Detection of non-standard EMG profiles in walking.

The amplitude of an EMG and the temporal pattern can be used when considering if an EMG profile is normal or not. In the method described in this paper a gain factor of the complete EMG profile was determined and then the profile normalised with this gain factor. This normalised individual profile was then compared with a standard profile, predicted on the basis of walking speed. Deviating profiles were identified when they fell outside the upper and lower 95% limits range for the average profiles of 14 leg muscles. The amount of deviation from the normal profile can be quantified with the normalised mean square difference D2. Gain factors varied over a factor of 4 within a group of 10 normal subjects. For a normal population D2 was below 1. Most muscles had consistent profiles but some patterns could be discerned which showed marked variability among muscles and subjects.