Comparison of mechanomyographic amplitude and mean power frequency for the rectus femoris muscle: Cycle versus knee-extensor ergometry

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.…”

“…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.…”

“…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).…”