3) Changes in the geometry between muscle belly and electrode
site
Any change of distance between signal origin and detection site will
alter the EMG reading. It is an inherent problem of all dynamic
movement studies and can also be caused by external pressure.
4) External noise
Special care must be taken in very noisy electrical environments. The most demanding is the direct interference
of power hum, typically produced by incorrect grounding of other external devices.
5) Electrode and amplifiers
The selection/quality of electrodes and internal amplifier noise may add signal contents to the EMG baseline.
Internal amplifier noise should not exceed 5 Vrms (ISEK Standards, see chapter “Guidelines…”)
Most of these factors can be minimized or controlled by accurate preparation and checking the given
room/laboratory conditions.