Linearity and reliability of the mechanomyographic amplitude versus dynamic torque relationships for the superficial quadriceps femoris muscles

Abstract

The purpose of this investigation was to examine the linearity and reliability of the mechanomyographic (MMG) amplitude versus dynamic torque relationships for the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles. Nine healthy men and 11 healthy women performed submaximal to maximal, concentric, isokinetic muscle actions of the leg extensors at 30 degrees s(-1) on two occasions. Surface MMG signals were detected from the VL, RF, and VM of the dominant thigh during both trials. The ranges of the coefficients of determination for the MMG amplitude versus dynamic torque relationships were 0.01-0.94 for the VL, 0.01-0.84 for the RF, and 0.19-0.96 for the VM. The intraclass correlation coefficients for the linear MMG amplitude versus torque slope coefficients were 0.823 (VL), 0.792 (RF), and 0.927 (VM). These results indicate that, when analyzed for individual subjects, the MMG amplitude versus dynamic torque relationships demonstrated inconsistent linearity. When using MMG in the clinical setting, dynamic muscle actions of the superficial quadriceps femoris muscles do not appear to be appropriate for assessing changes in muscle function during strength training.