Inter-individual variability in the patterns of responses for electromyography and mechanomyography during cycle ergometry using an RPE-clamp model

Purpose To examine inter-individual variability versus composite models for the patterns of responses for electromyography (EMG) and mechanomyography (MMG) versus time relationships during moderate and heavy cycle ergometry using a rating of perceived exertion (RPE) clamp model. Methods EMG amplitude (amplitude root-mean-square, RMS), EMG mean power frequency (MPF), MMG-RMS, and MMG-MPF were collected during two, 60-min rides at a moderate (RPE at the gas exchange threshold; RPEGET) and heavy (RPE at 15 % above the GET; RPEGET+15%) intensity when RPE was held constant (clamped). Composite (mean) and individual responses for EMG and MMG parameters were compared during each 60-min ride. Results There was great inter-individual variability for each EMG and MMG parameters at RPEGET and RPEGET+15%. Composite models showed decreases in EMG-RMS (r(2) = -0.92 and R-2 = 0.96), increases in EMG-MPF (R-2 = 0.90), increases in MMG-RMS (r(2) = 0.81 and 0.55), and either no change or a decrease (r(2) = 0.34) in MMG-MPF at RPEGET and RPEGET+15 %, respectively. Conclusions The results of the present study indicated that there were differences between composite and individual patterns of responses for EMG and MMG parameters during moderate and heavy cycle ergometry at a constant RPE. Thus, composite models did not represent the unique muscle activation strategies exhibited by individual responses when cycling in the moderate and heavy intensity domains when using an RPE-clamp model.