Evaluating FAST walk system for neuromodulation-assisted gait recovery in chronic stroke

Stroke remains one of the leading causes of long-term disability worldwide, affecting millions each year. Among its most debilitating consequences is gait impairment, which affects over 80% of stroke survivors. Impaired walking not only reduces independence but also limits participation in daily and social activities, significantly diminishing the quality of life. While some patients regain partial ambulatory function, walking speed and coordination often remain impaired. Alarmingly, up to 22% of survivors never regain the ability to walk and are confined to indoor or severely limited community ambulation.

Physical rehabilitation is essential for post-stroke gait recovery. Conventional therapies such as therapist-assisted walking, treadmill training, and strength exercises offer benefits but often fail to fully restore efficient and functional gait in patients with chronic stroke. As a result, there is a growing interest in non-invasive neuromodulation techniques to enhance neuroplasticity and support motor recovery.

In an effort to address the ongoing challenge of gait impairment after stroke, researchers have developed an innovative rehabilitation approach known as FAST walk. This study was led by Professor Toshiyuki Fujiwara and Dr. Mami Tani from the Department of Rehabilitation Medicine, Juntendo University Graduate School of Medicine, Japan. Prof. Fujiwara explains, “More than 80% of stroke survivors experience gait disturbances. Particularly, reduced gait speed limits outdoor mobility and makes it difficult for individuals to return to work. Walking is a complex function, controlled by spinal neural circuits that respond to commands from the brain. To address this, we developed the FAST walk system to support gait rehabilitation in patients with post-stroke impairments.” The findings were published in Volume 22 of the Journal of NeuroEngineering and Rehabilitation on July 07, 2025.

FAST walk is an innovative, electromyography (EMG)-triggered system that synchronizes transcutaneous spinal cord stimulation with hip extensor stimulation. This dual approach uses the patient’s own muscle signals to stimulate precisely during key gait phases. By enhancing the spinal circuit excitability and activating reflexes such as the crossed extensor reflex, the system aims to improve lower limb coordination and gait efficiency.

To evaluate the clinical potential, researchers conducted a randomized controlled trial involving three groups: FAST walk, spinal stimulation alone, and treadmill training. Each group received two gait training sessions per week for five weeks (10 sessions in total). The study’s design was shaped by Japan’s healthcare regulation, which limits rehabilitation to 260 minutes per month, making this research especially relevant to time-constrained, real-world settings.

All groups demonstrated improvements in walking speed that exceeded the minimum clinically important difference for chronic stroke (0.15 m/s). Specifically, the FAST walk group improved from 0.55 m/s to 0.70 m/s, the spinal stimulation group from 0.90 to 1.16 m/s, and the treadmill group from 0.90 to 1.09 m/s. However, only the FAST walk group showed a statistically significant improvement in gait speed within groups, suggesting that the combined stimulation may offer added benefit over either approach alone.

The study also assessed spinal reciprocal inhibition (RI) as a potential marker of neural modulation. No significant changes were observed, likely due to the measurement being done at rest rather than during gait, where phase-specific modulation would be more pronounced. The use of orthoses in some participants may have further limited voluntary ankle movement, reducing observable RI changes.

Despite these limitations, the study provides early evidence of FAST walk’s feasibility, safety, and potential efficacy. The fact that meaningful improvements were observed within a short and constrained intervention window underscores its clinical promise. Prof. Fujiwara shares, “This is expected to become a new rehabilitation therapy that can enable recovery from gait disorders in patients with chronic stroke (who have had a stroke for more than 6 months), a condition that has been considered difficult to treat with ordinary rehabilitation therapy.”

Future research should aim for larger sample sizes, extended follow-up periods, and more intensive protocols. Incorporating real-time gait analysis and spasticity assessments during movement may help refine stimulation parameters. Further studies should also evaluate the independent role of hip extensor stimulation.

In conclusion, FAST walk represents a promising, non-invasive strategy to improve gait in patients with chronic stroke. While additional validation is needed, this study marks an important step forward in integrating neuromodulation into post-stroke rehabilitation.

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About Professor Toshiyuki Fujiwara from Juntendo University Graduate School of Medicine, Japan

Dr. Toshiyuki Fujiwara, M.D., Ph.D., is a Professor and Chair of the Department of Rehabilitation Medicine at Juntendo University, Japan, with over 32 years of experience in clinical practice and academic research. He earned his M.D. from Fukui Medical School in 1993 and his Ph.D. from Keio University in 2002. He has published over 100 peer-reviewed English articles, with research centered on neurorehabilitation, neural plasticity, brain-machine interfaces, and non-invasive stimulation therapies. In addition to holding key academic positions at Keio and Tokai Universities, he has been honored with several awards, including the Young Researcher’s Award of Clinical Neurophysiology in 2012.