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A review on crosstalk in myographic signals

Talib I, Sundaraj K, Lam CK, Hussain J, Ali MA

Eur J Appl Physiol, 2019 Jan;119(1):9-28.
PMID: 30242464 DOI: 10.1007/s00421-018-3994-9

PURPOSE: Crosstalk in myographic signals is a major hindrance to the understanding of local information related to individual muscle function. This review aims to analyse the problem of crosstalk in electromyography and mechanomyography.
METHODS: An initial search of the SCOPUS database using an appropriate set of keywords yielded 290 studies, and 59 potential studies were selected after all the records were screened using the eligibility criteria. This review on crosstalk revealed that signal contamination due to crosstalk remains a major challenge in the application of surface myography techniques. Various methods have been employed in previous studies to identify, quantify and reduce crosstalk in surface myographic signals.
RESULTS: Although correlation-based methods for crosstalk quantification are easy to use, there is a possibility that co-contraction could be interpreted as crosstalk. High-definition EMG has emerged as a new technique that has been successfully applied to reduce crosstalk.
CONCLUSIONS: The phenomenon of crosstalk needs to be investigated carefully because it depends on many factors related to muscle task and physiology. This review article not only provides a good summary of the literature on crosstalk in myographic signals but also discusses new directions related to techniques for crosstalk identification, quantification and reduction. The review also provides insights into muscle-related issues that impact crosstalk in myographic signals.

Matched MeSH terms: Myography/methods*
Fulltext Mechanomyographic parameter extraction methods: an appraisal for clinical applications

Ibitoye MO, Hamzaid NA, Zuniga JM, Hasnan N, Wahab AK

Sensors (Basel), 2014;14(12):22940-70.
PMID: 25479326 DOI: 10.3390/s141222940

The research conducted in the last three decades has collectively demonstrated that the skeletal muscle performance can be alternatively assessed by mechanomyographic signal (MMG) parameters. Indices of muscle performance, not limited to force, power, work, endurance and the related physiological processes underlying muscle activities during contraction have been evaluated in the light of the signal features. As a non-stationary signal that reflects several distinctive patterns of muscle actions, the illustrations obtained from the literature support the reliability of MMG in the analysis of muscles under voluntary and stimulus evoked contractions. An appraisal of the standard practice including the measurement theories of the methods used to extract parameters of the signal is vital to the application of the signal during experimental and clinical practices, especially in areas where electromyograms are contraindicated or have limited application. As we highlight the underpinning technical guidelines and domains where each method is well-suited, the limitations of the methods are also presented to position the state of the art in MMG parameters extraction, thus providing the theoretical framework for improvement on the current practices to widen the opportunity for new insights and discoveries. Since the signal modality has not been widely deployed due partly to the limited information extractable from the signals when compared with other classical techniques used to assess muscle performance, this survey is particularly relevant to the projected future of MMG applications in the realm of musculoskeletal assessments and in the real time detection of muscle activity.

Matched MeSH terms: Myography/methods*
Fulltext Longitudinal, lateral and transverse axes of forearm muscles influence the crosstalk in the mechanomyographic signals during isometric wrist postures

Islam MA, Sundaraj K, Ahmad RB, Sundaraj S, Ahamed NU, Ali MA

PLoS One, 2014;9(8):e104280.
PMID: 25090008 DOI: 10.1371/journal.pone.0104280

In mechanomyography (MMG), crosstalk refers to the contamination of the signal from the muscle of interest by the signal from another muscle or muscle group that is in close proximity.

Matched MeSH terms: Myography/methods
Mechanomyography and muscle function assessment: a review of current state and prospects

Ibitoye MO, Hamzaid NA, Zuniga JM, Abdul Wahab AK

Clin Biomech (Bristol, Avon), 2014 Jun;29(6):691-704.
PMID: 24856875 DOI: 10.1016/j.clinbiomech.2014.04.003

Previous studies have explored to saturation the efficacy of the conventional signal (such as electromyogram) for muscle function assessment and found its clinical impact limited. Increasing demand for reliable muscle function assessment modalities continues to prompt further investigation into other complementary alternatives. Application of mechanomyographic signal to quantify muscle performance has been proposed due to its inherent mechanical nature and ability to assess muscle function non-invasively while preserving muscular neurophysiologic information. Mechanomyogram is gaining accelerated applications in evaluating the properties of muscle under voluntary and evoked muscle contraction with prospects in clinical practices. As a complementary modality and the mechanical counterpart to electromyogram; mechanomyogram has gained significant acceptance in analysis of isometric and dynamic muscle actions. Substantial studies have also documented the effectiveness of mechanomyographic signal to assess muscle performance but none involved comprehensive appraisal of the state of the art applications with highlights on the future prospect and potential integration into the clinical practices. Motivated by the dearth of such critical review, we assessed the literature to investigate its principle of acquisition, current applications, challenges and future directions. Based on our findings, the importance of rigorous scientific and clinical validation of the signal is highlighted. It is also evident that as a robust complement to electromyogram, mechanomyographic signal may possess unprecedented potentials and further investigation will be enlightening.

Matched MeSH terms: Electromyography/methods; Myography/methods*
Fulltext Cross-talk in mechanomyographic signals from the forearm muscles during sub-maximal to maximal isometric grip force

Islam MA, Sundaraj K, Ahmad RB, Sundaraj S, Ahamed NU, Ali MA

PLoS One, 2014;9(5):e96628.
PMID: 24802858 DOI: 10.1371/journal.pone.0096628

This study aimed: i) to examine the relationship between the magnitude of cross-talk in mechanomyographic (MMG) signals generated by the extensor digitorum (ED), extensor carpi ulnaris (ECU), and flexor carpi ulnaris (FCU) muscles with the sub-maximal to maximal isometric grip force, and with the anthropometric parameters of the forearm, and ii) to quantify the distribution of the cross-talk in the MMG signal to determine if it appears due to the signal component of intramuscular pressure waves produced by the muscle fibers geometrical changes or due to the limb tremor.

Matched MeSH terms: Electromyography/methods; Myography/methods
Fulltext "A Step and a Ceiling": mechanical properties of Ca2+ spark vasoregulation in resistance arteries by pressure-induced oxidative activation of PKG

Csato V, Kadir SZSA, Khavandi K, Bennett H, Sugden S, Gurney AM, et al.

Physiol Rep, 2019 Nov;7(22):e14260.
PMID: 31782255 DOI: 10.14814/phy2.14260

We investigated the biomechanical relationship between intraluminal pressure within small mesenteric resistance arteries, oxidant activation of PKG, Ca2+ sparks, and BK channel vasoregulation. Mesenteric resistance arteries from wild type (WT) and genetically modified mice with PKG resistance to oxidative activation were studied using wire and pressure myography. Ca2+ sparks and Ca2+ transients within vascular smooth muscle cells of intact arteries were characterized using high-speed confocal microscopy of intact arteries. Arteries were studied under conditions of varying intraluminal pressure and oxidation. Intraluminal pressure specifically, rather than the generic stretch of the artery, was necessary to activate the oxidative pathway. We demonstrated a graded step activation profile for the generation of Ca2+ sparks and also a functional "ceiling" for this pressure --sensitive oxidative pathway. During steady state pressure - induced constriction, any additional Ca2+ sensitive-K+ channel functional availability was independent of oxidant activated PKG. There was an increase in the amplitude, but not the Area under the Curve (AUC) of the caffeine-induced Ca2+ transient in pressurized arteries from mice with oxidant-resistant PKG compared with wild type. Overall, we surmise that intraluminal pressure within resistance arteries controls Ca2+ spark vasoregulation through a tightly controlled pathway with a graded onset switch. The pathway, underpinned by oxidant activation of PKG, cannot be further boosted by additional pressure or oxidation once active. We propose that these restrictive characteristics of pressure-induced Ca2+ spark vasoregulation confer stability for the artery in order to provide a constant flow independent of additional pressure fluctuations or exogenous oxidants.

Matched MeSH terms: Myography/methods