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By Tommy Sutor, MS, CSCS

Former Program Director at Push to Walk NJ, currently pursuing a PhD in movement science exploring the coordination between walking and breathing.

In October, a scientific article written by researchers from the University of Louisville and Frazier Rehab Institute presented with some pretty incredible results; a man who had been paralyzed from a spinal cord injury for over 4 years had regained the ability to voluntarily move his legs and stand. These results came after another study performed at UCLA in 2015, which reported similar results, of the return of voluntary movement at least two years after a spinal cord injury. Importantly, all the participants in these studies had been diagnosed with “complete” spinal cord injury, meaning they had no ability to move or feel any part of their body below their injury. In both studies, the movements were not perfect, and were not always useful to the study participants in everyday life. Nonetheless, they served as important proof-of-concept studies, showing that return of movement after a spinal cord injury is at least possible.

How is this possible? Both studies involved long periods of physical rehabilitation and exercises. What set both of these studies apart is they employed methods of electrically stimulating the spinal cord of the research participants, giving the participants more “bang for their buck” from the exercises they were doing. In the Louisville study, an epidural stimulator was used, which is a device that is actually surgically implanted inside the spine to stimulate nerves in the spinal cord. In the UCLA study, a transcutaneous stimulator was used; transcutaneous means “over the skin”. Thus, this stimulator used adhesive pads on the lower back and the abdomen, combined with a special electrical wave form that could stimulate nerves in the spinal cord from outside the body.

In both studies, the electrical stimulation to the spinal cord was the crucial ingredient needed to enable voluntary movement after it had been lost due to spinal cord injury. In the words of Dr. Reggie Edgerton, who has been involved in many transcutaneous and epidural stimulation studies, the electrical stimulation excites the spinal cord, and acts as a “hearing aid”, allowing nerves in the spinal cord to “hear” the intention to move that comes from the brain.

As studies like this one have been released, many people have wondered, “Can riding an FES bike do the same thing?” This is a reasonable question – after all, an FES bike uses electrical stimulation to excite nerves in your body to make your muscles contract. However, many people with complete spinal cord injuries who diligently use their FES bike know that, in most cases, the use of an FES bike alone is not enough to return the ability to voluntarily move one’s legs. But why is that true, when both FES cycling and spinal cord stimulation involve electrical stimulation?

To understand this better, let’s explore the two main ways movement occurs: reflexes and/or the voluntary intent to move. In a reflex, like when a doctor hits below your kneecap with her reflex hammer and your leg kicks out, the reflex hammer hitting below your kneecap activates sensory nerves (the green circles and lines in the drawings below) in your leg. These sensory nerves send “activation” signals to other nerves in your spinal cord (represented by the purple box), including motor nerves (the red stars in the drawings). These motor nerves send long projections out from your spinal cord, called axons (the red lines that go to the muscle), to your leg muscles, and your leg muscles contract, briefly Comparisonkicking your leg out in front of you. Similarly, when a person voluntarily intends to move, this intent originates in the brain; nerves in the brain send signals down the spinal cord (represented by the blue arrow and lines) to other nerves, including motor nerves, which then send signals down their axons to a muscle to make it contract.

FES bikes use a specific type of electrical wave form to target just the axons that project out from motor nerves. By placing FES pads over a specific muscle, the electrical wave form will activate those motor nerve axons directly (as seen by the lightning bolts in drawing “A”). The intention of the FES bike is to skip over the sensory nerves and nerves from the brain and provide enough electrical stimulation to a motor nerve axon to bring it above a certain threshold to induce a muscle contraction, whether the user is thinking about moving or not.

Spinal cord stimulation, whether epidural or transcutaneous, works quite differently. Because of the waveform and the location where it’s applied, spinal cord stimulation actually activates all the nerves in and around the spinal cord, including both sensory and motor nerves. An even bigger difference between spinal cord stimulation and FES, however, is that with spinal cord stimulation, the intention is to provide enough electrical stimulation to be just below the threshold that will induce a muscle contraction (represented by the smaller lightning bolts in drawing B, now near all the nerves in the spinal cord). Why is that? The idea is, the spinal cord stimulation plus the voluntary intent to move/reflex activation together cause the motor nerve axon to fire and the muscle to contract. As was mentioned earlier, the intention of spinal cord stimulation is to enable motor nerves to “hear” activation signals from sensory nerves or brain nerves.

Despite promising results, spinal cord stimulation studies are still in their infancy in humans, and it will take much more safety data and many years of development before spinal cord stimulation is used regularly for spinal cord injury rehabilitation. Because of this, almost all rehabilitation professionals agree that people with a spinal cord injury should do everything they can to keep their bodies in optimal condition to be ready for better medical treatments in the future. For example, spinal cord stimulation may benefit people more if they already have strong muscles and cardiovascular systems when they begin using it. Thus, people who are already using FES bikes to keep their muscles and cardiovascular system in shape should continue doing so, with the added knowledge that you are preparing your body for even better things to come. If you don’t currently use an FES bike but want to start, the MyoCycle is a low-cost, high-quality option that I highly recommend.

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YMCA Receives New MyoCycle Therapy System to Help Locals with Disabilities

Gainesville, FL – December 27, 2017 – MYOLYN, a medical technology company dedicated to improving health and human performance, announced today that the YMCA in Batavia, NY has purchased the MyoCycle Pro FES cycling therapy system for its members with neurological disabilities.

The MyoCycle Pro uses Functional Electrical Stimulation (FES) technology to allow disabled individuals to exercise and maintain a healthier lifestyle.

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The University of Miami is currently conducting research on the effects that cycling with functional electrical stimulation (FES-cycling) has on people with spinal cord injury. The research team, led by Mark Nash, PhD, FACSM, and his student, David McMillan, is interested in how energy expenditure and fuel partitioning, as well as cardiac output, are affected by FES-cycling exercise performed on two different FES bikes: the MyoCycle and the RT300.

So far, the team has completed experiments with four men with various levels of spinal cord injury, and the results were recently presented during a poster session at the American Spinal Injury Association (ASIA) conference in Albuquerque. The full poster is presented below, but the concluding points are as follows:

  • Moderate stimulation intensity FES cycling qualifies as “low intensity” aerobic exercise according to authoritative guidelines (aerobic effect similar to walking).
  • The MyoCycle relies less on carbohydrate fuels and more on fatty fuels at the selected moderate stimulation intensity.
  • The MyoCycle promotes a more extensive excessive post-exercise oxygen consumption (EPOC) for 30 minutes after termination of stimulation.
  • The greater gross mechanical efficiency (23.3% as opposed to only 16.7% from the RT300) observed for the MyoCycle may have implications for more substantial sparing of muscle fatigue accompanying FES cycling.

Click Image to View Full Size

What do these results mean?

These are still preliminary results, but there are three key take-away points:

    1. Both the MyoCycle and the RT300 can give people with spinal cord injury a good workout.
    2. The unique characteristics of the MyoCycle cause some interesting positive effects not seen when using the RT300 (more fat burn and greater EPOC).
    3. The MyoCycle is significantly more efficient than the RT300 (more cycling power output for the same amount of calories burned).

The research team also collected some interesting cardiac output data from the study, but these results won’t be presented until the American College of Sports Medicine (ACSM) annual meeting at the end of the month.

MYOLYN is committed to supporting research into the benefits of FES for people with neurological disorders. Sign up for our newsletter to keep up to date with the results!

If you’d like to learn more about how the MyoCycle can help someone with paralysis to get a great workout, click here!

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Thursday, 04 May 2017 18:36

What is spasticity?

Spasticity is one of the many secondary health effects caused by paralysis. People with a spinal cord injury, stroke, cerebral palsy, and multiple sclerosis most often have trouble with spasticity, but it can affect anyone with an upper motor neuron lesion. That includes a wide range of neurological disorders and injuries, and it means that millions of people are affected by spasticity.

When most people think of spasticity, they imagine simple muscle spasms, where a muscle twitches involuntarily. However, spasticity, also known as spastic hypertonia, can be more accurately defined as “disordered sensori-motor control, resulting from an upper motor neuron lesion, presenting as intermittent or sustained involuntary activation of muscles’’ [1], and the effects of spasticity can range from slight muscle stiffness to intense, uncontrollable muscle spasms that can literally launch someone out of their chair.

What causes spasticity?

Upper motor neuron lesions cause spasticity in much the same way that they cause paralysis and loss of feeling – by disrupting communication between the brain, the spinal cord, muscles, and the sensory system (sensory organs in the skin, muscles, tendons, etc.). Normally, if you want to relax a muscle, you only have to think about it, and your brain will communicate with your muscles through your spinal cord to make them relax. But if your brain or spinal cord is damaged, your muscles never get the message to relax. For this reason, if anything tells your muscles to activate, like a reflex that makes you pull away from something hot, the activation is often exaggerated or never stops. Spasticity can be triggered by movement, pain, discomfort, posture, and even other medical problems like urinary tract infections and pressure sores.

What does spasticity look like?

Many people with spasticity have increased muscle tone, meaning that some of their muscles never relax fully and are always somewhat contracted. This increased tone, also known as hypertonia, can range from mild and uncomfortable to severe and debilitating, like rigidity. Hypertonia is most commonly seen affecting the upper limb, resulting in a constantly flexed elbow, bent wrist, and/or clenched fist.

hands and spasicity

Figure 1: Presentation of spasticity in the upper limb.

The other common presentation of spasticity is hyperreflexia (exaggerated reflexes). When a reflex arc is activated in someone with spasticity, like when the patellar tendon is struck or you touch a hot stove and recoil, oftentimes the reflex will be exaggerated. In extreme cases, the reflex will repeat itself over and over again, echoing through the nervous system, which is known as clonus. Check out this video to see what hyperreflexia and clonus look like.

Pros and cons of spasticity

While spasticity is a symptom of a neurological disorder, it’s not always a bad thing. The table below lists some of the pros and cons of spasticity.

Pros Cons
Stiff muscles can help with some activities, like transferring from a wheelchair  Stiff muscles can hinder other activities, like getting dressed or brushing your teeth
     Controlled reflex spasms can help with some activities, like standing & grasping                       Uncontrolled reflex spasms can hinder other activities and lead to injury                  
   Hypertonia and spasms work the muscles, preventing atrophy & bone density loss                              Spasticity can be uncomfortable and even painful
     Metabolic requirements of spasms can improve blood circulation and breathing           Extreme hypertonia can lead to joint contractures and pressure sores
      Spasticity can be a warning sign that something else is wrong, like an infection                Extreme hyperreflexia can lead to injuries from collisions and falls

For more on the pros and cons of spasticity, check out this video from the University of Washington.

Managing spasticity

If the cons of spasticity outweigh the pros, then treatment may be necessary. There are several options for managing spasticity, each with its own pros and cons:

  • Surgery
    • Surgery is sometimes used as a last resort to release contractures, lengthen muscles, or reshape joints.
    • Pros: Permanent solution
    • Cons: Irreversible, painful, potentially dangerous, expensive
  • Implanted pump
    • An intrathecal pump can be implanted in the body and programmed to automatically deliver anti-spasm medication right where it’s needed.
    • Pros: Precise and low-dose so reduced side effects, reversible, refillable
    • Cons: Requires surgery, can malfunction, may cause infections, expensive
  • Injections
    • Chemicals can be injected directly into the muscle to block nerves and eliminate spasticity.
    • Pros: Only needed once every few months, directly targets the spastic muscles
    • Cons: Effectiveness diminishes over time, expensive
  • Medications
    • Medications can be taken orally or transdermally (through a patch) to manage spasticity.
    • Pros: Non-invasive, easy to manage, more affordable
    • Cons: Requires higher doses and affects the whole body with increased side effects
  • Stretching and exercise
    • The majority of time in inpatient rehab following a spinal cord injury is spent on range of motion (stretching) and strengthening exercises [2], which have a positive effect on spasticity.
    • Pros: Easy to do for some people, strengthening can improve function, most affordable
    • Cons: Time-consuming, can be difficult without assistance or special equipment
  • Electrical stimulation
    • Electrical stimulation can activate paralyzed muscles, enabling someone to exercise muscles that they otherwise could not.
    • Pros: Reduces number of spasms, best way to exercise paralyzed muscles, can have beneficial side effects, can be done without much time and effort, affordable options available
    • Cons: Can strengthen muscles, making spasms stronger; may not work well for everyone; can be expensive and complicated

Electrical stimulation and spasticity

There is a lot of confusion out there as to how electrical stimulation can be used to manage spasticity. Arjan van der Salm, a researcher from the Netherlands who wrote his doctoral dissertation on managing spasticity with electrical stimulation, provides a great analysis in his journal paper published in 2006 [3]. He demonstrated that electrical stimulation does not reduce spasticity, but it does relax spasms, meaning that the muscle will spasm less for a period of time, usually for several hours after stimulation. This can be achieved by either stimulating the spastic muscle itself, or by stimulating its antagonist. For example, if a person’s calf muscles (triceps surae) are spastic, electrical stimulation can be applied to the calf muscle or to the shin muscles (tibialis anterior), and either will relax the spasms. Van der Salm showed that stimulating the spastic muscle itself was most effective in relaxing spasms, probably because the stimulation fatigues the muscle and improves blood circulation to the muscle.

The takeaway here is that electrically stimulating a muscle can prevent spasms for several hours afterwards, so it can be used as needed to manage spasticity.

Final thoughts

There are many different factors to consider when choosing how to manage spasticity. The cause of spasticity, your situation and medical condition, and other factors like financing and support can all affect your decision. At the end of the day, a combination of methods will probably be best. For example, many people are fine with a low dose of medications combined with regular stretching and strengthening. It’s always best to consult your physician to find out what approach will be best for you.

For more information about spasticity, check out the resources below.

If you know someone who could use some help in managing spasticity, please share this article with them using the social media links at the top of the post.

The MyoCycle combines electrical stimulation with range of motion and strengthening exercise and is cleared by the FDA for general rehab for:

  1. Relaxation of muscle spasms
  2. Prevention or retardation of disuse atrophy
  3. Increasing local blood circulation
  4. Maintaining or increasing range of motion

To learn more about managing spasticity with the MyoCycle, click here.

Resources

WebMD: Spasticity

Cleveland Clinic: Spasticity

National MS Society: Spasticity

MedlinePlus: Caring for muscle spasticity or spasms

UAB-SCIMS: Spastic Hypertonia Spasticity following SCI

CareCure: FAQ about implanted baclofen pumps for managing spasticity

References

[1] Pandyan AD, Gregoric M, Barnes MP, Wood D, Van Wijck F, Burridge J, Hermens H, Johnson GR. Spasticity: clinical perceptions, neurological realities and meaningful measurement. Disability and Rehabilitation 2005;27(1/2):2-6.

[2] Taylor-Schroeder S, LaBarbera J, McDowell S, Zanca JM, Natale A, Mumma S, Gassaway J, Backus D. The SCIRehab project: physical therapy treatment time during inpatient spinal cord injury rehabilitation. The Journal of Spinal Cord Medicine 2011; 34(2):149-161.

[3] van der Salm A, Veltink PH, Ijzerman MJ, Groothius-Oudshoorn KC, Nene AV, Hermens HJ. Comparison of electric stimulation methods for reduction of triceps surae spasticity in spinal cord injury. Arch Phys Med Rehabil 2006; 87:222-228.

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Tuesday, 28 February 2017 14:16

The Benefits of FES-Cycling After a Stroke

Stroke (cerebrovascular accident or CVA) is a leading cause of death in the United States, killing more than 130,000 Americans every year [1]. Moreover, stroke is a leading cause of long-term disability, especially hemiparesis (weakness or paralysis on one side of the body). In fact, roughly 80% of stroke survivors have hemiparesis [2], which can cause difficult speaking, grasping objects, or walking. Therefore, rehabilitation following a stroke resulting in hemiparesis usually involves a combination of occupational therapy, speech therapy, and physical therapy. Independence in daily living, especially independent walking, is a priority for stroke survivors, so a major objective of rehabilitation post-stroke is to recover the ability to walk normally.

Recovery walking ability after a stroke is a complicated process, as walking function depends on motor control, muscular strength/power, cardiorespiratory fitness, and other factors [3]. There are many different therapeutic interventions aimed at improving walking function that address one or more of these factors. Recently, therapists have increased their use of task-specific training using bodyweight-supported treadmills or robotic gait trainers, but such systems are often complex, expensive, and difficult to use in a timely manner. Gait training is particularly difficult for patients with severely limited walking ability, limiting its effectiveness for the people who may need it most.

Stationary cycling is a tried and true means of exercise and rehabilitation, and it may be just as effective at improving gait as bodyweight-supported or robotic gait training devices [4]. Cycling is an effective therapeutic tool for improving walking post-stroke for a number of reasons:

  • it allows for continuous, repetitive motion involving symmetric, coordinated flexion and extension of the joints with agonist/antagonist muscle activation through a greater range of motion than that in walking
  • it can be used early post-stroke, when patients may not yet be able to participate in traditional gait training
  • it can easily be continued beyond rehab and incorporated into a healthy lifestyle, minimizing the risk for subsequent strokes
  • it may be safer than gait training, as balance isn’t required, minimizing the fear and risk of falling
  • cycling outcomes are easily quantifiable, and different training effects can be achieved by altering only a few parameters (e.g., muscular strength can be trained with low cadence and high resistance, while cardiorespiratory fitness can be trained with high cadence and low resistance)

When functional electrical stimulation (FES) is added to cycling (FES-cycling), the benefits of cycling for people post-stroke can be amplified. Several studies have demonstrated the benefits of FES-cycling for people post-stroke [5]-[9], including:

  • improved aerobic capacity and cardiopulmonary function;
  • improved symmetry and smoothness of cycling;
  • improved muscle strength, tone, and power output;
  • improved postural control and motor coordination;
  • reduced muscle spasticity; and
  • increased walking speed, step length, symmetry, and balance.

FES itself adds the benefits of preventing muscle atrophy, increasing blood flow, re-educating the muscles, and maintaining/increasing joint range of motion. FES-cycling may also provide afferent sensory input to the central nervous system that enhances brain plasticity and cortical motor output, which may further improve functional outcomes in a manner similar to the effect of FES-cycling for people with Parkinson’s disease.

Clearly, combining the benefits of cycling with the benefits of FES can dramatically improve the health and functional performance of people who have suffered a stroke. The MyoCycle is an FES bike that combines the benefits of cycling, isokinetic exercise, and FES into one affordable, easy-to-use system. If you or someone you love has had a stroke and is interested in FES-cycling, contact us today to learn how the MyoCycle can meet your needs!

  1. https://www.cdc.gov/stroke/facts.htm
  2. http://www.stroke.org/we-can-help/survivors/stroke-recovery/post-stroke-conditions/physical/hemiparesis
  3. Bowden, M. G.; Embry, A. E.; and Gregory, C. M. 2011. Physical Therapy Adjuvants to Promote Optimization of Walking Recovery After Stroke. Stroke Research and Treatment.
  4. Barbosa, D.; Santos, C. P.; and Martins, M. 2015. The Application of Cycling and Cycling Combined with Feedback in the Rehabilitation of Stroke Patients: A Review. Journal of Stroke and Cerebrovascular Disease. 24(2):253-273.
  5. Peng, C.-W. et al. 2011. Review. Clinical Benefits of Functional Electrical Stimulation Cycling Exercise for Subjects with Central Neurological Impairments. Journal of Medical and Biological Engineering. 31(1):1-11.
  6. Lee, S. Y. et al. 2013. The effects of assisted ergometer training with a functional electrical stimulation on exercise capacity and functional ability in sub-acute stroke patients. Ann Rehabil Med. 37:619.
  7. Ambrosini, E. et al. 2011. Cycling induced by electrical stimulation improves motor recovery in postacute hemiparetic patients: a randomized controlled trial. Stroke. 42:1068-1073.
  8. Lo, H.-C. et al. 2012. Cycling exercise with functional electrical stimulation improves postural control in stroke patients. Gait Posture. 35:506-510.
  9. Ambrosini, E. et al. 2012. Cycling induced by electrical stimulation improves muscle activation and symmetry during pedaling in hemiparetic patients. IEEE Trans Neural Syst Rehabil Eng. 20:320-330.
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