Relevance of spectral peaks in electromyographic recordings during force-modulated vibration exercise

Vibration exercise (VE) has been suggested for effective muscle training and conditioning. Surface electromyogram (EMG) is employed as a powerful tool for the analysis of VE. However, sharp peaks are observed in the EMG spectrum. The interpretation of these peaks is controversial, complicating the extraction of EMG parameters for VE analysis. The present study is therefore aiming at quantifying the relevance of these spectral peaks in EMG recording during VE. To this end, surface EMG was recorded on the biceps brachii during VE at different amplitudes and frequencies. The power percentage contained in the two narrow bands (±0.5 Hz) around the vibration frequency and its first harmonic (PPv) was calculated. The root mean square (RMS) value of the EMG was calculated with and without including the spectral peaks and then compared. The results show an average PPv value of 20.7 ± 7.9 % and a relative RMS difference (∆RMS) of 12.2 ± 3.8 %. In PPv and addition, RMS∆ seem to be influenced by vibration amplitude and frequency. Our results provide useful information for the analysis of VE and contribute to better understanding of the EMG spectral peaks.