractory period, early and late supernormality, and extra-late supernormality were compared between the recording techniques. Results: Surface recordings were possible in all subjects. The multifiber action potentials recorded with surface electrodes were smaller than those recorded with needles, but there was no significant difference between any of their MVRC properties. Conclusions: MVRCs can be recorded with surface electrodes in healthy subjects. The use of surface electrodes may facilitate the technique of recording MVRCs.