Maximal Voluntary and Electrically Stimulated Torque – Angle – Angular Velocity Profiles of the Knee Extensors and Flexors

In vivo measurements of maximum voluntary force – velocity show differences to the in vitro tetanic profile, with eccentric forces not increasing much above isometric and tending to decline with increasing lengthening velocity. Using transcutaneous electrical stimulation maximal eccentric torque has been found to be 1.4 times the isometric value and does not drop off at higher eccentric velocities. The aim of this study was to determine maximal voluntary and electrically evoked torque – angle – angular velocity profiles for the knee extensors and flexors in a group of healthy males. Fourteen male subjects performed a set protocol on an isovelocity dynamometer consisting of maximal voluntary and submaximally stimulated eccentric and concentric knee extension and flexion series at constant angular velocities (+ 100, 200, 300, 400 and 50 ° /s). Peak isometric torque was compared to the peak eccentric torque (Ecc/Iso) for the different muscle groups and conditions on a per subject basis. Evoked Ecc/Iso ratios in the knee extensors and flexors were significantly different from each other at 1.61 and 1.50, respectively, with the extensor value found here higher than previously measured across a lower velocity range.