The effect of shoulder position on motor evoked and maximal muscle compound action potentials of the biceps brachii

•Motor evoked potential amplitude of the biceps brachii was dependent on shoulder position and level of muscle contraction.•The stimulation intensities to induce evoked potentials were dependent on shoulder position and level of muscle contraction.•Biceps brachii electromyography was shoulder position-dependent at rest and during 10% MVC. The purpose of the study was to assess the effect of shoulder position, 0° versus 90° shoulder flexion, on stimulation intensity and maximal muscle compound action potentials (Mmax) and motor evoked potentials (MEP) of the biceps brachii during both rest and 10% maximum voluntary contraction (MVC). Nine participants completed two experimental sessions with four conditions. During each condition, transcranial magnetic (TMS) and Erb’s point stimulation were used to elicit MEPs and Mmax, respectively. During rest, the TMS intensity to elicit a MEP response (p