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BioMed Research International
Volume 2018 (2018), Article ID 5373846, 9 pages
Research Article

Relationship between Isometric Muscle Force and Fractal Dimension of Surface Electromyogram

1Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Manno, Switzerland
2Criams-Sport Medicine Centre Voghera, University of Pavia, Pavia, Italy
3NeuroMuscular Function Research Group, School of Exercise and Sport Sciences, Department of Medical Sciences, University of Turin, Turin, Italy
4CeRiSM (Research Centre for Sport, Mountain, and Health), Rovereto, Italy
5University of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland

Correspondence should be addressed to Matteo Beretta-Piccoli; hc.ispus@iloccipattereb.oettam

Received 14 November 2017; Revised 1 February 2018; Accepted 11 February 2018; Published 15 March 2018

Academic Editor: Laura Guidetti

Copyright © 2018 Matteo Beretta-Piccoli et al. 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.


The relationship between fractal dimension of the surface electromyogram (sEMG) and the intensity of muscle contraction is still controversial in simulated and experimental conditions. To support the use of fractal analysis to investigate myoelectric fatigue, it is crucial to establish the interdependence between fractal dimension and muscle contraction intensity. We analyzed the behavior of fractal dimension, conduction velocity, mean frequency, and average rectified value in twenty-eight volunteers at nine levels of isometric force. sEMG was obtained using bidimensional arrays in the biceps brachii muscle. The values of fractal dimension and mean frequency increased with force unless a plateau was reached at 30% maximal voluntary contraction. Overall, our findings suggest that, above a certain level of force, the use of fractal dimension to evaluate the myoelectric manifestations of fatigue may be considered, regardless of muscle contraction intensity.