Analysis of sEMG signals associated with isometric contraction of triceps brachii muscles using multifractals

In this work, isometric contraction of triceps brachii muscles are analyzed using surface electromyography (sEMG) signals and multifractals. The signals are recorded from 20 healthy adult volunteers at three different angles of elbow flexions namely 30°, 60° and 90° using standard experimental protocol. The recorded signals are preprocessed and subjected to Multifractal Detrended Fluctuation Analysis (MF-DFA). The three extracted MF-DFA features namely, peak exponent event, rare exponent event and smooth exponent event, are used for further analysis. The results show that multifractal spectrum response are distinct for all the three angles of flexion. It is observed that multifractal spectrum is shifting from higher order exponents to lower order with the increase in the angle of flexion. The features are statistically highly significant between 30° and 90° flexion. The smooth exponent is found to be statistically highly significant for both 60°-90° and 30°-90° flexion. It appears that this method of multifractal technique is an useful approach to understand muscle contractions in fatigue and in varied clinical conditions.