Antagonist mechanical contribution to resultant maximal torque at the ankle joint in young and older men

Human muscle fascicle behavior in agonist and antagonist isometric contractions

“…Identification of the time at which the iEMG activity of the GM, now an agonist , was the same as in -the torque then exerted was assumed to be equal to the torque generated by the antagonist GM during the DF MVC. 9,10 Identification of the corresponding ultrasound scans. Finally, examination of the GM architecture via these scans obtained in DF and PF efforts for a comparison of the muscle's behavior while at rest or acting isometrically either as an agonist or an antagonist.…”

“…Alternatively, step contractions can also be used to investigate relations between muscle activity and mechanical output in isometric conditions by using an EMG biofeedback set-up. 9,10 Although this method is effective, it requires special equipment for the visual biofeedback. Instead, ramp contractions can be performed without biofeedback and allow assessment of several levels of contraction with one single effort.…”

“…1,2,[5][6][7][8] Nevertheless, an implicit assumption of this method is that, during an isometric contraction, the relationship between the level of EMG activity and the mechanical output is the same when a muscle is acting either as an agonist or as an antagonist. 9,10 If this were the case, one would expect changes in EMG to be reflected by changes in architecture 11,12 that would be identical when the muscle is acting either as an agonist or as an antagonist.…”

Age-related relative increases in electromyography activity and torque according to the maximal capacity during upright standing

“…However, Simoneau et al (2009) and Billot et al (2009) demonstrated that coactivation phenomenon and antagonist torque cannot be neglected when interpreting maximal capacity of torque production. These authors observed some modifications in agonist/antagonist activation regulation with aging.…”

Enhanced precision of ankle torque measure with an open-unit dynamometer mounted with a 3D force-torque sensor

“…The assessment of the mechanical properties of the ankle joint during isometric and/or dynamic conditions is typically achieved by means of specific ankle dynamometers, often developed in research laboratories (Kawakami et al 1998;Lambertz et al 2008;Ochala et al 2004;Pasquet et al 2006;Reeves et al 2005;Sale et al 1982, Simoneau et al 2009Simoneau et al 2012;Tognella et al 1997;Vandervoort and McComas 1986), or by isokinetic dynamometers (Ferri et al 2003;Karamanidis et al 2005;Karatsolis et al 2009;Mademli et al 2004;Maffiuletti et al 2002;Maganaris et al 1998;Morse et al 2004;Ohta et al 2009;Porter et al 1997;Scaglioni et al 2002;Simoneau et al 2007). For these dynamometers, isometric torque at the ankle joint is measured through a footplate connected to a unidirectional (1D) force sensor (generally placed away from the axis of rotation of the dynamometer) or by the footplate connected to a 1D torque sensor placed at the axis of rotation of the dynamometer.…”