Figure 2. Example of SHLP EMG data during one trial of isometric protrusion. (A) Five steps of force-tracking [400 gwt (3.92 N) to 800 gwt (7.84 N)] and filtered EMG. Regions between the vertical lines indicate the defined stable periods (see METHODS) for each force step. (B) Four SMUs were discriminated during the most stable two-second holding period from this trial. Each trace represents the spike train of a SMU. Each short vertical line of the spike train is an action potential of a SMU. The period delineated by the vertical lines in A and B is expanded in (C) and illustrates the waveforms of 4 SMUs and their spike trains.