Ramakrishnan Swaminathan

In this work, an attempt has been made to analyze surface electromyography signals (sEMG) by estimating maximum singular value. sEMG signals are recorded from biceps brachii muscles of 50 healthy volunteers during repetitive elbow flexion and extension exercise. Maximum singular values are estimated from the signals. The results show a decrease in MSV at the point of first muscle discomfort experienced by subjects. For most of the subjects, the point of first discomfort occur in fourth and fifth regions of the time axis. It appears that this method can be used to analyze progress of muscle condition towards fatigue.

In this work an attempt has been made to analyze the surface Electromyography signals recorded during dynamic contractions using quadratic time frequency distribution. Surface EMG signals are recorded from biceps brachii muscle in 50 healthy volunteers. These signals are subjected to Zhao-Atlas-Marks based Quadratic Time-Frequency Distribution (QTFD). Instantaneous median frequency (IMDF) and instantaneous mean frequency (IMNF) are estimated from the time frequency domain. In addition, IMDF are interpolated with time by using linear regression technique. The result shows that IMDF and IMNF are distinct in fatigue and non fatigue conditions and these parameters reduce significantly in fatigue case. Further, it is observed that IMDF decreases with time.

In this work, an attempt has been made to analyze progression of muscle fatigue in surface electromyography (sEMG) signals by estimating the complexity. The sEMG signals are acquired from biceps brachii of 50 healthy volunteers during dynamic contraction. The pre-processed signals are segmented into non-overlapping epochs of various sizes (500ms, 750ms and 1000ms) and Lempel-Ziv Complexity (LZC) is computed for each epoch. The linear regression technique is used to track the slope variations of LZC. The values of LZC show a decreasing trend during the progression of muscle fatigue. The magnitude of negative trend remained nearly constant irrespective of epoch size. Further, inter-subject variability of LZC measure is found to be minimum. The results shows that this method is useful in analyzing progression of muscle fatigue during dynamic contractions.