Example of the construction of a low frequency common drive plot. A low-pass, moving average Hanning window filter of length 400 ms was applied to two motor unit spike trains recorded from the FDI muscle. (a) A 5 s epoch of the time-varying smoothed firing rates; (b) the high-pass filtered version of the smoothed firing rates shown in (a); and (c) the low frequency common drive coefficient function between two motor unit spike trains. This results in an effective pass band of 0–5 Hz. The peak of the signal is 0.75 and occurs at a lag of 3.5 ms.