High-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.

Effects of Neuromuscular Electrical Stimulation in People with Spinal Cord Injury.

Muscle force production is usually impaired in people with spinal cord injury (SCI). The use of high-intensity neuromuscular electrical stimulation (NMES) strength training can help promote metabolically active lean muscle mass and, thus, increase muscle mass and improve physical health and quality of life (QoL). Nonetheless, NMES is usually used at low-stimulation intensities, and there is limited evidence on the effects of high-intensity NMES strength training into improving muscle force and mass, symptoms of spasticity, or physical health and QoL in people with SCI. Five individuals with chronic SCI completed five 10-repetition sets of high-intensity knee extension NMES strength training sessions for 12 wk in both quadriceps muscles. Quadriceps femoris (QF) knee extensor torque was measured on a dynamometer, and cross-sectional area (CSAQF) was measured with extended field-of-view ultrasonography. Venous blood samples were collected for blood lipid profiling and C-reactive protein analyses. The Spinal Cord Injury Spasticity Evaluation Tool was used to assess symptoms of spasticity, and the QoL index SCI version III was used for QoL measures. QF tetanic knee extensor torque increased on average by 35% (2%-92%), and CSAQF increased by 47% (14%-145%). A significant increase in the HDL/LDL cholesterol ratio (P < 0.001) and a mean significant improvement of 4.8% ± 2.3% (absolute value = 0.26) in the Spinal Cord Injury Spasticity Evaluation Tool score was observed, whereas QoL showed a near-significant improvement in the health and functioning domain (15.0 ± 4.2 and 17.3 ± 5.1; P = 0.07). High-intensity NMES strength training in people with SCI may improve muscle strength, mass, physical health, and QoL. However, replication of these results is necessary before clinical implementation.

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.

The Effects of High Intensity Neuromuscular Electrical Stimulation on Abdominal Strength and Endurance, Core Strength, Abdominal Girth, and Perceived Body Shape and Satisfaction

Background: Neuromuscular electrical stimulation (NMES) has been used clinically for many years as a modality to improve muscular strength and endurance. Recently, equipment manufacturers have developed over-the-counter NMES units to target specific muscle groups, particularly the abdominal region. Objective: To study the effects of self-administered neuromuscular electrical stimulation (NMES) on changes in abdominal muscle strength and endurance, core strength, abdominal girth, and subjective measures of body satisfaction and shape. Methods: Fifty-three adults were randomly assigned into high intensity (HI: n=27) or low intensity (LI: n=26) groups. The NMES device for the LI group had been altered so that subjects felt some tactile sensation, but the intensity was not sufficient to elicit a muscular contraction. All subjects stimulated their abdominal muscles 5 days per week (30 minutes per session) for 6 weeks. Subjects were tested at Baseline, 2, 4, and 6 weeks. Results: The HI group had a significantly greater increase in strength at 4 weeks (19%) and 6 weeks (29%) compared to the LI group and performed significantly more curl-ups than the LI group at 2 weeks (62%). Both groups had a significant increase in core strength over the course of the study, with no difference between groups. There was no change in abdominal girth between groups. Both groups had significant improvements in body satisfaction from Baseline to 4 weeks and Baseline to 6 weeks, with no significant interaction. Conclusions: Results of the current study indicate that high intensity NMES can significantly increase abdominal strength and endurance compared to LI intensity (control) stimulation. Results for subjective measures tended to favor the HI group, but were less conclusive, since the LI group also had some positive changes.

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.

Effect of neuromuscular electrical stimulation on motor cortex excitability upon release of tonic muscle contraction

The aim of the present study was to investigate the neurophysiological triggers underlying muscle relaxation from the contracted state, and to examine the mechanisms involved in this process and their subsequent modification by neuromuscular electrical stimulation (NMES). Single-pulse transcranial magnetic stimulation (TMS) was used to produce motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) in 23 healthy participants, wherein motor cortex excitability was examined at the onset of voluntary muscle relaxation following a period of voluntary tonic muscle contraction. In addition, the effects of afferent input on motor cortex excitability, as produced by NMES during muscle contraction, were examined. In particular, two NMES intensities were used for analysis: 1.2 times the sensory threshold and 1.2 times the motor threshold (MT). Participants were directed to execute constant wrist extensions and to release muscle contraction in response to an auditory “GO” signal. MEPs were recorded from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles, and TMS was applied at three different time intervals (30, 60, and 90 ms) after the “GO” signal. Motor cortex excitability was greater during voluntary ECR and FCR relaxation using high-intensity NMES, and relaxation time was decreased. Each parameter differed significantly between 30 and 60 ms. Moreover, in both muscles, SICI was larger in the presence than in the absence of NMES. Therefore, the present findings suggest that terminating a muscle contraction triggers transient neurophysiological mechanisms that facilitate the NMES-induced modulation of cortical motor excitability in the period prior to muscle relaxation. High-intensity NMES might facilitate motor cortical excitability as a function of increased inhibitory intracortical activity, and therefore serve as a transient trigger for the relaxation of prime mover muscles in a therapeutic context.

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

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

Quadriceps Activation Failure After Anterior Cruciate Ligament Rupture Is Not Mediated by Knee Joint Effusion

Descriptive prospective cohort study. To investigate the relationships between knee joint effusion, quadriceps activation, and quadriceps strength. These relationships may help clinicians better identify impaired quadriceps activation. After anterior cruciate ligament (ACL) injury, the involved quadriceps may demonstrate weakness. Experimental data have shown that quadriceps activation and strength may be directly mediated by intracapsular joint pressure created by saline injection. An inverse relationship between quadriceps activation and the amount of saline injected has been reported. This association has not been demonstrated for traumatic effusion. We hypothesized that traumatic joint effusion due to ACL rupture and postinjury quadriceps strength would correlate well with quadriceps activation, allowing clinicians to use effusion and strength measurement as a surrogate for electrophysiological assessment of quadriceps activation. Prospective data were collected on 188 patients within 100 days of ACL injury (average, 27 days) referred from a single surgeon. A complete clinical evaluation of the knee was performed, including ligamentous assessment and assessment of range of motion and effusion. Quadriceps function was electrophysiologically assessed using maximal volitional isometric contraction and burst superimposition techniques to quantify both strength and activation. Effusion grade did not correlate with quadriceps central activation ratio (CAR) (zero effusion: mean ± SD CAR, 93.5% ± 5.8%; trace effusion: CAR, 93.8% ± 9.5%; 1+ effusion: CAR, 94.0% ± 7.5%; 2+/3+ effusion: CAR, 90.6% ± 11.1%). These values are lower than normative data from healthy subjects (CAR, 98% ± 3%). Joint effusion after ACL injury does not directly mediate quadriceps activation failure seen after injury. Therefore, it should not be used as a clinical substitute for electrophysiological assessment of quadriceps activation. Patients presenting to physical therapy after ACL injury should be treated with high-intensity neuromuscular electrical stimulation to help normalize this activation.

A systematic review of evidence for anterior cruciate ligament rehabilitation: how much and what type?

This paper provides an evidence-based review of the effectiveness of various rehabilitation programs that have been used for surgically or non-surgically treated anterior cruciate ligament (ACL) injuries in adult patients. The methodological quality of the studies was assessed using specific criteria. The databases disclosed 33 randomized clinical trials (RCTs). Several of the RCTs in this systematic review have significant flaws, and limited evidence could be derived from them. The review of the literature revealed the following evidence for ACL rehabilitation: Immediate weight-bearing after ACL reconstruction is useful, rehabilitation programs must be monitored by a physical therapist, but continuously monitoring may not be necessary. The literature supports the use of closed kinetic chain exercises at knee joint motions of less than 60° and open kinetic chain exercises with knee flexion angles greater than 40° for quadriceps muscle strength training without increasing the strain on the ACL, and without increased stresses on the patellofemoral joint. There is evidence that high intensity neuromuscular electrical stimulation in addition to volitional exercises significantly improves isometric quadriceps muscle strength compared to volitional exercises alone. There is some evidence for neuromuscular training. Future studies should focus on high quality RCTs, reporting randomization procedures, power calculations, compliance to intervention programs, and long term follow-up results.

NEUROMUSCULAR ELECTRICAL STIMULATION FOR QUADRICEPS MUSCLE STRENGTHENING AFTER BILATERAL TOTAL KNEE ARTHROPLASTY

Study Design A case series. Objectives The purpose of this case series was to assess the effect of high-intensity neuromuscular electrical stimulation (NMES) on quadriceps strength and voluntary activation following total knee arthroplasty (TKA). Background Following TKA, patients exhibit long-term weakness of the quadriceps and diminished functional capacity compared to age-matched healthy controls. The pain and swelling that results from surgery may contribute to quadriceps weakness. The use of high-intensity NMES has previously been shown to be effective in quickly restoring quadriceps strength in patients with weakness after surgery. Methods and Measures All patients were treated for 6 weeks, 2 to 3 visits per week, in outpatient rehabilitation. Five patients (NMES group) participated in a voluntary exercise program for both knees and NMES for the weaker knee. Three patients (exercise group) participated in a voluntary exercise program for both knees without NMES For each treatment session, 10 isometr...

Electrical stimulation of quadriceps femoris in an elite weight lifter: a single subject experiment.

The response to treatment of high intensity neuromuscular electrical stimulation (NMES) to both quadriceps femoris muscles as an adjunct to ongoing weight training was evaluated using a single subject experimental design. For an elite weight lifter weekly maximal measurements of snatch (S), clean and jerk (CJ), and front squat (SQ) were obtained over 4 months during which the subject weight trained daily for 3 h. The 1st month, baseline data were collected. After baseline measurements, a 1-month period of high-intensity NMES was added to the subject's weight training. NMES was then withdrawn for 1 month and administered once more for 2 weeks. Three quadriceps femoris muscle biopsies were taken, two during the initial baseline period and one just before the end of the first stimulation period. The results showed a significant and clear relationship between performance gains and NMES administration and withdrawal. Steep gains for S, CJ, and SQ were seen after 2 weeks of stimulation, with front squat showing a 20-kg increase within the 1st week of both stimulation periods. Muscle biopsy showed an increased type I fiber area, decreased type IIa and IIb fiber area, and an increase of type II fibers after NMES. The results of this study support the use of high-dose NMES as an adjunct to weight training in elite lifters.