The mechanomyographic and electromyographic responses to passive leg extension movements.

The purpose of this investigation was to examine the mechanomyographic (MMG) responses to maximal concentric (CON) and passive leg extension movements. Eight adult females performed maximal CON muscle actions and passive leg extension movements of the dominant leg on a calibrated CYBEX 6000 dynamometer at velocities of 30, 90, and 150 degrees x s-1. MMG and electromyographic (EMG) signals were simultaneously recorded from the vastus lateralis (VL). The results indicated velocity-related dissociations among MMG amplitude, EMG amplitude, and peak torque during the maximal CON muscle actions. For the passive leg extension movements, however, the EMG amplitude values at each velocity were not significantly (p > 0.05) different from the values at rest, but the MMG amplitude increased significantly (p < 0.05) with velocity. It was hypothesized that the velocity-related increase in MMG amplitude for the passive leg extension movements was independent of VL activation and may have been associated with turbulences of the intracellular and extracellular fluid mediums and/or cross-talk from the hamstring muscles. [ABSTRACT FROM AUTHOR]