FES Cycling - Health & Rehabilitation Technology after Spinal Cord Injury

We know that for good health we all need adequate exercise and this is normally difficult if not impossible for individuals following a spinal cord injury.

However, if exercise could become possible, those with such a condition potentially have a lot to gain. It is known that physical fitness, muscle mass and bony density will diminish fairly quickly following such an injury.

The function of an FES Cycling system (FES is an acronym for Functional Electrical Stimulation) is to allow such individuals to operate a stationary cycle (a motorised ergometer) with their own muscle power.

FES is available as a therapy method in quite a number of guises. Here the discussion is restricted to its use with a motorised ergometer (cycle)

We know that in order to have a beneficial effect on the bones, muscles and cardiovascular system, exercise should involve working the larger muscles of the body against some form of resistance. An FES Cycling system is an easy, effective and safe way of activating these leg muscles and achieving exercise health benefits.

This was very concisely described by Michael Kjare in the British Journal of Sports Medicine and here is the reference.

Kjaer, Michael (2000) Why exercise in paraplegia. Br J Sports Med 2000;34:322-323

Spinal cord injury leads to two dramatic changes: not only is there loss of muscle function and a large amount of muscle, but also susceptibility to inactivity related diseases, such as obesity, insulin resistance, type II diabetes, and coronary heart disease, increases.1

Previously, one of the major problems and causes of death for people with spinal cord injuries was infection, but recently, coronary heart disease has become more prominent. The possibilities for exercise in people with spinal cord injuries are limited to either performing voluntary exercise with non-paralysed muscle groups for example, arm exercises, especially in the paraplegic-or subjecting themselves to electrically induced exercise through stimulation of motor nerves either with surface electrodes or after implantation of electrodes.

Whereas voluntary arm exercise can provide a certain stimulus to the cardiorespiratory system, it has recently been shown that stimulation of paralysed lower extremity muscles alone or in combination with arm cranking will not only increase energy combustion', but also activate more muscle groups and thus influence metabolic changes such as insulin resistance in a potentially better way.

After the use of electrical stimulation for bladder and intestines, the possibility of stimulating paralysed muscle in a functional manner came to the fore at the beginning of the 1980s and allowed the development of a computerised bicycle (FES).' The use of such a bicycle for functional electrical stimulation has been shown not only to improve maximal oxygen uptake and endurance of the stimulated muscles, but also to cause muscle hypertrophy and muscle fibre shift from fast twitch type 2X to 2A.'

In addition to these effects, oxidative enzyme activity has also been shown to increase after several weeks of training.' This occurs at a faster rate than the shift in fibre type, indicating different time patterns for the adaptation of these two systems. In addition, the collagen in muscle adapts to electrical stimulation, and it has been shown that type 4 collagen, which is predominant in the basal membrane, increases its turnover without any net increase in total amount, indicating possible reorganisation of this connective tissue.'

In addition to these effects, expression of the protein used for glucose transport (Glut4) increases with training and so does insulin stimulated glucose uptake in the muscle:

Finally, it has been shown that functional electrical stimulation of paralysed legs increases bone mineral content of the tibial region. In studies using FES bicycling, high frequencies were used for stimulation, and no type I fibres were observed after this training. However, stimulation with lower frequencies actually seems to produce an
increase in mRNA for myosin heavy chain type I after several weeks of training.7

In combination, the effects of functional electrical stimulation counteract the enzyme activity associated changes in people with spinal cord injuries and should thereby have a preventive effect.

In addition to these effects, electrical stimulation of partially paralysed muscle groups such as wrist extensor and muscles in tetraplegic people has been shown to result in improved function and endurance of the affected arm allowing more daily functions to be performed than before the training programme. '

Finally, it seems that training in people with spinal cord injuries improves their general wellbeing, temperature regulation, and sleeping patterns and reduces pressure sores, all important effects in addition to those mentioned above. It is therefore vital to encourage physical activity, including the use of electrical stimulation devices, in this group of patients in order to prevent diseases associated with physical inactivity. Such diseases not only occur in this group of people, but also reflect the general pattern in our modern inactive society. Results obtained in research on people with spinal cord injuries may therefore help to provide a basis for recommendations on exercise in the general population also.

References
1 Phillips WT, Kiratli BI, Sarkarati M, et al. Effect of spinal cord injury on the heart and cardiovascular fitness. Curr Probl Cardiol 1998;23:641- 716.
2 Phillips CA, Petrofsky IS, Hendershot DM, et at. Functional electrical exercise. A comprehensive approach for psysicai conditioning of the spinal cord injured patient. Orthopedics 1984;7: 1112-23.
3 Andersen IL, Mohr T, Biering-Serensen F, et al. Myosin heavy chain isoform transformation in single fibres from m. vastus lateralis in spinal cord injured individuals: effects of long-term, functional electrical stimulation (FES). Pflugers Arch 1996;431:513-18.
4 Hjeltnes N, Galuska D, Bjornholm M, et al. Exercise-induced overexpression of key regulatory proteins involved in glucose uptake and metabolism in tetraplegic persons: molecular mechanism for improved glucose homeostasis. FASEBJ 1998;12:1701-12.
5 Koskinen S, Kjaer M, Mohr T, et al. Type IV collagen and its degradation in paralysed human muscle. Effects of functional electrical stimulation. Muscle Nerve 2000;23:580-9.
6 Chilibeck PD, Bell G, Jeon], et al. Functional electrical stimulation exercise increases GLUT-I and GLUT-4 in paralyzed skeletal muscle. Metabolism 1999;48:1409-13.
7 Harridge SDR, Andersen jL, Kjrer M, et al. The effects of low-frequency electrical stimulation on myosin heavy chain isoform expression and contractile characteristics of the tibialis anterior in spinal cord injured males. Abstracts of the Physiological Society. London: Cambridge University Press, 1998;506: 108P.
8 Hartkopp A. Training of wrist extensor muscles by electrical stimulation in spinal cord injured tetraplegic individuals.: with special reference to contractile and metabolic properties. PhD thesis, Faculty of health, University of Copenhagen, 1999:1-97.

A sophisticated control system delivers electrical stimulation to selected muscles of the leg to develop muscle power over time. At the push of a button the ergometer starts to rotate, the system detects the position of the crank arms, calculates the time at which each muscle needs to be stimulated and sends the correct stimulation impulses to the electrodes. Thus it creates a fluent cycling movement.

Over time, as the condition of the leg muscles improves, they are able to take a greater share of the effort required to pedal against resistance producing a training effect. The system senses the contribution that the users muscles can make from moment to moment during the cycling task and adjusts how hard the user is working - making up the difference with motor power.

FES Cycling Systems are applicable to spinal cord injured persons with complete or incomplete lesions where the lower motor neurons are still intact. It is important to realise that this technology is not a cure for spinal cord injury. What it does is provide improved health through the ability to exercise.

FES Cycling systems are also valid in rehabilitation following a stroke - the research evidence showing value is getting stronger.

This quite a big deal because the numbers of people affected by Stroke is very large. In the USA around 750,000 new strokes occur each year. In Scotland where I live we expect 1 in 7 persons to have a stroke in their lifetimes; with many persons requiring rehabilitation as a result.

Any approach that maximises recovery and minimises the need for longterm care is a big deal.

Often persons recovering from a stroke lose balance, an awareness of limb position as well as muscle weakness or even spasticity. FES Cycling seems to help individuals to re-learn how to use their muscles and gain greater functional independence.

In future, those affected by Multiple Sclerosis could benefit although the research is less clear cut at this stage.

Spasticity in the limbs is generally managed by the system, which automatically senses and adapts to the onset of muscle spasm in the lower limbs during use. Some contraindications and cautions are pointed apply. If is also necessary to be guided by a physician such as a spinal injuries consultant to identify and manage any potential risks that might apply in an individual case.

To use the system effectively it is necessary that the user, perhaps with the support of a helper, can place electrodes correctly, position a wheelchair or appropriate seating system close to the motion trainer and secure the feet within the motion trainer pedals.

Multiple Sclerosis can restrict exercise participation and lead to a reduction in fitness. Along with this restriction goes a higher risk of health complications and illness in the longer term.

It's understandable that many people with Multiple Sclerosis steer clear of regular exercise because they're afraid it might increase their fatigue or because they feel they simply aren't up to it. But with a properly managed regime, always taking into account a person's individual limitations, exercise is a good thing both physically and mentally.

In this section we examine whether FES Cycling can provide that precisely controlled exercise sought by persons with Multiple Sclerosis.

We know that exercise helps increase mobility, build up muscle strength and strengthens the heart. Importantly regular exercise has been shown to release "happy chemicals" in the brain, known as endorphins, so can help combat depression or emotional problems brought on by living with Multiple Sclerosis.

We are looking to apply a new exercise approach to the challenge of enhancing fitness in Multiple Sclerosis.

This approach relies on combining FES (Functional Electrical Stimulation) with a motorised exercise cycle. We have a great deal of experience applying this FES Cycling technology in Spinal Cord Injury and new work ongoing in Germany with Multiple Sclerosis has encouraged us to apply the knowledge and skills we have developed in this direction too.

The latest multi-center trials based on FES Cycling programmes with Spinal Cord Injury show important improvements in cardiopulmonary (heart and lung) fitness, bone density (resistance to fractures), circulatory function and muscle bulk and strength can be expected through regular exercise.

In clinical terms there are some aspects of FES Cycling that will transfer directly to Multiple Sclerosis from what we have already learned with Spinal Cord Injury. As you already know, it is difficult to perform controlled research trials with Multiple Sclerosis but there is an emerging clinical consensus in Germany that supports the value of FES Cycling.

The Process is as follows:
A client with Multiple Sclerosis is tested to determine their individual exercise performance limits.
Clients train under supervision for up to 2 hours per session, depending on their individual performance capability.
This session is repeated every 2 weeks to see if there is a confirmed medical benefit.
After a few weeks training with confirmed positive benefits clients may continue at home or at a Centre without direct supervision.

In Munich, this test training is free of charge and participants who apply via their health insurance are able to purchase equipment for home use.

Outcomes
In Munich they recommend FES Cycling for clients who have leg weakness and/or spasticity. These individuals are showing positive effects however researchers have not found an explanation for this.

It seems to work but the reasons are not scientifically confirmed. Many of the clients report a benefit in reducing spasticity and researchers are suggesting that this is because of a change in nerve structures.

However there is no evidence or suggestion that FES can make nerves grow again. This is potentially an important finding as it is known that a spasticity is highly prevalent and associated with a reduced level of functional independence. (See Barnes et al).

Some participants commencing exercise had hyperesthesia, or oversensitivity to touch although the researchers suggest that participants have adjusted quickly to the stimulation and reported improvements - although again there is no known reason for this.

How does it work?
You may have already heard of FES because it is being widely using used to assist with muscle weakness causing drop foot in Multiple Sclerosis. This technology is well established and FES Cycling is a more sophisticated application of the same principles. FES has decades of research behind it although it is only in recent years that this has started to be routinely applied in therapy situations.

RehaMove
To use the system, sticky pads (electrodes) are placed over leg muscles - up to four muscle groups on each leg are exercised at one time. A sophisticated control system delivers precisely controlled stimulation to the muscles of the legs in the right sequence to allow the muscles to contract and generate power. At the push of a button the cycle pedals starts to rotate, the system detects the position of the crank arms, calculates the time at which each muscle needs to work and sends the correct stimulation impulses to the electrodes. Thus it creates a fluent cycling movement.

Over time, as the condition of the muscles improve, they can take a greater share of the effort required to work against resistance - producing a training effect. The system automatically senses the contribution that a users muscles can make from moment to moment and adjusts how hard the user is working - making up the difference with motor power.

Any time a user wishes a break or if the muscles start to fatigue, the built-in motor takes over and passively moves the users legs. By adjusting the stimulation, the user can easily set exercise targets to work progressively against resistance.

How is this better than using a motiontrainer alone?
One component of the RehaMove system is the popular Reck MOTOMed Viva2 motion trainer. Many people with Multiple Sclerosis already use such a trainer to keep their legs moving at home. Reck's partner company, Hasomed GmbH, developed the stimulator unit and the sophisticated software that made RehaMove possible.

Although, in theory each user of a motion trainer can use it to exercise their legs, in practice the precise control and quality of muscle contraction, makes FES Cycling with RehaMove a much more effective form of exercise. The stimulator unit is programmed through an intuitive touch screen interface ensuring precise control of exercise.

Does the system need maintenance?
In an institutional setting we generally expect to work with that organisation via a contract to ensure that the system is inspected regularly because of the likely high frequency of usage.

For home users we suggest that the stimulator unit is returned to us after two years for routine safety testing. There are no particular maintenance requirements other than following our guidance on keeping the equipment clean. Care needs to be taken with the electrode cables to keep them clear of the cycle pedals.

What ongoing costs are there?
Electrodes are the only consumable cost. Electrodes we provide are good quality, reusable ones that last between 15 and 25 sessions before replacement. Each user needs their own electrode set.

References
'Management of MS Related Fatigue'. Expert Opinion Paper, Medical Advisory Board of the National Multiple Sclerosis Society. (2002)
Mostert, S. & Kesselring, J. (2002). 'Effects of a short term exercise training program on aerobic fitness, fatigue, health perception and activity level of subjects with MS' Mult Scler. 2002 Apr; 8(2):161-168. Department of Neurology, Rehabilitation Centre, CH-7317 Valens, Switzerland.

Petajan, J.H.; Gappmaier, E.; White, A.T.; Spencer, M.K.; Mino, L. & Hicks, R.W. (1996). 'Impact of aerobic training on fitness and quality of life in multiple sclerosis.' Ann Neurol. 1996 Apr; 39(4):432-41. Department of Neurology, University of Utah, Salt Lake City 84112, USA.

Stui'ergen, A.K. (1997). 'Physical activity and perceived health status in persons with multiple sclerosis.' J Neurosci Nurs. 1997 Aug; 29(4):238-243. University of Texas at Austin, School of Nursing 78701, USA.

Rehab Center for Physical Medicine, Ichenhausen, Germany - Reduction of spasm using movement trainers, a report for Medicamedizintechnik, Hochdorf, Germany.

Barnes, M. P.; Kent, R. M.; Semlyen, J. K. & McMullen, K. M. (2003). 'Spasticity in Multiple Sclerosis'. Neurorehabilitation and Neural Repair, 2003 März; Vol. 17, No. 1, 66-70.

Krause, P.; Szecsi, J. & Straube, A. (2007). 'FES cycling reduces spastic muscle tone in a patient with multiple sclerosis'. In: Neurorehabilitation 22 (4), 335-337. Department of Neurology, University of Munich, Germany.

The key question for potential users of FES Cycling systems is "How can I benefit?"

In soon to be published research by Professor Ken Hunt and his team from Glasgow University the benefits are clear.

Regular clinical measurements, during a 1-year fes cycling training programme, showed important improvements in cardiopulmonary fitness, bone density and muscle bulk and strength.

The study participants in London, Glasgow and Switzerland trained at home and were monitored by scientists who were able to identify their progress with measurement equipment.

FES Cycling technology gives feedback to clients - we all want to know that progress is being made on the road to improved fitness.

At present the users of an FES Cycling system can monitor a range of parameters that point to progress

Duration of training and the proportion of training that was active (using the users muscles) and the proportion that was passive.

The total distance covered
The energy consumption
The average work done and power generated
Of all of these measures perhaps the most relevant to progress is power generation.

Heart rate may not be the most accurate indicator of effort with all spinal cord injured persons. How else will you know that you are working hard enough? You will notice the perspiration alright.

The RehaBike was the fruit of research by Hasomed GmbH and the University of Glasgow, Centre for Rehab Engineering. In this mode, FES is used to stimulate the muscles of the legs to achieve independent, outdoor cycling using a tricycle.