Introduction to EMG for the Study of Movement: From Bipolar to High-Density
Abstract
Appropriate inter-electrode distance (IED) is needed to enable the reconstruction of detailed muscle activity and obtain correct map’s features of a High Density surface EMG (HDsEMG). The spatial frequency bandwidth of sEMG was estimated by placing a grid of 16 × 8 pin electrodes (IED = 5 mm) on biceps brachii (BB) and medial deltoid (MD) of a subject and sampling the signals at 2048 Hz. The zero padded 2D FFT (64 × 64 points) was performed for each instantaneous map without removing the offset of the map. Two arbitrary definitions of spatial bandwidth f max were tested: (1) f max ≤ 87.5 c/m that supports 90 % of total power, (2) f max ≤ 87.5 c/m such that the amplitudes of all spectral lines after it are <5 % of PSD max. We found that 90 % of the f max values for BB (MD) muscle lies between 25.0–87.5 (21.9–87.5) c/m and 18.8–46.9 c/m for definition 1 and 2 respectively.
Keywords
Spatial Frequency Biceps Brachii sEMG Signal Fourth Quadrant Instantaneous AmplitudeReferences
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