On the measurement of fibre density in human muscles

A computer simulation model and an analytical model simulating the measurement of fibre density during single fibre electromyography is described. The relation between the measured fibre density (including the triggering fibre) and the true theoretical fibre density (including in the measurement also positions with zero fibre counts) is derived. A good agreement was found between the two models, and between laboratory values for fibre density measurements and count histograms. The assumption of a uniform distribution of the fibres in the motor unit territory vs. a Gaussian distribution of the fibres is discussed.