Localized Electrical Impedance Myography of the Biceps Brachii Muscle during Different Levels of Isometric Contraction and Fatigue

Abstract

This study assessed changes in electrical impedance myography (EIM) at different levels of isometric muscle contraction as well as during exhaustive exercise at 60% maximum voluntary contraction (MVC) until task failure. The EIM was performed on the biceps brachii muscle of 19 healthy subjects. The results showed that there was a significant difference between the muscle resistance (R) measured during the isometric contraction and when the muscle was completely relaxed. Post hoc analysis shows that the resistance increased at higher contractions (both 60% MVC and MVC), however, there were no significant changes in muscle reactance (X) during the isometric contractions. The resistance also changed during different stages of the fatigue task and there were significant decreases from the beginning of the contraction to task failure as well as between task failure and post fatigue rest. Although our results demonstrated an increase in resistance during isometric contraction, the changes were within 10% of the baseline value. These changes might be related to the modest alterations in muscle architecture during a contraction. The decrease in resistance seen with muscle fatigue may be explained by an accumulation of metabolites in the muscle tissue.

Fatigue-Induced Cole Electrical Impedance Model Changes of Biceps Tissue Bioimpedance

“…The decrease in resistance parameters is consistent with the previous studies investigating skeletal muscle fatigue using bioimpedance measurements [6,7]. These studies hypothesized that the decreases in resistance may be the result of mechanisms that include: (i) increased blood flow to the muscle due to the hemodynamic response to exercise [7], (ii) heat dissipation in the tissue increasing cutaneous blood flow and vasodilation [7], and (iii) an increase in metabolites in the tissue increasing its electrical conductivity [6]. An increase in muscle edema paired with a decrease in muscle quality has been hypothesized as the reason for decreased muscular strength following exercise [28].…”

“…The resistance parameters of the 60% group had mean decreases of 5.0% and 13.2% for R ∞ and R 1 , respectively, with the 75% group having mean decreases of 5.4% and 12.3%. The decrease in resistance parameters is consistent with the previous studies investigating skeletal muscle fatigue using bioimpedance measurements [6,7]. These studies hypothesized that the decreases in resistance may be the result of mechanisms that include: (i) increased blood flow to the muscle due to the hemodynamic response to exercise [7], (ii) heat dissipation in the tissue increasing cutaneous blood flow and vasodilation [7], and (iii) an increase in metabolites in the tissue increasing its electrical conductivity [6].…”

“…Using this setup, which is detailed in Figure 2, measurements were collected from 10 kHz to 100 kHz at 67 logarithmically spaced frequencies. This frequency range was selected because it is widely employed in bioimpedance applications [6]. It should be noted that before data collection, the Keysight E4990A was calibrated using the open/short/load procedure with the developed interface.…”

“…These measurements are being used in a wide range of applications including: As a method to monitor hydration during hemodialysis [2], to detect changes resulting from muscle injury [3], assessing lympoedema [4], and to assess neuromuscular disorders [5]. There is also a small set of studies that have investigated the bioimpedance of skeletal muscle for changes that result from fatigue [6][7][8].…”

Design and Evaluation of an Electrical Bioimpedance Device Based on DIBS for Myography during Isotonic Exercises

“…There are diverse applications of EBIM in literature, some are: evaluation of paretic muscle changes after stroke [22], fatigue [24][25][26][27], equine muscle diseases [28], detection of muscle activation [29], skeletal muscle injuries [30,31] and identification of many neuromuscular diseases [32].…”