A novel approach to the analysis of muscle synergies based on the average threshold crossing technique

The work herein presented aimed to investigate the application of the Average Threshold Crossing (ATC) technique in the analysis of muscle synergies. The ability of the technique to approximate different modulations of the electromyographic (EMG) data was assessed via simulations. By selecting the proper threshold and window length, it was possible to obtain R2 similarity values above 0.8. This result improved by averaging the ATC envelopes over multiple epochs. The technique was also tested on real EMG data collected from 8 subjects during over ground walking. The synergies extracted using the ATC technique showed high similarity with the ones obtained with a standard approach using the EMG envelopes for both weights and temporal activations.