title: Two dimensional spatial coherence of the natural vibrations of the biceps brachii muscle generated during voluntary contractions.
abstract: Surface mechanomyograms (S-MMGs) are recorded from low frequency (〈100 Hz) mechanical oscillations that are naturally generated by skeletal muscle during voluntary contractions. This study investigates a method to determine the propagation directionality of the S-MMG waves. A 3×5 grid of skin mounted accelerometers was mounted on the biceps brachii muscle during submaximal voluntary contractions. This method resulted in findings that the propagation directionality of the S-MMGs are frequency dependent. At high frequencies (>25 Hz), high spatial coherence values were only measured for sensor pairs aligned along the proximal to distal (i.e. longitudinal) orientation, thus indicating that coherent S-MMG were mainly propagating along the muscle fibers direction of the biceps brachii at those frequencies. On the other hand, at lower frequencies (〈25 Hz), the S-MMG spatial coherence values did not exhibit a specific directionality. This method provides results that have an important implication of finding the average phase velocity of the propagating S-MMG wave, which can be used to determine viscoelastic properties of skeletal muscles.
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA. aarcher6@mail.gatech.edu
authors.forename: Akibi
authors.initials: A
authors.lastname: Archer
authors.forename: Karim G
authors.initials: KG
authors.lastname: Sabra
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D001696:Biomechanical Phenomena / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000379:methods*; D057918:Fiducial Markers; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009213:Myography / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D019415:Torque; D014732:Vibration