Impedance Changes in Biceps Brachii Due to Isometric Contractions and Muscle Fatigue Using Electrical Impedance Myography (EIM)

Electrical impedance myography (EIM) is a non-invasive technique used to evaluate neuromuscular conditions by using a quantitative parameter called impedance (Z). It relies upon the application and measurement of high-frequency, low-intensity electrical current imbedded over a localized muscle to determine its opposition to current flow. In brevity, impedance determines the resistance of muscle fibers due to changes in muscle composition. The objective of this thesis was to establish a relationship between muscles at rest and during isometric contractions at various force levels(25%, 50%, and 100% of maximum voluntary contraction) of the biceps brachii over a multifrequency spectrum. Impedance measurements due to muscle fatigue was further studied and compared to muscles under static conditions. It was discovered that isometric contractions had a direct, but nonlinear effect on impedance measurements; as force increased, resistance and reactance decreased on the bicep. On the other hand during muscle fatigue, only the resistance increased and the reactance saw a decline. Supporting data was presented for seven healthy males, with ages ranging from 22 to 26 years. Evidence justified that resistance at maximum voluntary isometric contraction (MVIC) correlated to the greatest difference of 12.80% whereas a percent difference of 4.63 was calculated for 25% of the MVIC. Reactance decreased from an average of 11.165 Ω at rest to 9.6025 Ω at 100% maximum isometric contraction. In a similar fashion, the resistance values saw a reduction during muscle fatigue of the biceps brachii with an 11.24% decrease. However, the average reactance increased 3.58% from the muscle at rest to the muscle during fatigue. This research study will provide an understanding of underlying muscle tissue composition during dynamic changes using a quick, pain-free, and portable bioimpedance device

A Review of Non-Invasive Techniques to Detect and Predict Localised Muscle Fatigue

Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives an overview of the various non-invasive techniques available for use in automated fatigue detection, such as mechanomyography, electromyography, near-infrared spectroscopy and ultrasound for both isometric and non-isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who wish to select the most appropriate methodology for research on muscle fatigue detection or prediction, or for the development of devices that can be used in, e.g., sports scenarios to improve performance or prevent injury. To date, research on localised muscle fatigue focuses mainly on the clinical side. There is very little research carried out on the implementation of detecting/predicting fatigue using an autonomous system, although recent research on automating the process of localised muscle fatigue detection/prediction shows promising results

Optimization of the electrode configuration of electrical impedance myography for wearable application

Electrical Impedance Myography (EIM) based on the four-electrode method is a novel method for assessing muscle state in the fields of sports, fitness, and medical rehabilitation. However, commonly used configuration of electrodes is not suitable for the wearable field, because of its large total area and low sensitivity. An optimized electrode configuration for wearable application is proposed as Mode B. Equivalent circuit model B of the four-electrode method is established by using the equivalent circuit of biological tissues, and in-vivo measurements of the electrical impedance of the biceps muscle are carried out on six volunteers using bioimpedance spectroscopy device ImpTM SFB7. The experimental results show that equivalent circuit model B of the four-electrode method is reliable. Moreover, the variation in muscle electrical impedance measured using the optimal configuration of model B is twice that measured using the optimal configuration of model A. The optimized electrode configuration of EIM based on this approach is model B (i.e. square electrodes in parallel array; size, 20 mm × 20 mm; spacing, 5–24 mm)

Noninvasive Myographical Assessments Following Unaccustomed Resistance Exercise

Traditionally, post-exercise muscular alterations have been examined using invasive techniques that lack the ability to single out individual muscle groups. Sonomyography, tensiomyography, and electrical impedance myography allow for noninvasive skeletal muscle assessment. This project aimed to examine changes in muscle contractility and composition that occur in the early stages of recovery following unaccustomed exercise. METHODS: Twenty-one untrained adults (21.9 ± 1.9 y) performed exercise – 10 × 10 maximal eccentric knee extensions – with their nondominant leg. For each repetition, participants moved through 90° range of motion at 90°•s-1 with a passive return to the start position. Each set was separated by 60 seconds of rest. Sonomyography, tensiomyography, electrical impedance myography, and maximal isometric contractions of the knee extensors (RF & VL) of both legs were performed before (BL), immediately after (IP), and 24 hours post-exercise (24H). RESULTS: Peak torque and rate of torque development were unaltered in response to the eccentric protocol. Significant limb × time interactions were noted for reactance, phase angle, and delay time of the exercised VL, and echo intensity of the exercised RF. Compared to the dominant leg, the nondominant leg displayed significantly greater changes (p \u3c 0.05) in VL delay time and RF echo intensity at IP. Following exercise, bilateral alterations were identified for reactance, phase angle, maximal displacement, delay time, contraction velocity, cross-sectional area, and thickness of the RF, as well as resistance, echo intensity, cross-sectional area, and thickness of the VL. No between-sex differences were noted in response to exercise. CONCLUSIONS: In the absence of performance decrements, sonomyography, tensiomyography, and electrical impedance myography successfully detected acute changes in skeletal muscle composition and function following an acute bout of eccentric exercise in untrained men and women. While the exercised leg exhibited specific responses in delay time and echo intensity, bilateral changes are theorized to have occurred due to contralateral stabilization of the non-exercised leg. The current results suggest that different muscle actions (i.e., eccentric and isometric) promote similar consequences to muscle strength, size, echogenicity, contractility, and bioelectrical properties

Mechanomyographic Parameter Extraction Methods: An Appraisal for Clinical Applications

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

Design of a low-cost sensor matrix for use in human-machine interactions on the basis of myographic information

Myographic sensor matrices in the field of human-machine interfaces are often poorly developed and not pushing the limits in terms of a high spatial resolution. Many studies use sensor matrices as a tool to access myographic data for intention prediction algorithms regardless of the human anatomy and used sensor principles. The necessity for more sophisticated sensor matrices in the field of myographic human-machine interfaces is essential, and the community already called out for new sensor solutions. This work follows the neuromechanics of the human and designs customized sensor principles to acquire the occurring phenomena. Three low-cost sensor modalities Electromyography, Mechanomyography, and Force Myography) were developed in a miniaturized size and tested in a pre-evaluation study. All three sensors comprise the characteristic myographic information of its modality. Based on the pre-evaluated sensors, a sensor matrix with 32 exchangeable and high-density sensor modules was designed. The sensor matrix can be applied around the human limbs and takes the human anatomy into account. A data transmission protocol was customized for interfacing the sensor matrix to the periphery with reduced wiring. The designed sensor matrix offers high-density and multimodal myographic information for the field of human-machine interfaces. Especially the fields of prosthetics and telepresence can benefit from the higher spatial resolution of the sensor matrix

Measurement of Electrical Impedance Myography

Práce se zabývá měřením elektroimpedanční myografie (EIM). Cílem práce bylo zhodnocení, zda se impedance svalů spolu s fázovým úhlem mění při změně úhlu kloubu nebo při kontrakci svalu a porovnání získaných výsledků s publikacemi, jenž se zabývají stejnou problematikou. Na začátku práce je seznámení s elektrickými vlastnostmi tkání, základními principy bioimpedance a EIM. Následně je provedena rešerše, ověření přesnosti přístroje a je navrženo schéma měření pro 11 subjektů, kdy je využíváno tetrapolární zapojení elektrod na bicepsu a potom na bicepsu a předloktí. Zprvu je měřena impedance a fázový úhel nejdříve pro různé úhly loketního kloubu a potom různé intenzity izometrické kontrakce pomocí dodaného přístroje. Výsledky průběhů jsou zprůměrovány dle jednotlivých úseků a vyhodnoceny na základě tabulek a grafů. Z dosažených výstupů lze konstatovat, že se impedance spolu s fázovým úhlem mění spolu se změnou úhlu loketního kloubu a taky spolu s kontrakcí (impedance v řádech Ohmů a fázový úhel v desetinných číslech stupňů).The thesis deals with the measurement of electroimpedance myography (EIM). The aim of the study was to evaluate whether the muscle impedance with the phase angle changes when the joint angle changes or when the muscle contracts, and to compare the obtained results with publications that deal with the same issues. At the beginning of the work is an introduction to the electrical properties of tissues, the basic principles of bioimpedance and EIM. Subsequently, review of literature, verification of the accuracy of the device is performed and a measurement is designed for 11 subjects, which uses a tetrapolar electrode connection on the biceps and then on the biceps and forearms. The impedance and phase angle are measured first for different elbow joint angles and then for different isometric contraction intensities using the supplied instrument. Measurement results are averaged according to individual sections and evaluated on the basis of tables and graphs. From the achieved outputs it can be claimed that the impedance and phase angle change due to changes in joint angle and also during different levels of isometric contraction of the measured muscles (impedance in the order of Ohms and the phase angle in decimal degrees).450 - Katedra kybernetiky a biomedicínského inženýrstvívelmi dobř