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Published on: February 20, 2018
Measuring increase in synchronization to identify muscle endurance limit.
Dinesh K Kumar1, Sridhar P Arjunan, Ganesh R Naik
1Biosignals Lab, School of Electrical and Computer Engineering, RMIT University, Melbourne 3001, Australia. dinesh@rmit.edu.au
Summary
A new method using surface electromyogram (sEMG) analyzes motor unit synchronization to determine muscle fatigue limits. The increase in synchronization (IIS) index reliably identifies endurance limits without needing baseline rested muscle data.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Sports Science
Background:
- Surface electromyogram (sEMG) spectral content changes are linked to muscle fatigue.
- Current sEMG methods require rested muscle data for comparison, limiting their use in identifying endurance limits.
- Variations in sEMG due to contraction strength, individual differences, and non-isometric contractions complicate fatigue assessment.
Purpose of the Study:
- To develop a novel sEMG-based method for studying muscle fatigue.
- To establish a reliable approach for identifying the limit of muscle endurance.
- To overcome limitations of existing sEMG analysis methods.
Main Methods:
- Developed the increase in synchronization (IIS) index, based on motor unit synchronization.
- IIS index quantifies the independence between two sEMG channels using independent component analysis.
- Calculated IIS index as the log of the determinant of the global matrix (log||G||).
Main Results:
- Resting biceps brachii showed high channel independence with IIS index > -0.7.
- Fatigued muscles exhibited increased channel dependency, with IIS index < -6.2 at the endurance limit.
- The IIS index effectively identified muscle endurance limits regardless of contraction type (isometric/cyclic) or intensity.
Conclusions:
- The IIS index provides a robust measure of muscle fatigue and endurance limits.
- This method eliminates the need for baseline rested muscle data for comparison.
- IIS index offers a universal approach for assessing muscle fatigue across various contraction conditions.
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