Mean power frequency and amplitude of the mechanomyographic and electromyographic signals during incremental cycle ergometry

The purpose of this investigation was to determine the relationships for me chanomyographic (MMG) amplitude, MMG mean power frequency (MPF), electromyo graphic (EMG) amplitude, and EMG MPF versus power output during incremental cycle ergometry. Seventeen adults volunteered to perform an incremental te st to exhaustion on a cycle ergometer. The test began at 50 W and the power output was increased by 30 W every 2 min until the subject could no longer maintain 70 rev min(-1). The MMG and EMG signals were recorded simultaneou sly from the vastus lateralis during the final 10 s of each power output an d analyzed. MMG amplitude, MMG MPF, EMG amplitude, EMG MPF, and power outpu t were normalized as a percentage of the maximal value from the cycle ergom eter test. Polynomial regression analyses indicated that MMG amplitude incr eased (P < 0.05) linearly across power output, but there was no change (P > 0.05) in MMG MPF. EMG amplitude and MPF were fit best (P < 0.05) with quad ratic models. These results demonstrated dissociations among the time and f requency domains of MMG and EMG signals, which may provide information abou t motor control strategies during incremental cycle ergometry. The patterns for amplitude and frequency of the MMG signal may be useful for examining the relationship between motor-unit recruitment and filing rate during dyna mic tasks. (C) 2001 Elsevier Science Ltd. All rights reserved.