Mechanomyographic Responses Research Articles

Relationships Among Mechanomyographic Responses, M-waves, and Twitch Forces during Incremental Increases in Tibial Nerve Stimulation

Relationships Among Mechanomyographic Responses, M-waves, and Twitch Forces during Incremental Increases in Tibial Nerve Stimulation

Relationships Among The M-wave, H-reflex, Twitch Torque, And The Mechanomyographic Responses During Standard Recruitment Curves

Relationships Among The M-wave, H-reflex, Twitch Torque, And The Mechanomyographic Responses During Standard Recruitment Curves

106. Mechanomyographic responses to transcranial magnetic stimulation are different between the tonic and phasic muscle contraction

106. Mechanomyographic responses to transcranial magnetic stimulation are different between the tonic and phasic muscle contraction

Mechanomyographic responses in quadriceps muscles during fatigue by continuous cycle exercise

The present study examined whether the mechanomyogram (MMG) could assess the fatigue-related changes in muscle mechanical properties during cycle exercise. In eight male subjects, the MMG signals were measured in vastus lateralis and rectus femoris by electret condenser microphones. It was found that the integrated MMG (iMMG) showed non linear increase against workload during continuous, incremental cycle exercise and the onset of abrupt changes in iMMG coincided with the ventilatory threshold (VT). Specifically, iMMG in vastus lateralis showed a significant decrement in the rate of increase against workload above VT, reflecting the fatigue-induced impairment of contractile properties of the fibers of active motor units. These results suggest that the MMG measured by electret condenser microphone could be practically used to retrieve the fatigue-related changes in muscle mechanical properties during cycle exercise.

Mechanomyographic and Electromyographic responses to transcranial magnetic stimulation at phasic contraction differ from those at tonic contraction

To investigate whether the activation pattern of the efferent pathway and muscle during voluntary movement differs according to the type of muscle contraction, we compared electromyographic (EMG) responses to transcranial magnetic stimulation (TMS) during different states of muscle contraction. We also tested mechanomyographic (MMG) responses because mechanomyography is the mechanical counterpart of EMG.

Interlimb Comparison of the Mechanomyographic Time and Frequency Domain Responses of the Vastus Medialis

Interlimb Comparison of the Mechanomyographic Time and Frequency Domain Responses of the Vastus Medialis

Patellofemoral Pain and the Mechanomyographic Responses of the Vastus Lateralis and Vastus Medialis Muscles

Patellofemoral Pain and the Mechanomyographic Responses of the Vastus Lateralis and Vastus Medialis Muscles

Mechanomyographic Responses of the Superficial Quadriceps Femoris Muscles to Incremental Isometric Muscle Actions

Mechanomyographic Responses of the Superficial Quadriceps Femoris Muscles to Incremental Isometric Muscle Actions

The Relationship Between Mechanomyographic Responses Of The Superficial Quadriceps Muscles And Excess Post-exercise Oxygen Consumption Following Constant Power Output Cycle Ergometry

The Relationship Between Mechanomyographic Responses Of The Superficial Quadriceps Muscles And Excess Post-exercise Oxygen Consumption Following Constant Power Output Cycle Ergometry

Sex Differences in Mechanomyographic Responses to Voluntary Isometric Contractions

This study was designed to compare mechanomyography (MMG) and the force relationship during isometric ramp contractions of biceps brachii muscles in females and males to identify sex differences in the MMG responses. Subjects (10 females and 9 males; age range, 20-26 yr) were asked to exert an isometric elbow flexion torque from 5 to 80% maximal voluntary contraction (MVC) at a constant rate of 10% MVC per second. The MMG signal was normalized to muscle cross-sectional area (CSA) as measured by ultrasound imaging. MVC and CSA were significantly different between the two sex groups (males>females); however, there was no sex difference in the MVC relative to muscle CSA (MVC/CSA). The root mean squared amplitude of the MMG (RMSMMG) was significantly greater in the male group than the female group. The RMSMMG relative to muscle CSA was also different between the two sex groups (males>females). The sex difference in the RMSMMG/CSA was more pronounced with increasing torque. The torque levels at which the inflection points in the MMG amplitude were located were different between the two sex groups. The mean power frequency (MPF) of the MMG in the female group increased monotonously, which was different from that in the male group. Our results suggest that the sex differences in MMG responses and motor unit (MU) activation strategy result from the predominant activity of the MU with slow-twitch fibers and an effective fused tetanus in females. In addition, the sex-related differences in muscle morphology, subcutaneous adipose tissue, and muscle stiffness appear to be insufficiently reflected in the present MMG responses, particularly relative to muscle CSA.

Mechanomyographic and Electromyographic Responses to Intermittent Voluntary Fatigue in Human Dorsiflexors

Mechanomyographic and Electromyographic Responses to Intermittent Voluntary Fatigue in Human Dorsiflexors

Mechanomyographic and electromyographic responses to eccentric muscle contractions

Little is known regarding the modulation of torque during eccentric muscle actions. Mechanomyographic (MMG) and electromyographic (EMG) signals have been used to examine motor control strategies. The purpose of this study was to examine the MMG and EMG amplitude and frequency in relation to torque during eccentric muscle contractions. Eight women performed eccentric leg extension muscle contractions at 10-100% of peak torque (PT). A piezoelectric crystal contact sensor and bipolar surface electrodes were placed on the vastus medialis to detect the MMG and EMG signals. Polynomial regression analyses indicated that EMG amplitude (r(2)=0.994) and MMG wavelet center frequency (CF) (r(2)=0.846) increased linearly to 100% eccentric PT, whereas there were no significant relationships for EMG wavelet CF or MMG amplitude and eccentric torque. These results suggested that eccentric torque is primarily modulated through changes in motor unit firing rate.

Effect of the Wingate Test on Mechanomyography and Electromyography

The purpose of this investigation was to examine mechanomyographic (MMG) and electromyographic (EMG) amplitude responses of the superficial quadriceps femoris muscles during the Wingate Anaerobic Test (WAnT). Ten healthy adults (age 21 +/- 1.2 years) volunteered to perform the WAnT on a calibrated Monark 894E cycle ergometer while the EMG and MMG signals were recorded. The EMG and MMG amplitude and power output (W) values per 5-second segments of the test were averaged and normalized to the highest value found during the test, respectively. The statistical analysis indicated that EMG amplitude did not change significantly over the 30-second test, but W and MMG amplitude decreased significantly. There is dissociation between EMG and MMG amplitude over the 30-second anaerobic test, providing evidence that MMG amplitude could be used as a monitor of W during such a task. MMG amplitude could potentially be used as a direct monitor of mechanical activity, which could be of benefit to those who train athletes when a direct assessment of mechanical contribution from a given muscle to a fatiguing activity is desired (such as when monitoring an injury), but it must be studied under various conditions, such as the current study, before such applications are made.

Non-invasive characterization of single motor unit electromyographic and mechanomyographic activities in the biceps brachii muscle

The aim of the study was to investigate amplitude and frequency content of single motor unit (MU) electromyographic (EMG) and mechanomyographic (MMG) responses. Multi-channel surface EMG and MMG signals were detected from the dominant biceps brachii muscle of 10 volunteers during isometric voluntary contractions at 20%, 50%, and 80% of the maximal voluntary contraction (MVC) force. Each contraction was performed three times in the experimental session which was repeated in three non-consecutive days. Single MU action potentials were identified from the surface EMG signals and their times of occurrence used to trigger the averaging of the MMG signal. At each contraction level, the MUs with action potentials of highest amplitude were identified. Single MU EMG and MMG amplitude and mean frequency were estimated with normalized standard error of the mean within subjects (due to repetition of the measure in different trials and experimental sessions) smaller than 15% and 7%, respectively, in all conditions. The amplitude of the action potentials of the detected MUs increased with increasing force (mean ± SD, 244 ± 116 μV at 20% MVC, and 1426 ± 638 μV at 80% MVC; P < 0.001) while MU MMG amplitude increased from 20% to 50% MVC (40.5 ± 20.9 and 150 ± 88.4 mm/s 2, respectively; P < 0.001) and did not change significantly between 50% and 80% MVC (129 ± 82.7 mm/s 2 at 80% MVC). MU EMG mean frequency decreased with contraction level (20% MVC: 97.2 ± 13.9 Hz; 80% MVC: 86.2 ± 11.4 Hz; P < 0.001) while MU MMG mean frequency increased (20% MVC: 33.2 ± 6.8 Hz; 80% MVC: 40.1 ± 6.1 Hz; P < 0.001). EMG peak-to-peak amplitude and mean frequency of individual MUs were not correlated with the corresponding variables of MMG at any contraction level.

Mechanomyographic Responses of the Vastus Medialis to Isometric and Eccentric Muscle Actions

The mechanomyographic (MMG) signal may be used to examine the motor control strategies used to modulate torque during various types of muscle actions. Therefore, the purpose of this study was to examine the MMG amplitude and mean power frequency (MPF) versus torque relationships during isometric and eccentric isokinetic muscle actions. Eleven adults (mean age +/- SD = 20.8 +/- 1.4 yr) volunteered to perform isometric and eccentric isokinetic leg extension muscle actions at 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100% of peak torque on a Cybex 6000 dynamometer. A piezoelectric crystal contact sensor was placed on the vastus medialis to detect the MMG signal. Polynomial regression analyses indicated that for the isometric muscle actions, the relationships for MMG amplitude (r2 = 0.984) and MPF (r2 = 0.989) versus torque were linear. For the eccentric isokinetic muscle actions, the relationships for MMG amplitude (r2 = 0.580) and MPF (r2 = 0.961) versus torque were also linear. The patterns for MMG amplitude and MPF may reflect the motor control strategies that modulate torque production for isometric and eccentric isokinetic muscle actions. Based on the results of this and previous studies, it appears that for the vastus medialis, torque is modulated in a similar manner for isometric, concentric, and eccentric isokinetic muscle actions. Specifically, these findings suggest that gradation of torque involves increases in recruitment and firing rate to 100% voluntary torque production.

Mechanomyographic and Electromyographic Responses to Repeated, Concentric Muscle Actions

Mechanomyographic and Electromyographic Responses to Repeated, Concentric Muscle Actions

The Effect of Glycerol on Torque, Electromyography, and Mechanomyography

The purpose of this investigation was to determine the effect of hyperhydration on the electromyographic (EMG) and mechanomyographic (MMG) responses during isometric and isokinetic muscle actions of the biceps brachii. Eight (22.1 +/- 1.8 years, 79.5 +/- 22.8 kg) subjects were tested for maximal isometric, submaximal isometric, and maximal concentric isokinetic muscle strength in either a control (C) or hyperhydrated (H) state induced by glycerol ingestion while the EMG and MMG signals were recorded. Although fluid retention was significantly greater during the H protocol, the analyses indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, or MMG MPF with hyperhydration. These results indicated that glycerol-induced fluid retention does not affect the torque-producing capabilities of a muscle, the impulses (EMG) going to a muscle, or muscular vibrations (MMG). It has been suggested that EMG and MMG can be used as direct electrical/mechanical monitoring, which could be presented to trainers and athletes; however, before determining the utility of these signals, the MMG and EMG responses should be examined under a variety of conditions such as in the present study.

THE EFFECT OF HYPERHYDRATION ON TORQUE, ELECTROMYOGRAPHY AND MECHANOMYOGRAPHY DURING ISOMETRIC MUSCLE ACTIONS

PURPOSE To investigate the effect of hyperhydration on the torque, electromyographic (EMG) and mechanomyographic (MMG) responses during isometric muscle action of the biceps brachii muscle. METHODS Nine college age (22 ± 1 yrs, 78 ± 27 kg) volunteers performed maximal isometric (MVC) muscle actions of the biceps brachii in a euhydrated (C) and hyperhydrated (H) state. Each trial was divided into pre-treatment testing (C1 and H1) and post-treatment testing (C2 and H2). In the C trial the subjects consumed 22 ml water/kg body weight over 150 min period, whereas in the H trial the subjects consumed the same volume of fluid over the same period of time with the addition of 1 g glycerol/kg body weight. EMG and MMG were detected midway over the biceps brachii muscle during all testing. The torque and amplitude (EMG and MMG) values were analyzed using two-way (trial by time) repeated measures ANOVAs. RESULTS Although fluid retention was significantly greater (H:48.9 ± 25.2, C: 22.5 ± 24.1%; P < 0.05) during the H trial, the analyses revealed no significant two-way interactions for torque, EMG, or MMG, which indicated that the subjects responded similarly to the control and hyperhydration protocols. CONCLUSION The results of the present investigation revealed that compared to the control state, glycerol-induced hyperhydration does not affect the torque producing capabilities of a muscle, the ability to activate a muscle (EMG), or the muscular vibrations (MMG).Table: No Caption Available

Mechanomyographic responses during voluntary ramp contractions of the human first dorsal interosseous muscle.

The aim of this study was to examine the mechanomyogram (MMG) and force relationship of the first dorsal interosseous (FDI) muscle as well as the biceps brachii (BB) muscle during voluntary isometric ramp contractions, and to elucidate the MMG responses resulting from the intrinsic motor unit (MU) activation strategy of FDI muscle with reference to the MMG of BB muscle. The subjects were asked to exert ramp contractions of FDI and BB muscle from 5% to 70% of the maximal voluntary contraction (MVC) at a constant rate of 10% MVC/s. In FDI muscle, the root-mean-squared amplitude (RMS) of the MMG decreased slowly with force up to 21%, and then a progressive increase was followed by a relatively rapid decrease beyond 41% MVC. The RMS/%MVC relationship in BB muscle consisted of an initial slow increase followed by a rapid increase from 23% MVC and a progressive decrease beyond 61% MVC. With respect to the mean power frequency (MPF), FDI muscle demonstrated no obvious inflection point in the MPF/%MVC relationship compared with that in BB muscle. Namely, the MPF of FDI muscle increased linearly through the force levels exerted. In contrast to FDI muscle, the MPF/%MVC relationship in BB muscle was decomposed into four specific regions: (1) a relative rapidly increase (<34% MVC), (2) a slow increment (34-53% MVC), (3) a temporary reduction (53-62% MVC), and (4) a further rapid increase (>62% MVC). The different MMG responses between FDI and BB muscles are considered to reflect the fact that the MU activation strategy varies among different muscles in relation to their morphology and histochemical type. Namely, the rate coding of the MUs plays a more prominent role in force production in relatively small FDI muscle than does MU recruitment compared with their respective roles in the relatively large BB muscle.

Mechanomyographic and Electromyographic Responses to Unilateral Isometric Training

Mechanomyographic and Electromyographic Responses to Unilateral Isometric Training