Functional Electrical Stimulation Cycling for Spinal Cord Injury

Top Contributors - Janelle Girard, Alejandra Gomez, Jessica Baglole, Josh Nickel and Miranda Umeri  


Overview

FES cycling.png

Functional electrical stimulation (FES) uses electrical pulses to stimulate motor neurons or denervated muscle fibers directly to elicit a contraction during a functional activity [1]. FES has an extensive history for its treatment of orthopedic and neurological conditions.[2] For example, FES can be used to activate tibialis anterior to help dorsiflex the foot throughout the gait cycle in patients with foot drop or to strengthen the quadriceps following a total knee arthroplasty.

FES cycling applies the electrical stimulation to the muscles and/or nerves to contract the muscles associated with cycling. After a full rotation, each of the muscles will have been stimulated once with the appropriate timing and magnitude appropriate for cycling.  For example, lower extremity cycling would activate the hamstrings, quadriceps, glutes and calf muscles.[1] The muscles that are activated with upper extremity FES cycling include the biceps, and triceps to name a few. [1]The FES bicycle will detect changes in the muscle’s power output and will activate a motor when the muscles begin to fatigue to assist in the cycling. Over time, progress can be tracked by monitoring the amount of motor contribution.[3]

FES cycling may maximize the amount of function that is recovered through activity dependent neuroplasticity as a result of the repeated exposure and stimulation of the nerves and muscles during the activity[2]. Griffin et al. (2009) observed 10 weeks of FES cycling 2-3 times per week with individuals with spinal cord injury (SCI). Results showed increased total cycling power, endurance, lean muscle, and improvements in lower extremity ASIA Impairment Scales scores for motor and sensory which is particularly important in individuals who experience the effects of chronic paralysis[4].

Individuals with a SCI face many barriers to participating in physical activity which increases their risk for chronic conditions associated with a sedentary lifestyle[5]. FES cycling provides an accessible form of exercise for individuals limited in the ability to participate in other forms of exercise to evoke both the physical and psychological benefits that exercise can have.

Cost and Accessibility

There are at least three companies currently producing FES bikes in the United States.

  • Therapeutic Alliances, Inc., one of the oldest manufacturers, produce the ERGYS 3 Rehabilitation system for lower extremity cycling (therapeutic alliances).
  • Restorative Therapies, Inc. offers the RT300-S which can be operated directly from the individual’s wheelchair, eliminating the need for a transfer. Restorative Therapies supplies to USA, Canada, Australia and to other countries internationally [6].
  • Myolin produce the MyoCycle Home and MyoCycle Pro both designed for at home use. Given that it is the most affordable and simple to operate FES bike, it empowers people to use the bike and exercise without having to face barriers related to accessibility [7]. The fee of  the MyoCycle Home is $9,000 USD; includes everything you need to get started at home, including shipping, a 3 month supply of electrodes, and weekly progress reports via email. MyoCycle Pro is currently $13, 500 USD, and rental is available as well [7].

FES bikes, however, are not inexpensive and range from $9,000 USD to $30,000 USD  and are not covered by all private insurance companies[8]. The general range for new cycles is $16,000 to $30, 000 USD [8]. Given the high cost of the device, many people access FES bicycles through community settings. Physiotherapists and other qualified exercise professionals at specialized gyms or rehabilitation centres can help to apply the electrodes and calibrate the machine [9]Currently there are few facilities with FES bicycles.

Benefits and Risks

Physical

  • Increased cardiovascular fitness[2]
  • Metabolic influences by means of increases in capillary number, and  increase in glucose metabolism[2]
  • Muscles increase in size, strength, and overall fiber area[2]
  • Increases in bone density and the ability to recover bone mass[2]
  • Improves and maintains AROM[10]
  • Increased power output[11]
  • Recover sensation[12]
  • Reduce spasm[10]
  • Improved glycemic control[4]

Psychological

  • Improvement in health from participating in regular exercise[13]
  • Patients feel content seeing their leg muscles contract and being able to cycle[13]
  • They can participate socially by cycling with other patients of similar conditions[13]
  • Improvements in overall quality of life[10]

Risks

  • Some patients have the risk of going into autonomic dysreflexia when utilizing the bike[13]
  • Some patients can experience more spasms after using the bike[13]
  • Injuries to the skin or joints (blisters, pressure sores, muscle tears, etc)[13]
  • Cycling provides a safer alternative than FES walking as it reduces the risk of falling[1]

Indications, Precautions and Contraindications

Indications

Contraindications

  • Active deep vein thrombosis or thrombophlebitis[15]
  • Hemorrhagic conditions[15]
  • Pregnancy[15]
  • Damaged or at-risk skin[15]
  • Cardiac failure (local)[15]
  • Infection (local)[15]
  • Malignancy (local)[15]
  • Recently radiated tissue (local)[15]
  • Tuberculosis (local)[15]
  • Electronic device (local)[15]
  • Impaired circulation (local)[15]

Precautions

  • Active epiphysis[15]
  • Impaired sensation[15]
  • Impaired cognition[15]
  • Impaired communication[15]
  • Skin disease[15]
  • Regenerating nerves[15]
  • Fatigue[2]

Protocols

Frequency: FES cycling typically requires frequencies of around 30Hz for effective stimulation. However, in order to optimize treatment, higher power output generated by the patient is ideal. For higher desired outputs, frequencies should be targeted at 50Hz- 60Hz for a 30 minutes exercise session. Fatigue, should not be an issue, if cadence is taken into consideration.[16]

Cadence: Training plateaus may be common among SCI patients using this type of treatment which is usually do to a lack of progression of the exercise intensity.[17] This is because FES causes rapid muscle fatigue compared to voluntary muscle stimulation. With faster pedalling cadences (50 RPM), the maximum torque produced by the patient decreases quickly, compared to a slower pedaling cadence which produces higher power outputs. [17]On the contrary, when cadence is slower (20 RPM), higher force is generated by the working muscles but the power production is decreased.[17] Therefore, choosing the right cadence (20 RPM to 50 RPM) for training should be depend on the individual’s goals to either increase power or increase strength.

Pulse Duration: Higher pulse durations, for example 350 and 500 microseconds, result in larger differences in energy expenditure (rest energy expenditure-exercise energy expenditure) compared to lower pulse duration of 200 microseconds.[18] Small bursts of higher pulse durations did not have any meaningful differences compared to the mentioned above and seemed to trigger more symptoms of DOMS (delayed onset muscle soreness). [18]It is important to be cautious when prescribing high pulse durations because these tend to trigger, autonomic dysreflexia reactions in patients with SCI.

Treatment Intensity: The intensity may vary depending on whether the motor neuron is intact or whether the muscle needs direct stimulation to elicit a contraction. Denervated muscles require up to 100x more electrical energy to elicit a contraction of the muscle fibers.[1]. Currents used for functional electrical stimulation typically range from 120 MA to 300 MA, the most commonly used parameter is 150 MA.[1]

Electrodes and their activation: There are different types of electrodes that can be used for functional electrical stimulation cycling. There are surface carbon electrodes, which are adhered to bicycle shorts and other electrodes can be implanted in the body. Electrical stimulation can occur through either implanted or surface electrodes[1]. While implanted microstimulators require surgery and are very costly, they can stimulate nerves of deeper muscles, such as iliopsoas [1] .Using a larger sized electrode can be more comfortable for patients especially when using more current for stimulation of denervated muscles[1] .This is due to the fact that the current density is less when the surface of application is larger. The main muscles that are stimulated include: quadriceps, hamstrings, glutes, and the calves.[1] A  minimum of 6 electrodes are used to stimulate the muscles, which occur at different times depending on the angle of the leg throughout the cycle [1].  An angle detector on the bike or the pedal will send information to the stimulation device in order to time the sequence of the leg contractions [1].

Categories:

Queens University Neuromotor Function Project

Spinal Cord Injuries

Cycling

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Berkelmans R. Fes cycling. Journal of Automatic Control. 2008;18(2):73-6
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Martin R, Sadowsky C, Obst K, Meyer B, McDonald J. Functional electrical stimulation in spinal cord injury: from theory to practice. Topics in spinal cord injury rehabilitation. 2012 Jan 1;18(1):28-33
  3. Canada's first arm cycling program at Parkwood Institute in London, Ontario for patients with a spinal cord injury [Internet]. Parkwood Institute | St. Joseph's Health Care London. St Joseph's Health Care London; [cited 2018May8]. Available from: https://www.sjhc.london.on.ca/our-stories/canada’s-first-arm-cycling-program-parkwood-institute-patients-spinal-cord-injury
  4. 4.0 4.1 4.2 4.3 Griffin L, Decker MJ, Hwang JY, Wang B, Kitchen K, Ding Z, Ivy JL. Functional electrical stimulation cycling improves body composition, metabolic and neural factors in persons with spinal cord injury. Journal of Electromyography and Kinesiology. 2009 Aug 1;19(4):614-22.
  5. Ginis KA, Jörgensen S, Stapleton J. Exercise and sport for persons with spinal cord injury. PM&R. 2012 Nov 1;4(11):894-900
  6. Therapies [Internet]. Frequently asked questions. [cited 2018May8]. Available from: https://www.restorative-therapies.com/therapies
  7. 7.0 7.1 Bellman MJ. FES cycle The MyoCycle by Myolyn [Internet]. MyoCycle FES Bike and FES Technology. [cited 2018May8]. Available from: https://myolyn.com/index.php/products/myocycle-pro
  8. 8.0 8.1 Andrews P. FES Cycle [Internet]. URO Medical Supplies, Your Logical Choice. [cited 2018May8]. Available from: http://www.uromed.ca/catalog
  9. New therapy helping patients cycle to independence [Internet]. Parkwood Institute | St. Joseph's Health Care London. 2015 [cited 2018May8]. Available from: https://www.sjhc.london.on.ca/your-st-josephs/newsroom/new-therapy-helping-patients-cycle-independence
  10. 10.0 10.1 10.2 Bremner LA, Sloan KE, Day RE, Scull ER, Ackland T. A clinical exercise system for paraplegics using functional electrical stimulation. Spinal Cord. 1992 Sep;30(9):647
  11. Hicks AL, Ginis KM, Pelletier CA, Ditor DS, Foulon B, Wolfe DL. The effects of exercise training on physical capacity, strength, body composition and functional performance among adults with spinal cord injury: a systematic review. Spinal cord. 2011 Nov;49(11):1103.
  12. Griffin L, Decker MJ, Hwang JY, Wang B, Kitchen K, Ding Z, Ivy JL. Functional electrical stimulation cycling improves body composition, metabolic and neural factors in persons with spinal cord injury. Journal of Electromyography and Kinesiology. 2009 Aug 1;19(4):614-22.
  13. 13.0 13.1 13.2 13.3 13.4 13.5 Physiotherapy Department Victorian Spinal Cord Service, Austin Health. Exercise and FES Fact sheet [Internet]. Spinal Hub Australia. 2009. [cited 1 May 2018] Availble from:  http://www.spinalhub.com.au/uploads/pdfs/FES_cycle_fact_sheet.pdf.
  14. 14.0 14.1 Gorgey AS, Poarch HJ, Dolbow DD, Castillo T, Gater DR. Effect of adjusting pulse durations of functional electrical stimulation cycling on energy expenditure and fatigue after spinal cord injury. Journal of Rehabilitation Research and Development. 2014;51(9):1455–68.
  15. 15.00 15.01 15.02 15.03 15.04 15.05 15.06 15.07 15.08 15.09 15.10 15.11 15.12 15.13 15.14 15.15 15.16 Rennie S. ELECTROPHYSICAL AGENTS - Contraindications And Precautions: An Evidence-Based Approach To Clinical Decision Making In Physical Therapy. Physiotherapy Canada. 2010;62(5):1–80.
  16. Eser PC, Donaldson NN, Knecht H, Stussi E. Influence of different stimulation frequencies on power output and fatigue during FES-cycling in recently injured SCI people. IEEE Transactions on neural systems and rehabilitation engineering. 2003 Sep;11(3):236-40.
  17. 17.0 17.1 17.2 Fornusek C, Davis G. Maximizing muscle force via low-cadence functional electrical stimulation cycling. Journal of rehabilitation medicine. 2004 Sep 1;36(5):232-7
  18. 18.0 18.1 Poarch HJ, Castillo T, Gater DR. Effect of adjusting pulse durations of functional electrical stimulation cycling on energy expenditure and fatigue after spinal cord injury. Journal of rehabilitation research and development. 2014 Oct 20;51(9):1455