The purposes of this investigation were to determine the: (1) reproducibility of the patterns of responses for electromyographic (EMG) amplitude and mean power frequency (MPF); and (2) intraclass correlation coefficient (ICC) of the EMG amplitude and MPF during three incremental cycle ergometer tests separated by 48 hours.
Ten men performed incremental cycle ergometry tests to exhaustion on three separate occasions. Surface EMG signals were recorded simultaneously from the three superficial quadriceps muscles at each trial.
Polynomial regression indicated that, for >95% of the cases, the best-fit model was the same at each trial for EMG amplitude but not for EMG MPF. The ICC values were high for EMG amplitude but low for EMG MPF.
These results indicate that EMG amplitude is a reliable measure of motor unit activation strategy during incremental cycle ergometry, whereas the EMG MPF was unreliable. Muscle Nerve 2011