Comparison of mechanomyographic sensors during incremental cycle ergometry for the quadriceps femoris

Abstract

The purpose of this study was to examine the mechanomyographic (MMG) amplitude and mean power frequency (MPF) versus power output relationships for the vastus lateralis and rectus femoris muscles during incremental cycle ergometry between the piezoelectric contact sensor (HP) and the accelerometer (ACC) sensor. Nine men performed an incremental cycle ergometry test to voluntary exhaustion. Polynomial regression analyses on a subject-by-subject basis indicated that the relationship between the normalized MMG amplitude versus normalized power output was best fit with either a linear, quadratic, or cubic model. These patterns were consistent between sensors for each muscle for each subject. No consistent relationship was found for MMG MPF within subjects and between muscle groups. In addition, there were no significant sensor x power output interactions for normalized MMG amplitude or MPF. These results suggest that, for cycle ergometry, the HP and ACC sensors provide similar information for the interpretation of motor control strategies during continuous exercise.

Mechanomyographic responses are not influenced by the innervation zone for the vastus medialis

“…Thereafter, each subject performed an incremental cycle ergometry test to voluntary fatigue. 8,9 Subjects. Ten healthy, college-aged men (mean 6 SEM: age, 24.4 6 1.3 years; mass, 94.0 6 6.0 kg; height, 1.81 6 0.03 m) volunteered as subjects for this investigation.…”

“…The MPF was selected to represent the power spectrum based on recommendations by Diemont et al, 28 and was calculated as described by Kwatny et al 29 The amplitude and MPF values for the MMG signals were calculated as the average of the last three complete pedal thrusts during the final 10 seconds of each power output. 8,9 Statistical Analyses. Each variable (power output, MMG amplitude, and MMG MPF) was normalized as a percentage of its maximal value for each subject.…”

“…1,2 Our laboratory has previously examined both the time and frequency domains of the MMG signal to provide insight into the motor control strategies that modulate force production during different exercise perturbations. [8][9][10][15][16][17] Previous studies have shown that the MMG signal can be influenced by factors such as muscle architecture 5 and location. 18,19 Stokes and Dalton stated, ''…greater activity is recorded over the muscle belly than over fascia…so the specificity of placement of the recording device may be more important than has been suggested…'' (p. 1425).…”

“…Barry and Cole 4 and Orizio 5 found that the lateral oscillations recorded as MMG are generated by: (a) a gross lateral movement of the muscle at the initiation of a contraction that is generated by non-simultaneous activation of muscle fibers; (b) smaller sequential lateral oscillations occurring at the resonant frequency of the muscle; and (c) dimensional changes of the active muscle fibers. The time and/or frequency domain of the MMG signal has been used to study various aspects of muscle function, including neuromuscular fatigue, 1,2 electromechanical delay, 6,7 differences in sensors and motor unit recruitment strategies between cycle and knee-extensor ergometry, 8,9 and changes in force production and muscle action velocity. [8][9][10] Clinically, MMG has been used to study a number of neuromuscular disorders across the lifespan, such as cerebral palsy, 11 myotonic dystrophy, 12,13 and as a control for external protheses.…”

“…The time and/or frequency domain of the MMG signal has been used to study various aspects of muscle function, including neuromuscular fatigue, 1,2 electromechanical delay, 6,7 differences in sensors and motor unit recruitment strategies between cycle and knee-extensor ergometry, 8,9 and changes in force production and muscle action velocity. [8][9][10] Clinically, MMG has been used to study a number of neuromuscular disorders across the lifespan, such as cerebral palsy, 11 myotonic dystrophy, 12,13 and as a control for external protheses. 14 The MMG signal is a nonlinear summation of the activity from individual motor units, and it has been suggested that the time and frequency domains of the MMG signal may provide information regarding the motor control strategies (i.e., motor unit recruitment and firing rate) of muscles during both isometric and dynamic muscle actions.…”