How the ankle joint angle alters the antagonist and agonist torques during maximal efforts in dorsi‐ and plantar flexion

Abstract

The aim of this study was to assess, via an EMG bio-feedback method, the ankle joint angle effect on the agonist and antagonist torques in plantar- (PF) and dorsi-flexion (DF). The isometric PF and DF maximal voluntary contractions (MVCs) torques were measured simultaneously with surface EMG activity of triceps surae (TS) and tibialis anterior (TA) muscles in 12 young adults (mean age 27) at five different ankle joint angles. Our results showed that: (i) The coactivation level does not properly reflect the mechanical effect of the antagonist muscle, (ii) TS antagonist torque significantly altered the DF MVC-angle relationship, whereas TA antagonist torque did not influence this MVC-angle relationship in PF. The alteration of the MVC with angular position was due, in part, to the coactivation phenomenon in DF, but not in PF. Thenceforth, when investigating the torque at the ankle joint, it is necessary to take into account both agonist and antagonist torque modifications with ankle joint angle.

Is co-contraction responsible for the decline in maximal knee joint torque in older males?

“…As age increases, it has been reported that the coactivation level could be higher than (Izquierdo et al 1999;Macaluso et al 2002) or similar to young adults (Morse et al 2004;Simoneau et al 2005). While no consensus has been observed in the literature, some recent studies have demonstrated that the coactivation level alone is not adequate to determine the mechanical impact of the antagonist muscles, particularly at the ankle joint (Simoneau et al 2009;Billot et al 2010Billot et al , 2011. This discrepancy can be explained by the linear or curvilinear relationship between the EMG activity and the exerted torque.…”

“…These studies demonstrated that the coactivation level overestimates the antagonist torque during plantar flexion and underestimates the antagonist torque during dorsiflexion. Furthermore, as for the coactivation level, previous studies have reported that antagonist torque depends on angular position (Krishnan and Williams 2010;Billot et al 2011), the muscles involved (Simoneau et al 2009;Billot et al 2010Billot et al , 2011Krishnan and Williams 2010), and age (Simoneau et al 2009). As age increases, while Simoneau et al (2009) indicated that the maximal resultant torque in dorsiflexion was not significantly altered, they showed that the agonist torque significantly declined.…”

Non‐invasive isometric force measurement of plantar flexors in rats

“…The walls of the restraint prevent internal rotation and external rotation and flexion of the hip joint. A bevel is placed on the surface abutting the dorsum of the foot to maintain the ankle in 20° of dorsiflexion which optimizes the force of plantar flexion . A railing along the platform's side holds a positionable arm connected to 1 of 2 load cells.…”

“…A bevel is placed on the surface abutting the dorsum of the foot to maintain the ankle in 20 of dorsiflexion which optimizes the force of plantar flexion. 11 A railing along the platform's side holds a positionable arm connected to 1 of 2 load cells. For stimulation we use a Grass S48 square pulse stimulator (Grass, Warwick, Rhode Island).…”

Is it possible to establish reference values for ankle muscle isokinetic strength? A meta-analytical study

“…Plantar flexion PT occurs at near full dorsiflexion [27] so fully extending the knee may prevent development of PT during a concentric contraction. However, during an eccentric contraction the increased tension in the plantar flexors as a result of extending the knee produces higher PT compared to a flexed knee [28].…”