Electromyograms of voluntary effort in man have been converted into two pulse trains, using the analyser described by Fitch (1967). By feeding the pulse trains to simple counters and to a special purpose digital computer (Biomac 500) the following data are obtained: 1. 1. Total number of reversals of potential (turns) occurring in a pre-set period of time. 2. 2. Histograms of the intervals between individual turns. 3. 3. The accumulated amplitude of all potentials, both positive-going and negative-going, in a pre-set period of time. 4. 4. Histograms of the amplitudes of individual potentials. © 1968.