Figure 10

Joint time-frequency analysis of a mechanomyographic (MMG) signal recorded during an eccentric isokinetic muscle action. (A) Example of the raw mechanomyographic (MMG) signal from the biceps brachii muscle during a maximal eccentric isokinetic muscle action of the forearm flexors at a velocity of 30°·s^-1. The MMG signal was detected by a contact sensor (HP 21050A) and was selected from the middle 50° of the range of motion (approximately 110° to 160° of forearm flexion). (B) The relationship between MMG instantaneous mean power frequency (IMPF) and time for the MMG signal shown in (A). The MMG signal was processed with the continuous wavelet transform (CWT) algorithm and a Daubechies 10 wavelet with a center frequency of 684.2 Hz at the lowest scale. (C) The scalogram of the signal shown in (A) demonstrates the changes in the signal's frequency content across the range of motion.