Temporal and spectral representation of the cumulative spike train (CST; A, B), the rectified EMG and EMGnc (C, D), and force (E, F).

In panel D, the normalized power spectrum of the raw (unrectified) EMG signal in the 0–250 Hz range is included in the dashed box. In this example, the muscle consisted of 100 motor units, the amplitude of the variability of the common synaptic input was high (force standard deviation: 1.8%MVC), and the average contraction level was 14.9%MVC. The power spectra (B, D, F) indicate power only for integer frequencies that were the frequency components used to simulate the common input.