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Sensors (Basel, Switzerland) Aug 2022Electromyography (EMG) sensors have been used for measuring muscle signals and for diagnosing neuromuscular disease. Available commercial EMG sensor are expensive and...
Electromyography (EMG) sensors have been used for measuring muscle signals and for diagnosing neuromuscular disease. Available commercial EMG sensor are expensive and not easily available for individuals. The aim of the study is to validate our designed low-cost sensor against a well-known commercial system for measuring muscle activity and fatigue assessment. The evaluation of the designed system was done through a series of dynamic exercises performed by volunteers. Our low-cost EMG sensor and the commercially available system were placed on the vastus lateralis muscle to concurrently record the signal in a maximum voluntary contraction (MVC). The signal analysis was done using two validation indicators: Spearman's correlation, and intra-class cross correlation on SPSS 26.0 version. For the muscle fatigue assessment, the root mean square (RMS), mean absolute value (MAV) and mean frequency (MNF) indicators were used. The results at the peak and mean level muscle contraction intensity were computed. The relative agreement for the two systems was excellent at peak level muscle contraction range (ICC 0.74-0.92), average 0.83 and mean level muscle contraction intensity range (ICC 0.65-0.85) with an average of 0.74. The Spearman's correlation average was 0.76 with the range of (0.71-0.85) at peak level contraction, whiles the mean level contraction average was 0.71 at a range of (0.62-0.81). In determining muscle fatigue, the RMS and MAV showed increasing values in the time domain, while the MEF decreased in the frequency domain. Overall, the results indicated a good to excellent agreement of the two systems and confirmed the reliability of our design. The low-cost sensor also proved to be suitable for muscle fatigue assessment. Our designed system can therefore be implemented for rehabilitation, sports science, and ergonomics.
Topics: Electromyography; Humans; Isometric Contraction; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Reproducibility of Results
PubMed: 35957354
DOI: 10.3390/s22155799 -
Proceedings of the American Thoracic... Jan 2008Airway smooth muscle cell contraction is regulated by changes in intracellular Ca2+ concentration ([Ca2+]i) and the responsiveness of the airway smooth muscle cell to... (Review)
Review
Airway smooth muscle cell contraction is regulated by changes in intracellular Ca2+ concentration ([Ca2+]i) and the responsiveness of the airway smooth muscle cell to this Ca2+. The mechanism controlling [Ca2+]i primarily involves agonist-induced release of Ca2+ from internal stores to generate Ca2+ oscillations. The extent of contraction correlates with the persistence and frequency of these Ca2+ oscillations. The maintenance of the Ca2+ oscillations requires Ca2+ influx, but membrane depolarization appears to have a minor role in initiating or sustaining contraction. Contraction also requires agonist-induced Ca2+ sensitization, which is mediated mainly by decreases in myosin light-chain phosphatase activity. Although it is not clear if airway hyperresponsiveness associated with asthma results from the specific modulation of these Ca2+-based regulatory mechanisms, bronchodilators relax airways by both attenuating the Ca2+ oscillations and by decreasing the Ca2+ sensitivity.
Topics: Animals; Asthma; Calcium Channels; Calcium Signaling; Humans; Inositol 1,4,5-Trisphosphate Receptors; Membrane Potentials; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; Ryanodine Receptor Calcium Release Channel
PubMed: 18094081
DOI: 10.1513/pats.200704-050VS -
Nature Reviews. Drug Discovery Sep 2016
Topics: Animals; Diaphragm; Humans; Muscle Contraction; Muscular Diseases; Oximes; Piperidines
PubMed: 27681795
DOI: 10.1038/nrd.2016.196 -
World Review of Nutrition and Dietetics 2009
Review
Topics: Cholesterol; Health Status; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertrophy; Motor Activity; Muscle Contraction; Muscle, Skeletal; United States
PubMed: 19696529
DOI: 10.1159/000235713 -
Journal of Theoretical Biology Oct 1995
Topics: Animals; Models, Biological; Muscle Contraction; Muscle Fibers, Skeletal
PubMed: 8538220
DOI: 10.1006/jtbi.1995.0210 -
Biofabrication Jul 2023Biohybrid robots are robots composed of both biological and artificial materials that can exhibit the unique characteristics commonly found in living organisms. Skeletal...
Biohybrid robots are robots composed of both biological and artificial materials that can exhibit the unique characteristics commonly found in living organisms. Skeletal muscle tissues can be utilized as their actuators due to their flexibility and ON/OFF controllability, but previous muscle-driven robots have been limited to one-degree of freedom (DOF) or planar motions due to their design. To overcome this limitation, we propose a biohybrid actuator with a tensegrity structure that enables multiple muscle tissues to be arranged in a 3D configuration with balanced tension. By using muscle tissues as tension members of tensegrity structure, the contraction of muscle tissues can cause the movement of the actuator in multiple-DOFs. We demonstrate the fabrication of the biohybrid tensegrity actuator by attaching three cultured skeletal muscle tissue made from C2C12 cells and fibrin-based hydrogel to an actuator skeleton using a snap-fit mechanism. When we applied an electric field of more than 4 V mmto the skeletal muscle tissue, the fabricated actuator had a structure to tilt in multiple directions through the selective displacement of about 0.5 mm in a specific direction caused by the contractions of muscle tissue, resulting in 3D multi-DOF tilting motion. We also show that the actuator possesses superior characteristics of tensegrity structure such as stability and robustness by assessing the response of the actuator to external force. This biohybrid tensegrity actuator provides a useful platform for the development of muscle-driven biohybrid robots with complex and flexible movements.
Topics: Muscle Contraction; Muscle, Skeletal
PubMed: 37385238
DOI: 10.1088/1758-5090/ace2ec -
BioMed Research International 2018The relationship between fractal dimension of the surface electromyogram (sEMG) and the intensity of muscle contraction is still controversial in simulated and...
The relationship between fractal dimension of the surface electromyogram (sEMG) and the intensity of muscle contraction is still controversial in simulated and experimental conditions. To support the use of fractal analysis to investigate myoelectric fatigue, it is crucial to establish the interdependence between fractal dimension and muscle contraction intensity. We analyzed the behavior of fractal dimension, conduction velocity, mean frequency, and average rectified value in twenty-eight volunteers at nine levels of isometric force. sEMG was obtained using bidimensional arrays in the biceps brachii muscle. The values of fractal dimension and mean frequency increased with force unless a plateau was reached at 30% maximal voluntary contraction. Overall, our findings suggest that, above a certain level of force, the use of fractal dimension to evaluate the myoelectric manifestations of fatigue may be considered, regardless of muscle contraction intensity.
Topics: Adult; Arm; Electromyography; Female; Fractals; Humans; Isometric Contraction; Male; Mechanical Phenomena; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal
PubMed: 29736393
DOI: 10.1155/2018/5373846 -
The Journal of Physiology Oct 19671. Conditions are defined which determine the level of catch after acetylcholine stimulation of Mytilus muscle.2. Catch tension in dissected muscle is absent when...
1. Conditions are defined which determine the level of catch after acetylcholine stimulation of Mytilus muscle.2. Catch tension in dissected muscle is absent when connexions with ganglia are intact.3. Catch tension is absent at temperatures above 30 degrees C.4. Catch tension decreases when intervals between stimuli are increased.5. Increasing concentrations of 5-hydroxytryptamine (5-HT) from 10(-8)M to 10(-6)M quantitatively decreases catch tension.6. The length-tension curve of ganglion-free Mytilus muscle bundles suggests that catch tension varies in proportion to the tension developed in contraction.7. External Ca(2+) concentration has no selective influence on catch.8. All factors which reduce catch also increase muscle excitability, suggesting that catch may depend on a mechanism controlling the intracellular concentration of an activator such as Ca(2+).
Topics: Acetylcholine; Animals; Calcium; In Vitro Techniques; Mollusca; Muscle Contraction; Muscle, Smooth; Neuromuscular Junction; Serotonin; Temperature
PubMed: 6059005
DOI: 10.1113/jphysiol.1967.sp008335 -
International Journal of Biological... Jun 2005Piazzesi et al. [G. Piazzesi, L. Lucii, V. Lombardi, J. Physiol. 545 (2002) 145-151] made a study on the muscle transients due to step changes in force using improved...
Piazzesi et al. [G. Piazzesi, L. Lucii, V. Lombardi, J. Physiol. 545 (2002) 145-151] made a study on the muscle transients due to step changes in force using improved time resolution and recorded filament movement and shortening velocities in the four phases. They point to Phase 2 and to Phase 4 (working muscle) and claim that their results do not contradict the swinging-cross-bridge (SCB) model which has a much-quoted constant power stroke of about 150 A (their value of 70 A was smaller). Siding with the SCB model, they nevertheless record that the power stroke decreases with load. We are pleased with this experimental result as it conforms to our theory, published in 1996, of an impulsive model with a much smaller step-size distance z (approximately 20 A). Using their data we obtain precise interval times and estimates of filament movement in Phase 2 and in working muscle. Our first result is that the time frames (interval times) for Phase 2 are the same as in working muscle. Moreover, we demonstrate that the authors' data verify the correctness of our calculated z values. There are eight active ATP events in Phase 2 in time frame t compared to one in working muscle in the same time frame t. This gives, for the first time, precise numbers for contractile events. We show that the SCB model is incorrect and our analysis supports the impulsive model with a much smaller filament (zero-load) motion, approximately 20 A per ATP split.
Topics: Models, Biological; Muscle Contraction; Muscles
PubMed: 15862865
DOI: 10.1016/j.ijbiomac.2005.03.001 -
Journal of Electromyography and... Aug 2010Percutaneous low-frequency electrical muscle stimulation (LF-ES) is a new alternative exercise prescription for individuals who cannot adequately perform voluntary...
Percutaneous low-frequency electrical muscle stimulation (LF-ES) is a new alternative exercise prescription for individuals who cannot adequately perform voluntary exercise. However, substantial undesirable elevation of both systolic blood pressure (SBP) and cardiac afterload occurs during LF-ES and must be resolved. Therefore, this study examined whether or not the synchrony between cardiac systole and skeletal muscle contraction affects instantaneous blood pressure and cardiac afterload during intermittent evoked muscle contractions. In eight subjects, the quadriceps and biceps femoris muscles of each limb were simultaneously stimulated at 20 Hz with a duty cycle of 0.3s stimulation and 0.7s pause for 15 min. The phase difference between the ECG R-peak and the onset of muscle contraction (tau(c-s)) was measured for all heartbeats. Then, instantaneous SBP, tension-time index (TTI), and peripheral vascular resistance (PVR) associated with each heartbeat were plotted as functions of tau(c-s). The results showed that SBP, TTI, and PVR were significantly lowered at positive tau(c-s) (i.e., the moment at which a muscle contraction started during the cardiac recovery phase). These results suggest that a well-designed stimulator, one that induces muscle contractions coupled with heartbeats with appropriate phase difference, would effectively attenuate the elevation of SBP and cardiac afterload during LF-ES.
Topics: Adult; Blood Pressure; Diastole; Electromyography; Heart Rate; Humans; Leg; Muscle Contraction; Muscle, Skeletal; Systole; Transcutaneous Electric Nerve Stimulation
PubMed: 20378373
DOI: 10.1016/j.jelekin.2010.03.004