Effectiveness of Functional Electrical Stimulation (FES) Alone or Combined with Rehabilitation on Gait Recovery in Chronic Stroke: A Systematic Review of Randomized Controlled Trials

1. Introduction

Stroke is one of the leading causes of disability worldwide, and its impact has grown over recent decades. In 2019, an estimated 12.2 million new cases occurred, with 101 million people living with its consequences and 6.55 million deaths associated with the disease. Between 1990 and 2019, incidence rose by about 70%, while mortality increased by 43% [1]. These trends reflect population aging and the increasing prevalence of vascular risk factors, including hypertension, obesity, and metabolic disorders [1,2,3]. Notably, most stroke-related deaths, around 86%, occur in low- and middle-income countries [4].

From a functional perspective, most individuals who experience a stroke develop some degree of motor impairment, including deficits in coordination, muscle strength, and motor control [5,6]. Gait dysfunction is one of the most common and disabling consequences of stroke, often associated with chronic hemiparesis and reduced mobility [5,6]. These deficits are associated with low independence, poorer quality of life, and a substantial burden on patients, their families, and healthcare systems. [5,6,7,8]. Although intensive rehabilitation can promote meaningful improvements in the early stages, many patients continue to experience considerable motor deficits in the chronic phase (around six months after the event) [6,9]. At this stage, therapeutic options are more limited, and exercise-based conventional rehabilitation remains the main approach, often resulting in limited long-term functional gains [6]. As a result, individuals continue to experience persistent difficulties with activities of daily living (ADLs), underscoring the need for further research on new or adapted interventions during this phase.

Functional electrical stimulation (FES) is one of the approaches currently used in the rehabilitation of individuals during the chronic phase after a stroke. This technique uses electrical stimulation to induce muscle contractions, thus improving motor function [6]. Several studies have demonstrated that FES can improve muscle strength, promote neuroplasticity, and enhance gait performance after a stroke [10]. However, some studies have shown modest or non-significant improvements when FES is used just in post-stroke rehabilitation or alone [11,12,13]. This review synthesizes evidence from randomized controlled trials evaluating the impact of functional electrical stimulation (FES) on lower-limb function in patients with chronic stroke. Studies published between 2016 and 2026 were identified using predefined inclusion and exclusion criteria. The analyzed outcomes encompass gait speed, balance, overall motor function, and execution of activities of daily living (ADLs). These findings offer further insights into the potential role of FES in chronic stroke rehabilitation, providing updated information to consider in clinical practice.

2. Methods

2.1. Study Design

To ensure transparency and methodological rigor, the protocol of this systematic review was prospectively registered in PROSPERO (International Prospective Register of Systematic Reviews) under the registration number CRD420261345060. The objective of this study was to examine and compare the effects of functional electrical stimulation (FES) or FES combined with other techniques in the treatment of post-stroke gait in the chronic phase (from 6 months onward), based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

2.2. Inclusion and Exclusion Criteria

2.2.1. Inclusion Criteria

Studies including adult participants (age ≥ 18 years) with a diagnosis of stroke in the chronic phase, defined as a time since onset greater than six months, were included. Regarding the intervention, participants received treatment with functional electrical stimulation (FES) associated with conventional rehabilitation treatment. In the control groups, participants received conventional treatment alone or sham FES, characterized by stimulation of minimal intensity, without inducing muscle contraction.

The main outcome indicators were as follows: Activities of daily living (ADL), assessed by the Barthel Index for activities of daily living (ADL) and the Modified Barthel Index (MBI): evaluation of independence in activities of daily living, with scores ranging from 0 to 100; change in functional mobility, assessed using the Rivermead Mobility Index (RMI); motor capacity and functional independence; other motor outcomes were as follows: walking test (WT): measurement of walking endurance based on the total distance covered during a period of time; timed walking test: assessment of gait speed over a standardized distance; maximum independent walking distance. The included studies were randomized controlled trials (RCTs).

2.2.2. Exclusion Criteria

Studies were excluded if they: (1) included participants younger than 18 years of age or individuals in the acute or subacute phase of stroke (≤ 6 months after stroke onset); (2) evaluated interventions other than functional electrical stimulation (FES) combined with conventional rehabilitation, or did not include an appropriate comparison group (conventional rehabilitation alone or sham FES); (3) did not report at least one of the predefined outcomes related to activities of daily living, functional mobility, gait performance, motor capacity, or functional independence; (4) were not randomized controlled trials (RCTs); (5) were conference abstracts, case reports, case series, study protocols, reviews, editorials, letters, dissertations, or animal studies; (6) had duplicate publications, with only the most complete or recent report being retained; (7) had unavailable full text or insufficient original data after reasonable attempts to obtain them; or (8) presented evident methodological or statistical inconsistencies that compromised data reliability.

2.3. Search Strategy

A systematic search was conducted in the following electronic databases: PubMed, MEDLINE, ClinicalTrials.gov, Cochrane Central Register of Controlled Trials (Cochrane Central), EMBASE, and the Physiotherapy Evidence Database (PEDro). The search strategy was developed using a combination of controlled vocabulary (e.g., MeSH and Emtree terms, when applicable) and free-text terms related to stroke, functional electrical stimulation, and the lower limb.

Terms and Boolean operators were used to combine the descriptors, as presented below:

#1 (Stroke* OR CVA* OR (Cerebrovascular NEXT Accident*) OR (Brain NEXT Stroke*) OR (Cerebral NEXT Stroke*) OR (Cerebral NEXT Infarction*) OR (Brain NEXT Infarction*) OR (Cerebral NEXT Ischemia*) OR (Transient NEXT Ischemic NEXT Attack*))

#2 ((Functional NEXT Electrical NEXT Stimulation*) OR FES OR (FES NEXT Therapy) OR (FES NEXT Training) OR (Functional NEXT Electrotherapy) OR (Functional NEXT Neuromuscular NEXT Stimulation*) OR (Functional NEXT NMES) OR (Neuromuscular NEXT FES) OR (Functional NEXT Electric NEXT Stimulation*) OR (Functional NEXT Electrical NEXT Stimulation NEXT Therapy) OR (Therapy NEXT Functional NEXT Electrical NEXT Stimulation) OR (Functional NEXT Stimulation NEXT Electrical) OR (Electrical NEXT Functional NEXT Stimulation) OR (Functional NEXT Electrical NEXT Stimulation NEXT Training) OR (Training NEXT Functional NEXT Electrical NEXT Stimulation) OR (Functional NEXT Electrical NEXT Stimulation NEXT Program) OR (Program NEXT Functional NEXT Electrical NEXT Stimulation))

#3 ((randomized NEXT controlled NEXT trial*) OR (controlled NEXT clinical NEXT trial*) OR (random NEXT allocation) OR (double NEXT blind NEXT method) OR (single NEXT blind NEXT method) OR (clinical NEXT trial*) OR ((singl* OR doubl* OR trebl* OR tripl*) AND (mask* OR blind*)) OR (latin NEXT square) OR placebo* OR random* OR (research NEXT design) OR (comparative NEXT study) OR (evaluation NEXT studies) OR (follow-up NEXT studies) OR (prospective NEXT studies) OR (crossover NEXT studies) OR control* OR prospectiv* OR volunteer*) NOT (animal NOT human)

#4 ((Lower NEXT Extremity*) OR (Extremity* NEXT Lower) OR (Lower NEXT Limb*) OR (Limb* NEXT Lower) OR (Inferior NEXT Limb*) OR (Pelvic NEXT Limb*) OR Leg* OR Crus OR Crura OR Thigh* OR Femur OR Femoral OR Knee* OR Tibia OR Fibula OR Shank OR Calf OR Calves OR Ankle* OR Foot OR Feet OR Pes OR Pedal OR Toe*)

The final search strategy was defined by the combination #1 AND #2 AND #3 AND #4.

The search period included studies published up to 2016. In addition, a manual search method using cross-references (snowball method) was used in order to identify additional studies from the reference lists of the selected articles.

2.4. Study Selection and Quality Assessment

2.4.1. Literature Screening

The screening of studies was performed independently by two researchers, according to the previously defined search strategy. Initially, the titles and abstracts of the identified studies were analyzed, considering the type of study, research objectives, and characteristics of the interventions. When an article met the inclusion criteria, the full text was obtained for detailed evaluation. After independent screening, the results were compared between the researchers, and any disagreements were discussed. If differences still remained after discussion, the corresponding author of this article resolved the disagreements.

2.4.2. Data Extraction

Data extraction was performed independently by two researchers, using a standardized data extraction form developed for this study. Information on the general characteristics of the included studies, sample size, participant characteristics, applied interventions, control groups, intervention frequency and intensity, and evaluated outcomes was collected. After extraction, the data were compared by the researchers to ensure the consistency and accuracy of the collected information.

2.4.3. Quality Assessment of the Literature

The methodological quality of the included studies was assessed independently by two researchers using the Cochrane Risk of Bias 2 (RoB 2) tool for randomized controlled trials, as recommended by the Cochrane Handbook for Systematic Reviews of Interventions. The five domains defined by RoB 2 were analyzed: bias arising from the randomization process; bias due to deviations from intended interventions; bias due to missing outcome data; bias in the measurement of the outcome; and bias in the selection of the reported result.

Based on these domains, each study was classified according to the judgments established by the tool: low risk of bias when all domains were considered adequate; some concerns when there was uncertainty in at least one domain; and high risk of bias when one or more domains presented critical issues. Only studies classified as low risk of bias or with some concerns were included in the analysis. The assessments performed by the researchers were compared, and in cases of disagreement, the final decision was made by the corresponding author.

3. Results

3.1. Search Results

A total of 363 related studies were identified in the preliminary search, and 11 studies, including 328 patients, were finally included. A flow chart detailing the article screening process is shown in Figure 1.

All included studies were in English, published between 2016 and 2026, and conducted in United State of America (USA), Italy, Brazil, China, Argentina, Japan, Montenegro, and South Korea. The basic characteristics of the studies are shown in Table 1.

Table 1. Characteristics of included studies investigating functional electrical stimulation (FES) in post-stroke gait rehabilitation.

Study (Author/Year)	Country	Participants	Intervention measures	Measurement (Outcomes)	Study design
Piatti et al., 2025	Italy	28 patients with chronic stroke and foot drop	Gait training with Functional Electrical Stimulation (FES) combined with conventional rehabilitation vs. conventional rehabilitation alone	Rivermead Mobility Index (RMI), Modified Barthel Index (MBI), Two-Minute Walk Test (2MWT), Timed 25-Foot Walk Test (T25FW)	Randomized controlled trial
Purohit et al., 2024	USA	12 ambulatory individuals with hemiparetic stroke	Quadriceps FES applied during unexpected slip perturbations during gait	Fall incidence, reactive balance responses, step initiation time, compensatory step length	Experimental randomized condition study
Ray et al., 2021	USA	Post-stroke individuals with gait impairment	User-driven treadmill control combined with ankle FES	Walking speed, propulsion biomechanics, trailing limb angle	Experimental laboratory study
Choe et al., 2024	USA	Community-dwelling individuals with chronic stroke	FES-based propulsion neuroprosthesis to enhance paretic limb propulsion during walking	Walking speed, paretic limb propulsion, gait mechanics	Experimental intervention study
Huang et al., 2022	China	70 patients with within 6 months post-stroke	Contralaterally controlled FES vs. neuromuscular electrical stimulation (NMES) applied to ankle dorsiflexors	Fugl-Meyer Assessment Lower Extremity (FMA-LE), Barthel Index (BI), Functional Ambulation Category (FAC), ankle AROM, 10-meter walk test, sEMG	Randomized controlled trial
Dantas et al., 2023	Brazil	28 people with stroke	Treadmill training with FES (TT-FES) vs. treadmill training alone	Mobility tests, balance, endurance, coordination, sensorimotor function	Randomized crossover study
Dujović et al., 2017	Montenegro	16 stroke patients	Multi-pad FES combined with conventional rehabilitation vs. conventional therapy	10-Meter Walk Test (10MWT), Fugl-Meyer Assessment (FMA), Berg Balance Scale (BBS), Modified Barthel Index (MBI)	Single-blind randomized study
Biswas et al., 2024	USA	66 patients with chronic stroke	Brain-computer interface controlled FES (BCI-FES) combined with physical therapy vs. conventional therapy	Gait velocity (10-meter walk test), secondary functional outcomes	Randomized controlled clinical trial (Phase II)
Lee & Kim, 2022	South Korea	34 stroke patients	Gait training with portable FES vs. placebo FES with gait training	Fugl-Meyer Assessment (FMA), Performance-Oriented Mobility Assessment (POMA), OptoGait parameters	Single-blind randomized controlled trial
Ueda et al., 2022	Japan	20 post-stroke patients with spastic hemiplegia	Robotic stepping therapy using dynamic tilt table combined with FES vs. stepping therapy alone	Walking speed, cadence, number of steps (10MWT), Modified Ashworth Scale (MAS), Fugl-Meyer Assessment (FMA), ROM	Randomized crossover controlled trial
Parikh et al., 2024	USA	12 individuals with chronic stroke (>6 months)	Randomized crossover design where all participants received both interventions: FAST (Fast treadmill gait training) FAST–FES: FAST combined with phase-specific Functional Electrical Stimulation	Primary outcomes (neurophysiological): Corticospinal excitability. Secondary outcomes (functional): Fast overground walking speed Clinical baseline measures (characterization): Fugl-Meyer Lower Extremity; Berg Balance Scale; Timed Up and Go	Randomized crossover trial with repeated measures

*Abbreviations: FES = functional electrical stimulation; NMES = neuromuscular electrical stimulation; EMG = electromyography; BCI = brain–computer interface; RMI = Rivermead Mobility Index; MBI = Modified Barthel Index; 2MWT = Two-Minute Walk Test; T25FW = Timed 25-Foot Walk Test; FMA = Fugl-Meyer Assessment; FMA-LE = Fugl-Meyer Assessment Lower Extremity; FAC = Functional Ambulation Category; BI = Barthel Index; BBS = Berg Balance Scale; MAS = Modified Ashworth Scale; POMA = Performance-Oriented Mobility Assessment; ROM = range of motion; TUG = Timed Up and Go.

Table 1. Characteristics of included studies investigating functional electrical stimulation (FES) in post-stroke gait rehabilitation.

Study (Author/Year)	Country	Participants	Intervention measures	Measurement (Outcomes)	Study design
Piatti et al., 2025	Italy	28 patients with chronic stroke and foot drop	Gait training with Functional Electrical Stimulation (FES) combined with conventional rehabilitation vs. conventional rehabilitation alone	Rivermead Mobility Index (RMI), Modified Barthel Index (MBI), Two-Minute Walk Test (2MWT), Timed 25-Foot Walk Test (T25FW)	Randomized controlled trial
Purohit et al., 2024	USA	12 ambulatory individuals with hemiparetic stroke	Quadriceps FES applied during unexpected slip perturbations during gait	Fall incidence, reactive balance responses, step initiation time, compensatory step length	Experimental randomized condition study
Ray et al., 2021	USA	Post-stroke individuals with gait impairment	User-driven treadmill control combined with ankle FES	Walking speed, propulsion biomechanics, trailing limb angle	Experimental laboratory study
Choe et al., 2024	USA	Community-dwelling individuals with chronic stroke	FES-based propulsion neuroprosthesis to enhance paretic limb propulsion during walking	Walking speed, paretic limb propulsion, gait mechanics	Experimental intervention study
Huang et al., 2022	China	70 patients with within 6 months post-stroke	Contralaterally controlled FES vs. neuromuscular electrical stimulation (NMES) applied to ankle dorsiflexors	Fugl-Meyer Assessment Lower Extremity (FMA-LE), Barthel Index (BI), Functional Ambulation Category (FAC), ankle AROM, 10-meter walk test, sEMG	Randomized controlled trial
Dantas et al., 2023	Brazil	28 people with stroke	Treadmill training with FES (TT-FES) vs. treadmill training alone	Mobility tests, balance, endurance, coordination, sensorimotor function	Randomized crossover study
Dujović et al., 2017	Montenegro	16 stroke patients	Multi-pad FES combined with conventional rehabilitation vs. conventional therapy	10-Meter Walk Test (10MWT), Fugl-Meyer Assessment (FMA), Berg Balance Scale (BBS), Modified Barthel Index (MBI)	Single-blind randomized study
Biswas et al., 2024	USA	66 patients with chronic stroke	Brain-computer interface controlled FES (BCI-FES) combined with physical therapy vs. conventional therapy	Gait velocity (10-meter walk test), secondary functional outcomes	Randomized controlled clinical trial (Phase II)
Lee & Kim, 2022	South Korea	34 stroke patients	Gait training with portable FES vs. placebo FES with gait training	Fugl-Meyer Assessment (FMA), Performance-Oriented Mobility Assessment (POMA), OptoGait parameters	Single-blind randomized controlled trial
Ueda et al., 2022	Japan	20 post-stroke patients with spastic hemiplegia	Robotic stepping therapy using dynamic tilt table combined with FES vs. stepping therapy alone	Walking speed, cadence, number of steps (10MWT), Modified Ashworth Scale (MAS), Fugl-Meyer Assessment (FMA), ROM	Randomized crossover controlled trial
Parikh et al., 2024	USA	12 individuals with chronic stroke (>6 months)	Randomized crossover design where all participants received both interventions: FAST (Fast treadmill gait training) FAST–FES: FAST combined with phase-specific Functional Electrical Stimulation	Primary outcomes (neurophysiological): Corticospinal excitability. Secondary outcomes (functional): Fast overground walking speed Clinical baseline measures (characterization): Fugl-Meyer Lower Extremity; Berg Balance Scale; Timed Up and Go	Randomized crossover trial with repeated measures

*Abbreviations: FES = functional electrical stimulation; NMES = neuromuscular electrical stimulation; EMG = electromyography; BCI = brain–computer interface; RMI = Rivermead Mobility Index; MBI = Modified Barthel Index; 2MWT = Two-Minute Walk Test; T25FW = Timed 25-Foot Walk Test; FMA = Fugl-Meyer Assessment; FMA-LE = Fugl-Meyer Assessment Lower Extremity; FAC = Functional Ambulation Category; BI = Barthel Index; BBS = Berg Balance Scale; MAS = Modified Ashworth Scale; POMA = Performance-Oriented Mobility Assessment; ROM = range of motion; TUG = Timed Up and Go.

Table 2. Qualitative evidence synthesis matrix summarizing the direction and consistency of effects of functional electrical stimulation (FES)-based interventions on post-stroke gait outcomes.

	ADL	Function Capacity	Biomechanical Parameters
FES + Conventional Rehabilitation (n=4)	↔	↑	↑
FES + Gait Training (n=3)	?	↑↑	↑↑
FES Alone (n=2)	?	↑	↑
FES + Advanced (n=4)	?	↑	↑↑

* Legend: Darker shades indicate stronger and more consistent evidence across studies. Strong consistent improvement (↑↑), moderate improvement (↑), no consistent effect (↔), and Limited, heterogeneous or insufficient evidence (?).

Table 2. Qualitative evidence synthesis matrix summarizing the direction and consistency of effects of functional electrical stimulation (FES)-based interventions on post-stroke gait outcomes.

	ADL	Function Capacity	Biomechanical Parameters
FES + Conventional Rehabilitation (n=4)	↔	↑	↑
FES + Gait Training (n=3)	?	↑↑	↑↑
FES Alone (n=2)	?	↑	↑
FES + Advanced (n=4)	?	↑	↑↑

* Legend: Darker shades indicate stronger and more consistent evidence across studies. Strong consistent improvement (↑↑), moderate improvement (↑), no consistent effect (↔), and Limited, heterogeneous or insufficient evidence (?).

3.2. Results from Included Studies

3.2.1. Impact of Functional Electrical Stimulation on Activities of Daily Living in Stroke Patients

Two articles [14,15] included in this study used functional electrical stimulation (FES), alone or combined with conventional rehabilitation, to evaluate the impact on activities of daily living (ADL) in post-stroke patients. In [14], sixteen stroke patients were randomly allocated to the FES group (FES therapy combined with a conventional rehabilitation program) (n = 8) and the control group (conventional rehabilitation program only) (n = 8). FES was applied for 30 minutes during gait training to induce ankle plantarflexion and dorsiflexion. The results showed that the FES group demonstrated improvement in functional independence in activities of daily living, motor recovery, and gait performance compared with the control group. These findings suggest that the addition of FES to conventional rehabilitation may be more effective in improving daily living activities and functional outcomes than conventional rehabilitation alone.

In the randomized clinical trial [15], the objective was to investigate the effects of FES combined with conventional rehabilitation on gait and activities of daily living in stroke patients presenting with foot drop. Twenty-eight participants were randomized into two groups: an experimental group that received gait training with FES associated with conventional rehabilitation and a control group that received conventional rehabilitation only. The results indicated improvements in overall functional performance in both groups; however, the between-group analysis did not demonstrate statistically significant differences between the FES intervention combined with physiotherapy and conventional treatment alone.

3.2.2. Effects of Functional Electrical Stimulation on Functional Motor Capacity in Stroke Patients

Six articles [14,16,17,18,19] included in this study used functional electrical stimulation (FES), alone or combined with other rehabilitation strategies, to evaluate its impact on functional motor capacity in post-stroke patients. Although the studies used different stimulation protocols and outcome measures, they consistently assessed motor performance related to gait, balance, lower-limb function, and, more recently, neurophysiological adaptations associated with motor recovery.

In the study [14], sixteen stroke patients were randomly allocated to an intervention group receiving FES combined with a conventional rehabilitation program and a control group receiving only conventional rehabilitation. FES was delivered for 30 minutes during gait training to induce ankle plantarflexion and dorsiflexion. The results showed a significant increase in gait speed in the FES group (p < 0.001), exceeding the minimal detectable change. These findings suggest that FES combined with conventional rehabilitation can improve walking speed and lower-extremity mobility more effectively than conventional rehabilitation alone.

[16] compared the efficacy of contralaterally controlled functional electrical stimulation (CCFES) with conventional neuromuscular electrical stimulation (NMES) for lower-extremity motor recovery in patients with subacute stroke. Seventy patients within six months post-stroke were randomly assigned to either the CCFES group (n = 35) or the NMES group (n = 35). Both groups received routine rehabilitation combined with 20 minutes of electrical stimulation targeting ankle dorsiflexion muscles, five days per week for three weeks. Improvements were observed in both groups in the Fugl-Meyer Assessment of the lower extremity (FMA-LE), Barthel Index (BI), active range of motion (AROM) of ankle dorsiflexion, and Functional Ambulation Category (FAC) (p < 0.05). However, the CCFES group demonstrated significantly greater improvements in FMA-LE scores and sEMG responses of the tibialis anterior (p < 0.05), indicating superior motor recovery compared with conventional NMES.

[17] examined the effects of gait training combined with portable FES on motor function, balance, and gait ability in stroke patients. In this single-blind randomized controlled trial, 34 participants were allocated to either an FES plus gait training group or a placebo FES plus gait training group. Both groups received interventions for 30 minutes, five days per week, for four weeks. The results demonstrated that the FES group showed significantly greater improvements in motor function, balance, and gait ability compared with the placebo group, suggesting that integrating FES into task-specific gait training enhances functional motor recovery.

[18] investigated whether FES could improve reactive balance control in individuals with post-stroke hemiparesis during unexpected gait perturbations. Twelve ambulatory participants with moderate-to-severe motor impairment were included. The results demonstrated that FES significantly reduced the incidence of laboratory-induced falls and improved reactive stability and vertical limb support (p < 0.05). The authors suggested that stimulation of the quadriceps may rapidly enhance the paretic limb’s capacity to support body weight during balance disturbances, thereby reducing fall risk.

[19] explored the neurophysiological effects of combining high-intensity gait training with FES (FAST-FES) in a repeated-measures crossover study involving 11 individuals in the chronic post-stroke phase. Participants underwent both FAST-FES and high-intensity gait training alone. Corticospinal tract (CST) excitability was assessed using motor evoked potentials (MEPs) recorded from the tibialis anterior and soleus muscles. The results showed that FAST-FES induced significantly greater increases in MEP amplitude compared with gait training alone (p = 0.01), specifically in the paretic limb, without affecting the nonparetic side. These findings suggest that FES combined with high-intensity, task-specific training may preferentially promote neuroplasticity within the lesioned corticospinal pathways. Overall, these studies indicate that FES-based interventions can positively influence functional motor capacity in stroke patients, particularly in gait performance, balance, and lower-limb motor recovery.

3.2.3. Effects of Functional Electrical Stimulation on Motor and Biomechanical Parameters

Ten studies [14,15,16,17,18,20,21,22,23,24] included in this review evaluated the effects of functional electrical stimulation (FES), alone or combined with other rehabilitation strategies, on motor and biomechanical parameters in individuals after stroke. The studies assessed a range of outcomes related to lower-limb motor function, gait performance, balance control, and biomechanical characteristics of locomotion. [16] compared the effects of contralaterally controlled functional electrical stimulation (CCFES) with neuromuscular electrical stimulation (NMES) for lower-limb motor recovery in patients with chronic stroke. After a three-week intervention, both groups showed improvements in Fugl-Meyer Assessment for the lower extremity (FMA-LE), Barthel Index (BI), ankle dorsiflexion active range of motion (AROM), and Functional Ambulation Category (FAC) (p < 0.05). However, the CCFES group demonstrated significantly greater improvements in FMA-LE scores and in the surface electromyography (sEMG) response of the tibialis anterior muscle (p < 0.05), suggesting enhanced neuromuscular activation and motor recovery with the contralateral control strategy.

Similarly, [14] evaluated the use of a multi-pad FES system combined with conventional rehabilitation in stroke patients. Sixteen participants were randomly assigned to either FES plus rehabilitation or rehabilitation alone. The intervention involved 30 minutes of FES during gait training to induce ankle plantarflexion and dorsiflexion. The results demonstrated a significant increase in gait speed in the FES group (p < 0.001), exceeding the minimal detectable change. Improvements were also observed in motor recovery, balance performance, and functional mobility. [20] investigated treadmill training combined with FES (TT-FES) compared with treadmill training alone in individuals after stroke. The results showed improvements in mobility, balance, endurance, and coordination of the non-paretic limb in the group that started with TT-FES. Sensorimotor function improved regardless of the training sequence; however, coordination of the paretic limb improved only after exposure to TT-FES. Although the study did not include direct biomechanical measurements, the findings suggest that combining FES with locomotor training may enhance functional motor outcomes.

[17] examined the effects of gait training combined with portable FES on motor function, balance, and gait ability in stroke patients. In this randomized controlled trial, 34 participants were allocated to either an FES plus gait training group or a placebo FES plus gait training group. After four weeks of intervention, both groups showed improvements in motor function and gait performance; however, the FES group demonstrated significantly greater improvements in motor function, balance, and gait ability, indicating the potential of FES to enhance locomotor rehabilitation outcomes. [21] evaluated the combination of robotic stepping therapy and FES using a dynamic tilt table in post-stroke patients with spastic hemiplegia. The results showed that the combined intervention significantly improved walking speed, number of steps during the 10-meter walking test, and ankle inversion range of motion compared with robotic stepping alone. These findings suggest that integrating FES with robotic-assisted therapy may enhance locomotor recovery and joint mobility.

[18] investigated the effects of functional electrical stimulation (FES) synchronized with unexpected gait perturbations in 12 ambulatory stroke survivors with moderate-to-severe motor impairment. Participants experienced unpredicted gait slips with and without FES applied to the paretic quadriceps, and biomechanical outcomes related to reactive balance were compared between conditions. The FES intervention significantly reduced laboratory falls while increasing reactive stability and vertical limb support, in addition to promoting a longer compensatory step and shorter step initiation time. These findings suggest that FES can positively influence key biomechanical parameters involved in balance recovery by enhancing knee extensor torque, improving weight-bearing capacity, and facilitating more efficient compensatory stepping during gait perturbations.

[15] conducted a randomized clinical trial investigating the effects of FES combined with conventional rehabilitation in stroke patients with foot drop. Although both the intervention and control groups demonstrated significant improvements in mobility and gait-related outcomes after four weeks, no statistically significant differences were observed between groups. The authors suggested that the small sample size and short intervention period may have limited the detection of significant differences in functional outcomes. [22] investigated the combination of user-driven treadmill control and FES on gait velocity in post-stroke individuals. The results showed that the condition combining active treadmill control with FES increased self-selected walking speed by approximately 0.13 m/s compared with conventional treadmill walking. However, no significant differences were observed in biomechanical propulsion parameters, suggesting that improvements in gait speed may be associated with behavioral adaptations rather than changes in propulsive biomechanics.

Additional studies exploring advanced FES technologies also demonstrated promising biomechanical effects. [23] investigated an overground propulsion neuroprosthesis that adaptively coordinated dorsiflexor and plantarflexor stimulation during gait. Individualized FES timing resulted in a significant 10% increase in paretic propulsion and an 8% increase in plantarflexor power during assisted walking. Moreover, after a single intervention session, participants demonstrated a 9% increase in walking speed, a 28% increase in paretic propulsion, and a 12% improvement in propulsion symmetry during unassisted walking. These findings indicate that adaptive coordination of muscle stimulation through FES can enhance gait propulsion and optimize key biomechanical parameters associated with locomotor performance after stroke. Finally, [24] described a clinical trial protocol evaluating a brain-computer interface-controlled FES (BCI-FES) system for gait rehabilitation in individuals with chronic stroke. The trial aims to assess whether coupling neural intention signals with electrical stimulation can improve gait velocity and functional motor outcomes. This approach is based on Hebbian principles of neuroplasticity and represents a promising direction for future neurorehabilitation strategies. Overall, the evidence suggests that FES-based interventions can positively influence motor recovery and several biomechanical aspects of gait in individuals after stroke. Improvements were reported in parameters such as gait speed, coordination, balance control, neuromuscular activation, and propulsive force generation.

4. Discussion

The findings of this review suggest that functional electrical stimulation (FES) is a promising therapeutic strategy for post-stroke rehabilitation, with beneficial effects observed across activities of daily living, functional motor capacity, and motor and biomechanical outcomes. Collectively, the evidence indicates that FES may contribute to improvements in gait performance, balance, lower-limb motor recovery, functional independence, neuromuscular activation, and locomotor function, supporting its role as an important adjunct to conventional rehabilitation interventions.

Regarding activities of daily living, the available evidence suggests that FES may facilitate improvements in functional independence and overall recovery, particularly when combined with conventional rehabilitation. [14] demonstrated improvements in daily living activities, motor recovery, and gait performance when FES was integrated into a rehabilitation program. In contrast, [15] observed functional improvements in both intervention and control groups but did not identify statistically significant differences between treatments. This finding suggests that while FES may represent a safe and potentially useful therapeutic resource for facilitating neuromotor gait recovery, particularly in individuals with foot drop, its additional benefits over conventional rehabilitation may be more difficult to detect under certain clinical conditions. The authors proposed that the relatively small sample size and short intervention period may have limited the ability to detect clinically meaningful between-group differences. Therefore, the absence of statistical significance should not necessarily be interpreted as a lack of therapeutic effect, but rather as an indication that further investigations involving larger samples and longer intervention periods are needed to better establish the clinical impact of FES on functional recovery and activities of daily living.

Similarly, the evidence related to functional motor capacity suggests that FES can positively influence gait performance, balance, and lower-limb motor recovery after stroke. Improvements in walking speed, motor function, ambulation capacity, and balance were consistently reported across several studies. Importantly, emerging evidence indicates that these functional gains may be supported by underlying neurophysiological mechanisms, including increased corticospinal excitability and task-specific neuroplasticity. These findings support the hypothesis that FES may not only improve motor performance but also facilitate neural reorganization processes that contribute to motor recovery. Nevertheless, substantial variability was observed among studies regarding stimulation protocols, intervention duration, and outcome measures, making it difficult to determine the magnitude and consistency of these effects across different patient populations and clinical settings.

The biomechanical findings further reinforce the therapeutic potential of FES. Improvements were reported in gait speed, coordination, balance control, neuromuscular activation, joint mobility, and propulsive force generation. In addition, advanced stimulation approaches, including propulsion neuroprostheses, synergy-based stimulation systems, and brain-computer interface-controlled FES technologies, demonstrated promising effects on locomotor biomechanics and motor coordination. These findings suggest that FES may influence not only clinical measures of motor function but also the underlying biomechanical mechanisms involved in gait recovery. However, the interpretation of these results should be approached with caution due to the considerable heterogeneity observed among studies regarding experimental design, patient characteristics, stimulation protocols, intervention duration, and outcome assessments. Such variability limits direct comparisons and reduces the generalizability of the available evidence.

Another important limitation identified in this review concerns the relatively small sample sizes included in several studies. Small cohorts may reduce statistical power and increase the likelihood of type II errors, potentially masking clinically relevant treatment effects. This limitation may partially explain why some investigations, including [15], failed to identify significant between-group differences despite observing improvements in functional outcomes. Consequently, future studies should prioritize larger and more homogeneous populations to improve the robustness and reliability of clinical findings.

Beyond methodological limitations, the current literature also highlights important technological challenges associated with conventional FES systems. Although FES has demonstrated clinically relevant benefits, several studies reported only modest or non-significant improvements when the technology was applied as a standalone intervention. One possible explanation is that most commercially available FES systems rely on fixed stimulation patterns and predefined parameters that remain unchanged throughout treatment. Such static approaches fail to account for the dynamic, nonlinear, and highly individualized neuromuscular adaptations that occur during the rehabilitation process. As motor function, muscle responsiveness, fatigue, and neural excitability evolve over time, stimulation parameters that were initially appropriate may become progressively suboptimal, potentially limiting therapeutic effectiveness and reducing the capacity to maximize functional recovery and neuroplastic adaptations.

In this context, adaptive FES systems represent a promising direction for future neurorehabilitation. By continuously adjusting stimulation parameters according to physiological, biomechanical, or behavioral feedback, adaptive systems may better accommodate both inter-individual and intra-individual variability throughout recovery. The integration of closed-loop control systems, wearable sensors, electromyographic monitoring, and artificial intelligence-based algorithms may enable more personalized stimulation delivery, optimize neuromuscular recruitment, and facilitate activity-dependent neuroplasticity. Consequently, adaptive FES approaches may overcome several limitations associated with conventional stimulation paradigms and contribute to superior functional outcomes.

Overall, the current evidence supports the feasibility and therapeutic potential of FES in post-stroke rehabilitation. Nevertheless, the heterogeneity of study methodologies, variability in stimulation protocols, limited sample sizes, and the widespread use of static stimulation paradigms highlight important gaps in the literature. Future research should prioritize large-scale multicenter randomized controlled trials, greater standardization of stimulation protocols and outcome measures, and the development of adaptive and intelligent stimulation systems capable of continuously responding to patients’ physiological and functional needs. Such advances may be essential for maximizing the clinical effectiveness of FES and optimizing long-term recovery following stroke.

5. Conclusions

This review demonstrated that functional electrical stimulation (FES) is a promising therapeutic intervention for post-stroke rehabilitation, with evidence supporting improvements in activities of daily living, functional motor capacity, and motor and biomechanical aspects of gait. The findings indicate that FES may contribute to enhanced gait performance, balance, lower-limb motor recovery, neuromuscular activation, and functional independence, particularly when combined with task-specific rehabilitation strategies. Emerging evidence further suggests that the benefits of FES may extend beyond functional improvements, involving neurophysiological mechanisms such as increased corticospinal excitability and activity-dependent neuroplasticity. These findings reinforce the role of FES not only as a compensatory tool for motor impairments but also as a potential facilitator of neural recovery processes following stroke.

Despite these promising outcomes, the current body of evidence presents important limitations, including substantial heterogeneity in stimulation protocols, intervention duration, outcome measures, and patient characteristics. In addition, several studies were conducted with relatively small sample sizes, limiting statistical power and reducing the generalizability of findings. Furthermore, the widespread use of conventional FES systems based on fixed stimulation parameters may restrict therapeutic effectiveness, as such approaches do not account for the dynamic and individualized neuromuscular adaptations that occur throughout rehabilitation.

Taken together, these findings highlight the need for future research focused on larger and more standardized clinical trials, as well as the development of adaptive and personalized FES technologies. Systems capable of continuously adjusting stimulation parameters according to physiological and functional responses may better address patient-specific needs, optimize neuromuscular activation, and enhance neuroplasticity. Consequently, adaptive and intelligent FES approaches represent a promising avenue for improving rehabilitation outcomes and maximizing long-term functional recovery following stroke. In conclusion, current evidence supports the clinical feasibility and therapeutic potential of FES in post-stroke rehabilitation. However, advancing toward adaptive, closed-loop, and patient-centered stimulation paradigms may be essential to fully realize the benefits of this technology and to achieve more effective, personalized, and sustainable recovery outcomes for individuals affected by stroke.