**2.2. Surface EMG (sEMG)**

sEMG is a technique to measure muscle activity noninvasively using surface electrodes placed on the skin overlying the muscle, and has several advantages. First, sEMG recording is pain‐ less, especially when used in the absence of peripheral nerve stimulation. Furthermore, sEMG electrodes record from a wide area of muscle territory providing a more global view of MUs. Finally, it allows prolonged simultaneous recordings of muscle activity from multiple sites.

However, sEMG has a relatively low-signal resolution, is highly susceptible to movement artifacts [9] and body temperature. In addition, sEMG signals are dominated by the contribu‐ tions of superficial MUs, while deeper MUs are not assessed; conditions that increase skin resistance subsequently disturb the sEMG signal (e.g. obesity and edema).
