The benefit of FES cycling for neurological conditions
Although FES (Functional electrical stimulation) has been around for a long time it is only just becoming widely accepted as the powerful and safe therapy tool it actually is. I ?rst worked with FES in the 1970’s which is, by any one’s standards, a long time ago now. The technology available in those days was not so easy to use compared with the systems we have available today although of course the principles havent changed.
Many technologies seem to come in and out of fashion for a variety of reasons. With functional electrical stimulation, I feel that the growth in popularity is in part due to the increased sophistication of the technology today. Modern systems o?er ?ne control of the stimulation and as a result produce a more predictable result.
Origins of the RehaMove FES Cycling system
We have worked with the RehaMove 2 FES cycling system from Hasomed GmbH for around 13 years now. We were introduced to Hasomed by David B Allan, Consultant Orthopaedic Surgeon and then Director of the National Spinal Injuries Unit in Glasgow and Professor Ken Hunt. In the early days there were too versions - one which was designed for outdoor use to work with a tricycle and the indoor version.
Following years of research the indoor product was ready for commercialisation. We could see from the research that there were clear benefits of FES cycling exercise for rehabilitation compared with passive leg cycling for users with a wide variety of conditions including stroke patients, following a spinal cord injury, multiple sclerosis, cerebral palsy and other neurological impairments. In the early days we were not entirely sure whether anyone would embrace these system commercially but were confident that they offered real clinical benefit for neurological disorder management.
The Rehamove FES cycling system
There are two main components to a RehaMove FES cycling system. The ?rst is a motorised passive/active bike from the Reck MOTOmed range and the second system is the FES unit or stimulator. These two systems communicate with each other in a sophisticated control system. Electrodes are placed on leg muscles and these electrodes are used to deliver precise electrical energy to the muscle groups to induce functionally useful muscle contractions.
Stimulation of each muscle group must be synchronised with the movement of the bike’s pedals. Consequently, the FES unit continuously monitors the bike's pedal position, cycling speed and the power being generated by the user. We almost use use an adaptive stimulation approach in which the FES is automically adjusted so that the user achieves a cycling goal related to active cycling against resistance. As the user makes progress and muscle strength is gained, the resistance to cycling can be increased,
The quadriceps, hamstrings and other muscle groups involved in cycling are e?ectively "turned on" and o? at the necessary times during each revolution of the bike pedals.
This information flow is used by the FES cycle to modulate the stimulation been delivered to the muscles. Depending on the exercise goals and the training level of the user, the intensity of stimulation can be varied by the stimulation programme.
Some of the bike models support upper limb exercise with FES. We also offer Sequence Mode software which, as the name suggests, allows the FES unit to be used independently from a bike to augment other forms of exercise. For example, the adjacent image shows an application of FES for shoulder stabilisation with a stroke patient. This constitutes a powerful tool for the therapist interested in motor recovery and restorative therapies.
The RehaMove FES unit generates what are called bipolar rectangular pulses. The fact that this has both positive and negative pulses helps to prevent skin irritation and increases e?ectiveness. The pulse shapes are high ?delity - in other words close to pure rectangular form. This helps e?ciency as the area of each pulse is related to the intensity of stimulation. It helps us to use less energy overall in producing a particular level of response. Many inexpensive FES units will produce waveforms that have poorly controlled wave shapes. This means that much higher levels of stimulation current and longer pulse widths would be needed to produce the same e?ect as with a high quality system.
Three aspects of the waveform have to be controlled to shape the nature of the muscle contractions. These are the stimulation frequency, current and pulse width. These have to be controlled for each muscle involved in the exercise program. The RehaMove system generates current levels up to 130 milliamps, Frequencies up to 50 Hz (and down to 5 Hz) and pulse widths up to 500 microseconds. Varying these parameters can produce different physiological effects. For example, by choosing our stimulation frequency with care we can in?uence the muscle ?bre types we are targeting, whether we train for muscle strength or endurance, relax muscles or even accelerate wound healing.
Leaving aside the technical aspects "under the hood", the RehaMove systems are generally very easy to use and many users are happy and competent to make their own changes - it's child's play to use.
Passive cycling versus FES Cycling
Consider a client with a complete spinal cord injury who would have no ability to consciously contract the leg muscles and pedal a bike. If we use a motorised bike such as a MOTOmed Loop without FES this bike will move the legs passively through a range of motion.
领英推荐
Although this is commonly carried out in physical therapy and has some benefit in preserving range of motion, reducing troublesome spasticity and perhaps reducing oedema, adding FES synchronised with the pedals turns passive exercise training into much more powerful active exercise.
Where the user has an ability to consciously contribute and generate cycling power, the RehaMove system can be set to "get out of the way" - allowing the user to pedal by themselves at first and then gradually support the user as they fatigue. This can be very useful with incomplete spinal cord injury, with stroke and multiple sclerosis. Often clients will see a "carry over" effect after such FES Cycling support.
Active muscle contraction preserves the bulk and tissue quality, enhances circulation and to some extent enhances or preserves bone density. Research in fact shows a broad spectrum of possible benefits
Although less commonly seen, FES Cycling can also be very effective for patients in ICU when the Letto version of the RehaMove 2 allows FES Cycling with unconscious persons. This approach can be very effective at reducing the incidence of intensive care syndrome.
FES Cycling systems such as the RehaMove 2 are commonly recommended following the development of a neurological condition although finance will not allow these to be adopted by all who could benefit.
We find that, in common with most forms of exercise, motivation to participate can vary. We have clients who use FES Cycling everyday and derive sufficient motivation from the sense of wellbeing that is naturally generated and from the fact that their legs are "normal" in appearance as a result.
These benefits are much more meaningful to clients than more abstract concepts such as cardiovascular fitness that their physicians think about. It is understandable that efforts would be made to enhance the FES Cycling training experience and encourage sustained participation and deter disuse atrophy
A recent pilot study [1] investigated the effects of a one-month training programme using a novel device, the iCycle, in which voluntary effort is encouraged by virtual reality biofeedback during FES cycling
We too offer the excellent Bike Labyrinth system to enhance the experience for our RehaMove 2 adopters. This provides a virtual reality environment for clients to cycle through with many sensory enhanced routes in different parts of the world.
I have often said to clients about FES Cycling - "It's good for you but it's not a great spectator sport". Products like Bike Labyrinth help to make the RehaMove 2 system a more engaging experience.
Interested in FES Cycling research - a quick web search will quickly show a wealth of literature for you to explore. If you would like to see the RehaMove up close then give us a call.
Reference
[1] Duffell, L.D., Paddison, S., Alahmary, A.F. et al.
The effects of FES cycling combined with virtual reality racing biofeedback on voluntary function after incomplete SCI: a pilot study. J NeuroEngineering Rehabil 16,
149 (2019). https://doi.org/10.1186/s12984-019-0619-4
About the Author
Derek Jones PhD, MBA is a bioengineer and a Director of Anatomical Concepts (UK) Ltd.
Information Technology, Services Business Consultant and Contractor
3 年Thanks for posting