METHODS FOR ESTIMATING THE NUMBERS OF MOTOR UNITS IN HUMAN MUSCLES

After the introduction by A. J. McComas of the original method for est imating the number of motor units based on manual incremental stimulat ion of a motor nerve, several new techniques have been developed, desi gned to correct for some of the errors inherent in the original techni que. These methods incorporate algorithms to adjust for alternation an d, to a greater or lesser extent, automate the methods, rendering the techniques less subject to operator bias and various physiological and technical errors. This review explores the advantages and drawbacks i n the multiple-point stimulation (MPS), spike-triggered averaging (STA ), and decomposition-enhanced STA techniques, illustrates some of the current applications of the techniques, and explores some tantalizing prospects for new studies of motor-unit physiology in the future.