Skin impedance measurements are very difficult to make, and have a very high variability. Once known, this value alone carries little significance. The more informative parameter used to gauge EMG signal quality is the Signal-to-Noise Ratio. Delsys EMG systems have a noise baseline of 5uV (pk-pk). This extremely low noise baseline allows individual motor unit action potentials to be identified from minimal contractions when sensors are properly placed on the skin.