Emg Signal Amplitude Differences during Maximal Isometric and Isokinetic Activity

The use of maximal voluntary isometric contractions (MVICs) for the purpose of electromyographic (EMG) data normalization is a well accepted practice within exercise and sport science literature. Benoit et al. (2003) reported that treadmill walking in ACL injured subjects elicited normalized medial gastrocnemius surface EMG values of 160% MVIC, indicating muscular activation during dynamic activity generates higher peak EMG values than MVICs. Further, Arsenault et al. (1986) demonstrated normalized soleus EMG values during sub-maximal walking trials of up to 120% MVIC. This peak soleus muscle activity occurred at approximately two-thirds of the stance phase of gait, where ankle plantar flexion velocity is estimated to be 30°/second.