Technical aspects of acoustic myography (AMG) of human skeletal muscle: contact pressure and force/AMG relationships

Smith T.G. and Stokes M.J. (1993) Technical aspects of acoustic myography (AMG) of human skeletal muscle: contact pressure and force/AMG relationships. Journal of Neuroscience Methods, 47 1-2: 85-92. doi:10.1016/0165-0270(93)90024-L


Author Smith T.G.
Stokes M.J.
Title Technical aspects of acoustic myography (AMG) of human skeletal muscle: contact pressure and force/AMG relationships
Journal name Journal of Neuroscience Methods   Check publisher's open access policy
ISSN 0165-0270
Publication date 1993-01-01
Sub-type Article (original research)
DOI 10.1016/0165-0270(93)90024-L
Open Access Status Not yet assessed
Volume 47
Issue 1-2
Start page 85
End page 92
Total pages 8
Subject 2800 Neuroscience
Abstract The effect of contact pressure on acoustic myographic (AMG) recordings was examined during voluntary isometric contractions of the human quadriceps muscle in 20 normal males. A piezoelectric disk for recording muscle sounds was placed over rectus femoris at approximately mid-thigh and secured with a rubber electromyography (EMG) strap. Contact pressure was monitored by a load cell placed between the AMG device and the strap. With the subject seated, force at different percentage levels of maximum voluntary contraction (MVC) were held for 5 s each. Both AMG and EMG recordings were full-wave rectified and integrated (IAMG and IEMG) and expressed as a percentage of activity at MVC. Two contraction series were performed with 2 different contact pressures. Pressure 1 (P1), of 180 Pa was applied in all subjects. A higher pressure of either 790 Pa (P2; in 5 subjects) or 1200 Pa (P3; in 15 subjects) was also applied. No significant changes in IAMG activity (P > 0.1) occurred between P1 and P2 but P3 produced increases in IAMG at all force levels (P < 0.05 at 10, 50 and 75% MVC). Both linear and non-linear relationships between force and IAMG were observed in different subjects but the relationship also varied with the 2 contact pressures within some subjects. The force/IEMG relationship was linear in all cases. These results provide quantitative evidence that contact pressure can influence the degree of IAMG activity if the pressure is high enough. The change in the force/IAMG relationship with pressure in some subjects suggests that the different relationships observed are not determined by physiological differences between subjects but rather by technical factors.
Keyword Acoustic myography
Muscle activity
Muscle sound
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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