Cycling with functional electrical stimulation (FES), or FES-cycling, is known to be beneficial for people with spinal cord injuries. Is FES-cycling effective for people with traumatic brain injuries, as well?
Few studies have investigated the benefits of FES-cycling after traumatic brain injury (TBI), specifically. Fortunately, many studies have demonstrated the benefits of FES-cycling after other causes of upper motor neuron (UMN) damage .
UMNs are nerves in the brain or spinal cord that connect to muscles. TBI can damage UMNs, spinal cord injury (SCI), cerebrovascular accident (CVA or stroke), multiple sclerosis (MS), cerebral palsy (CP), and other injuries and illnesses.
The primary symptoms of UMN damage – weakness and spasticity – often cause secondary conditions, including bone weakness and metabolic syndrome, which can further lead to new conditions, like bone fractures and heart disease. As a result, UMN damage often contributes to a downward spiral in health from which escape can be difficult.
FES therapy for patients after UMN lesion can prevent and treat secondary health conditions by directly treating the primary symptoms of weakness and spasticity.
FES works by activating the weakened, spastic muscle directly, without relying on damaged nerves in the brain or spinal cord. (More on how FES works.)
Regularly activating muscles using FES makes them grow, especially if the muscles are worked through their range of motion with progressive loading during an activity like cycling. Having larger, stronger muscles can improve functional independence, even if those muscles are neurologically impaired.
Critically, muscle works as a metabolic engine. Larger muscles burn more calories, even at rest, and increasing muscle mass decreases the risk of metabolic syndrome .
Muscles also pull on bones, and larger muscles pull harder on bones, signaling them to strengthen in response to the stress. Loss of muscle activation leads to osteoporosis. FES induces muscle activations that can strengthen bones , and stronger bones are less likely to fracture.
FES also relaxes spasticity, clonus, and hyperreflexia by activating antagonists and fatiguing lower motor neurons, reducing their excitability. The relationship between muscle and bone causes abnormal ossification to follow prolonged spasticity, so reducing spasticity can reduce contractures and bone deformation. Unexpectedly, reducing muscle spasticity can also improve sleep quality for people frequently awoken by spasms.
In other words, the benefits of FES-cycling for people with TBI are equivalent to the benefits of FES-cycling for people with SCI, stroke, MS, CP, and other conditions. FES-cycling works by regularly working muscles that are weakened, paralyzed, and spastic. Reducing atrophy, relaxing spasms, increasing circulation, maintaining joint range of motion – these benefits of FES work together to prevent long term secondary health conditions associated with UMN damage, like heart disease, osteoporosis, contractures, and reduced independence.
 Peng, Chen, Lai, Chen, Chen, Mizrahi, Handa. Review: clinical benefits of functional electrical stimulation cycling exercise for subjects with central neurological impairments. Journal of Medical and Biological Engineering, 2011.
 Moon, Choo, Kim. Relationship between low muscle mass and metabolic syndrome in elderly people with normal body mass index. J Bone Metab, 2015.
 Andrews, Shippen, Armengol, Gibbons, Holderbaum, and Harwin. A design method for FES bone health therapy in SCI. Eur J Transl Myol, 2016.