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Stroke commonly results in persistent leg impairments that limit mobility and reduce quality of life. This study investigates whether combining low-intensity resistance training with blood flow restriction (LIRT-BFR) and transcutaneous electrical nerve stimulation (TENS) can effectively improve leg function in stroke survivors.
Participants with chronic stroke will be randomly assigned to one of four intervention groups: 1) LIRT with simulated BFR and simulated TENS; 2) LIRT with actual BFR and simulated TENS; 3) LIRT with simulated BFR and actual TENS; 4) LIRT with both actual BFR and actual TENS. The resistance training utilizes 20% of each participant's maximum lifting capacity. For blood flow restriction, an automated pressure cuff (SmartCuffs 4.0) will be placed on the upper portion of the affected leg, inflated to 50% of the individual's occlusion pressure during exercises and deflated during rest periods. TENS therapy delivers controlled electrical impulses through electrodes positioned on the anterior thigh.
Each 60-minute session includes a 10-minute warm-up followed by 40 minutes of targeted resistance exercises (leg extensions, leg presses, and weight-bearing squats) and concludes with 10 minutes of stationary cycling. The resistance protocol involves 3 sets of 20 repetitions with standardized rest intervals between sets and exercises. Participants will attend three sessions weekly for six weeks.
Assessments will be conducted at baseline, midpoint (3 weeks), completion (6 weeks), and follow-up (1 month post-intervention). The primary outcome measure is the Fugl-Meyer Assessment for Lower Extremity function, with secondary measures including muscle strength, stiffness, balance, mobility, walking capacity, and gait parameters. To understand the underlying mechanisms, we will measure muscle oxygenation using near-infrared spectroscopy, evaluate muscle structure via ultrasound, and monitor physiological responses including heart rate variability and perceived exertion for safety monitoring.
Stroke often leads to persistent lower-limb impairments, limiting functional recovery and quality of life. Low-intensity resistance training with blood flow restriction (LIRT-BFR) has shown promise in improving muscle function in healthy populations, but its effects in stroke rehabilitation remain underexplored. Additionally, while BFR and electrical stimulation have been beneficial for pain relief and muscle activation, the impact of combining BFR with transcutaneous electrical nerve stimulation (TENS) in stroke patients remains unknown. The objectives of this study is to evaluate whether a multi-mode exercise rehabilitation training program of LIRT-BFR and TENS can restore lower extremity strength, mobility, and quality of life.
In this randomized controlled trial, chronic stroke patients will be allocated to one of four groups: 1) LIRT + sham BFR + sham TENS, 2) LIRT + BFR + sham TENS, 3) LIRT + sham BFR + TENS, and 4) LIRT + BFR + TENS. The LIRT protocol utilizes 20% of one-repetition maximum (1-RM) as the standardized training load. BFR implementation involves an automated restriction band (SmartCuffs 4.0) positioned at the proximal region of the affected lower extremity, calibrated to 50% of the individual's lower limb occlusion pressure (LOP). The pressure system remains inflated throughout active training phases and is systematically deflated during inter-exercise intervals. TENS application targets the anterior thigh region.
The intervention protocol comprises a structured 60-minute session beginning with a 10-minute preparatory warm-up, followed by 40 minutes of targeted resistance exercises including leg extensions, leg presses, and load-bearing squats focused on the affected limb, concluding with 10 minutes of aerobic cycling. Each resistance exercise consists of 3 sets of 20 repetitions with rest intervals. The assessments will be conducted at baseline, mid-intervention (3 weeks), post-intervention (6 weeks), and follow-up (1 month post-completion).
The primary outcome measure will be the Fugl-Meyer Assessment Lower Extremity (FMA-LE) score, and secondary outcome measures including muscle strength, stiffness, balance, functional mobility, walking capacity, gait speed, etc. To elucidate the underlying mechanisms, the study will use near-infrared spectroscopy (NIRS) to assess muscle oxygenation and hemodynamics, ultrasound for muscle morphology, and exercise measures like heart rate variability (HRV) and rating of perceived exertion (RPE) for safety consideration.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| LIRT + BFR + TENS | Experimental | All subjects will receive 60-minute sessions of LIRT with both actual BFR and actual TENS intervention, 3 sessions per week for 6 weeks. |
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| LIRT + sham BFR + TENS | Sham Comparator | All subjects will receive 60-minute sessions of LIRT with simulated BFR and actual TENS, 3 sessions per week for 6 weeks. |
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| LIRT + BFR + sham TENS | Sham Comparator | All subjects will receive 60-minute sessions of LIRT with actual BFR and simulated TENS, 3 sessions per week for 6 weeks. |
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| LIRT + sham BFR + sham TENS | Placebo Comparator | All subjects will receive 60-minute sessions of LIRT with simulated BFR and simulated TENS, 3 sessions per week for 6 weeks. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Blood flow restriction (BFR) | Device | BFR implementation involves an automated restriction band (SmartCuffs 4.0) positioned at the proximal region of the affected lower extremity, calibrated to 50% of the individual's lower limb occlusion pressure (LOP). The pressure system remains inflated throughout active training phases and is systematically deflated during inter-exercise intervals. |
| Measure | Description | Time Frame |
|---|---|---|
| Fugl-Meyer Assessment of Lower Extremity (FMA-LE) | FMA-LE is used to evaluate the lower extremity motor control, including reflexes, voluntary control of isolated movement and coordination. The scale score ranging from 0 to 34, with 17 items and ordinal scoring from 0 to 2. A higher score indicates a better lower extremity motor control. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Measure | Description | Time Frame |
|---|---|---|
| Paretic ankle dorsiflexor/plantarflexor strength | The paretic ankle dorsiflexor/plantarflexor strength (in kilograms) is measured with a Nicholas hand-held dynamometer (model 01165, Lafayette Instrument Company, Lafayette, IN) in supine lying position. The muscle strength will be measured twice. The average strength of the 2 trials will be recorded. A higher value indicated a better paretic ankle dorsiflexor/plantarflexor strength. |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Shamay NG, PhD | Contact | +852 27664889 | shamay.ng@polyu.edu.hk |
| Name | Affiliation | Role |
|---|---|---|
| Shamay NG, PhD | The Hong Kong Polytechnic University | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| The Hong Kong Polytechnic University | Recruiting | Hong Kong | Hong Kong |
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| Transcutaneous electrical nerve stimulation (TENS) | Device | TENS will be delivered to the anterior thigh region of the paretic leg using a 120z Dual-Channel TENS Unit (ITO Physiotherapy & Rehabilittaion, Co, Ltd, Tokyo, Japan). The TENS stimulation will be at 100 Hz, with 0.2 ms square pulses at an intensity of twice the sensory threshold (defined as the minimum intensity at which subject reported feeling a tingling sensation and below the motor threshold as indicated by the absence of muscle twitching. |
|
| Sham blood flow restriction (Sham-BFR) | Device | Sham BFR implementation involves an automated restriction band (SmartCuffs 4.0) positioned at the proximal region of the affected lower extremity, calibrated to 50% of the individual's lower limb occlusion pressure (LOP). But the pressure system remains deflated throughout active training and resting phases. |
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| Sham transcutaneous electrical nerve stimulation (Sham-TENS) | Device | Sham TENS will be delivered to the anterior thigh region of the paretic leg using a 120z Dual-Channel TENS Unit (ITO Physiotherapy & Rehabilittaion, Co, Ltd, Tokyo, Japan). The TENS stimulation will be at 100 Hz, with 0.2 ms square pulses at an intensity of twice the sensory threshold (defined as the minimum intensity at which subject reported feeling a tingling sensation and below the motor threshold as indicated by the absence of muscle twitching. But the stimulator will only be applied for the first and last 30 seconds. |
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| Low-intensity resistance training (LIRT) | Behavioral | The LIRT protocol utilizes 20% of one-repetition maximum (1-RM) as the standardized training load. LIRT including leg extensions, leg presses, and load-bearing squats focused on the affected limb. Each resistance exercise consists of 3 sets of 20 repetitions with rest intervals. |
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| Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Knee extension strength | Knee extension strength is measured using a Cybex isokinetic dynamometer in isometric mode. Participants will be seated with their back supported and hips flexed at 90°. The axis of rotation of the dynamometer will be aligned with the lateral femoral epicondyle, and the resistance pad will be secured just proximal to the malleoli on the anterior aspect of the leg. The test will be conducted with the knee positioned at 90° of flexion. Following familiarization with the procedure, participants will perform three maximal voluntary isometric contractions, each held for 5 seconds with a 60-second rest period between attempts. The average peak torque value from the three trials will be recorded in Newton-meters (Nm). Higher values indicate greater knee extension strength. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| 10-Meter Walk Test (10MWT) | The subject will be asked to walk 10 meter in a comfortable speed. The completion time will be records by stopwatch. The test will be repeated for 2 times. The completion time will be averaged. The shorter the completion time, the better performance is. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Timed 'Up and Go' test (TUG) | The TUG is used to measure the functional mobility. Each subject will be required to rise from a chair with armrests, walk 3 m forward, turn around, return to the chair and sit down. The time taken to complete this task will be measured in seconds with a stopwatch. Each condition will be repeated for 2 times. The completion time will be averaged. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Gait Parameters (via GAITRite) | Gait parameters will be assessed using the GAITRite system (CIR system, Inc., Havertown, Pennsylvania), a pressure-sensitive mat that automatically captures spatiotemporal gait characteristics. Participants will walk at their self-selected comfortable pace along the instrumented walkway. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Berg Balance Scale (BBS) | BBS is a 14-item objective measure that assesses static balance and fall risk in adult patients. Items include tasks such as sitting to standing, standing unsupported, transfers, reaching, turning 360 degrees, and single-leg stance. Each item is scored from 0-4 points (0=unable to perform, 4=independent), with a maximum total score of 56 points. Higher scores indicate better balance. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Limits of Stability (LOS) Test | The Limits of Stability (LOS) test quantifies participants' ability to intentionally shift their center of gravity (COG) to their stability limits without losing balance using Bertec Balance Advantage System (Bertec Corporation, Columbus, OH, USA). Participants stand on a force plate and shift their weight to move a cursor on a screen toward 8 targets arranged in a circular pattern at their theoretical limits of stability (100% LOS). Key parameters measured reaction time (RT) , movement velocity (MVL), directional control (DCL), endpoint excursion (EPE), maximum excursion (MXE). Higher scores indicate better dynamic balance control, except for reaction time where lower scores are better. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Weight bearing distribution | Weight bearing distribution will be assessed using the Bertec Balance Advantage System (Bertec Corporation, Columbus, OH, USA). Participants will stand barefoot on the dual force plate platform with feet positioned at shoulder width and arms resting at their sides. The system's integrated software will measure vertical ground reaction forces under each foot to calculate the percentage of weight distribution between the affected and unaffected lower extremities. Weight bearing measurements will be conducted under four conditions: (1) relaxed standing balance, (2) squat position at 30° knee flexion, (3) squat position at 60° knee flexion, (4) squat position at 90° knee flexion. For each squat position, participants will be instructed to maintain the position for 10 seconds while a handrail will be available for safety but not for weight support. | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| Ultrasound muscle thickness | Muscle thickness will be evaluated using B-mode ultrasonography with a 5-12 MHz linear-array transducer. Measurements will be performed with participants in a supine position after 10 minutes of rest to allow fluid redistribution. Standard anatomical landmarks will be used to ensure measurement consistency: Rectus Femoris at 50% of the distance between the anterior superior iliac spine and the superior border of the patella; Vastus Lateralis at 2/3 of the distance from the anterior superior iliac spine to the lateral side of the patella; Tibialis Anterior at 30% of the distance from the lateral condyle of the tibia to the lateral malleolus; and Gastrocnemius Medialis at 30% of the distance from the popliteal crease to the lateral malleolus. The transducer will be positioned perpendicular to the muscle surface with minimal pressure to avoid tissue compression. Three consecutive images will be captured for each muscle, and muscle thickness will be measured as the perpendicular distance | Baseline (0 week), Mid-intervention (3 weeks), Post-intervention (6 weeks), 1-month follow-up (10 weeks) |
| ID | Term |
|---|---|
| D020521 | Stroke |
| ID | Term |
|---|---|
| D002561 | Cerebrovascular Disorders |
| D001927 | Brain Diseases |
| D002493 | Central Nervous System Diseases |
| D009422 | Nervous System Diseases |
| D014652 | Vascular Diseases |
| D002318 | Cardiovascular Diseases |
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| ID | Term |
|---|---|
| D000090003 | Blood Flow Restriction Therapy |
| D004561 | Transcutaneous Electric Nerve Stimulation |
| ID | Term |
|---|---|
| D005081 | Exercise Therapy |
| D012046 | Rehabilitation |
| D000359 | Aftercare |
| D003266 | Continuity of Patient Care |
| D005791 | Patient Care |
| D013812 | Therapeutics |
| D026741 | Physical Therapy Modalities |
| D004599 | Electric Stimulation Therapy |
| D000698 | Analgesia |
| D000760 | Anesthesia and Analgesia |
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