Motor unit profile: A new way to describe the scanning-EMG potential

•The MU profile is proposed as a new characterization of the scanning-EMG signal.•An algorithm to obtain the MU profile is proposed, described and evaluated.•The influence of the parameter values in the algorithm performance is studied.•A set of default parameter values that can be routinely used is provided.

The motor unit profile, a representation of the trajectories of positive and negative turns of a scanning-EMG signal, is a new way to characterize the motor unit potential. Such characterization allows quantification of the scanning-EMG signal's complexity, which is closely related to the anatomy and physiology of the motor unit. To extract the motor unit profile, an algorithm that detects the turns of the scanning-EMG signal and links them using point-tracking techniques has been developed. The performance of this algorithm is sensitive to three parameters: the turn detection threshold, the maximum tracking interval threshold, and the trajectory purge threshold. Real scanning-EMG signals have been used to analyze the algorithm's behavior and the influence of the algorithm's parameters and to determine which parameter values provide the best performance.