Multifractal analysis of sEMG signal of the complex muscle activity

The neuro--muscular activity while working on laparoscopic trainer is the example of the complex (and complicated) movement. This class of problems are still waiting for the proper theory which will be able to describe the actual properties of the muscle performance. Here we consider the signals obtained from three states of muscle activity: at maximum contraction, during complex movements (at actual work) and in the completely relaxed state. In addition the difference between a professional and an amateur is presented. The Multifractal Detrended Fluctuation Analysis was used in description of the properties the kinesiological surface electromyographic signals (sEMG). Based on the results obtained in the form of multifractal spectra together with the parameters which effectively describes it, like the spectrum half--width, or the Hurst or the singularity exponents, we demonstrate the dissimilarity between each state of work for the selected group of muscles as well as between trained and untrained individuals. For the well-trained person (professional) at work mf-spectrum shows similarity with the relaxed state, i.e. the spectrum will be truncated at the right side which show the dominance of the low fluctuations. On the contrary the spectrum for the untrained person at actual work will tend to be rather broad and symmetric. This feature hidden in the sEMG fluctuations allows for the determination of the level of training not only in the case of surgeons but also opens a possibility for similar analysis in any other complex motion with the use of the noninvasive surface electromyography.