Assessment of repeatability of surface electromyography signals by singular value decomposition

Singular value decomposition (SVD) of full-wave rectified surface electromyography (sEMG) signals was investigated for repeatability indices of sEMG linear envelopes (LE) during biceps curl. The SVD based repeatability indices were compared with a well-known method, the variance ratio (VR). The usefulness of the offered indices was examined by a simulation and it was applied to the sEMG LEs. The results have shown that the VRs were correlated with the SVD based indices significantly. The usefulness of the offered indices on real world EMG signals practically comes from decreasing amplitudes of the first few singular values of EMG LE matrix. If repeatability is high, singular values decay fast and vice versa. If justified by further researches, the offered indices may be used practically for repeatability measurement of sEMG LEs.