Electrode surface area is inversely related to total current flow. So a smaller electrode will deliver a higher current density. Use size in proportion to target tissue, ie: large electrodes for motor response for quadriceps muscles. Smaller electrodes for forearm muscles. Make sure there is good contact with the skin on placement, if the electrode is drying out you can place a little water or gel on the skin first for better conductivity. Also, make sure leads are firmly connected at both ends, ie: to stimulator and electrodes.
Electrode placement sites are important for specific functions.
- Motor Points are anatomic locations where motor nerve enters the muscle. The amount of electrical current needed is less than other areas of the muscle to get a motor response. These are located in the center of muscle belly and you use these points to get a muscle contraction.
- Trigger Points: if palpation of a trigger point elicits referred pain, try to use it as an electrode placement site for estim or TENS to block the signal.
- Acupuncture Points: these points are electrically active and decrease resistance to electrical flow
Electrical Stimulation for relief of pain involves encasing the painful area with electrodes. Edema Reduction using motor response patterns lowers edema by causing muscle contraction with ESTIM to "pump out" the edematous area. Ideal placement for "Muscle Pumping" involves elevating the limb for return blood flow, and use of 4 electrodes; 2 for agonist and 2 for antagonist muscles with reciprocal stimulation.