What is FES?

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FES stands for Functional Electrical Stimulation. Before we can understand what FES is and how it works, we first need to understand why we need FES.

The human brain controls the body’s movement by sending electrical signals through nerves to muscles. These signals tell the muscles to contract and cause movement. If the brain or nerves get damaged, the electrical signals won’t reach the muscles, so the muscles won’t contract when we want them to. When a muscle won’t contract at all when we want it to, we call that paralysis. When only part of the muscle contracts when we want it to, we call that partial paralysis or paresis. When the muscles contract on their own when we don’t want them to, we call that a muscle spasm or spasticity.

Paralysis and spasticity are caused by the loss of electrical signals that tell the muscles when to contract. We can replace these lost electrical signals with electrical stimulation. An electrical stimulation device, called a stimulator, takes electricity from a battery or power outlet, converts the electricity to electrical pulses, and then sends those pulses through cables and electrodes directly into the body. The electrical pulses activate undamaged nerves, which then tell the muscles to contract. Since electrical stimulation can make a muscle contract when we want it to, it can help people with paralysis use their muscles to move again. Stimulating a muscle also helps reduce spasticity by making the muscle tired.

Paralysis can stop someone from doing something functional, like standing up, walking, or grabbing something. Electrical stimulation can be used to help them regain that lost functionality.

For example, we can use electrical stimulation on the leg muscles of a person with paralysis to let them pedal a bicycle whenever they want.

When electrical stimulation is used to help someone do something functional, we call it Functional Electrical Stimulation (FES). FES is used to help people with paralysis caused by neurological disorders like spinal cord injury, multiple sclerosis, stroke, cerebral palsy, and other conditions. It can also help people with muscle weakness after surgery like knee replacement.

The benefits of FES include:

  • Relaxing muscle spasms
  • Preventing muscle atrophy
  • Increasing local blood circulation
  • Maintaining or increasing range of motion

Some studies have also shown that FES can increase bone density, re-educate muscles, improve functionality, and improve cardiovascular health. Check out our clinical research page or our blog for more information about the benefits of FES.

MYOLYN has years of experience researching and developing FES devices. MYOLYN’s first products use FES to help people with paralysis perform therapeutic exercise in the form of stationary cycling. Click here to learn more about the MyoCycle FES cycling therapy system.


While FES-cycling is typically associated with spinal cord injury, its benefits extend to people with other neurological disorders, especially stroke and MS. These benefits include:

· Improved walking and cycling ability
· Increased muscle strength
· Improved physical, mental, and social well-being
· Better quality of life

Exciting research into the benefits of FES-cycling for people with MS is being conducted at places like the Shepherd Center and the University of Illinois at Urbana-Champaign.



Parkinson’s causes stiffness, weakness, loss of coordination, tremors, and other effects on movement that can be treated by motor-assisted cycling, especially if cueing is provided. It makes perfect sense then that motor-assisted cycling with functional electrical stimulation (FES-cycling) would be a great therapy option for people with PD. However, surprisingly, only MYOLYN’s co-founder, Matthew Bellman, Ph.D., together with Chris Hass, Ph.D., have investigated the potential benefits of FES-cycling for people with Parkinson’s [4]. Their pilot data suggests that a person with Parkinson’s can pedal faster and more smoothly when assisted by FES, likely because the added FES can enhance muscle force production and provide cueing via the sensation of the stimulation during cycling.