Flexor carpi radialis surface electromyography electrode placement for evoked and voluntary measures

Introduction: In this study we evaluated the reliability of bipolar electrode recordings, which allow for undistorted compound muscle action potentials (CMAPs) while minimizing cross-talk during voluntary contractions. Methods: Twenty-four men completed maximal voluntary wrist flexion contractions in 4 test sessions. Compound muscle action potentials were also evoked during each session. Surface electromyography was recorded from the flexor carpi radialis (FCR) with the recording electrode (G1) placed on the motor point and a second recording electrode (G2) adjacent to G1. Reliability was assessed using intraclass correlational analysis of variance and standard error of measurement. Results: Root-mean-square (RMS) amplitude and mean power frequency (MPF) were highly reliable (R=0.89 and 0.84, respectively). The CMAPs also exhibited good reliability (R=0.75). Normalization of RMS amplitude reduced the intraclass reliability coefficient (R=0.85). Conclusion: The electrode placement resulted in reliable measures from voluntary contractions and CMAPs. Normalization can decrease reliability. Muscle Nerve52: 818-825, 2015