  Intervals between electrical pulses generated by the electrical activity
produced by the motor units of an external anal sphincter were studied at four
time intervals during multimodal rectal cancer treatment. Probability
distribution function of such intervals does not exhibit significant
differences for all considered time intervals. It is found that the probability
distribution rescaled with an average interval time can be described by means
of the stretched exponential function with the threshold dependent scale and
shape parameters. Interval trains possess rather strong correlations as their
shuffled counterparts show exponential Poisson like probability distribution.
Finally the clustering effects were not found as the conditional probability
distributions can also be described by the exponential function.
