Influence of Viscoelasticity on Dynamic Fatiguing Behavior of Muscle Using Myotonometry and Surface Electromyography Measurements

In this work, an attempt has been made to analyze the influence of tissue viscoelasticity on the fatiguing behavior of skeletal muscle. For this purpose, myotonometry and surface electromyography (sEMG) signals are recorded from the biceps brachii muscle of adult volunteers. Viscoelastic characterization of muscle is carried out using two parameters, namely dynamic stiffness (DS) and relaxation time (RT), which are computed from the myotonometry signal. Fatiguing contraction is characterized using time to task failure (TTF) and mean absolute value (MAV) extracted from the sEMG signal. Linear regression is performed to find the association between myotonometric parameters and TTF. Results show that the TTF values are comparable between both hands, but the values are higher in the dominant hand. Linear relationship between myotonometric parameters and TTF is observed with adjusted
$R^{2} > 30$
% for the dominant hand and adjusted
$R^{2} > 40$
% for the nondominant hand. Furthermore, there is variation in the myotonometric parameters between nonfatigue and fatigue states. Similarly, MAV is also noted to increase from nonfatigue to fatigue state. Percentage variation of RT from nonfatigue to fatigue is linearly correlated with average MAV values. The results indicate that viscoelastic properties of muscle along with myoelectrical features can provide better characterization of fatiguing contraction in skeletal muscle and could be helpful in the domain of sports medicine and rehabilitative design.