Mechanomyographic responses to maximal eccentric isokinetic muscle actions

The purpose of the present investigation was to examine the mechanomyographic (MMG) responses to maximal eccentric isokinetic muscle actions. Eight adult male volunteers [age 22 +/- 2 (SD) yr] performed maximal eccentric muscle actions of the leg extensors at 60, 90, 120, and 180 degrees /s on a Cybex 6000 isokinetic dynamometer. MMG was detected by a piezoelectric crystal contact sensor placed over the vastus lateralis muscle. Test-retest intraclass correlations ranged from R = 0.88 to 0.97 for peak torque and from R = 0.97 to 0.98 for root mean square MMG amplitude values. There was no significant (P > 0.05) velocity-related change in eccentric peak torque; however, there was a significant (P < 0.05) increase in MMG between 60 [119 +/- 44 (SE) mV] and 180 degrees/s (302 +/- 128 mV). These findings indicated a velocity-related dissociation between MMG and peak torque for maximal eccentric isokinetic muscle actions.