Neuromuscular Electrical Stimulation Intervention Research Articles

Effect of prior neuromuscular electrical stimulation of vastus lateralis on the fatigue induced by a sustained voluntary knee extension in men

PurposeThe purpose of this study was to investigate the effect of vastus lateralis (VL) selective fatigue induced by neuromuscular electrical stimulation (NMES) on knee extensor electromyographic (EMG) activity during a sustained submaximal isometric contraction. MethodsThirteen healthy men (28 ± 5 years) completed two experimental sessions in which either the VL was pre-fatigued for 17 min (NMES session) or no intervention was performed (control session, CTRL). Subsequently, participants were asked to sustain an isometric knee extension at 20 % of maximal voluntary contraction (MVC) torque until task failure. ResultsVL M−wave amplitude was reduced (−34 ± 26 %, P = 0.008) following the NMES intervention, while MVC torque was reduced by 26 ± 10 %. The time to task failure was 23 ± 10 % shorter (P = 0.002) in NMES (186 ± 75 s) than in CTRL (251 ± 128 s). EMG activity measured during the sustained contraction was higher for vastus medialis and rectus femoris muscles in NMES compared to CTRL (P < 0.001), but was comparable for VL (P > 0.05). The extent and origin of neuromuscular fatigue at task failure measured through MVCs combined with electrically-evoked contractions did not differ between NMES and CTRL. ConclusionCompensatory activity from synergist muscles occurred in response to a pre-fatigue intervention, which reduced the time to task failure of a sustained submaximal contraction but did not affect the extent and origin of neuromuscular fatigue.

Benefits of home-based foot neuromuscular electrical stimulation on self-reported function, leg pain and other leg symptoms among community-dwelling older adults: a sham-controlled randomised clinical trial

IntroductionLower leg pain and symptoms, and poor leg circulation are common in older adults. These can significantly affect their function and quality of life. Neuromuscular electrical stimulation (NMES) applied via the feet as ‘foot NMES’ activates the leg musculovenous pump. This study investigated the effects of foot NMES administered at home using Revitive® among community-dwelling older adults with lower leg pain and/or other lower leg symptoms such as cramps, or sensations of tired, aching, and heavy feeling legs.MethodsA randomised placebo-controlled study with three groups (2 NMES, 1 Sham) and three assessments (baseline, week 8, week 12 follow-up) was carried out. Self-reported function using Canadian occupational performance measure (COPM), leg pain, overall leg symptoms score (heaviness, tiredness, aching, or cramps), and ankle blood flow were assessed. Analysis of covariance (ANCOVA) and logistic regression were used to compare the groups. Statistical significance was set at p < 0.05 (two-sided 5%).ResultsOut of 129 participants enrolled, 114 completed the study. The improvement in all outcomes were statistically significant for the NMES interventions compared to Sham at both week 8 (p < 0.01) and week 12 (p < 0.05). The improvement in COPM met the minimal clinically important difference (MCID) for the NMES interventions compared to Sham at both week 8 (p < 0.005) and week 12 (p < 0.05). Improvement in leg pain met MCID at week 8 compared to Sham (p < 0.05). Ankle blood flow increased approximately 3-fold during treatment compared to Sham. Compliance with the interventions was high and no device-related adverse events were reported.ConclusionsThe home-based foot NMES is safe, and significantly improved self-reported function, leg pain and overall leg symptoms, and increased ankle blood flow compared to a Sham among older adults.Trial registrationThe trial was prospectively registered in ISRCTN on 17/06/2019 with registration number ISRCTN10576209. It can be accessed at https://www.isrctn.com/ISRCTN10576209.

Motoneuron persistent inward current contribution to increased torque responses to wide-pulse high-frequency neuromuscular electrical stimulation

PurposeTo assess the effect of a remote handgrip contraction during wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) on the magnitude of extra torque, progressive increase in torque during stimulation, and estimates of the persistent inward current (PIC) contribution to motoneuron firing in the plantar flexors.MethodsTen participants performed triangular shaped contractions to 20% of maximal plantar flexion torque before and after WPHF NMES with and without a handgrip contraction, and control conditions. Extra torque, the relative difference between the initial and final torque during stimulation, and sustained electromyographic (EMG) activity were assessed. High-density EMG was recorded during triangular shaped contractions to calculate ∆F, an estimate of PIC contribution to motoneuron firing, and its variation before vs after the intervention referred to as ∆F change score.ResultsWhile extra torque was not significantly increased with remote contraction (WPHF + remote) vs WPHF (+ 37 ± 63%, p = 0.112), sustained EMG activity was higher in this condition than WPHF (+ 3.9 ± 4.3% MVC EMG, p = 0.017). Moreover, ∆F was greater (+ 0.35 ± 0.30 Hz) with WPHF + remote than control (+ 0.03 ± 0.1 Hz, p = 0.028). A positive correlation was found between ∆F change score and extra torque in the WPHF + remote (r = 0.862, p = 0.006).DiscussionThe findings suggest that the addition of remote muscle contraction to WPHF NMES enhances the central contribution to torque production, which may be related to an increased PIC contribution to motoneuron firing. Gaining a better understanding of these mechanisms should enable NMES intervention optimization in clinical and rehabilitation settings, improving neuromuscular function in clinical populations.

Longitudinal Retrospective Study of a Wearable NMES System to Determine the Effects on Arm Usage in Hemiparetic and Hemiplegic Patients

ABSTRACT Introduction Brain disorders such as traumatic brain injury (TBI), stroke, cerebral palsy (CP), and surgical interventions can result in aberrant motor function in the contralateral limbs, resulting in paralysis, weakness, and/or spasticity. It is known that, in the short term, neuromuscular electrical stimulation (NMES), the application of low-level electrical currents to motor nerves to induce muscle contractions in paralyzed muscles, can stimulate affected muscle groups and increase arm mobility. However, there remains a paucity of longitudinal evidence examining NMES-mediated improvements of arm usage. Objective The aim of this study was to determine the effectiveness of a long-term BioSleeve intervention on the recovery of arm mobility in hemiparetic patients. Study Design The design of this study is a retrospective cohort study. Methods We examined self-reported arm usage in patients with 1) TBI, 2) stroke, 3) hemispherectomy, or 4) CP who wore Axiobionics’ BioSleeve NMES device and compared this to arm usage achieved from years of conventional therapy. Results The device was well-tolerated. Patients reported an average increase in arm usage from 9.9% to 43.5%, with the TBI subcohort reporting a consistent increase in arm usage of 5.7% per year over the treatment period. Conclusions This study supports the literature suggesting that longitudinal NMES can be used to increase arm usage in hemiplegic patients. Clinical Relevance Statement This study supports the use of wearable NMES intervention in the treatment of arm hemiparesis.

Effect of muscle length on maximum evoked torque, discomfort, contraction fatigue, and strength adaptations during electrical stimulation in adult populations: A systematic review.

Neuromuscular electrical stimulation (NMES) can improve physical function in different populations. NMES-related outcomes may be influenced by muscle length (i.e., joint angle), a modulator of the force generation capacity of muscle fibers. Nevertheless, to date, there is no comprehensive synthesis of the available scientific evidence regarding the optimal joint angle for maximizing the effectiveness of NMES. We performed a systematic review to investigate the effect of muscle length on NMES-induced torque, discomfort, contraction fatigue, and strength training adaptations in healthy and clinical adult populations (PROSPERO: CRD42022332965). We conducted searches across seven electronic databases: PUBMED, Web of Science, EMBASE, PEDro, BIREME, SCIELO, and Cochrane, over the period from June 2022 to October 2023, without restricting the publication year. We included cross-sectional and longitudinal studies that used NMES as an intervention or assessment tool for comparing muscle lengths in adult populations. We excluded studies on vocalization, respiratory, or pelvic floor muscles. Data extraction was performed via a standardized form to gather information on participants, interventions, and outcomes. Risk of bias was assessed using the Revised Cochrane risk-of-bias tool for cross-over trials and the Physiotherapy Evidence Database scale. Out of the 1185 articles retrieved through our search strategy, we included 36 studies in our analysis, that included 448 healthy young participants (age: 19-40 years) in order to investigate maximum evoked torque (n = 268), contraction fatigability (n = 87), discomfort (n = 82), and muscle strengthening (n = 22), as well as six participants with spinal cord injuries, and 15 healthy older participants. Meta-analyses were possible for comparing maximal evoked torque according to quadriceps muscle length through knee joint angle. At optimal muscle length 50° - 70° of knee flexion, where 0° is full extension), there was greater evoked torque during nerve stimulation compared to very short (0 - 30°) (p<0.001, CI 95%: -2.03, -1.15 for muscle belly stimulation, and -3.54, -1.16 for femoral nerve stimulation), short (31° - 49°) (p = 0.007, CI 95%: -1.58, -0.25), and long (71° - 90°) (p<0.001, CI 95%: 0.29, 1.02) muscle lengths. At long muscle lengths, NMES evoked greater torque than very short (p<0.001, CI 95%: -2.50, -0.67) and short (p = 0.04, CI 95%: -2.22, -0.06) lengths. The shortest quadriceps length generated the highest perceived discomfort for a given current amplitude. The amount of contraction fatigability was greater when muscle length allowed greater torque generation in the pre-fatigue condition. Strength gains were greater for a protocol at the optimal muscle length than for short muscle length. The quality of evidence was very high for most comparisons for evoked torque. However, further studies are necessary to achieve certainty for the other outcomes. Optimal muscle length should be considered the primary choice during NMES interventions, as it promotes higher levels of force production and may facilitate the preservation/gain in muscle force and mass, with reduced discomfort. However, a longer than optimal muscle length may also be used, due to possible muscle lengthening at high evoked tension. Thorough understanding of these physiological principles is imperative for the appropriate prescription of NMES for healthy and clinical populations.

Neuromuscular Electrical Stimulation of Peroneal Longus on Balance Control Ability in Young Adults with Chronic Ankle Instability: A Randomized Controlled Trial.

This study aimed to investigate the effects of six weeks of peroneal longus neuromuscular electrical stimulation (NMES) on the balance control ability in young adults with chronic ankle instability (CAI). This study is a double blind randomized controlled trial. Six weeks of NMES and placebo intervention were conducted in the NMES and control groups for 20 minutes, three times a week, respectively. Thirty-eight participants successfully completed the whole intervention and single-leg standing tests. The kinetics data of the center of pressure (COP) trajectory during static single-leg stance were measured using a Kistler force platform. Two-way repeated measures ANOVA was used to analyze the electrical stimulation effects. Significant interactions were detected in CAIT scores and all balance parameters including Displacement X (Dx), Displacement Y(Dy), 95% confidence ellipse area (95%AREA), root-mean-square (RMS) and COP mean displacement velocity (MV) (p < 0.05, 0.103 ≤ η2 ≤ 0.201). Significant between-group differences were found in CAIT scores (p = 0.003, Cohen's d = 0.215), Dx (p = 0.045, Cohen's d = 0.107), RMS-ml (p = 0.019, Cohen's d = 0.143) and 95%AREA (p = 0.031, Cohen's d = 0.123) after the six weeks interventions. Six weeks of NMES on the peroneus longus can improve static balance control ability in young adults with CAI, especially the stability of ankle frontal plane.

Inhibition of tibialis anterior spinal reflex circuits using frequency-specific neuromuscular electrical stimulation.

Neuromuscular electrical stimulation (NMES) can generate muscle contractions and elicit excitability of neural circuits. However, the optimal stimulation frequency for effective neuromodulation remains unclear. Eleven able-bodied individuals participated in our study to examine the effects of: (1) low-frequency NMES at 25 Hz, (2) high-frequency NMES at 100 Hz; and (3) mixed-frequency NMES at 25 and 100 Hz switched every second. NMES was delivered to the right tibialis anterior (TA) muscle for 1 min in each condition. The order of interventions was pseudorandomized between participants with a washout of at least 15 min between conditions. Spinal reflexes were elicited using single-pulse transcutaneous spinal cord stimulation applied over the lumbar enlargement to evoke responses in multiple lower-limb muscles bilaterally and maximum motor responses (Mmax) were elicited in the TA muscle by stimulating the common peroneal nerve to assess fatigue at the baseline and immediately, 5, 10, and 15 min after each intervention. Our results showed that spinal reflexes were significantly inhibited immediately after the mixed-frequency NMES, and for at least 15 min in follow-up. Low-frequency NMES inhibited spinal reflexes 5 min after the intervention, and also persisted for at least 10 min. These effects were present only in the stimulated TA muscle, while other contralateral and ipsilateral muscles were unaffected. Mmax responses were not affected by any intervention. Our results indicate that even a short-duration (1 min) NMES intervention using low- and mixed-frequency NMES could inhibit spinal reflex excitability of the TA muscle without inducing fatigue.

Neuromuscular Electrical Stimulation Improves Frontal Ankle Motor Control in Individuals With Chronic Ankle Instability During Drop Landing.

This study investigated the effect of neuromuscular electrical stimulation on the frontal ankle motor control in individuals with chronic ankle instability during drop landing. This was a randomized, controlled, double-blind trial. Thirty-six individuals with chronic ankle instability were randomly assigned to each group. Participants received 6-wk neuromuscular electrical stimulation intervention and sham stimulation in the neuromuscular electrical stimulation and control groups, respectively. Data were collected at week 0 and week 6 . A mixed-effects model and analysis of covariance were employed to investigate the between-group differences in continuous and discrete outcome variables at week 6 , with the outcome variables at week 0 as covariates. Compared to control group, neuromuscular electrical stimulation group exhibited a 2.66° (2.45, 2.86) reduction in frontal ankle inversion angle, a 47.41°/sec (-16.05, -78.77) decrease in peak ankle inversion angular velocity, and a 0.43 Nm/kg (0.18, 0.68) increase in peak ankle eversion moment during drop landing at week 6 . Applying 6-wk neuromuscular electrical stimulation to the fibularis longus resulted in decreased ankle inversion angle and ankle inversion angular velocity and increased peak ankle eversion moment during drop landing. Consequently, neuromuscular electrical stimulation could be considered an effective modality for individuals with chronic ankle instability to enhance the frontal ankle movement patterns and overall ankle motor control.

Effects of Neuromuscular Electrical Stimulation on Spasticity and Walking Performance among Individuals with Chronic Stroke: A Pilot Randomized Clinical Trial.

Stroke and its associated complications are a major cause of long-term disability worldwide, with spasticity being a common and severe issue. Physical therapy, involving stretching exercises and electrical stimulation, is crucial for managing spasticity. Therefore, this study aimed to evaluate the effects of neuromuscular electrical stimulation (NMES) combined with a conventional rehabilitation program (CRP) on plantarflexor muscle spasticity and walking performance among individuals with chronic stroke. A pilot randomized clinical trial (RCT) with two groups (active NMES and placebo) was conducted at the physical therapy departments of King Fahad Specialist Hospital, Buraydah, and Sultan Bin Abdulaziz Humanitarian City, Riyadh, Saudi Arabia (November 2020). The assessor and participants were blinded for the group assignment. The active NMES group received exercise and stimulation at the dorsiflexor muscles on the paretic leg for 30 min for 12 sessions. The placebo group received exercise and sham stimulation at the same position and duration as the active group. Of interest were the outcomes for plantarflexor muscle spasticity measured by the modified Ashworth scale (MAS), gait speed measured by 10 m walk test (10-MWT), and functional mobility measured by functional ambulatory category (FAC). Nineteen participants were randomized into active NMES (n = 10) and sham NMES (n = 9) groups, with no significant baseline differences. Within the active NMES group, significant improvements were observed in MAS (p = 0.008), 10-MWT (p = 0.028), and FAC (p = 0.046), while only 10-MWT time improved significantly in the sham NMES group (p = 0.011). Between-group analysis showed that only MAS was significantly lower in the active NMES group (p = 0.006). Percent change analysis indicated a significantly higher increase in percent change for MAS in the active NMES group compared to the sham NMES group (p = 0.035), with no significant differences in other outcome measures. This study showed that NMES in the active group led to significant improvements in spasticity, walking performance, and functional ambulation. Further research is needed to determine the ideal parameters, protocols, and patient selection criteria for NMES interventions in stroke rehabilitation.

Immediate Effects of Blood Flow Restriction Combined with Neuromuscular Electrical Stimulation in Female Amateur Football Players: A Pilot Trial

We aimed to investigate the acute effects of blood flow restriction (BFR) combined with neuromuscular electrical stimulation (NMES) on muscle strength, thigh circumference, and knee joint reposition sense in female amateur football players, as well as to determine whether this procedure is safe. Methods: This was a pilot trial. Twenty female amateur football players were randomized into two groups: group 1 (n = 10) received a single NMES session; group 2 (n = 10) received NMES + BFR. The measured variables included maximal voluntary eccentric contraction (MVEC) and maximal voluntary concentric contraction (MVCC), thigh circumference, and knee joint reposition sense test. The type of electrical current used was TENS (symmetrical biphasic rectangular pulse, 350 μs, and 50 Hz), combined simultaneously with active knee extension (75 repetitions in 4 sets, 20% MVCC, 30 s rest between sets), for both groups. Group 2 had BFR added (80% of arterial occlusion pressure). Results: Statistically significant differences (p ≤ 0.05) were obtained for thigh circumference in both groups. The comparison between groups did not show statistically significant differences (p ≤ 0.05) in MVEC, MVCC, thigh circumference, or the knee joint reposition sense test. Conclusions: Both the isolated NMES intervention and its combination with BFR induced immediate changes in thigh circumference without impairing the muscle strength or proprioceptive ability of the football players. However, these results should be interpreted with caution, and future studies including a control group and isolated BFR application are needed.

Effects of neuromuscular electrical stimulation on glycemic control: a systematic review and meta-analysis.

Physical inactivity increases the risk for metabolic diseases such as obesity and type 2 diabetes. Neuromuscular electrical stimulation (NMES) is an effective method to induce muscle contraction, particularly for populations with physical impairments and/or metabolic diseases. However, its effectiveness to improve glycemic control is unclear. This review aimed to determine the effectiveness of NMES on glycemic control. Electronic search consisted of MEDLINE (PubMed), EMBASE, Cochrane Library, Google Scholar, and Web of Science to identify studies that investigated the effects of NMES on glycemic control for this systematic review. The meta-analysis consists of the studies designed as randomized controlled trials. Effect sizes were calculated as the standardized mean difference (SMD) and meta-analysis was conducted using a random-effects model. Thirty-five studies met the inclusion criteria for systematic review and of those, nine qualified for the meta-analysis. Existing evidence suggested that NMES effectively improves glycemic control predominantly in middle-aged and elderly population with type 2 diabetes, obesity, and spinal cord injury. The meta-analysis is comprised of 180 participants and reported that NMES intervention lowered fasting blood glucose (SMD: 0.48; 95% CI: 0.17 to 0.78; p=0.002; I²=0%). Additional analysis using the primary measures reported by each study to indicate glycemic control (i.e., OGTT, HOMA-IR, and fasting glucose) also confirmed a significant effect of NMES on improving glycemic control (SMD: 0.41; 95% CI, 0.09 to 0.72; p=0.01; I²=11%). NMES protocol varied across studies and requires standardization. NMES could be considered as a therapeutic strategy to improve glycemic control in populations with physical impairments and/or metabolic disorders. https://www.crd.york.ac.uk/prospero/, identifier CRD42020192491.

The effect of neuromuscular electrical stimulation applied at different muscle lengths on muscle architecture and sarcomere morphology in rats.

Neuromuscular electrical stimulation (NMES) is often used to increase muscle strength and functionality. Muscle architecture is important for the skeletal muscle functionality. The aim of this study was to investigate the effects of NMES applied at different muscle lengths on skeletal muscle architecture. Twenty-four rats were randomly assigned to four groups (two NMES groups and two control groups). NMES was applied on the extensor digitorum longus muscle at long muscle length, which is the longest and stretched position of the muscle at 170° plantar flexion, and at medium muscle length, which is the length of the muscle at 90° plantar flexion. A control group was created for each NMES group. NMES was applied for 8 weeks, 10 min/day, 3 days/week. After 8 weeks, muscle samples were removed at the NMES intervention lengths and examined macroscopically, and microscopically using a transmission electron microscope and streo-microscope. Muscle damage, and architectural properties of the muscle including pennation angle, fibre length, muscle length, muscle mass, physiological cross-sectional area, fibre length/muscle length, sarcomere length, sarcomere number were then evaluated. There was an increase in fibre length and sarcomere number, and a decrease in pennation angle at both lengths. In the long muscle length group, muscle length was increased, but widespread muscle damage was observed. These results suggest that the intervention of NMES at long muscle length can increase the muscle length but also causes muscle damage. In addition, the greater longitudinal increase in muscle length may be a result of the continuous degeneration-regeneration cycle.

Effective corticospinal excitability neuromodulation elicited by short-duration concurrent and synchronized associative cortical and neuromuscular stimulations

Optimal parameters of combined repetitive associative transcranial magnetic stimulation (rTMS) and neuromuscular electrical stimulation (NMES) for neuromodulation of central nervous system (CNS) excitability are not well understood. We examined corticospinal excitability after short-duration concurrent and synchronized associative stimulation applied using primary motor cortex rTMS and upper-limb NMES. Intermittent theta burst stimulation (iTBS) was delivered with burst at 50 Hz and repeated at 5 Hz over the course of 192 s as an established cortical facilitation rTMS protocol. NMES was applied to activate the extensor carpi radialis muscle over the same 192 s duration. Four interventions were compared: (1) iTBS with concurrent and synchronized 50 Hz NMES; (2) iTBS with concurrent and synchronized 5 Hz NMES; (3) iTBS with concurrent and asynchronized 41 Hz NMES; (4) iTBS with 5 s delayed and synchronized 50 Hz NMES. Single-pulse motor evoked potential (MEP) responses elicited by transcranial magnetic stimulation of the primary motor cortex and maximum motor responses (Mmax) elicited by radial nerve stimulation were compared before and for 30 min after each intervention. Our results showed that corticospinal excitability (MEP/Mmax) was only facilitated after the iTBS and concurrent 50 Hz NMES intervention, but the responses returned to baseline within 10 min of completing the intervention. This result demonstrates that short-duration concurrent and synchronized stimulation could be applied to effectively neuromodulate corticospinal excitability. Therefore, repetitive synchronized associative stimulation of the primary motor cortical networks and sensorimotor peripheral circuits may be enhanced using synchronized 50 Hz frequency of activation during concurrent stimulation.

Effect of neuromuscular electrical stimulation on muscle strength in patients with mechanical ventilation in intensive care unit: cumulative Meta-analysis and trial sequential analysis

To evaluate the effect of neuromuscular electrical stimulation (NMES) on muscle strength and duration of mechanical ventilation through cumulative Meta-analysis and sequential trial analysis (TSA). Randomized controlled trial (RCT) of NMES intervention in intensive care unit (ICU) patients with mechanical ventilation were searched from PubMed database of US National Library of Medicine, EMbase database of Netherlands Medical Abstract, Web of Science, SinoMed database of China, CNKI, Wanfang data, VIP and other Chinese and English databases from database construction to July 15, 2021. The control group received ICU routine nursing or rehabilitation exercise; the experimental group received NMES (low frequency electric current through electrode stimulation to make muscle groups twitch or contract) based on routine care in ICU. Relevant data were screened, evaluated and extracted by two researchers independently. After extracting data, STATA 15.0 and TSA software were used to analyze the data and evaluate the research results. A total of 9 studies were enrolled, including 619 subjects. Among the 9 articles included, 2 were grade A and 7 were grade B, indicating good overall quality. Cumulative Meta-analysis showed that compared with ICU routine care, NMES improved muscle strength of patients undergoing mechanical ventilation [standardized mean difference (SMD) = 0.64, 95% confidence interval (95%CI) was 0.07 to 1.21] and shortened the duration of mechanical ventilation (SMD = -1.84, 95%CI was -2.58 to -1.10). TSA analysis of the two outcomes showed that the sample size of muscle strength outcome index (n = 518) and mechanical ventilation outcome index (n = 419) did not meet the expected information (RIS; n values of 618 and 685); the cumulative Z-value line of the muscle strength outcome index crossed the traditional boundary line and TSA boundary line, indicating that more tests were not needed to verify this result. In the outcome index of mechanical ventilation duration, it was found that the cumulative Z-value line only crossed the traditional boundary line, but did not cross the TSA boundary line, indicating that further studies in this area should be carried out in the future to demonstrate this result. NMES can improve ICU patients' muscle strength and reduce the duration of mechanical ventilation.

Short-term facilitation effects elicited by cortical priming through theta burst stimulation and functional electrical stimulation of upper-limb muscles.

Non-invasive theta burst stimulation (TBS) can elicit facilitatory or inhibitory changes in the central nervous system when applied intermittently (iTBS) or continuously (cTBS). Conversely, neuromuscular electrical stimulation (NMES) can activate the muscles to send a sensory volley, which is also known to affect the excitability of the central nervous system. We investigated whether cortical iTBS (facilitatory) or cTBS (inhibitory) priming can affect subsequent NMES-induced corticospinal excitability. A total of six interventions were tested, each with 11 able-bodied participants: cortical priming followed by NMES (iTBS + NMES and cTBS + NMES), NMES only (iTBSsham + NMES and cTBSsham + NMES), and cortical priming only (iTBS + rest and cTBS + rest). After iTBS or cTBS priming, NMES was used to activate right extensor capri radialis (ECR) muscle intermittently for 10min (5s ON/5s OFF). Single-pulse transcranial magnetic stimulation motor evoked potentials (MEPs) and maximum motor response (Mmax) elicited by radial nerve stimulation were compared before and after each intervention for 30min. Our results showed that associative facilitatory iTBS + NMES intervention elicited greater MEP facilitation that lasted for at least 30min after the intervention, while none of the interventions alone were effective to produce effects. We conclude that facilitatory iTBS priming can make the central nervous system more susceptible to changes elicited by NMES through sensory recruitment to enhance facilitation of corticospinal plasticity, while cTBS inhibitory priming efficacy could not be confirmed.

Home-Based Nonoperative-Side Quadriceps Neuromuscular Electrical Stimulation Prevents Muscle Weakness Following Anterior Cruciate Ligament Reconstruction

We compared the effectiveness of a home-based neuromuscular electrical stimulation (NMES) program applied to the quadriceps of the nonoperative side against sham-NMES as a complement to standard rehabilitation on knee extensor neuromuscular function in patients following anterior cruciate ligament (ACL) reconstruction. Twenty-four patients completed the 6 week NMES (n = 12) and sham-NMES (n = 12) post-operative interventions and were tested at different time points for neuromuscular function and self-reported knee function. Isometric, concentric, and eccentric strength deficits (muscle weakness) increased significantly from pre-surgery to 24 weeks post-surgery in the sham-NMES group (p < 0.05), while no significant changes were observed in the NMES group. On the stimulated (nonoperative) side, quadriceps voluntary activation and muscle thickness were respectively maintained (p > 0.05) and increased (p < 0.001) as a result of the NMES intervention, contrary to sham-NMES. Self-reported knee function improved progressively during the post-operative phase (p < 0.05), with no difference between the two groups. Compared to a sham-NMES intervention, a 6 week home-based NMES program applied to the quadriceps of the nonoperative side early after ACL reconstruction prevented the occurrence of knee extensor muscle weakness 6 months after surgery. We conclude that nonoperative-side NMES may help counteract muscle weakness after ACL reconstruction.

Hemodynamic responses to neuromuscular electrical stimulation and to metaboreflex activation.

Metabolites produced during muscle exercise can sensitize types III and IV fibers, which account for increasing blood pressure (BP) and vascular resistance in non-exercising limbs, as well as for redistributing the blood flow to active muscles; reflex response is called metaboreflex. Neuromuscular electrical stimulation (NMES) induces greater local muscle metabolic demand than voluntary isometric contractions. Metabolic accumulation is essential to activate muscle metaboreflex; thus, the hypothesis of the current study is that one NMES session can induce metaboreflex with different hemodynamic responses in upper and lower limbs. Objective - to investigate whether one acute NMES session could activate metaboreflex by inducing different hemodynamic responses between arms and legs. Twenty (20) healthy subjects (mean age = 47.7±9.4 years, 13 women, mean body mass index = 26 ± 3 kg/m2) participated in this randomized crossover study. All participants were subjected to two NMES interventions, one in the upper limbs (UPL) and the other in the lower limbs (LL). Mean blood pressure (MBP), blood flow (BF) and vascular resistance (VR) were used to selectively evaluate metaboreflex responses at baseline, during NMES interventions, and recovery periods with, and without, postexercise circulatory occlusion (PECO+ and PECO-, respectively) through the area under the curve (AUC) in VR. MBP increased by 13% during UPL interventions and only remained high during PECO+. Changes in MBP were not observed in LL, although BF in the contralateral leg has decreased by 14% during PECO+ protocol. Muscle metaboreflex activation (AUC differences in VR between PECO+ and PECO-) was not different between UPL and LL (P=0.655). Acute NMES session has induced similar metaboreflex activation in both arms and legs, although hemodynamic responses differed between interventions.

UK Stroke Supplement: 001 – High Scoring Oral Presentation – Swallowing and Nutrition: SWALLOWING THERAPY FOR DYSPHAGIA IN ACUTE AND SUB-ACUTE STROKE (COCHRANE SYSTEMATIC REVIEW)

Introduction Swallowing difficulties (oropharyngeal dysphagia (OD)) are common post-stroke but there is no specific guidance on treatment. We have updated the 2018 Cochrane review of dysphagia interventions to explore whether there is evidence of a significant benefit from OD interventions on swallowing impairment. Methods RCT’s of patients with a new onset of OD after stroke published before January 2021 were included. Results were screened and analysed by two independent researchers. Trials were divided to specific intervention types and data was analysed against 8 outcomes, the primary outcome being swallowing impairment (SI). Results 83 additional trials were analysed producing a review to a total of 129 trials. Three interventions were associated with reductions in outcomes: Acupuncture: SI (SMD −0.94 [95% CI−1.25,−0.63], p &lt; 0.0001); dysphagia (OR 0.41 [95% CI 0.33, 0.49], p &lt; 0.0001); and penetration aspiration scale score (PAS) (MD −0.68 [95% CI −1.17, −0.19], p = 0.006). Behavioural therapy: SI (SMD −0.88 95% CI −1.28, −0.48], p &lt; 0.0001); dysphagia (OR 0.41 [95% CI 0.29, 0.59], p &lt; 0.0001); PAS (MD −0.77 [95% CI −1.11, −0.42], p &lt; 0.0001); and chest infection/pneumonia (OR 0.43 [0.25, 0.74], p = 0.002). Neuromuscular electrical stimulation (NMES): SI (SMD −0.96 95% CI −1.38, −0.54], p &lt; 0.0001) and dysphagia (OR 0.39 [95% CI 0.27, 0.56], p &lt; 0.0001). The limited number of trials precluded comment on other interventions included within the review. Heterogeneity of trials ranged from mild-significant. Conclusions Low-to-moderate quality evidence from small-moderate sized trials suggest that Acupuncture, Behavioural and NMES interventions reduce swallowing impairment after stroke. Large, high-quality trials are needed to test whether specific interventions are effective.

Effects of Neuromuscular Electrical Stimulation on Quadriceps Muscle Strength and Mass in Healthy Young and Older Adults: A Scoping Review.

Although neuromuscular electrical stimulation (NMES) has been used as a safe and relevant complement to voluntary resistance training, its effectiveness in increasing quadriceps femoris muscle strength and mass in healthy young and older adults has not been determined. The aim of this scoping review was to assess the effects of NMES on quadriceps muscle strength and mass in healthy young and older adults. CENTRAL, Pedro, MEDLINE, and PubMed were searched from inception to September 2019. Randomized controlled trials (RCTs) that compared NMES with control group or voluntary resistance training for healthy young and older adults were included. Study characteristics, primary and secondary outcome parameters, and details of the NMES intervention were extracted by 2 reviewers. Only studies for which full text was available in English were included. Thirty-two RCTs including 796 healthy participants were identified as being eligible for young adults, and 5 RCTs including 123 healthy participants were identified as being eligible for older adults. The available evidence strongly suggests that NMES improves quadriceps muscle strength compared with a control group in young adults, but its efficacy seems lower than that of voluntary resistance training. The available limited evidence regarding the effects of NMES on quadriceps muscle mass compared with control in young adults is inconclusive, with 3 RCTs showing positive effects and 3 RCTs not showing positive effects. The very limited available evidence from 5 RCTs in older adults suggests that NMES might be beneficial for increasing quadriceps muscle strength and mass. Overall, the evidence indicates that NMES is an efficacious method for increasing quadriceps muscle strength in young adults, whereas its impact on muscle mass requires further investigations. In addition, the effectiveness of NMES needs to be confirmed in older adults on the basis of more high-quality RCTs with larger sample sizes. This scoping review of 37 RCTs including 919 people is the first study, to the authors' knowledge, to show that the use of NMES increases quadriceps muscle strength in young adults and might improve quadriceps muscle strength compared with control interventions in older adults. In both young and older adults, the effects of NMES on quadriceps muscle mass are still unclear.

A randomised clinical trial comparing 35\xa0Hz versus 50\xa0Hz frequency stimulation effects on hand motor recovery in older adults after stroke

More solid data are needed regarding the application of neuromuscular electrical stimulation (NMES) in the paretic hand following a stroke. A randomised clinical trial was conducted to compare the effects of two NMES protocols with different stimulation frequencies on upper limb motor impairment and function in older adults with spastic hemiparesis after stroke. Sixty nine outpatients were randomly assigned to the control group or the experimental groups (NMES with 50 Hz or 35 Hz). Outcome measures included motor impairment tests and functional assessment. They were collected at baseline, after 4 and 8 weeks of treatment, and after a follow-up period. NMES groups showed significant changes (p < 0.05) with different effect sizes in range of motion, grip and pinch strength, the Modified Ashworth Scale, and the muscle electrical activity in the extensors of the wrist. The 35 Hz NMES intervention showed a significant effect on Barthel Index. Additionally, there were no significant differences between the groups in the Box and Block Test. Both NMES protocols proved evidence of improvements in measurements related to hand motor recovery in older adults following a stroke, nevertheless, these findings showed that the specific stimulation frequency had different effects depending on the clinical measures under study.