title: Motor unit firing rates and synchronisation affect the fractal dimension of simulated surface electromyogram during isometric/isotonic contraction of vastus lateralis muscle.
abstract: During fatiguing contractions, many adjustments in motor units behaviour occur: decrease in muscle fibre conduction velocity; increase in motor units synchronisation; modulation of motor units firing rate; increase in variability of motor units inter-spike interval. We simulated the influence of all these adjustments on synthetic EMG signals in isometric/isotonic conditions. The fractal dimension of the EMG signal was found mainly influenced by motor units firing behaviour, being affected by both firing rate and synchronisation level, and least affected by muscle fibre conduction velocity. None of the calculated EMG indices was able to discriminate between firing rate and motor units synchronisation.
authors.affiliation: Mathematical Biology and Physiology, Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Mesin
authors.affiliation: Motor Science Research Center, School of Exercise and Sport Sciences, SUISM, Department of Medical Sciences, University of Turin, Piazza Bernini 12, 10143 Torino, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Dardanello
authors.affiliation: Motor Science Research Center, School of Exercise and Sport Sciences, SUISM, Department of Medical Sciences, University of Turin, Piazza Bernini 12, 10143 Torino, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Rainoldi
authors.affiliation: Motor Science Research Center, School of Exercise and Sport Sciences, SUISM, Department of Medical Sciences, University of Turin, Piazza Bernini 12, 10143 Torino, Italy; CeRiSM Research Center 'Sport, Mountain, and Health', Via Matteo del Ben 5/B, 38068 Rovereto (TN), Italy . Electronic address: gennaro.boccia@unito.it.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Boccia
mesh_terms: D004576:Electromyography; D017709:Fractals; D007537:Isometric Contraction; D007551:Isotonic Contraction; D008954:Models, Biological; D052097:Quadriceps Muscle / Q000502:physiology*
keywords: Geometrical complexity; Muscle fatigue; Muscle fibre conduction velocity; Surface EMG