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Brachialis Muscle Activity Can Be Measured With Surface Electromyography: A Comparative Study Using Surface and Fine-Wire Electrodes.

ABSTRACT: Muscle activities of the elbow flexors, especially the brachialis muscle (BR), have been measured with intramuscular electromyography (EMG) using the fine-wire electrodes. It remains unclear whether BR activity can be assessed using surface EMG. The purpose of this study was to compare the EMG patterns of the BR activity recorded during elbow flexion using surface and fine-wire electrodes and to determine whether surface EMG can accurately measure the BR activity. Six healthy men were asked to perform two tasks-a maximum isometric voluntary contractions (MVICs) task and an isotonic elbow-flexion task without lifting any weight. The surface and intramuscular EMG were simultaneously recorded from the BR and the long and short heads of the biceps brachii muscle (BBLH and BBSH, respectively). The locations of the muscles were identified and marked under ultrasonographic guidance. The peak cross-correlation coefficients between the EMG signals during the MVICs task were calculated. For the isotonic elbow-flexion task, the EMG patterns for activities of each muscle were compared between the surface and the fine-wire electrodes. All cross-correlation coefficients between the surface EMG signals from the muscles were lower than 0.3. Furthermore, the EMG patterns of the BR activity were not significantly different between the surface and the fine-wire electrodes. The BR has different EMG pattern from the BBLH and the BBSH. The BR activity, conventionally measured with intramuscular EMG, can be accurately accessed with surface EMG during elbow flexion performed without lifting any weight, independent from the BBLH and BBSH activities.

SUBMITTER: Date S

PROVIDER: S-EPMC8733609 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Investigating muscle activity and coactivation with surface electromyography (sEMG) gives insight into pathological muscle function during activities like walking in people with neuromuscular impairments, such as children with cerebral palsy (CP). There is large variation in the amount of coactivation reported during walking in children with CP, possibly due to the inconsistent handling of sEMG and in calculating the coactivation index. The aim of this study was to evaluate how different approaches of handling sEMG may affect the interpretation of muscle activity and coactivation, by looking at both absolute and normalized sEMG. Twenty-three ambulatory children with CP and 11 typically developing (TD) children participated. We conducted a three-dimensional gait analysis (3DGA) with concurrent sEMG measurements of tibialis anterior, soleus, gastrocnemius medialis, rectus femoris, and hamstring medialis. They walked barefoot at a self-selected, comfortable speed back and forth a 7-m walkway. The gait cycle extracted from the 3DGA was divided into six phases, and for each phase, root mean square sEMG amplitude was calculated (sEMG-RMS-abs), and also normalized to peak amplitude of the linear envelope (50-ms running RMS window) during the gait cycle (sEMG-RMS-norm). The coactivation index was calculated using sEMG-RMS-abs and sEMG-RMS-norm values and by using two different indices. Differences between TD children's legs and the affected legs of children with CP were tested with a mixed model. The between-subject muscle activity variability was more evenly distributed using sEMG-RMS-norm; however, potential physiological variability was eliminated as a result of normalization. Differences between groups in one gait phase using sEMG-RMS-abs showed opposite differences in another phase using sEMG-RMS-norm for three of the five muscles investigated. The CP group showed an increased coactivation index in two out of three muscle pairs using sEMG-RMS-abs and in all three muscle pairs using sEMG-RMS-norm. These results were independent of index calculation method. Moreover, the increased coactivation indices could be explained by either reduced agonist activity or increased antagonist activity. Thus, differences in muscle activity and coactivation index between the groups change after normalization. However, because we do not know the truth, we cannot conclude whether to normalize and recommend incorporating both.

Project description:OBJECTIVE:Needle EMG remains the standard clinical test for neuromuscular disease (NMD) assessment, but it only characterizes myofiber membrane depolarization. On the other hand, electrical impedance provides non-electrically active structural and compositional data of tissues. Here, we designed a prototype of needle electrode integrating electrical impedance and EMG measurement capabilities, the so-called I-EMG needle electrode. APPROACH:We use finite element method models to study the impedance recording characteristics of I-EMG needle electrodes. The simulated electrical and mechanical design specifications are then manufactured to create a prototype of an I-EMG needle electrode. We pilot these new needle electrodes by conducting in vivo impedance measurements with muscle at rest on healthy wild-type (wt, n = 5) and muscular dystrophy (mdx, n = 5) mice. Comparisons between wt and mdx mice are performed using Mann-Whitney test, two-tailed, p < 0.05. The electrical characterization of the EMG electrode in the developed I-EMG needles was performed in vitro on saline solution and through EMG detection in wt animal at rest and during voluntary contractions. RESULTS:Muscle impedance demonstrate good repeatability (p < 0.05 and p < 0.005 for resistance and reactance at 50 kHz, respectively) and agreement between different I-EMG needles. Impedance data allows us to discriminate between mdx and wt muscle (p < 0.05 and p < 0.005 for resistance and reactance at 10 kHz, respectively). EMG broadband noise power and peak amplitude using the I-EMG needle were similar to that of a commercial monopolar EMG needle. EMG recordings using the I-EMG needle measured electrical activity similar to a standard monopolar needle with muscle at rest and during voluntary contraction. SIGNIFICANCE:Needle I-EMG technology may offer the opportunity to enhance the diagnostic capability and quantification of NMD beyond that possible with either impedance or EMG techniques separately. Ultimately, needle I-EMG could serve as a new bedside tool to assess NMD without increasing the complexity or duration of the EMG test.

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Brachialis Muscle Activity Can Be Measured With Surface Electromyography: A Comparative Study Using Surface and Fine-Wire Electrodes.

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