spinal cord injuries are basically an electrical impedance (resistance) problem. FES works on different levels. For one, many FES systems cycle electricity to

spinal cord injuries are basically an electrical impedance (resistance) problem. FES works on different levels. For one, many FES systems cycle electricity to various muscle groups in a coordinated fashion to try to get the patients body to 'take over'. Examples of this would be with electrodes on the glutes, thighs, and around the knees in an effort to get an incomplete spinal cord patient to stand. This exploits the patients natural spasticity, along with the physiology of the body (joints can only go so many ways) to get the patient able to stand with parallel bars or in some other controlled manner. Nerve stimulation also supposedly reduces the 'trigger energy' of certain muscle sets, thus sidestepping the impedance problem. An overly simplistic example : imagine a knee muscle requires 1mW to trigger into an action, however the circuit leading to this nerve only allows for half of that due to damage adding resistance along the pathway. FES can artificially increase the energy available to that muscle set so that the trigger may be more properly interpreted, hopefully leading to a successful 'firing' of the muscle. source: i'm a quadriplegic, and FES makes me spasm into a 'stiff as a board' plank.