Relationship between EMG signals and force in human vastus lateralis muscle using multiple bipolar wire electrodes

The Relationship Between Electromyography and Muscle Force

“…Some authors have concluded , for various muscles, that the magnitude of the EMG signal is directly proportional to muscle strength for isometric and/or isotonic contractions with constant speed, but others claim that this relationship is not linear (Bilodeau et al, 2003;Gerdle et al, 1991;Gregor et al, 2002;Herzog et al, 1998;Karlsson & Gerdle, 2001;Moritani & Muro, 1987;Onishi et al, 2000). In most cases, the EMG increases non-linearly with increasing force of muscle contraction (Guimaraes et al, 1994;Madeleine et al, 2000;Lawrence & De Luca, 1983;Solomonow et al, 1990).…”

“…For example, one can find examples in the literature, in which strength has been related to the intensity, or to the median or mean frequency of the EMG signal. Among the most used EMG parameters for such analysis, is the time series analysis, in which the the effective value of the signal, is derived from the root mean square -RMS (Basmajian & De Luca, 1985;Bigland-Ritchie, 1981;Bilodeau et al 2003;Gerdle et al 1991; www.intechopen.com Gregor et al 2002;Guimaraes et al 1994;Herzog et al 1998;Lawrence & De Luca, 1983;Madeleine et al, 2000;Onishi et al, 2000;Solomonow et al, 1990). This is a method to quantify the signal amplitude, recommended to assess the level of muscle activity, since the parameter is not affected by the superposition of APMU (Acierno et al, 1995;Basmajian & De Luca, 1985;De Luca, 1997).…”

“…In this respect, it is pertinent to mention other methods, such as: i) the use of PCA (principal component analysis) to identify the pulse trains of action potentials on a surface electromyography signal collected with multiple electrodes (Nakamura et al, 2004); ii) application of multivariate statistical techniques and multidimensional visualization in 3D space -Viz3D (Artero, 2005), to identify differences between isometric activities carried out against a rigid obstacle and with a weight of equivalent inertial load (Mello, 2007); iii) applications in studies of muscle coordination, techniques that allow, through measures of EMG, set parameters for determining the action of various muscles; and iv) studies of the relationship between force sensation and muscle stretching (Branco et al, 2006). The magnitude of force or torque has also been compared with the spectral variables of the EMG signal (Bernardi et al, 1996, Bilodeau et al, 2003Gerdle et al, 1991;Hermans et al, 1999;Karlsson & Gerdle, 2001;Moritani & Muro, 1987;Onishi et al, 2000). The calculation of these parameters should involve the application of appropriate techniques to obtain the power spectrum of the EMG signal.…”

Spectral properties of myoelectric signals from different motor units in the leg extensor muscles

“…It should be expected that the recruitment of faster motor units at the higher forces results in higher frequencies within the myoelectric signal. However, previous studies investigating the dependence of mean myoelectric frequencies on contractile force during graded isometric contractions showed mixed results, with some papers reporting correlations (Bilodeau et al, 1991;Gerdle et al, 1988a;Moritani and Muro, 1987;Karlsson and Gerdle, 2001;Farina et al, 2002) whilst others reported lack of correlations (Bilodeau, 1991;Gerdle et al, 1988b;Onishi et al, 2000;Farina et al, 2002a). One reason for these conflicting results is that when measuring myoelectric signals with surface electrodes, the volume conductor effects of the tissue layers surrounding the muscle play a role in shaping the signal.…”

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

“…Therefore, the relation between EMG and muscle contraction level (described as force or torque alternatively) offers a useful tool for examining muscle functions and deficits, with wide biomedical and biomechanical applications [3,[5][6][7]. Among them, the EMG signals were usually analyzed with time-domain amplitude-associated and frequency-domain parameters including root mean square (RMS), averaged rectified value (ARV), median frequency (MDF) and mean power frequency (MPF) of EMG signal [8][9][10][11][12][13][14][15][16][17]. Sbriccoli et al [8] reported that the RMS of the Subjects completed a series of isometric elbow flexion tasks while the forearm of the dominant side was positioned on an equipment with the elbow joint at 90 • , the shoulder abducted at 45 • and flexed at approximately 30 • .…”