Articles in PresS. J Neurophysiol (August 30, 2017). doi:10.1152/jn.00527.2017

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Corticospinal excitability of the biceps brachii is shoulder position-dependent

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BW. Collins1, E.W.J. Cadigan1, L. Stefanelli1 and DC. Button1,2*

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Human Neurophysiology Laboratory, School of Human Kinetics and Recreation and

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BioMedical Sciences, Faculty of Medicine, Memorial University, St. John’s, Newfoundland and

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Labrador, Canada.

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Correspondence

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Duane C. Button, PhD School of Human Kinetics and Recreation, Memorial University of Newfoundland 230 Elizabeth Avenue St. John's, Newfoundland, Canada A1C 5S7. Phone: 709-864-4886 Email: [email protected]

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Running Head: Corticospinal excitability of the biceps brachii

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1 Copyright © 2017 by the American Physiological Society.

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ABSTRACT

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The purpose of this study was to examine the effect of shoulder position on corticospinal

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excitability (CSE) of the biceps brachii during rest and a 10% maximal voluntary contraction

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(MVC). Participants (n=9) completed two experimental sessions with four conditions: 1) rest, 0°

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shoulder flexion, 2) 10% MVC, 0° shoulder flexion 3) rest, 90° shoulder flexion 4) 10% MVC,

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90° shoulder flexion. Transcranial magnetic, transmastoid electrical and Erb’s point stimulation

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were used to induce motor-evoked potentials (MEPs), cervicomedullary MEPs (CMEPs) and

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maximal muscle compound potentials (Mmax), respectively, in the biceps brachii in each

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condition. At rest, MEP, CMEP and Mmax amplitudes increased (p