I am often asked where the best positions are to place self-adhesive electrodes, for patients using FES or TES, or even those using an APS or TENS machine for pain. In this article, I would like to give you some pointers as to where to place the electrodes when wanting to stimulate the muscles to contract.
General rule of thumb for electrode placements
You will notice that there are 2 electrode leads connecting your stimulation device to the electrodes. They are typically red and black, with the red being the anode / positive lead, and the black being the cathode / negative lead.
The electrode attached to the black electrode lead should be placed over the area that you require to contract under the action of the stimulator. So if you are for example stimulating the quadriceps muscle (the muscle that straightens your knee), then the black electrode needs to be placed over the inside lower thigh area, on the front of the leg.
The electrode attached to the red electrode lead should be placed over the area of the nerve supplying the specific muscle. Once again using the same example of above, this would then be placed over femoral nerve, which is higher up the front of the leg, in the centre. What is important though is that you ensure that the correct placement is achieved by testing the resultant contraction by turning on your stimulator. Use of any form of medical stimulator needs to be done in consultation with your therapist or doctor to ensure correct use. It is also important to ensure that you do not have a condition which contra-indicates the use of electrical stimulation. If you are unsure, please contact us through this website first!
Where not to place the electrodes
Never place the electrodes over an area where the skin is broken, from a scratch, insect bite etc. This will cause undue discomfort and could be painful. Also be sure not to stimulate over an area still showing redness from the previous stimulation session. Overstimulation on fragile or broken skin can result in the skin breaking down and causing an open wound. If there are any signs of skin breakdown, stop stimulation immediately and consult your healthcare practitioner.
How do I know if my electrode placement is correct?
The first thing you need to confirm is that the correct movement is achieved through your electrode placement. If you are getting the desired movement, be sure that you are not getting this at too high an intensity. Should you need to increase the intensity more than usual, you may have the incorrect electrode placement, the electrodes may need replacing, the skin may have cream or oil on it, or your battery may be deteriorating. Be sure not to increase the intensity more than usual to achieve the same contraction, as this would be aggressive to the skin.
While we have some standard anatomy references, everyone is different in their individual anatomy. Should you not be getting the desired movement from the electrical stimulation at comfortable intensity, you may move the electrodes around slightly in an attempt to improve the response. I often find that it is the black electrode that needs adjustment ,as this is typically the more position sensitive electrode, so start there.
We will be posting some picture guidelines on standard electrode placements shortly, so please revisit us. You can also keep up to date by joining us on Facebook or LinkedIn, or subscribe to our RSS or Twitter feeds.