Physically disabled people are the least active group in society but make up around a fifth of Britain’s population – almost 14 million people.
According to Sports England, disabled people are twice as likely to be inactive as able-bodied people and this creates a multitude of health challenges.
Fitness can reduce and the risk of health complications and illness are likely to increase.
In this Q&A we speak to Dr Derek Jones of Anatomical Concepts, to explore how to exercise paralysed limbs despite having experienced a spinal cord injury or other neurological condition (including stroke, MS, Transverse Myelitis and more) using Functional Electrical Stimulation.
How does FES Cycling work?
Whilst motorised bikes that can move paralysed legs with passive cycling are popular and they do help prevent joint contractures, the addition of FES ensures that exercise is active and this has a more powerful health benefit.
For example, various combinations of leg muscle groups – at least the quadriceps and hamstrings – can be activated in order to achieve an effective cycling action.
Each muscle group is “switched on” during only part of the 360 degree crank rotation, to ensure that stimulation of each group results in a positive crank moment.
This is achieved by synchronising the delivery of muscle stimulation to the movement of the bike pedals.
An FES bike typically monitors the speed of the pedals and the effort generated by the user and uses this information to modulate the stimulation delivered to the muscles.
Products like the RehaMove system allow the user to set a target cycling speed and level of resistance to pedalling.
This allows the user to get stronger over time.
Most products are available in a form that will also allow upper limb exercise too and utilise the arm and shoulder muscles if these have been affected by the condition.
There is even a version that allows a person lying in bed and in intensive care to use FES Cycling and there are many
benefits of this.
You mentioned using a stimulator with other functional exercise. How does this work?
Some clients will use the FES unit of the RehaMove system independently from the bike, with software called Sequence Mode, that allows other forms of exercise to be augmented with FES.
Instead of the stimulator reading data from the bike to know when to turn on or off the stimulation, we can set the unit to run on a sequence set by the number of seconds of stimulation of each channel, or programme a sequence to a manual button press.
For example, clients often use the RehaMove stimulator to aid in sit to stand work.
Usually the client would set up in a standing frame, then use a standing programme which would activate the quadriceps to get to standing, followed by a short activation of the glutes to add stability.
These would then turn off, followed by an activation of the hamstrings to allow a controlled return to the
seated position.
This sequence can be set to run automatically on a loop, or with further control using a manual trigger press.
Clients find this to be very engaging and challenging to perform.
We can use this software in lots of ways including things link shoulder stabilisation, dorsiflexion, hand flection and torso stabilisation, and there are preset templates with the software.
We see therapists getting creative and integrating cable machines, bands, and other gym equipment for challenge.
Equally, using every day objects such as forks, cups etc to work on movements that help clients work towards feeding themselves or brushing their hair.
FES can really cover the bases of a device that can aid in every day functional health (cycling) and specific rehab goals
(sequence mode).
How much electricity is being used?
The amount of electricity is very small. Technically, the electrical waveform used will normally be a bipolar, rectangular pulse.
The maximum current will be around 130 mA. The FES unit that makes the muscles contract delivers stimulation to the surface of the limbs via two surface electrodes placed on the limb segments with a gap between them.
The current flows in to the tissues via one electrode and out via the other one and in doing so, providing the amount of energy is sufficient, activates the nerves that bring about a muscle contraction.
There are other stimulation parameters to consider beyond current; namely pulse width and frequency.
The combination of current, frequency and pulse width can be varied by the FES unit to influence how strong the muscle contraction will be.
Some products will vary some of the parameters automatically within safe limits and of course allow the user to make changes.
Who can and cannot use FES Cycling or Sequence Mode Exercises?
Although most commonly practices by people with a spinal cord injury, FES Cycling is also used successfully in people with upper and or lower-limb dysfunction in a range of other neurological populations such as Stroke, MS, Transverse Myelitis and in children with cerebral palsy.
Just as with any medical product there are also contraindications and some cautions to using them.
These include things such as active fractures in the limbs being exercised, joint contractures that prevent a cycling action, pregnancy and the presence of certain types of
implanted medical devices.
Contraindications will tend to vary over time and with developments of the technology but these should always be checked in each individual case.
When the upper limbs are to be exercised with FES it is important to verify the integrity of the shoulder joints.
When indicated, this exercise can be fine tuned to preserve shoulder function and prevent contractures in the upper limbs.
What does FES feel like?
Many of our clients have an injury which means they have little or no sensation in the area in which the electrodes are applied. So nothing is felt.
This doesn’t mean that you can make the stimulation as strong as possible as there are other things to consider.
For example, you need to be aware of skin irritation at the electrode sites and provoking muscle fatigue resulting in a
metabolic insult, by having the intensity of stimulation too high.
With some users who have sensation, the level of stimulation can be reduced to diminish any discomfort.
We have met some people who find it difficult to tolerate useful levels but this is quite unusual.
With some levels of injury, (above T6 level) care must be taken, especially at the beginning of use,
to avoid autonomic dysreflexia.
Most people who might be susceptible to this condition will have learned to recognise how the onset of this feels at an earlier stage of rehabilitation.
If someone feels unwell when using a FES bike this should be halted immediately.
It’s also good idea to ensure that bowel and bladder are clear before exercising.
What are the other benefits to FES Cycling and training?
A range of physiological benefits has been observed in clinical studies of subjects with spinal cord injuries, including improvements in cardiopulmonary fitness, muscle strength and bone density.
Sometimes FES Cycling helps to calm muscle spasms.
Stimulating the gluteal muscles during cycling can help reduce the risk of pressure ulcers and the stimulator can also be carefully used to assist with wound healing.
Of course there are also psychological benefits of exercise and regular activity.
Some clients also report that they feel positively about retaining / improving their muscle mass for aesthetic reasons.
Can you build muscle with electrical stimulation?
Regular training with a RehaMove system or other FES bike will definitely encourage growth of the leg muscles and fight off muscle atrophy.
By varying the stimulation parameters, lower limb muscles can be conditioned for endurance or power.
Although the technology has improved over time, it is less efficient to trigger a muscle contraction using FES than it is for the body working “naturally”.
The body has a much more efficient process for recruiting muscle fibres to contract. It is unlikely that someone starting to use an FES bike for
the first time will generate much power.
It takes time and patience – think – more of a marathon than a sprint.
Does electrical stimulation relax muscles?
Some users have troublesome spasms in the legs. These can be a nuisance and often medication is offered to try and reduce these.
Unfortunately, oral medication is not always effective, can make the patient drowsy or lose its effectiveness over time.
Some patients elect to use an implant which can deliver precise amounts of medication to manage the spasms.
An FES Cycling intervention can help a majority of persons to damp down their leg spasms.
Sometimes these get worse initially as the legs get stronger but in these cases the stimulation parameters can be fine tuned to help. Also stretching, and leg massage prior to a session can help.
How does someone get started with FES Cycling or training?
Functional electrical stimulation in general and FES Cycling in particular is a safe and widely used modality with a good evidence base for supporting long term health.
We would always encourage exploring the various options and thinking carefully about the possibilities.
The technology available from ourselves and other suppliers will fundamentally attempt to do similar things but with differences in the user interface.
Our approach to working with the RehaMove FES Cycling system asks potential clients to complete a short risk assessment.
Providing the client is safe and suitable to use FES, we ask a
therapist to visit the client with a system to talk over their specific goals and give a full demonstration.
We then follow up with a report which details the discussions, the exercise programmes that were demonstrated, and a recommendation on how they may adopt the system into their routine.
In an ideal world, FES Cycling and FES Training would be utilised daily to simply help individuals stay active, reducing the risk of longer term ill health or complications.
With driven clients and therapist input it can also help improve targeted, rehabilitation outcomes.
