Low-intensity Neuromuscular Electrical Stimulation Research Articles

Efficacy of intradialytic neuromuscular electrical stimulation and oral nutritional supplementation in hemodialysis patients: a multicenter, randomized controlled trial.

Sarcopenia is common in hemodialysis patients. This study aimed to evaluate the effect of simultaneous nutritional support and intradialytic neuromuscular electrical stimulation (NMES) in hemodialysis patients. We performed a 12-week, multicenter, randomized controlled trial. The participants were randomly assigned to the control group, the protein group (25 g of protein at every dialysis session), the NMES group (intradialytic NMES to quadriceps femoris muscles), and the NMES + P group (NMES with protein supplementation). The primary outcome was the difference in hand grip strength (HGS) and leg muscle strength (LMS) among groups. Secondary outcomes included body composition, physical performance (the 10-m walk test and the timed up and go test [TUG]), and questionnaires about quality of life (QoL), physical activity, and depression. In addition, subgroup analysis was performed by dividing NMES and NMES + P groups into high- and low-intensity NMES groups. Fifty-nine patients completed all the study outcomes. There was no difference in muscle strength (HGS and LMS) and muscle mass among groups. Gait speed improved in NMES and NMES + P groups. Subscale scores for QoL (kidney disease effect, role limitations due to physical or emotional problems, and overall health ratings) improved in the NMES + P group. In subgroup analysis, LMS and TUG improved only in the high-intensity NMES group. In this study, NMES and-/or- protein supplementation did not make a significant difference in HGS and LMS. However, NMES or NMES + P improved functional capacity and QoL. Furthermore, higher NMES was superior in improving LMS and functional capacity.

Neuromuscular electrical stimulation in garments optimized for compliance

PurposePhysical inactivity is associated with muscle atrophy and venous thromboembolism, which may be prevented by neuromuscular electrical stimulation (NMES). This study aimed to investigate the effect on discomfort, current amplitude and energy consumption when varying the frequency and phase duration of low-intensity NMES (LI-NMES) via a sock with knitting-integrated transverse textile electrodes (TTE).MethodsOn eleven healthy participants (four females), calf-NMES via a TTE sock was applied with increasing intensity (mA) until ankle-plantar flexion at which point outcomes were compared when testing frequencies 1, 3, 10 and 36 Hz and phase durations 75, 150, 200, 300 and 400 µs. Discomfort was assessed with a numerical rating scale (NRS, 0–10) and energy consumption was calculated and expressed in milli-Joule (mJ). Significance set to p ≤ 0.05.Results1 Hz yielded a median (inter-quartile range) NRS of 2.4 (1.0–3.4), significantly lower than both 3 Hz with NRS 2.8 (1.8–4.2), and 10 Hz with NRS 3.4 (1.4–5.4) (both p ≤ .014). Each increase in tested frequency resulted in significantly higher energy consumption, e.g. 0.6 mJ (0.5–0.8) for 1 Hz vs 14.9 mJ (12.3–21.2) for 36 Hz (p = .003). Longer phase durations had no significant effect on discomfort despite generally requiring significantly lower current amplitudes. Phase durations 150, 200 and 400 µs required significantly lower energy consumption compared to 75 µs (all p ≤ .037).ConclusionLI-NMES applied via a TTE sock produces a relevant plantar flexion of the ankle with the best comfort and lowest energy consumption using 1 Hz and phase durations 150, 200 or 400 µs.

Does adding neuromuscular electrical stimulation to rehabilitation following total knee arthroplasty lead to a better quadriceps muscle strength recovery? A systematic review.

Patients undergoing total knee arthroplasty (TKA) show postsurgical quadriceps weakness. Neuromuscular electrical stimulation (NMES) has been shown to be an effective treatment for muscle strength recovery in a number of orthopaedic conditions. The aim of this review is to investigate whether adding NMES to TKA rehabilitation leads to a better quadriceps strength recovery in comparison with standardized rehabilitation. A second aim is to investigate which are the most commonly used NMES pulse settings and their effectiveness. A systematic review of literature was conducted on PubMed, Cochrane, Scopus and Web-of-Science. Intervention studies evaluating the effects of a rehabilitation intervention based on quadriceps NMES in patients undergoing TKA were retrieved. Methodological quality was assessed using the risk of bias-2 Cochrane tool. Features of NMES rehabilitation and technical data on NMES settings were extracted from the studies. Four studies met the inclusion criteria. Due to the limited number and the heterogeneity of the selected studies, it was not appropriate to carry out a meta-analysis. All the studies reported higher quadriceps strength in patients undergoing quadriceps NMES, particularly early after TKA. The addition of NMES or traditional strength training shows similar long-term effects. Short duration and low-intensity NMES have limited effects on quadriceps strength. Heterogeneity was found on NMES methodologies and pulse settings. In conclusion, NMES is effective for quadriceps strength recovery following TKA. NMES intensity and duration are essential for good NMES outcomes on quadriceps strength. Further studies on NMES methodologies, pulse features and settings are required to address the gaps in knowledge on NMES following TKA.

Effects of electrode size and placement on comfort and efficiency during low-intensity neuromuscular electrical stimulation of quadriceps, hamstrings and gluteal muscles

BackgroundNeuromuscular electrical stimulation (NMES) may prevent muscle atrophy, accelerate rehabilitation and enhance blood circulation. Yet, one major drawback is that patient compliance is impeded by the discomfort experienced. It is well-known that the size and placement of electrodes affect the comfort and effect during high-intensity NMES. However, during low-intensity NMES the effects of electrode size/placement are mostly unknown. Therefore, the purpose of this study was to investigate how electrode size and pragmatic placement affect comfort and effect of low-intensity NMES in the thigh and gluteal muscles.MethodsOn 15 healthy participants, NMES-intensity (mA) was increased until visible muscle contraction, applied with three electrode sizes (2 × 2 cm, 5 × 5 cm, 5 × 9 cm), in three different configurations on quadriceps and hamstrings (short-transverse (ST), long-transverse (LT), longitudinal (L)) and two configurations on gluteus maximus (short-longitudinal (SL) and long-longitudinal (LL)). Current–density (mA/cm2) required for contraction was calculated for each electrode size. Comfort was assessed with a numerical rating scale (NRS, 0–10). Significance was set to p < 0.05 and values were expressed as median (inter-quartile range).ResultsOn quadriceps the LT-placement exhibited significantly better comfort and lower current intensity than the ST- and L-placements. On hamstrings the L-placement resulted in the best comfort together with the lowest intensity. On gluteus maximus the LL-placement demonstrated better comfort and required less intensity than SL-placement. On all muscles, the 5 × 5 cm and 5 × 9 cm electrodes were significantly more comfortable and required less current–density for contraction than the 2 × 2 cm electrode.ConclusionDuring low-intensity NMES-treatment, an optimized electrode size and practical placement on each individual muscle of quadriceps, hamstrings and gluteals is crucial for comfort and intensity needed for muscle contraction.

Modulation of the rate of force development in hip abductor muscles by neuromuscular electrical stimulation during gait

Purpose/aim of the study: An increase of hip abductor muscle strength contributes to the increase in gait speed. It is known that the rate of force development (RFD), an indicator of muscle strength, is increased by the combined use of low-intensity neuromuscular electrical stimulation (NMES) to the glutaeus medius (GM) and low-load resistance training (RT). However, it is unclear whether low-intensity neuromuscular electrical stimulation of the glutaeus medius during walking also increases the rate of force development. The aim of this study was to clarify whether NMES to the GM during gait modulates the RFD of the hip abductor muscles in healthy adults.Materials and methods: Twenty-two healthy adults randomly received both gait with sub-motor threshold NMES and gait with sham NMES conditions. The RFD was assessed at pre- and post-intervention. A two-way repeated measures analysis of variance was used to analyse the effects of time and intervention.Results: Gait with sub-motor threshold NMES condition significantly increased the RFD in shorter time interval (0–50 and 0–100 ms) compared to gait with sham NMES condition.Conclusions: These findings suggest that the adding low-intensity NMES of the GM to gait is effective in increasing the RFD of the hip abductor muscles.

Effects of training intensity in electromyostimulation on human skeletal muscle.

High-intensity neuromuscular electrical stimulation (NMES) training can induce muscle hypertrophy at the whole muscle and muscle fiber levels. However, whether low-intensity NMES training has a similar result is unknown. This study aimed to investigate whether low-intensity NMES training could elicit muscle hypertrophy at the whole muscle and muscle fiber levels in the human skeletal muscle. Eight untrained young males were subjected to 18min of unilateral NMES training for 8 weeks. One leg received NMES at maximal tolerable intensity (HIGH); the other leg received NMES at an intensity half of that in the HIGH condition (LOW). Quadriceps muscle thickness (MT), muscle fiber cross-sectional area (CSA), and knee extension strength were measured before and after the training period. The average training intensity throughout the intervention period in the HIGH and LOW conditions were 62.5 ± 4.6% maximal voluntary contraction (MVC) and 32.6 ± 2.6% MVC, respectively. MT, CSA, and muscle strength increased in both exercise conditions (p < 0.05); however, training effects in the LOW condition were lower than those in the HIGH condition (p < 0.05). The average training intensity showed a positive correlation with percent changes in muscle strength (r = 0.797, p = 0.001), MT (r = 0.876, p = 0.001), type I fiber CSA (r = 0.730, p = 0.01), and type II fiber CSA (r = 0.899, p = 0.001). Low-intensity NMES could increase MT, muscle fiber CSA, and muscle strength in healthy human skeletal muscles. However, the magnitude of increase is lower in low-intensity than in high-intensity NMES training.

Wide-pulse, high-frequency, low-intensity neuromuscular electrical stimulation has potential for targeted strengthening of an intrinsic foot muscle: a feasibility study

BackgroundStrengthening the intrinsic foot muscles is a poorly understood and largely overlooked area. In this study, we explore the feasibility of strengthening m. abductor hallucis (AH) with a specific paradigm of neuromuscular electrical stimulation; one which is low-intensity in nature and designed to interleave physiologically-relevant low frequency stimulation with high-frequencies to enhance effective current delivery to spinal motoneurones, and enable a proportion of force produced by the target muscle to be generated from a central origin. We use standard neurophysiological measurements to evaluate the acute (~ 30 min) peripheral and central adaptations in healthy individuals.MethodsThe AH in the dominant foot of nine healthy participants was stimulated with 24 × 15 s trains of square wave (1 ms), constant current (150% of motor threshold), alternating (20 Hz–100 Hz) neuromuscular electrical stimulation interspersed with 45 s rest. Prior to the intervention, peripheral variables were evoked from the AH compound muscle action potential (Mwave) and corresponding twitch force in response to supramaximal (130%) medial plantar nerve stimulation. Central variables were evoked from the motor evoked potential (MEP) in response to suprathreshold (150%) transcranial magnetic stimulation of the motor cortex corresponding to the AH pathway. Follow-up testing occurred immediately, and 30 min after the intervention. In addition, the force-time-integrals (FTI) from the 1st and 24th WPHF trains were analysed as an index of muscle fatigue. All variables except FTI (T-test) were entered for statistical analysis using a single factor repeated measures ANOVA with alpha set at 0.05.ResultsFTI was significantly lower at the end of the electrical intervention compared to that evoked by the first train (p < 0.01). Only significant peripheral nervous system adaptations were observed, consistent with the onset of low-frequency fatigue in the muscle. In most of these variables, the effects persisted for 30 min after the intervention.ConclusionsAn acute session of wide-pulse, high-frequency, low-intensity electrical stimulation delivered directly to abductor hallucis in healthy feet induces muscle fatigue via adaptations at the peripheral level of the neuromuscular system. Our findings would appear to represent the first step in muscle adaptation to training; therefore, there is potential for using WPHF for intrinsic foot muscle strengthening.

Effects of neuromuscular electrical stimulation on contralateral quadriceps function

Because maximal voluntary strength of the knee extensor muscles can be facilitated by the concomitant application of neuromuscular electrical stimulation (NMES) to the contralateral homologous muscle, we aimed to determine whether this was associated with an enhanced neural drive to the agonist muscles. A secondary goal of this study was to examine the potential dose-response relationship between NMES intensity and contralateral facilitation. Twelve healthy men (age: 30 ± 7 yr) completed several maximal voluntary contractions (MVC) of the left knee extensors while the right quadriceps received low-intensity NMES (10% MVC), high-intensity NMES (30% MVC) or no NMES. Supramaximal paired stimuli were delivered to the left quadriceps muscle during and immediately after the MVCs to assess voluntary activation. The EMG activity of vastus lateralis (VL) and biceps femoris (BF) was recorded. MVC torque, voluntary activation and VL EMG activity were higher for both low-intensity and high-intensity NMES compared to no NMES (P < .05), with no difference between the two NMES conditions. The acute application of NMES to the right quadriceps facilitated MVC strength of the contralateral homonymous muscle by enhancing its efferent neural drive. No evident dose-response relationship between NMES intensity and contralateral facilitation was observed.

The Effects of Blood Flow Restricted Electrostimulation on Strength and Hypertrophy.

The combined effect of neuromuscular electrical stimulation (NMES) and blood flow restriction (BFR) on muscle mass and strength has not been thoroughly investigated. To examine the effects of combined and independent BFR and a low-intensity NMES on skeletal muscle adaptation. Exploratory study. Laboratory. Twenty recreationally active subjects. Subjects had each leg randomly allocated to 1 of 4 possible intervention groups: (1)cyclic BFR alone, (2)NMES alone, (3)BFR + NMES, or (4)control. Each leg was stimulated in its respective intervention group for 32minutes, 4days per week for 6weeks. Mean differences in size (in grams) and isometric strength (inkilograms), between week 0 and week 6, were calculated for each group. Leg strength increased 32 (19)kg in the BFR + NMES group, which differed from the 3 (11)kg change in the control group (P = .03). The isolated NMES and BFR groups revealed increases of 16 (28)kg and 18 (17)kg, respectively, but these did not statistically differ from the control, or one another. No alterations were statistically significant for leg size. Compared with a control that received no treatment, the novel combination of BFR and NMES led to increasing muscular strength of the knee extensors, but not muscle mass which had a large interindividual variability in response.

Effects of Electrostimulation with Blood Flow Restriction on Muscle Size and Strength.

Low-load voluntary exercise can induce muscle hypertrophy and strength gain in working muscles when combined with blood flow restriction (BFR). However, it is unknown whether such hypertrophy and strength gain can be induced by involuntary muscle contractions triggered via low-intensity neuromuscular electrical stimulation (NMES) combined with BFR. The purpose of this article was to investigate whether low-intensity NMES combined with BFR (NMES-BFR) could elicit muscle hypertrophy and strength gain in the quadriceps. Eight untrained young male participants (mean ± SE; age, 26.2 ± 0.7 yr; height, 1.74 ± 0.02 m; body weight, 71.4 ± 4.8 kg) were subjected to 23 min of unilateral low-intensity (5%-10% of maximal voluntary contraction) NMES twice per day (5 d·wk⁻¹) for 2 wk: one leg received NMES-BFR and the other leg received NMES alone. Quadriceps muscle thickness and isometric and isokinetic strength were measured before and every week throughout the training and detraining periods. In NMES-BFR legs, muscle thickness increased after 2 wk of training (+3.9%) and decreased after 2 wk of detraining (-3.0%). NMES-BFR training also increased maximal knee extension strength in isometric (+14.2%) and isokinetic (+7.0% at 90°·s⁻¹ and +8.3% at 180°·s⁻¹) voluntary contractions. In addition, maximal isometric strength decreased (-6.8%), whereas no large fall (-1.9% at 90°·s⁻¹ and -0.6% at 180°·s⁻¹) in isokinetic maximal strength was evident after 2 wk of detraining. In legs that received NMES alone, no prominent change was observed; there was a negligible effect on isometric strength. Low-intensity NMES-BFR induces muscle hypertrophy and strength gain in untrained young male participants.

Neuromuscular Electrical Stimulation During Recovery From Exercise

The use of subtetanic low-intensity neuromuscular electrical stimulation (NMES) for the purpose of promoting recovery from exercise has increased in recent years. The aim of this systematic review was to assess the effects of NMES on exercise recovery. A computerized database search of PubMed, CINAHL Plus, Sport Discus, and Cochrane Library electronic databases was conducted for the time period of January 1, 1970 to March 8, 2012. Only studies that used healthy uninjured humans and motor threshold electrical stimulation compared with at least one other recovery modality for the purpose of promoting recovery from exercise were eligible for selection. Thirteen studies satisfied the inclusion criteria and were included for analysis (11 randomized crossover trials, 1 randomized control trial [RCT], and 1 classified as other [OTH]). A quality assessment rating of the studies was performed using an extended version of The Cochrane Collaboration's tool for assessing risk of bias. Because of the heterogeneity of the study protocols, a qualitative review (best evidence synthesis) was performed for all outcomes, whereas the results for blood lactate (BLa) were also included in a meta-analysis. Eight studies were classified as high quality, 4 as medium quality, and 1 as low quality. Three studies found a positive outcome for a subjective measure of muscle pain, 3 for BLa, 1 for lowering creatine kinase, and only 1 for a performance parameter. The meta-analysis showed no evidence in favor of NMES vs. active (ACT) and mixed evidence vs. passive (PAS) recovery for BLa. In conclusion, although there may be some subjective benefits for postexercise recovery, evidence is not convincing to support NMES for enhancing subsequent performance.

CSM 2014 Sports Physical Therapy Section Platform Presentations (Abstracts SPL1–SPL66)

CSM 2014 Sports Physical Therapy Section Platform Presentations (Abstracts SPL1–SPL66)

Changes in spinal but not cortical excitability following combined electrical stimulation of the tibial nerve and voluntary plantar-flexion

Unilateral training involving voluntary contractions, neuromuscular electrical stimulation (NMES), or a combination of the two can increase the excitability of neural circuits bilaterally within the CNS. Many rehabilitation programs are designed to promote such "neuroplasticity" to improve voluntary movement following CNS damage. While much is known about this type of activity-dependent plasticity for the muscles that dorsi-flex the ankle, similar information is not available for the plantar-flexors. Presently, we assessed the excitability of corticospinal (CS) and spinal circuits for both soleus (SOL) muscles before and after voluntary contractions of the right plantar-flexors (VOL; 5 s on-5 s off, 40 min), NMES of the right tibial nerve (tnNMES; 5 s on-5 s off, 40 min), or both together (V + tnNMES). CS excitability for the right (rSOL) and left SOL (lSOL) muscles was assessed by quantifying motor evoked potentials elicited by transcranial magnetic stimulation. Spinal excitability was assessed using measures from the ascending limb of the M-wave versus H-reflex recruitment curve. CS excitability did not change for rSOL (the activated muscle) or lSOL following any condition. In contrast, there was a marked increase in spinal excitability for rSOL, but only following V + tnNMES; the slope of the M-wave versus H-reflex recruitment curve increased approximately twofold (pre = 7.9; post = 16.2) and H-reflexes collected when the M-wave was ~5 % of the maximal M-wave (M(max)) increased by ~1.5× (pre = 19 % M(max), post = 29 % M(max)). Spinal excitability for lSOL did not change following any condition. Thus, only voluntary contractions that were coupled with NMES increased CNS excitability, and this occurred only in the ipsilateral spinal circuitry. These results are in marked contrast to previous studies showing NMES-induced changes in CS excitability for every other muscle studied and suggest that the mechanisms that regulate activity-dependent neuroplasticity are different for SOL than other muscles. Further, while rehabilitation strategies involving voluntary training and/or NMES of the plantar-flexors may be beneficial for producing movement and reducing atrophy, a single session of low-intensity NMES and voluntary training may not be effective for strengthening CS pathways to the SOL muscle.

The physiological effects of low-intensity neuromuscular electrical stimulation (NMES) on short-term recovery from supra-maximal exercise bouts in male triathletes

This study investigated the acute effects of NMES on blood lactate (BLa) and performance parameters in trained male triathletes. On three separate days, 13 trained male triathletes performed six 30 s Wingate tests (30 WanT) on a cycle ergometer. Each session consisted of performing 3 × 30 WanT (bouts 1-3) followed by a randomly assigned 30 min recovery intervention of either: (i) passive (seated), (ii) active (cycling at 30% VO(2 max)) or (iii) NMES (1 Hz/500 μs-ON:OFF 2:6 s). The 3 × 30 WanT bouts were then repeated (bouts 4-6) and compared to bouts 1-3 for peak power (PP), mean power (MP) and fatigue index (FI). BLa and heart rate (HR) were recorded at designated time points throughout. Data were analyzed using repeated measures ANOVA with Tukey's honestly significant difference post hoc test. BLa decreased significantly faster during the active recovery intervention (P < 0.001), however, there were no significant differences between interventions for PP (P = 0.217), MP (P = 0.477) and FI (P = 0.234) when the post intervention bouts (4-6) where compared to the pre intervention bouts (1-3). NMES during recovery was not more effective than active or passive recovery for improving subsequent performance. Despite BLa clearing at a significantly faster rate for the active recovery intervention, PP, MP or FI did not improve significantly compared to NMES and passive. In conclusion, NMES does not appear to be more effective than traditional methods for enhancing short-term recovery from supra-maximal exercise bouts in trained male triathletes.