Which impedance level is considered acceptable for EMG channels, such as limbs or chin?

Which impedance level is considered acceptable for EMG channels, such as limbs or chin?

• A. Less than or equal to 5kΩ
• B. Greater than 15kΩ
• C. Less than or equal to 10kΩ
• D. Less than or equal to 25kΩ

Answer: (C)

Low electrode-skin impedance is crucial for reliable surface EMG because the muscle signal is small and easily polluted by noise. Keeping the electrode-skin impedance under about ten kiloohms helps ensure the interface is well coupled to the skin and the amplifier sees a manageable source resistance, which supports a better signal-to-noise ratio. If impedance gets much higher, noise rises, motion artifacts become more pronounced, and the interaction with the amplifier can degrade signal quality. Skin preparation—cleaning the skin, light abrasion if appropriate, and using conductive gel or Ag/AgCl electrodes—helps achieve this target. While some setups may strive for even lower impedance (around 5 kΩ or less), ten kiloohms is commonly accepted as a practical upper limit for EMG recordings from limbs or the chin. Values like 15 kΩ or 25 kΩ would more likely compromise signal quality and stability.

Low electrode-skin impedance is crucial for reliable surface EMG because the muscle signal is small and easily polluted by noise. Keeping the electrode-skin impedance under about ten kiloohms helps ensure the interface is well coupled to the skin and the amplifier sees a manageable source resistance, which supports a better signal-to-noise ratio. If impedance gets much higher, noise rises, motion artifacts become more pronounced, and the interaction with the amplifier can degrade signal quality. Skin preparation—cleaning the skin, light abrasion if appropriate, and using conductive gel or Ag/AgCl electrodes—helps achieve this target. While some setups may strive for even lower impedance (around 5 kΩ or less), ten kiloohms is commonly accepted as a practical upper limit for EMG recordings from limbs or the chin. Values like 15 kΩ or 25 kΩ would more likely compromise signal quality and stability.