Next Article in Journal
Variational Characterization of Free Energy: Theory and Algorithms
Next Article in Special Issue
Parametric PET Image Reconstruction via Regional Spatial Bases and Pharmacokinetic Time Activity Model
Previous Article in Journal
Digital Image Stabilization Method Based on Variational Mode Decomposition and Relative Entropy
Previous Article in Special Issue
Multiscale Sample Entropy of Cardiovascular Signals: Does the Choice between Fixed- or Varying-Tolerance among Scales Influence Its Evaluation and Interpretation?
Article Menu
Issue 11 (November) cover image

Export Article

Open AccessArticle
Entropy 2017, 19(11), 624;

Re-Evaluating Electromyogram–Force Relation in Healthy Biceps Brachii Muscles Using Complexity Measures

Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China
Department of Rehabilitation Medicine, First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
Author to whom correspondence should be addressed.
Received: 9 August 2017 / Revised: 26 September 2017 / Accepted: 17 October 2017 / Published: 19 November 2017
(This article belongs to the Special Issue Information Theory Applied to Physiological Signals)
Full-Text   |   PDF [1209 KB, uploaded 19 November 2017]   |  


The objective of this study is to re-evaluate the relation between surface electromyogram (EMG) and muscle contraction torque in biceps brachii (BB) muscles of healthy subjects using two different complexity measures. Ten healthy subjects were recruited and asked to complete a series of elbow flexion tasks following different isometric muscle contraction levels ranging from 10% to 80% of maximum voluntary contraction (MVC) with each increment of 10%. Meanwhile, both the elbow flexion torque and surface EMG data from the muscle were recorded. The root mean square (RMS), sample entropy (SampEn) and fuzzy entropy (FuzzyEn) of corresponding EMG data were analyzed for each contraction level, and the relation between EMG and muscle torque was accordingly quantified. The experimental results showed a nonlinear relation between the traditional RMS amplitude of EMG and the muscle torque. By contrast, the FuzzyEn of EMG exhibited an improved linear correlation with the muscle torque than the RMS amplitude of EMG, which indicates its great value in estimating BB muscle strength in a simple and straightforward manner. In addition, the SampEn of EMG was found to be insensitive to the varying muscle torques, almost presenting a flat trend with the increment of muscle force. Such a character of the SampEn implied its potential application as a promising surface EMG biomarker for examining neuromuscular changes while overcoming interference from muscle strength. View Full-Text
Keywords: FuzzyEn; SampEn; complexity; torque; EMG FuzzyEn; SampEn; complexity; torque; EMG

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Zhu, X.; Zhang, X.; Tang, X.; Gao, X.; Chen, X. Re-Evaluating Electromyogram–Force Relation in Healthy Biceps Brachii Muscles Using Complexity Measures. Entropy 2017, 19, 624.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Entropy EISSN 1099-4300 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top