*5.2.1. Interference Pattern (IP) analysis*

As mentioned earlier, the term "interference pattern" is used to refer to the complete EMG signal detected from a contracting muscle. The term "interference pattern" is sometimes used to describe the EMG signal detected during a maximal contraction only but the former definition is more common. The characteristics of an interference pattern (IP) depend on the level of muscle activation maintained during its detection and the type of electrode used. The level of activation determines the number of recruited MUs and their firing rates. The type of electrode used determines the shape characteristics of the MUPs (duration, area, amplitude, etc.) that are created by the active MUs and which in turn comprise the IP.

The term "interference pattern analysis" (IPA) refers to those techniques that analyze an IP. IPA is used when a global analysis of an EMG signal is desired. IPA is a quantitative analysis which can be completed using either a frequency or time domain representation of the IP [6]. Following are brief descriptions of common IPA techniques.
