Assessment of Muscle Excitation During Physical Activity Based on Surface Electromyography

Background. Surface electromyography (sEMG) is a technique for recording and evaluating the electrical activity in response to a nerve’s stimulation of the skeletal muscles. It is commonly used in sport and rehabilitation. The voltage potential of sEMG signals varies over time and is influenced by personal qualities. One of the main disadvantages of EMG analysis is that the amplitude of signal (milivolt scaled) is strongly dependent on the given acquisition conditions. For these reasons, the amplitude of raw sEMG is not reliable. To provide an objective analysis of the muscle excitation, sEMG signals are normalized by using maximum voluntary contraction (MVC). The MVC test is performed for each investigated muscle separately. Method: Muscle excitation is adopted as the threshold value of processed sEMG. It is determined as the mean of sEMG signal in assumed window normalized by MVC. Results: The presented method of EMG analysis was validated using sEMG of six subjects recorded during a single leg Romanian deadlift (slrdl) for rectus femoris, vastus medialis, and biceps femoris. Conclusions: Assessment of muscle excitation seems to be effective, but the exercises dedicated to MVC estimation should be properly selected and precisely performed.