Functional Electrical Stimulation – What is it?
Posted: Friday, June 22, 2007
by Dr Andy
http://www.pain-rehab.co.uk
Muscles need to contract to move any part of the body. To bend your arm at the elbow you contract your biceps muscle and to straighten it you contact your triceps muscle. Functional electrical stimulation (FES) is the gentle stimulation of muscles using small electrical currents so that the muscles contract. A small portable muscle stimulation machine or stimulator for short supplies the current. It is used to speed recovery or improve symptoms after illness, strokes, spinal cord injury, sports injuries and multiple sclerosis. Athletes also use it as part of their training regime. It’s also known as neuromuscular electrical stimulation (NMES) or electrical muscle stimulation (EMS).
FES makes muscles work! They contract and relax. This increases blood flow to the muscles, strengthens them, the extra blood flow helps the muscle fibres work more efficiently and removes lactic acid and other metabolites from the muscles and also relaxes the muscles if they are tense.
Any muscle that isn’t used no matter what the reason rapidly becomes weaker, shrinks and gets tight. This reduces the blood flow to the muscle, which keeps it tight. FES helps muscles recover.
How FES is used.
Most machines nowadays have pre-set programmes to make them much easier to use. All you need to alter is the current. You can buy machines you need to set up yourself, which with instructions is soon understood.
Imagine you want to exercise the biceps and bend your arm at the elbow. The 2 pads are stuck over the biceps, one over the middle of the muscle and the other just above the elbow crease. Each pad is joined to a lead, which is plugged into the stimulator. The stimulator is switched on and the current increased until the biceps contracts and bends your arm.
When using FES the muscle isn’t constantly contracted. That would be unhelpful. The current has on and off cycles called work and rest times. The current flows and bends the elbow during work time. The current stops and the arm straightens during rest time. The end result is a smooth rhythmical movement of your arm bending and straightening. Usually the rest time is twice as long as the work time. This avoids excessive fatigue. Typically work time is 4-8 seconds and rest 8-16 seconds. The shorter the rest time the harder the muscles are worked.
FES and rehabilitation
Stroke, knee replacement, spinal cord injury and cerebral palsy are all helped by FES. The use of FES on children with cerebral palsy can help relax muscles and decrease pain. It is however a specialised area and should only be done by experts.
FES is used more and more to speed stroke recovery. Studies have shown improvements in function after using FES for a few weeks in the majority of stroke patients. Even several years after a stroke, FES has been shown to help.
By gently exercising muscles they are strengthened and relaxed, are less painful and easier to move. The movement of the arm sends information back to the brain which stimulates it to bypass the damaged area and improve voluntary movement.
FES has been shown to improve recovery after a knee replacement by strengthening the thigh muscles post op which speeds up recovery and return to walking.
FES is a well established therapy for helping a wide range of problems. For more information on FES and strokes please visit www.pain-rehab.co.uk
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