An estimate of the standard deviation (amplitude) of the signal over a given time window or epoch. The RMS value is the square root of the mean square value estimated over an epoch (or window) of duration T (or N samples). RMS is the square root of the power of the signal. The root mean square value, V_RMS, for one signal epoch is defined in Formula 1, where N is the total number of samples being averaged (over the epoch of the EMG signal under analysis) and V_n is the value of the n^th sample within the epoch. The epoch/window duration must be stated when reporting the V_RMS. The equation for V_RMS can also be expressed in continuous time as expressed in Formula 2, where T is the length of the signal epoch in seconds.