Maximal contraction methods influence the magnitude and reliability of global electromyographic signal characteristics.

OBJECTIVE

The purpose was two-fold: (1) to examine differences in maximal voluntary isometric torque (MVIT) production, and electromyographic signal amplitude (EMG) and mean power frequency (EMG) values obtained during traditional (MVIC), rapid (MVIC), and ramp (MVIC) maximal voluntary isometric contractions, and (2) to determine if there were differences in the reliability of MVIT, EMG and EMG among the three MVIC types.

APPROACH

Twenty-two young males and females completed MVIC, MVIC, and MVIC muscle actions on two separate visits separated by 48 h. During all MVICs, MVIT and EMG and EMG of the vastus lateralis (VL) and rectus femoris (RF) were quantified.

MAIN RESULTS

MVIT was greater during MVIC and MVIC than during MVIT (both p < 0.001). VL and RF EMG were greater during MVIC than during MVIC (p = 0.02 and 0.004). For EMG, there were no significant differences among MVIC types. Although all MVIC types generally resulted in reliable measurements of MVIT and EMG, reliability was stronger for EMG quantified during the MVIC.

SIGNIFICANCE

Investigators may choose MVIC type based on preference or equipment availability. However, investigators should note that MVIC contractions will likely yield the greatest EMG values and more reliable measurements of VL and RF EMG.