Comparison of an accelerometer and piezoelectric contact sensor
for examining the mechanomyographic signal from the vastus medialis during
isometric muscle actions
Affiliations: [a] California State University, Fullerton, Fullerton, CA,
USA | [b] Wayne State University, Detroit, MI, USA | [c] University of Nebraska, Lincoln, NE, USA | [d] University of Oklahoma, Norman, OK, USA
Note: [] Address for correspondence: Jared W. Coburn, Ph.D., Department
of Kinesiology, 800 N. State College Blvd., KHS-235, California State
University, Fullerton, Fullerton, CA 92834, USA. Tel.: +1 657 278 2629; Fax: +1
657 278 1548; E-mail: [email protected]
Abstract: Background and objective: The purpose of this study was to compare
an accelerometer (ACC) and a piezoelectric contact sensor (PEC) for the
measurement of mechanomyographic (MMG) signals during submaximal to maximal
isometric muscle actions of the vastus medialis. Materials and methods: Following the determination of maximal isometric strength (MVC), eight
subjects (20.4 ± 1.3 years) performed isometric muscle actions at 10 to
90% isometric MVC in random order. An ACC and PEC were used to
simultaneously record the MMG signal. Results: For the composite data,
there were linear increases in normalized MMG amplitude for both the ACC
(r^{2} = 0.930) and PEC (r^{2} = 0.875), with no difference in slope
coefficients (p > 0.05). Similarly, there were linear increases in MMG
mean power frequency (MPF) for the ACC (r^{2} = 0.957) and PEC (r^{2} =
0.982), with no difference in slope coefficients (p > 0.05). Analysis of
individual subject data revealed there were no significant differences in slope
coefficients between sensors for MMG amplitude or MPF for any subject with the
exception of a significant difference (p < 0.05) for MMG MPF for one
subject. In addition, there were no significant (p > 0.05) mean
differences between the ACC and PEC for normalized MMG amplitude or MPF. Conclusion: These results indicated that the ACC and PEC provide comparable
information regarding MMG amplitude and MPF vs. isometric torque relationships
of the vastus medialis.
Keywords: MMG amplitude, MMG mean power frequency, isometric leg extension torque
