Stroke & recovery
Can timed nerve stimulation boost ankle strength after stroke?
Open access · cc by · source: Europe PMC
Syncing physical movements with targeted electrical pulses to the leg nerve significantly increases ankle strength and brain-to-muscle signal delivery in stroke survivors.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
The same stimulation without the pairing did nothing — the contingency was the active ingredient.
Timing is what separates an effective protocol from an ineffective one. Peripheral electrical stimulation delivered in time with movement-related cortical potentials increased ankle strength by 7.33 N (9.75% over baseline) and voluntary activation by 6.99 percentage points, while sham stimulation produced no such change.
Evidence for the claim as stated.
Force, connectivity and symptom scores — no synaptic measurement among them.
Human protocols in this library induce lasting change but measure it downstream. Pairing peripheral stimulation with movement-related cortical potentials raised ankle strength by 7.33 N and voluntary activation by 6.99 percentage points against sham; network-targeted TMS raised retrieval-related connectivity that predicted episodic memory performance; and transcranial alternating current stimulation produced alpha-band connectivity increases that outlasted the sessions alongside a 34% anxiety reduction.
Evidence for the claim as stated.
The contingency requirement transfers even though the measurement does not.
Timing dependence is the principle that does carry across levels. The peripheral protocol produced strength and activation gains only when stimulation was delivered in time with movement-related cortical potentials, matching the correlated-activity requirement that defines potentiation at the cellular level.
Evidence for the claim as stated.
Inspect source passages
Can timed nerve stimulation boost ankle strength after stroke?
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
15 participants
Of the 15 participants, eight were male and 11 had a left hemiparesis.
7 days
The second and third sessions were intervention sessions, separated by 7 days, during which participants received one ePAS intervention and one sham intervention, in a randomized order.
Key findings
The active stimulation led to a 7.33 Newtons increase in absolute ankle strength, which represented a 9.75% improvement from their baseline state. The treatment also increased voluntary activation—the strength of the signal the brain sends to the muscle—by 6.99 percentage units. In contrast, the inactive sham stimulation produced no meaningful changes in strength or muscle activation.
Methodology
Researchers conducted a double-blind crossover study with 15 stroke survivors who had leg weakness on one side. Across sessions separated by 7 days, participants completed 50 repetitions of voluntary ankle movement paired with either active nerve stimulation or a fake sham stimulation. The active stimulation was precisely timed to reach the brain at the exact moment the participant prepared to move, as determined by brainwave scans.
Limitations
This small-scale study only evaluated the immediate effects after a treatment session, so it does not show if the strength gains are long-lasting or build up over time. It also cannot confirm whether these lab-based strength improvements translate to real-world mobility improvements like walking. Additionally, because the trial was limited to individuals with chronic stroke who volunteered from the community, the findings may not apply to patients in the acute stages of stroke recovery or those with different types of brain lesions.
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