FES Cycling vs. Passive Movement Training: The Pros and Cons

Electrical stimulation (ES) and passive movement training (PMT) represent commonly used but distinct approaches to muscle rehabilitation, particularly in populations with limited or absent voluntary motor control, such as following a spinal cord injury.

A Passive Movement Trainer will move the users legs passively if they have complete or partial paralysis.

PMT uses motorised bikes such as the MOTOmed or Thera products, which are commonly used in hospital clinics and homes. They are easy to use, represent low-risk interventions, and can provide benefits that include maintaining ranges of joint motion and potentially helping reduce spasticity.

Based on evidence from spinal cord injury (SCI), cerebral palsy (CP), and stroke populations, we propose that adding synchronised electrical stimulation to PMT, as we find with FES Cycling systems, produces additional and significant clinical benefits. FES Cycling impacts muscle activation and generates hypertrophy, functional recovery, spasticity reduction, and metabolic health, in addition to preserving ranges of joint motion. These greater benefits are not seen with PMT alone.

A significant body of research over the last 30 to 40 years has shown the benefits of FES Cycling for a range of neurological conditions. However, the overall higher cost of adopting FES Cycling compared with PMT means that in the UK, it is most commonly used by persons who have experienced a catastrophic injury when funds are provided through medico-legal compensation. Let's consider these two approaches in more detail.

FES Cycling

FES cycling combines electrical stimulation with active pedalling to induce muscle contractions synchronised with pedal movement. Some systems support arm and leg exercises. Surface electrodes deliver stimulation pulses (typically biphasic rectangular pulses with 30–50 Hz, 250–500 μs pulse widths and currents up to 130 mA) to motor points of key muscles (quadriceps, hamstrings, gluteals, tibialis anterior gastrocnemius/soleus), enabling paralysed or weakened individuals to perform volitional cycling against resistance. 

FES Cycling normally integrates a programmable muscle stimulator with a PMT. The two devices are connected for communication between the two

The stimulation parameters are calibrated to maximize power output while minimizing fatigue, often using adaptive algorithms that adjust intensity based on real-time pedal position and muscle response. This method recruits high-threshold motor units, generating mechanical tension comparable to voluntary contractions (up to 75% maximal voluntary contraction). The most popular systems in the UK have been the Restorative Therapies (RT300) and Hasomed (RehaMove 2 systems). We could consider these as PMT systems integrated with an electrical stimulation system.

Passive Movement Training (PMT)

PMT involves motorised cycling without muscle activation, moving limbs through a predetermined range of motion. Some PMT bikes are used whilst seated and others support movement whilst lying on a bed or physio plinth.

While this preserves joint mobility and reduces spasticity transiently, it lacks the neuromuscular activation required for hypertrophy or strength gains. Most bikes can move the legs or arms passively, but the pedalling resistance and speed can be changed to support those users who have some ability to exercise their muscles actively and consciously. 

PMT’s benefits are primarily mechanical, such as stretching soft tissues and improving circulation, but it fails to engage the metabolic or neural pathways critical for functional recovery.

Muscle Hypertrophy and Strength Gains

FES Cycling Outcomes

• Muscle Volume: In children with SCI, 6 months of FES cycling increased quadriceps cross-sectional area (CSA) by 15–20% and reduced intramuscular fat by 53%. Adults with chronic SCI achieved 19–30.4% gains in thigh and knee extensor cross-sectional area after 8–12 weeks of FES cycling, surpassing PMT’s negligible effects (ΔCSA <1%).

• Strength: FES cycling improved lower extremity motor scores (LEMS) by 4.65 points (95% CI: 1.308–7.991) in SCI patients, correlating with enhanced pedalling power (6.5 W to 18.0 W post-training). Stimulated quadriceps strength increased by 80% MVC in responders using wide-pulse high-frequency protocols (100 Hz, 1 ms pulses).

PMT Outcomes

• Atrophy Prevention: PMT marginally preserved muscle bulk in pediatric SCI but failed to reverse atrophy. One study reported a 2.7% increase in femoral neck bone mineral density (BMD), likely due to mechanical loading rather than muscle activation.

• Strength Limitations: PMT showed no improvement in LEMS or voluntary strength without active contraction, even after 72 sessions.

Functional and Mobility Improvements

FES Cycling

• Walking Ability: Meta-analyses of incomplete SCI patients demonstrated 12.3-meter improvements in 6-minute walk tests (6MWT) and 31.9-second reductions in timed-up-and-go (TUG) scores post-FES cycling. These gains stemmed from enhanced muscle coordination and reduced energy cost of walking (↓14% VO₂ consumption).

• Cycling Performance: Adolescents with CP increased cadence by 25% and power output by 200% after 7 weeks of FES cycling, translating to improved pedalling symmetry and endurance.

PMT

• Limited Functional Transfer: Passive cycling improved joint range of motion but had no measurable impact on gait velocity or locomotor independence. A study of chronic stroke patients reported only a 0.1 m/sec increase in gait speed after PMT, versus 0.5 m/sec with FES

Spasticity Reduction

FES Cycling

• MAS Scores: Meta-analysis of 20+ FES cycling sessions reduced Modified Ashworth Scale (MAS) scores by 0.949 points (95% CI: −1.749 to −0.149), primarily through:

• Reflex Inhibition: Rhythmic muscle contractions restored post-activation depression, reducing hyperexcitable spinal reflexes.

• Renshaw Cell Activation: Antidromic stimulation of motor axons increased recurrent inhibition, dampening α-motoneuron hyperactivity.

• Long-Term Effects: SCI patients retained reduced spasticity for 6 months post-intervention, with pendulum test improvements (↑68% relaxation index) persisting beyond acute sessions.

PMT

• Transient Relief: Passive cycling decreased MAS scores by 0.3–0.5 points in acute sessions but failed to sustain benefits beyond 24 hours. The mechanism involves mechanical stretching rather than neural modulation, limiting its utility in chronic spasticity.

Metabolic and Cardiovascular Benefits

FES Cycling

• Energy Expenditure: Volitional FES cycling tripled caloric burn (2.2 kcal/min to 7.5 kcal/min) versus PMT, comparable to moderate-intensity aerobic exercise.

• Cardiorespiratory Fitness: VO₂peak increased by 14–29% in SCI patients, alongside improved lipid profiles (↓9.9% visceral fat) and insulin sensitivity (HOMA-IR: −1.2)

• Bone Health: Distal femur BMD increased by 46% in pediatric SCI after 6 months of FES Cycling versus 2.7% with PMT4.

PMT

• Minimal Metabolic Impact: Passive cycling elevated heart rate by 10–15 bpm but did not improve VO₂peak or glucose metabolism.

Critical Parameters Influencing FES Efficacy

FES Cycling is a modality that should be set up for each individual for best results. These seem to be the critical parameters.

1. Stimulation Intensity: Maximal tolerable amplitudes (60–100 mA) recruit more motor units, correlating with CSA gains (R² = 0.68). Submaximal intensities limit hypertrophy but may still improve endurance.

2. Session Duration: ≥20 sessions (30–60 minutes/session) are required for clinically meaningful spasticity reduction and functional gains. We typically start clients at 20 minutes and session durations can be increased after a few weeks.

3. Resistance Progression: Incremental resistance (0.14 Nm steps) prevents plateaus, enabling continuous strength adaptation. Most clients generate low power at first and onset of fatigue occurs. The aim is to achieve active contractions for the duration of the session before increasing the resistance to pedalling.

Clinical Recommendations

1. For Muscle Hypertrophy: Prioritise FES cycling at 50–75 Hz, 350–500 μs pulses, and ≥60 mA intensity, 3–5 sessions/week for 8+ weeks.

2. For Spasticity Management: Combine FES cycling with ankle joint mobilization (50 cycles/min) to enhance reflex inhibition.

3. For Metabolic Health: Prescribe 30-minute FES sessions targeting 35–50 rpm cadence with adaptive resistance. Many users generate smoother cycling patterns at higher cadences.

Limitations

• FES Cycling: Discomfort (VAS: 4–6/10) limits intensity in 15% of users (especially those with preserved sensation), while muscle fatigue curtails session duration, especially at the beginning of use.

• PMT: Lacks neuromuscular activation, rendering it ineffective for reversing atrophy or improving functional mobility.

Discussion

FES Cycling has clear benefits, and it has shown itself to be particularly effective for spinal cord injury, stroke, cerebral palsy, and MS. These systems are more complex to use than PMT and require individual setup.

Passive Movement Training (PMT) is limited to mobility maintenance and temporary spasticity relief. It does not benefit hypertrophy or strength.

The Stim2Go from Pajunk

Clinically, it seems clear that FES Cycling would be adopted in most situations with interest in strength, mobility, spasticity reduction, cardiovascular fitness, bone health and quality of life.

The key barrier to adopting FES Cycling has been cost, with systems typically costing many times the price of a PMT bike.

Here is our approach moving forward with our new stimulator Stim2Go from Pajunk.

1) Select your PMT bike it could be a Thera or MOTOmed bike.

2) Add Stim2Go, which will allow FES Cycling capability without the need for a direct connection between the bike and the stimulator. This is possible due to the sensors embedded in Stim2Go.

Conclusion

FES cycling outperforms PMT across all rehabilitation domains, inducing muscle hypertrophy, reducing spasticity, and enhancing cardiovascular health through active neuromuscular engagement. While PMT remains useful for joint preservation and acute spasticity relief, FES cycling should be the cornerstone of rehabilitation in neurological populations. Clinicians should tailor stimulation parameters to individual tolerance and combine FES with task-specific training for optimal functional outcomes.

• FES Cycling is superior for active neuromuscular engagement, inducing muscle hypertrophy, improving functional mobility, and promoting neuroplasticity.

• PMT is limited to maintaining joint mobility and transient spasticity relief, with no significant metabolic or strength benefits.

• Combined protocols (e.g., FES + resistance training) amplify outcomes27, while PMT serves as an adjunct for passive care.

Literature

[1] Armstrong EL, Boyd RN, Kentish MJ, et al. Effects of a training programme of functional electrical stimulation (FES) powered cycling, recreational cycling and goal-directed exercise training on children with cerebral palsy: a randomised controlled trial protocol. BMJ Open 2019;9:e024881. doi:10.1136/bmjopen-2018-024881
https://bmjopen.bmj.com/content/9/6/e024881

[2] Jones, D. The benefit of FES cycling for neurological conditions.
https://www.linkedin.com/pulse/benefit-fes-cycling-neurological-conditions-derek-jones/

3] Bellman, M. MyoCycle vs RT300.
https://myolyn.com/rt300-fes-cycle-vs-the-myocycle-which-is-right-for-you/

[4] https://www.anatomicalconcepts.com/articles/2019/07/04/2019-7-4-fes-cycling-builds-muscle-after-paralysis

[5]Krause P, Szecsi J, Straube A. Changes in spastic muscle tone increase in patients with spinal cord injury using functional electrical stimulation and passive leg movements. Clin Rehabil. 2008 Jul;22(7):627-34. doi: 10.1177/0269215507084648. PMID: 18586814.
https://pubmed.ncbi.nlm.nih.gov/18586814/

[6] Johnston TE, Smith BT, Oladeji O, Betz RR, Lauer RT. Outcomes of a home cycling program using functional electrical stimulation or passive motion for children with spinal cord injury: a case series. J Spinal Cord Med. 2008;31(2):215-21. doi: 10.1080/10790268.2008.11760715. PMID: 18581671; PMCID: PMC2565482.
https://pmc.ncbi.nlm.nih.gov/articles/PMC2565482/

[7] Fang Chia-Ying , Lien Angela Shin-Yu , Tsai Jia-Ling , Yang Hsiao-Chu , Chan Hsiao-Lung , Chen Rou-Shayn , Chang Ya-Ju. The Effect and Dose-Response of Functional Electrical Stimulation Cycling Training on Spasticity in Individuals With Spinal Cord Injury: A Systematic Review With Meta-Analysis. Frontiers in Physiology, VOL 12, 2021. DOI=10.3389/fphys.2021.756200.
https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.756200

[8] Yaşar, E., Yılmaz, B., Göktepe, S. et al. The effect of functional electrical stimulation cycling on late functional improvement in patients with chronic incomplete spinal cord injury. Spinal Cord 53, 866–869 (2015). https://doi.org/10.1038/sc.2015.19
https://www.nature.com/articles/sc201519

[9]Backus D, Burdett B, Hawkins L, Manella C, McCully KK, Sweatman M. Outcomes After Functional Electrical Stimulation Cycle Training in Individuals with Multiple Sclerosis Who Are Nonambulatory. Int J MS Care. 2017 May-Jun;19(3):113-121. doi: 10.7224/1537-2073.2015-036. PMID: 28603459; PMCID: PMC5460864.
https://pmc.ncbi.nlm.nih.gov/articles/PMC5460864/