Functional Electrical Stimulation (FES) is a technique of eliciting controlled neural activation through the application of low levels of electrical current. FES was initially referred to as Functional Electrotherapy by Liberson  and it was not until 1967 that the term Functional Electrical Stimulation was established by Moe and Post . In 1965 Offner patented a system used to treat foot drop with the title “Electrical stimulation of muscle deprived of nervous control with a view of providing muscular contraction and producing a functionally useful moment” . Another term often used equally to FES is Functional Neuromusclular Stimulation (FNS or FNMS).
The first commercially available FES devices treated foot drop in hemiplegic patients by stimulating the peroneal nerve during gait. In this case, a switch, located in the heel end of a user’s shoe, would activate a stimulator worn by the user.
Structural discontinuity in the spinal cord after injury results in a disruption in the impulse conduction resulting in loss of various bodily functions depending upon the level of injury. The initial goal of FES technology was to provide greater mobility to the patients after SCI. However, with the advances in biomedical engineering within the last 2 decades, FES is no more limited to locomotion alone. Therefore, the definition of FES has changed considerably and is now considered to be the technique of applying safe levels of electric current to stimulate various organs of the body rendered disabled due to SCI. Electrical stimulation in the form of functional electrical stimulation (FES) can help facilitate and improve limb mobility along with other body functions lost due to injury e.g. sexual, bladder or bowel functions.