Analyzing surface myoelectric signals recorded during isokinetic contractions

A time-frequency approach using wavelets to study movements at different angular velocities is considered. The authors summarized the application of the continuous wavelet transform (CWT) to the analysis of the surface myoelectric (ME) signal. The present technique of determining MNF has the advantage that it is possible to determine the frequency content of the ME signal during short and nonstationary contractions. In addition, the CWT method is very reliable for the analysis of nonstationary biological signals and does not require any smoothing function as do methods based on Wigner-Ville. However, using time-frequency methods involves two main tradeoffs: i.e., potential increases in performance for a given application versus computational complexity and storage requirements. Our results confirmed earlier studies that MNF is independent of angular velocity.