This paper provides an overview of techniques suitable for the estimation, interpretation and understanding of time variations that affect the surface electromyographic (EMG) signal during sustained voluntary or electrically elicited contractions. These variations concern amplitude variables, spectral variables and muscle fiber conduction velocity, are interdependent and are referred to as the `fatigue plot'. The fatigue plot provides information suitable for the classification of muscle behavior. In addition, the information obtainable by means of linear electrode arrays is discussed, and applications of mathematical models for the interpretation of array signals are presented. The model approach provides additional ways for the classification of muscle behavior.
Roberto Merletti graduated in electronics engineering from the Politecnico di Torino, Italy, and obtained his MS and PhD from Ohio State University. He is Associate Professor of Biomedical Instrumentation at the Department of Electronics of Politecnico di Torino, Italy, and at the Department of Biomedical Engineering of Boston University, and Research Professor at the NeuroMuscular Research Center of Boston University. His research focusses on surface electromyography, myoelectric signal processing and electrical stimulation.
Loredana Lo Conte graduated `summa cum laude' in computer science from the University of Torino, Italy. She has been a Visting Scientist at the NeuroMuscular Research Center of Boston University and is now with the Molecular Engineering Research Lab of the same University. Her research interests are in the field of pattern recognition, signal processing and computer science applied to biological problems.
