Effect of preparation on force and muscular activity during an isometric contraction: a study from a signal processing point of view

This paper studies the effect of preparation on EMG and force signals during an isometric contraction. To do it, two features are extracted and statistically analyzed. The first one represents the amount of muscular activity estimated from the root mean square of EMG signal. It is called Mean Normalized Root Mean Square (MNRMS). The second feature extracted from the force represents the Mean Normalized Force (MNF). Results showed that the force and muscular activity are higher when the subject does not apply on the grip just before the beginning of the exercise. Moreover, it was demonstrated a linear relationship between MNF and MNRMS whose slope is slightly higher when the subject exerts a mechanical preparation. Finally, results demonstrates that verbal encouragement during isometric contraction increases the physical activity in term of force when the subject prepare mentally his activity.