Authors: SCIRE Community Team | Reviewer: Shannon Sproule, PT | Last updated: Oct 10, 2017
Functional electrical stimulation is a treatment that activates muscles below the spinal cord injury (SCI) during exercise and activity. This page outlines basic information about functional electrical stimulation and its use for movement and strength after SCI.
- Electrical stimulation can be used to activate muscles that are weak or paralyzed after an SCI.
- Functional electrical stimulation (FES) involves stimulating the muscles during an activity like exercise or movement.
- FES is relatively safe and widely available treatment option for improving muscle strength and fitness after SCI.
- Overall, the research evidence suggests that FES is most likely effective for improving muscle strength after SCI. It may also improve fitness, walking skills, bone density and other symptoms, although more high quality research is needed to confirm.
Functional electrical stimulation (or FES) is a treatment where electrical stimulation is applied to the nerves that control muscles. This stimulation causes the muscles to contract and can assist with purposeful or functional movement in weak or paralyzed muscles FES is delivered using a variety of handheld or specialized commercial electrical therapy machines connected to electrodes that are placed on the skin’s surface.
Systems are also available with implanted electrodes in the muscles, although this is very specialized and not as widely available.
Muscle stimulation is used for several reasons after SCI:
To promote movement and strength in weak or paralyzed muscles: Muscles stimulation is used early in rehabilitation to promote movement in muscles that are not moving or only producing a flicker of movement. It may promote recovery of movement function by assisting with normal movements and with repetition of movements.
To improve fitness and health: When FES is used as part of a rhythmic exercise like cycling, walking, or rowing, it can help to maintain health of the heart, lungs, and circulation. It may also help to maintain healthy bones.
To assist with functional movement activities like stepping, getting up to standing, and grasping: FES can be used to assist with purposeful movements by improving muscle contractions (for weakened muscles), mobility or range of movement as well as possibly decreasing spasticity.
To maintain muscle mass below the SCI: Regular use of FES may help to prevent muscle loss that happens when the muscles that are paralyzed are not used. Unless neurological return occurs this improvement will stop if the FES is discontinued.
To control the muscles of breathing and bladder function: This includes the use of surgically implanted diaphragmatic pacers (FES systems that create muscle contractions in the diaphragm to stimulate regular breaths) and bladder control systems (FES systems that stimulate the muscles of urination). However, this page will focus on FES used for movement and strength after SCI.
It is important to speak with a health provider about using FES to make sure it is safe and suitable for you and to learn how to use the equipment correctly.
FES is usually applied through electrodes that are placed on the surface of the skin, although electrodes can also be implanted into the muscles. Electrodes are placed over nerves or part of the muscles below the SCI that respond well to electrical stimulation. The electrodes are then attached to an adjustable machine that generates the stimulation. Your health provider will determine the settings that are used for the treatment and how long it will last for.
The electrical stimulation is then gradually turned up until the muscles begin to tense or contract. Depending on your sensation, as the machine is turned up, you may feel pins and needles or other unusual sensations, which may take some time to get used to. The aim is to create a forceful but tolerable muscle contraction.
If the electrical stimulation goes well, it is then combined with a movement task. This may be as simple as lifting a wrist or ankle or more complex such as cycling on a stationary bike, rowing on a rowing machine, grasping, or stepping in parallel bars or a body weight support treadmill system.
The length of each session will vary depending on the goals of the treatment. Time may be required to enable your muscles to tolerate longer sessions as the muscles may fatigue quickly. Sessions are usually done several times per week for several weeks to gain training benefits.
Your health provider will monitor your response to the treatment and inspect the skin for any redness or irritation after the treatment has ended. Once you have learned to use FES safely, you may be able to use it on your own.
Our bodies naturally use electrical signals as part of the nervous system. When we move, the brain generates and sends electrical impulses along the spinal cord and nerves to tell the muscles to move.
Spinal cord injury can interrupt this pathway, preventing electrical impulses from passing through the spinal cord to reach the muscles. However, if the nerves and muscles below the injury are not damaged, they can still respond to electrical signals.
FES electrodes are placed over nerves or over electrically-sensitive parts of the muscles below the SCI. The specific type of electrical stimulation used with FES can trigger the nerve cells of movement (motor neurons) to send signals that cause muscle movement. An intact peripheral nerve and healthy muscle tissue is required to enable the external source of electricity to facilitate the muscle contraction.
Like exercise, regular treatment with FES is usually needed to maintain the effects of the treatment. For people with complete injuries, when FES treatments are stopped, the treatment effects will usually go away over time. For people with incomplete injuries , the goal is for some carryover of strength and movement be retained after the treatment is stopped.
There are some situations in which FES may be unsafe to use. This not a complete list, speak to a health provider about your health history and whether FES is safe for you.
FES should not be used in the following situations:
- Near implanted medical devices like heart pacemakers
- On areas of active cancer, or by people with bleeding disorders or other major medical conditions
- On areas with blood clots, bleeding, damaged skin, infection, or poor circulation
- By pregnant women
- Electrodes should not be placed over the eyes, through the head, through the chest or abdomen, or on the front of the neck or genitals
- By people with recent broken bones
- By people with damage to the nerves or muscles near the area where FES is used
FES should be used with caution in the following situations:
FES is often used with the following conditions after SCI but should be monitored closely. Speak to your health provider for more information.
- By people who have had seizures
- By people prone to severe autonomic dysreflexia (people with cervical and thoracic injuries)
- By people with uncontrolled spasticity
- By people with severe osteoporosis
- In areas where heterotopic ossification causes restricted movement
- In areas with reduced or absent sensation (below the level of injury)
- By people who are unable to follow instructions or provide accurate feedback
FES is generally well tolerated by people who can use it safely (see above for when FES may be unsafe). Serious medical complications from FES are rare. However, there are risks and side effects that should be discussed with a health provider before using FES.
More common risks and side effects of FES include:
- Discomfort or pain
- Skin redness or irritation
- Nausea, light-headedness, or autonomic dysreflexia
Other less common risks and side effects of FES include:
- Mild electrical burns near the electrodes
- Skin breakdown near the electrodes
- Worsening of muscle spasms (spasticity)
- Muscle and joint injuries, such as joint swelling or muscle strains
- Broken bones
- Mild electrical shocks (from improper use or faulty equipment)
In some cases, risks and side effects may be caused by improper use of the equipment. It is essential to learn to use the equipment from a health provider and to only use FES according to their direction and with the settings that they recommend.
For some people, side effects of FES may be stronger at first, but as their body gets used to FES with repeated treatments, their physical reactions may reduce over time.
Several studies have shown that FES helps to improve strength and fitness after SCI.
Studies have shown that both FES arm exercise and FES cycling helps to maintain or improve strength after SCI. However, FES cycling may be more effective for maintaining strength after injury than improving strength that has already been lost. This is supported by moderate evidence from five studies.
Fifteen studies have looked at FES for improving many different aspects of fitness after SCI. Taken altogether, these studies provide weak evidence that FES training done at least 3 days per week for 2 months helps to improve many aspects of cardiovascular fitness after SCI.
Studies show that FES improves walking speed and distance in people with both incomplete and complete SCI. Some of these studies also showed that regular use of FES carried over to improve walking even without FES. This is supported by weak evidence from eight studies.
The effects of FES treatment may also help to prevent complications of SCI like pressure sores, bone loss, spasticity, and orthostatic hypotension. These benefits may accompany gains in strength or fitness related to FES treatment.
Although it is commonly thought that increased muscle bulk from FES will reduce the risk of pressure sores, there are not very many studies which have looked at whether this actually happens. One study provides weak evidence that FES cycling for 2 years reduced the number of pressure ulcers that occurred after SCI. Another study showed that regular FES cycling showed a trend towards reducing seat pressures.
Research studies show that FES cycling does not prevent bone loss after SCI (moderate evidence from two studies). However, it may help to increase bone density that has already been lost, although the evidence for this is conflicting (based on six studies). It is not clear whether any gains in bone density last long-term or if continued FES treatment is needed for them to be maintained.
It is not clear what effects FES has on spasticity after SCI. There is conflicting evidence from three studies about whether FES cycling can help to reduce spasticity after SCI.
Three studies provide moderate evidence that FES of the legs during a single change in position reduced orthostatic hypotension. However, this only shows that FES prevents orthostatic hypotension while it is applied, and further research is needed to look at what benefits this could have to people living with SCI.
For a list of included studies, please see the Reference List.
Evidence for ‘Strength’ is based on the following studies:
 Baldi JC, Jackson RD, Moraille R, and Mysiw WJ. Muscle atrophy is prevented in patients with acute spinal cord injury using functional electrical stimulation. Spinal Cord 1998;36:463-469.
 Scremin AM, Kurta L, Gentili A, Wiseman B, Perell K, Kunkel C, and Scremin OU. Increasing muscle mass in spinal cord injured persons with a functional electrical stimulation exercise program. Arch Phys Med Rehabil 1999;80:1531-1536.
 Crameri RM, Weston A, Climstein M, Davis GM, and Sutton JR. Effects of electrical stimulation-induced leg training on skeletal muscle adaptability in spinal cord injury. Scand J Med Sci Sports 2002;12:316-322.
 Gerrits HL, de Haan A, Sargeant AJ, Dallmeijer A, and Hopman MT. Altered contractile properties of the quadriceps muscle in people with spinal cord injury following functional electrical stimulated cycle training. Spinal Cord 2000;38:214-223.
 Needham-Shropshire BM, Broton JG, Cameron TL, Klose J. Improved motor function in tetraplegics following neuromuscular stimulation-assisted arm ergometry. J Spinal Cord Med 1997;20:49-55.
 Cameron T, Broton JG, Needham-Shropshire B, Klose KJ. An upper body exercise system incorporating resistive exercise and neuromuscular electrical stimulation (nms). J Spinal Cord Med 1998;21:1-6.
Evidence for Cardiovascular Fitness based on:
 Berry HR, Kakebeeke TH, Donaldson N, Perret C, Hunt KJ. Energetics of paraplegic cycling: adaptation to 12 months of high volume training. Technology and Health Care 2012; 20: 73-84.
 Griffin L, Decker MJ, Hwang JY, Wang B, Kitchen K, Ding Z, et al. Functional electrical stimulation cycling improves body composition, metabolic and neural factors in persons with spinal cord injury. J Electromyogr Kinesiol 2009;19(4):614-22.
 Zbogar D, Eng JJ, Krassioukov AV, Scott JM, Esch BT, Warburton DE. The effects of functional electrical stimulation leg cycle ergometry training on arterial compliance in individuals with spinal cord injury. Spinal Cord 2008;46(11):722-6.
 Crameri RM, Cooper P, Sinclair PJ, Bryant G, Weston A. Effect of load during electrical stimulation training in spinal cord injury. Muscle Nerve 2004;29(1):104-11.
 Hjeltnes N, Aksnes AK, Birkeland KI, Johansen J, Lannem A, Wallberg-Henriksson H. Improved body composition after 8 wk of electrically stimulated leg cycling in tetraplegic patients. Am J Physiol 1997;273(3 Pt 2):R1072-9.
 Mohr T, Andersen JL, Biering-Sorensen F, Galbo H, Bangsbo J, Wagner A, et al. Long-term adaptation to electrically induced cycle training in severe spinal cord injured individuals. Spinal Cord 1997;35(1):1-16.
 Barstow TJ, Scremin AM, Mutton DL, Kunkel CF, Cagle TG, Whipp BJ. Changes in gas exchange kinetics with training in patients with spinal cord injury. Med Sci Sports Exerc 1996;28(10):1221-8.
 Faghri PD, Glaser RM, Figoni SF. Functional electrical stimulation leg cycle ergometer exercise: training effects on cardiorespiratory responses of spinal cord injured subjects at rest and during submaximal exercise. Arch Phys Med Rehabil 1992;73(11):1085-93.
 Hooker SP, Figoni SF, Rodgers MM, Glaser RM, Mathews T, Suryaprasad AG, et al. Physiologic effects of electrical stimulation leg cycle exercise training in spinal cord injured persons. Arch Phys Med Rehabil 1992;73(5):470-6.
 Gerrits HL, de Haan A, Sargeant AJ, van Langen H, Hopman MT. Peripheral vascular changes after electrically stimulated cycle training in people with spinal cord injury. Arch Phys Med Rehabil 2001;82(6):832-9.
 Ragnarsson KT, Pollack S, O’Daniel W, Jr., Edgar R, Petrofsky J, Nash MS. Clinical evaluation of computerized functional electrical stimulation after spinal cord injury: a multicenter pilot study. Arch Phys Med Rehabil 1988;69(9):672-7.
 Taylor JA, Picard G, Widrick JJ. Aerobic capacity with hybrid FES rowing in spinal cord injury: comparison with arms-only exercise and preliminary findings with regular training. PM R 2011;3(9):817-24.
 Kahn NN, Feldman SP, Bauman WA. Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study. J Spinal Cord Med 2010;33(2): 150-8.
 Hakansson NA, Hull ML. Can the efficacy of electrically stimulating pedaling using a commercially available ergometer be improved by minimizing the muscle stress-time integral? Muscle Nerve 2012; 45:393-402.
Evidence for ‘Walking’ is based on the following studies:
 Thrasher TA, Flett HM, and Popovic MR. Gait training regimen for incomplete spinal cord injury using functional electrical stimulation. Spinal Cord 2006;44:357-361.
 Ladouceur M, and Barbeau H. Functional electrical stimulation-assisted walking for persons with incomplete spinal injuries: changes in the kinematics and physiological cost of overground walking. Scand J Rehabil Med 2000a;32:72-79.
 Ladouceur M, and Barbeau H. Functional electrical stimulation-assisted walking for persons with incomplete spinal injuries: longitudinal changes in maximal overground walking speed. Scand J Rehabil Med 2000b;32:28-36.
 Wieler M, Stein RB, Ladouceur M, Whittaker M, Smith AW, Naaman S, Barbeau H, Bugaresti J, and Aimone E. Multicenter evaluation of electrical stimulation systems for walking. Arch Phys Med Rehabil 1999;80:495-500.
 Klose KJ, Jacobs PL, Broton JG, Guest RS, Needham-Shropshire BM, Lebwohl N, Nash MS, and Green BA. Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 1. Ambulation performance and anthropometric measures. Arch Phys Med Rehabil 1997;78:789-793.
 Granat MH, Ferguson AC, Andrews BJ, and Delargy M. The role of functional electrical stimulation in the rehabilitation of patients with incomplete spinal cord injury–observed benefits during gait studies. Paraplegia 1993;31:207-215.
 Stein RB, Belanger M, Wheeler G, Wieler M, Popovic DB, Prochazka A, and Davis LA. Electrical systems for improving locomotion after incomplete spinal cord injury: an assessment. Arch Phys Med Rehabil 1993;74:954-959.
 Granat M, Keating JF, Smith AC, Delargy M, and Andrews BJ. The use of functional electrical stimulation to assist gait in patients with incomplete spinal cord injury. Disabil Rehabil 1992;14:93-97.
Evidence for ‘Bone health’ is based on the following studies:
 Eser P, de Bruin ED, Telley I, Lechner HE, Knecht H, Stussi E. Effect of electrical stimulation-induced cycling on bone mineral density in spinal cord-injured patients. Eur J Clin Invest 2003;33:412-419.
 Lai CH, Chang WHS, Chan WP, Peng CW, Shen LK, Chen JJJ, Chen SC. Effects of Functional Electrical Stimulation Cycling Exercise on Bone Mineral Density Loss in the Early Stages of Spinal Cord Injury. J Rehabil Med 2010; 42:150-154.
 Mohr T, Podenphant J, Biering-Sorensen F, Galbo H, Thamsborg G, Kjaer M. Increased bone mineral density after prolonged electrically induced cycle training of paralyzed limbs in spinal cord injured man. Calcif Tissue Int 1997;61:22-25.
 Chen SC, Lai CH, Chan WP, Huang MH, Tsai HW, Chen JJ. Increases in bone mineral density after functional electrical stimulation cycling exercises in spinal cord injured patients. Disabil Rehabil 2005;27:1337-1341.
 Frotzler A, Coupaud S, Perret C, Kakebeeke TH, Hunt KJ, Donaldson Nde N, Eser P. High-volume FES-cycling partially reverses bone loss in people with chronic spinal cord injury. Bone. 2008 Jul;43(1):169-76. Epub 2008 Mar 20.
 Pacy PJ, Hesp R, Halliday DA, Katz D, Cameron G, Reeve J. Muscle and bone in paraplegic patients, and the effect of functional electrical stimulation. Clin Sci (Lond) 1988;75:481-487.
 Leeds EM, Klose J, Ganz W, Serafini A, Green BA. Bone mineral density after bicycle ergometry training. Archives of Physical Medicine and Rehabilitation 1990;71:207-9.
 BeDell KK, Scremin AM, Perell KL, Kunkel CF. Effects of functional electrical stimulation-induced lower extremity cycling on bone density of spinal cord-injured patients. Am J Phys Med Rehabil 1996;75:29-34.
Evidence for ‘Pressure Ulcers is based on the following studies:
 Dolbow DR, Gorgey AS, Dolbow JD, Gater DR. Seat pressure changes after eight weeks of functional electrical stimulation cycling: a pilot study. Top Spinal Cord Inj Rehabil. 2013 Summer;19(3):222-8.
 Petrofsky JS. Functional electrical stimulation, a two year study. J Rehabil. 1992;58(3):29–34
Evidence for ‘Spasticity’ is based on the following studies:
 Kapadia N, Masani K, Craven B, et al. A randomized trial of functional electrical stimulation for walking in incomplete spinal cord injury: Effects on walking competency. J Spinal Cord Med 2014;37:511-24.
 Manella K & Field-Fote E. Modulatory effects of locomotor training on extensor spasticity in individuals with motor-incomplete spinal cord injury. Restor Neurol Neurosci 2013;31:633-46.
 Ralston K, Harvey L, Batty J, et al. Functional electrical stimulation cycling has no clear effect on urine output, lower limb swelling, and spasticity in people with spinal cord injury: A randomised cross-over trial. J Physiother 2013;59:237-43.
 Kuhn D, Leichtfried V, Schobersberger W. Four weeks of functional electrical stimulated cycling after spinal cord injury: a clinical cohort study. Inter J Rehabil Res 2014;37:243-50.
 Mazzoleni S, Stampacchia G, Gerini A, Tombini T, Carrozza M. FES-cycling training in spinal cord injured patients. Eng Med Biol Soc 2013:5339-41.
 Sadowsky C, Hammond E, Strohl A, et al. Lower extremity functional electrical stimulation cycling promotes physical and functional recovery in chronic spinal cord injury. J Spinal Cord Med 2013;36:623-31.
 Reichenfelser W, Hackl H, Hufgard J, Kastner J, Gstaltner K, Gföhler M. Monitoring of spasticity and functional ability in individuals with incomplete spinal cord injury with a functional electrical stimulation cycling system. J Rehabil Med 2012;44:444-9.
 Krause P, Szecsi J, Straube A. Changes in spastic muscle tone increase in patients with spinal cord injury using functional electrical stimulation and passive leg movements. Clin Rehabil 2008;22:627-34.
 Mirbagheri M, Ladouceur M, Barbeau H, Kearney R. The effects of long-term FES-assisted walking on intrinsic and reflex dynamic stiffness in spastic spinal-cord-injured
 Granat M, Ferguson A, Andrews B, Delargy M. The role of functional electrical stimulation in the rehabilitation of patients with incomplete spinal cord injury–observed benefits during gait studies. Paraplegia 1993;31:207-15.
 Thoumie P, Le C, Beillot J, Dassonville J, Chevalier T, Perrouin-Verbe B et al. Restoration of functional gait in paraplegic patients with the RGO-II hybrid orthosis. A multicenter controlled study. II: Physiological evaluation. Paraplegia 1995;33:654-9.
Evidence for ‘Orthostatic Hypotension’ is based on the following studies:
 Faghri PD, Yount J. Electrically induced and voluntary activation of physiologic muscle pump: a comparison between spinal cord-injured and able-bodied individuals. Clin Rehabil 2002;16:878-885.
 Elokda AS, Nielsen DH, Shields RK. Effect of functional neuromuscular stimulation on postural related orthostatic stress in individuals with acute spinal cord injury. J Rehabil Res Dev 2000;37:535-542.
 Sampson EE, Burnham RS, Andrews BJ. Functional electrical stimulation effect on orthostatic hypotension after spinal cord injury. Arch Phys Med Rehabil 2000; 81: 139-143.
Electrophysical Agents – Contraindications And Precautions: An Evidence-Based Approach To Clinical Decision Making In Physical Therapy. Physiother Can. 2010 Fall;62(5):1-80.
Gibbons RS, Shave RE, Gall A, Andrews BJ. FES-rowing in tetraplegia: a preliminary report. Spinal Cord. 2014 Dec;52(12):880-6.
Martin R, Sadowsky C, Obst K, Meyer B, McDonald J. Functional electrical stimulation in spinal cord injury: from theory to practice. Top Spinal Cord Inj Rehabil. 2012 Winter;18(1):28-33.
Warms CA, Backus D, Rajan S, Bombardier CH, Schomer KG, Burns SP. Adverse events in cardiovascular-related training programs in people with spinal cord injury: a systematic review. J Spinal Cord Med. 2014 Nov;37(6):672-92.
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