Quadriceps Neuromuscular Electrical Stimulation Research Articles

Combining exercise, protein supplementation and electric stimulation to mitigate muscle wasting and improve outcomes for survivors of critical illness—The ExPrES study

BackgroundNeuromuscular electrical stimulation (NMES) with high protein supplementation (HPRO) to preserve muscle mass and function has not been assessed in ICU patients. We compared the effects of combining NMES and HPRO with mobility and strength rehabilitation (NMES+HPRO+PT) to standardized ICU care. ObjectivesTo assess the effectiveness of combined NMES+HPRO+PT in mitigating sarcopenia as evidenced by CT volume and cross-sectional area when compared to usual ICU care. Additionally, we assessed the effects of the combined therapy on select clinical outcomes, including nutritional status, nitrogen balance, delirium and days on mechanical ventilation. MethodsParticipants were randomized by computer generated assignments to receive either NMES+HPRO+PT or standard care. Over 14 days the standardized ICU care group (N = 23) received usual critical care and rehabilitation while the NMES+HPRO+PT group (N = 16) received 30 min neuromuscular electrical stimulation of quadriceps and dorsiflexors twice-daily for 10 days and mean 1.3 ± 0.4 g/kg body weight of high protein supplementation in addition to standard care. Nonresponsive participants received passive exercises and, once responsive, were encouraged to exercise actively. Primary outcome measures were muscle volume and cross-sectional area measured using CT-imaging. Secondary outcomes included nutritional status, nitrogen balance, delirium and days on mechanical ventilation. ResultsThe NMES+HPRO+PT group (N = 16) lost less lower extremity muscle volume compared to the standard care group (N = 23) and had larger mean combined thigh cross-sectional area. The nitrogen balance remained negative in the standard care group, while positive on days 5, 9, and 14 in the NMES+HPRO+PT group. Standard care group participants experienced more delirium than the NMES+HPRO+PT group. No differences between groups when comparing length of stay or mechanical ventilation days. ConclusionsThe combination of neuromuscular electrical stimulation, high protein supplementation and mobility and strength rehabilitation resulted in mitigation of lower extremity muscle loss and less delirium in mechanically ventilated ICU patients.Trial Registration: Clinicaltrials.gov identifier: NCT02509520. Registered July 28, 2015

Neuromuscular electrical stimulation effect on mRNA expression of skeletal muscle in elderly.

Considering the increasing number of elderly in the world, this research aimed to investigate the effect of neuromuscular electrical stimulation (NMES) on changes in muscle mRNA abundance of a number of gene targets for improving the balance of the elderly. Twenty-six elderly undertook 30 minutes of quadriceps NMES (50 Hz, current at the limit of tolerance). Vastus lateralis muscle biopsies were obtained at rest immediately before and 24 hours after the intervention. The expression of 384 targeted mRNA transcripts was assessed by Real-time TaqMan PCR. A significant change in expression from baseline was determined using the ΔΔCT method with a false discovery rate (FDR) of <5%. The results showed that the biological functions of upregulated genes included muscle protein turnover, hypertrophy, inflammation, and muscle growth, while downregulated genes included mitochondrial and cell signaling functions. In general conclusion, it can be said that NMES can improve balance in the elderly. Therefore, considering the importance of balance in old people, it is suggested to use this method to improve the balance of the elderly.

BJS Prize 1 Postoperative electrical muscle stimulation attenuates loss of muscle mass and function following major abdominal surgery: A split body randomised control trial

Abstract Aims Significant loss of muscle mass and function occurs after major abdominal surgery. Neuromuscular electrical stimulation (NMES) has been shown to reduce muscle atrophy in some patient groups, but evidence in postoperative patients is limited. This study assesses the efficacy of NMES in attenuating muscle atrophy following major abdominal surgery. Methods Fifteen patients undergoing open colorectal resection were recruited to a split body randomised control trial and their lower limbs randomised to control (CON) or NMES (STIM). The STIM limb underwent 15 minutes of quadriceps NMES twice daily on postoperative day (POD) 1 to 4. Ultrasound measurement of Vastus Lateralis (VL) cross sectional area (CSA) and muscle thickness (MT) was made preoperatively and on POD 5, as was dynamometer measurement of knee extensor strength (KES). All outcomes were analysed using linear mixed model techniques. The study was approved by NHS research ethics committee (ref 20/EM/069). Results NMES significantly reduced the loss of CSA (-2.52% vs -9.16%, p&amp;lt;0.001), MT (-2.76% vs -8.145, p=0.001) and KES (-10.35% vs -19.69%, p=0.03). No adverse events occurred, and patients reported that NMES caused minimal or no discomfort. Conclusions NMES reduces loss of muscle mass and function following major abdominal surgery and may be an important tool in aiding recovery to normal activity levels. This will be especially important in preventing postoperative loss of independence in the increasingly physiologically frail patients undergoing major abdominal surgery. Further studies should establish the efficacy of bilateral whole-leg NMES for improving patient-centred outcomes.

Hip and Knee Joint Angles Determine Fatigue Onset during Quadriceps Neuromuscular Electrical Stimulation.

Neuromuscular electrical stimulation (NMES) has been used to increase muscle strength and physical function. However, NMES induces rapid fatigue, limiting its application. To date, the effect of quadriceps femoris (QF) muscle length by knee and hip joint manipulation on NMES-induced contraction fatigability is not clear. We aimed to quantify the effects of different muscle lengths on NMES-induced contraction fatigability, fatigue index, and electromyographic (EMG) activity for QF muscle. QF maximum evoked contraction (QMEC) was applied in a 26 min protocol (10 s on; 120 s off; 12 contractions) in 20 healthy participants (24.0 ± 4.6 years old), over 4 sessions on different days to test different conditions. The tested conditions were as follows: supine with knee flexion of 60° (SUP60), seated with knee flexion of 60° (SIT60), supine with knee flexion of 20° (SUP20), and seated with knee flexion of 20° (SIT20). Contraction fatigability (torque decline assessed by maximal voluntary contraction [MVC] and during NMES), fatigue index (percentage reduction in MVC), and EMG activity (root mean square [RMS] and median frequency) of the superficial QF' constituents were assessed. After NMES, all positions except SUP20 had an absolute reduction in MVC (p < .001). Fatigue index was greater in SIT20 than in SIT60 (p < .001) and SUP20 (p = .01). There was significant torque reduction across the 12 QMEC in SUP60 and SIT60, up to 10.5% (p < .001–.005) and 9.49% (p < .001–.033), respectively. There was no torque reduction during NMES in SUP20 and SIT20. Fatigue was accompanied by an increase in RMS (p = .032) and a decrease in median frequency for SUP60 (p < .001). Median frequency increased only in the SUP20 condition (p = .021). We concluded that QF NMES-induced contraction fatigability is greater when the knee is flexed at 60° compared to 20°. In addition, a supine position promotes earlier fatigue for a 60° knee flexion, but it delays fatigue onset for a 20° knee flexion compared to the seated position. These results provide a rationale for lower limb positioning during NMES, which depends on training objectives, e.g., strengthening or task-specific functionality training.

Knee extensor force production and discomfort during neuromuscular electrical stimulation of quadriceps with and without gluteal muscle co-stimulation

PurposeTo investigate whether Neuromuscular Electrical Stimulation (NMES) simultaneously applied on the quadriceps (Q) and gluteal (G) muscles, as compared to single Q-stimulation alters the knee extensor force production and discomfort.MethodsA total of 11 healthy participants (6 females), with normal weight and age between 19 and 54 years were included. The unilateral, isometric maximal voluntary contraction (MVC) was assessed for each participant in an isokinetic dynamometer (Biodex, system 3). NMES was, in a randomized order, applied only on the Q-muscle and on the Q- and G-muscles (QG) simultaneously. NMES-intensity was increased stepwise until the maximal tolerable level was reached regarding discomfort, graded according to the visual analogue scale (VAS). VAS and the % of MVC produced by NMES, were registered for each level, expressed as median (inter-quartile range).ResultsThe maximum tolerated NMES-intensity applied on Q compared to QG resulted in equally high discomfort, 8.0 (6.0–9.0) vs 8.0 (6.3–9.0), and in equivalent knee extensor force production, 36.7 (29.9–47.5) and 36.2 (28.9–49.3), respectively, in % of MVC. At 20% of MVC, NMES applied on Q compared to QG resulted in equal acceptable discomfort, 3.0 (2.0–4.5) vs 3.0 (3–5.5), and comparable intensity levels, 41.5 (38.0–45.8) vs 43.5 (37.0–48.8), respectively.ConclusionsSimultaneous QG-NMES, as compared to single Q-NMES, does not seem to affect the knee extensor force production or discomfort. Q-NMES, without voluntary muscle contraction, can with an acceptable level of discomfort result in at least 20% of MVC.

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.

Effects of neuromuscular electrical stimulation on energy expenditure and postprandial metabolism in healthy men.

It is unclear whether neuromuscular electrical stimulation (NMES) has meaningful metabolic effects when users have the opportunity to self-select the intensity to one that can be comfortably tolerated. Nine healthy men aged 28 ± 9 y (mean ± SD) with a body mass index 22.3 ± 2.3 kg/m2 completed 3 trials involving a 2-h oral glucose tolerance test whilst, in a randomised counterbalanced order, (1) sitting motionless (SIT), (2) standing motionless (STAND); and (3) sitting motionless with NMES of quadriceps and calves at a self-selected tolerable intensity. The mean (95% confidence interval [CI]) total energy expenditure was greater in the NMES trial (221 [180-262] kcal/2 h) and STAND trial (178 [164-191] kcal/2 h) than during SIT (159 [150-167] kcal/2 h) (both, p < 0.05). This was primarily driven by an increase in carbohydrate oxidation in the NMES and STAND trials compared with the SIT trial (p < 0.05). Postprandial insulin iAUC was lower in both NMES and STAND compared with SIT (16.4 [7.7-25.1], 17 [7-27] and 22.6 [10.8-34.4] nmol·120 min/L, respectively; both, p < 0.05). Compared with sitting, both NMES and STAND increased energy expenditure and whole-body carbohydrate oxidation and reduced postprandial insulin concentrations in healthy men, with more pronounced effects seen with NMES. Self-selected NMES is a potential strategy for improving metabolic health. This trial is registered at ClinicalTrials.gov (ID: NCT04389736). Novelty: NMES at a comfortable intensity enhances energy expenditure and carbohydrate oxidation, and reduces postprandial insulinemia. Thus, self-selected NMES represents a potential strategy to improve metabolic health.

The effects of knee and hip joint angles on patellar tendon loading during quadriceps neuromuscular electrical stimulation

The effects of knee and hip joint angles on patellar tendon loading during quadriceps neuromuscular electrical stimulation

THE EFFECTS OF NEUROMUSCULAR ELECTRICAL STIMULATION IN ASSOCIATION WITH WHEY PROTEIN SUPPLEMENTATION AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

ABSTRACTObjective: To analyze the effects of neuromuscular electrical stimulation of the femoral quadriceps associated or not with whey protein supplementation on the electromyographic activity and body mass distribution in volunteers undergoing anterior cruciate ligament reconstruction. Methods: 24 volunteers were randomly divided into three groups: basal control, whey protein in association with neuromuscular electrical stimulation, and neuromuscular electrical stimulation alone. Results: In the postoperative evaluation, during the mini squat, the basal group showed a decrease in the electromyographic activity of the vastus medialis (p = 0.005, eyes open; p = 0.003, eyes closed), vastus lateralis (p = 0.005, eyes open; p = 0.020; eyes closed) and rectus femoris (p = 0.075, eyes open; p = 0.074, eyes closed) and of body mass distribution in the injured limb (p < 0.001, eyes open; p < 0.001, eyes closed), and in the healthy limb (p < 0.001, eyes open; p < 0.001, eyes closed). Conclusion: The early use of neuromuscular electrical stimulation of the quadriceps femoris maintained the electromyographic activity of the vastus medialis and vastus lateralis muscles and prevented asymmetries in body mass distribution 15 days after anterior cruciate ligament reconstruction. Level of Evidence I, High quality randomized trial.

Early neuromuscular electrical stimulation reduces the loss of muscle mass in critically ill patients - A within subject randomized controlled trial.

To investigate the effect of Neuromuscular Electrical Stimulation (NMES) on muscle thickness, strength and morphological and molecular markers of the quadriceps. Adult critically ill patients with an expected prolonged stay received unilateral quadriceps NMES sessions for 7 consecutive days. Before and after the intervention period, quadriceps thickness was measured with ultrasound. After the intervention period, strength was assessed in cooperative patients and muscle biopsies were taken. Multivariable regression was performed to identify factors affecting muscle thickness loss. Muscle thickness decreased less in the stimulated leg (-6±16% versus -12±15%, p=0.014, n=47). Strength was comparable. Opioid administration, minimal muscle contraction and more muscle thickness loss in the non-stimulated muscle were independently associated with better muscle thickness preservation. Stimulated muscles showed a shift towards larger myofibers and higher MyHC-I gene expression. NMES did not affect gene expression of other myofibrillary proteins, MuRF-1 or atrogin-1. Signs of myofiber necrosis and inflammation were comparable for both muscles. NMES attenuated the loss of muscle mass, but not of strength, in critically ill patients. Preservation of muscle mass was more likely in patients receiving opioids, patients with a minimal muscle contraction during NMES and patients more prone to lose muscle mass. clinicaltrials.govNCT02133300.

Computed Tomography Image Analysis of Neuromuscular Electrical Stimulation in the Treatment of Knee Osteoarthritis with Different Radiologic Characteristics Based on Iterative Reconstruction Algorithm

To use computed tomography image analysis of iterative reconstruction algorithm to understand effect of neuromuscular electrical stimulation of quadriceps on motor function rehabilitation after total knee arthroplasty. After total knee arthroplasty, 104 patients were randomly divided into 2 groups. The treatment group comprised 52 patients. The quadriceps femoris was stimulated by neuromuscular electrical stimulation, and patients were required to actively extend the knee along with the current stimulation. In the second group, which received cutaneous nerve electrical stimulation, 2 sets of electrodes were placed on knee pain points. All patients participated in conventional rehabilitation and were discharged from the hospital a mean 14.89 ± 3.65 days after treatment. Visual analog scale, range of motion of knee joint, and Knee Injury and Osteoarthritis Score were evaluated before discharge. The mean interval between follow-up evaluations after discharge was 9.5 months. Knee Society Score and Knee Injury and Osteoarthritis Score were assessed during follow-up. Visual analog scale scores of treatment and control groups at discharge were 18.11 ± 9.66 and 16.13 ±4.25, and active range of motion of the knee joint was 103.21° ± 15.44° and (99.21° ± 15.19°, respectively. Limitation of active knee extension in the treatment group was 1.93° ± 3.47°, which was significantly smaller than in the control group (6.26° ± 4.28°). Neuromuscular electrical stimulation of the quadriceps muscle early after total knee arthroplasty helps to improve the function of the knee extension device and accelerate functional rehabilitation. Computed tomography has found that changes in tibial subchondral bone plate and subchondral cancellous bone in patients with knee osteoarthritis are mainly due to destruction of ultrastructural homeostasis. This change may be the cause of knee osteoarthritis.

Training Effects Of Alternated And Pulsed Currents On Body Mass Of Competitive Athletes

Neuromuscular electrical stimulation (NMES) is widely used for strength training in healthy individuals and athletes. Previous studies have shown that alternated mid-frequency currents (MF) and low-frequency pulsed currents (PC) have similar effects on quadriceps evoked strength and level of discomfort in this population. However, little is known about the effects and best parameters of NMES to induce body mass loss. PURPOSE: To evaluate the effects of 6 weeks of training with 2 different NMES currents - medium alternated and low frequency pulsed current - on body mass of competitive athletes. METHODS: A double-blind controlled and randomized experimental study was carried out with 33 athletes (22.2 ± 2.6 yrs, 74.7 ± 9.8 kg, 176.8 ± 6.0 cm), divided into 3 groups: mid-frequency current (MF, n=12), pulsed current (PC, n=11) and control group (CG, n=10). Body mass was assessed before and after the intervention through a body mass scale (BC-418, Tanita Corporation of America Inc., Illinois, USA). NMES training was performed 3 times per week and consisted of 18 sessions, 15 min/session (36 involuntary isometric quadriceps contractions per session), 6s duration in each contraction interspersed with 18s rest. Data were expressed as means ± standard deviation (SD) and normality was checked using the Shapiro-Wilk test. A two-way analysis of variance (ANOVA) with repeated-measures and Tukey post-hoc test were used to analyze data (group and time effects). Statistical significance was accepted with p < 0.05. RESULTS: After the training period, body mass did not change in any group (PRE: PC = 76.1 ± 8.1 kg, MF = 74.7 ± 9.8 kg, CG = 73.5 ± 21.5 kg; POST: PC = 76.7 ± 8.9 kg, MF = 74.7 ± 9.4 kg, CG = 74.0 ± 11.3 kg; p > 0.05). All currents produced similar evoked torque and levels of discomfort (p > 0.05). CONCLUSION: Quadriceps NMES training applied through alternated or pulsed currents produced similar effects and did not change body mass in competitive athletes.

Functional electrical stimulation following anterior cruciate ligament reconstruction: a randomized controlled pilot study

BackgroundInadequate quadriceps strength following anterior cruciate ligament reconstruction (ACLR) often results in alterations in gait pattern that are usually reported during loading response. Neuro-muscular electrical stimulation (NMES) is frequently used to overcome this quadriceps weakness. Despite the beneficial effects of NMES, persistent deficits in strength and gait are reported. The aim of this study was to investigate the feasibility of applying quadriceps functional electrical stimulation (FES) during walking in addition to standard rehabilitation, in the initial stage of ACLR rehabilitation.MethodsSubjects were randomized to quadriceps FES synchronized with walking group (n = 10) or quadriceps NMES (duty cycle of 10 s on/10 s off) group (n = 13). Both interventions were performed for 10 min three days a week, in addition to a standard rehabilitation program. Assessments were performed up to 2 weeks before the ACLR (pre-ACLR), and 4 weeks postoperatively. Outcomes measured were gait speed, single limb stance gait symmetry, quadriceps isometric peak strength ratio (peak strength at 4 weeks/peak strength pre-ACLR) and peak strength inter-limb symmetry. Gait outcomes were also assessed 1-week post-surgery.ResultsSubjects in both groups regained pre-ACLR gait speed and symmetry after 4 weeks of rehabilitation, with no difference between groups. However, although pre-ACLR quadriceps peak strength was similar between groups (FES - 205 Nm, NMES − 225 Nm, p = 0.605), subjects in the FES group regained 82% of their pre-quadriceps strength compared to 47% in the NMES group (p = 0.02). In addition, after 4 weeks, the FES group had significantly better inter-limb strength symmetry 0.63 ± 0.15 vs. 0.39 ± 0.18 in the NMES group (p = 0.01).ConclusionsQuadriceps FES combined with traditional rehabilitation is a feasible, early intervention treatment option, post-ACLR. Furthermore, at 4 weeks post-surgery, FES was more effective in recovering quadriceps muscle strength than was NMES. While spatiotemporal gait parameters did not differ between groups, kinetic and kinematic studies may be useful to further understand the effects of quadriceps FES post-ACLR. The promising results of this preliminary investigation suggest that such studies are warranted.Trial registrationISRCTN 02817399. First posted June 29, 2016.

Effects of neuromuscular electrical stimulation of quadriceps on the quadriceps strength and functional performance in nursing home residents: A comparison of short and long stimulation periods.

To determine the effect of two neuromuscular electrical stimulation (NMES) periods on quadriceps strength (QS) and functional performance in nursing home residents. A total of 53 older adults living in a nursing home were randomized into two groups: NMES with a short stimulation period and NMES with a long stimulation period. The quadriceps muscles were bilaterally stimulated three times a week for 6 weeks in both groups. Strength was measured with a digital handheld dynamometer and 30-s chair stand test. Functional performance was evaluated with the Berg balance scale, Timed Up and Go test and 6-min walking test. Analysis was carried out on 44 older adults, who completed the study protocol. The isometric QS did not change within groups or between groups. Interestingly, the 30-s chair stand test score increased for both groups, but the improvements were similar among groups. The Berg balance scale score, Timed Up and Go test time and 6-min walking test distance also improved in both groups. However, no difference in any of the functional outcome measures was observed between groups. The present findings showed that both NMES protocols might be an alternative to achieve an improvement in functional strength of the lower extremities and functional performance in nursing home residents, whereas neither of the two protocols seems effective for improving isometric QS. Both methods might contribute to maintaining isometric QS during the aging process. Geriatr Gerontol Int 2019; 19: 409-413.

Training Effects of Alternated and Pulsed Currents on the Quadriceps Muscles of Athletes.

The aim of the study was to evaluate the effects of 6 weeks training with different neuromuscular electrical stimulation (NMES) currents (medium alternated and low-frequency pulsed current) on muscle architecture and neuromuscular performance of competitive athletes. A double-blind controlled and randomized experimental study was carried out with 33 athletes (22.2±2.6 yrs, 74.7±9.8 kg, 176.8±6.0 cm), divided into 3 groups: mid-frequency current (MF, n=12), pulsed current (PC, n=11) and the control group (CG, n=10). Quadriceps maximal voluntary peak torque (PT) and corresponding vastus lateralis electromyographic activity, evoked torque (PT-NMES), vastus lateralis muscle thickness, fascicle length, pennation angle, and level of discomfort were assessed before and after the interventions. NMES training was performed 3 times per week and consisted of 18 sessions, 15 min/session, 6 s duration in each contraction interspersed with 18 s rest. After the training period, muscle thickness increased in the MF and PC groups (p<0.05). PT-NMES increased only in the PC group (p<0.05). All currents produced similar levels of discomfort (p>0.05). Quadriceps NMES training applied through alternated or pulsed currents produced similar effects in architecture and neuromuscular performance in competitive athletes.

Whole Body Oxygen Uptake and Evoked Torque During Subtetanic Isometric Electrical Stimulation of the Quadriceps Muscles in a Single 30-Minute Session

ObjectiveTo evaluate the time course of fatigue in torque output and oxygen uptake during isometric subtetanic neuromuscular electrical stimulation (NMES) to facilitate the design of NMES-based rehabilitation protocols that can accumulate a defined aerobic exercise volume within a given time period. DesignSingle-arm intervention study with within-subject comparisons. SettingUniversity research laboratory. ParticipantsVolunteer sample of healthy men (N=11; mean age, 34.2±11.5y; range, 19–53y; body mass, 79.1±11.7kg; range, 58–100kg). InterventionA single 30-minute session of continuous bilateral isometric quadriceps NMES at 4Hz evoking a mean twitch amplitude of 12% of the maximum voluntary contraction. Main Outcome MeasuresWhole body oxygen consumption rate (V˙o2), and evoked torque were measured simultaneously throughout. ResultsMean increment in V˙o2 was 596±238mL/min, and average exercise intensity during the session was 3±.47 metabolic equivalents. The V˙o2 and torque declined slowly at a rate of −.54%±.31% and −.47%±.57% per minute, respectively. ConclusionsDespite having a higher incremental V˙o2, the observed fatigue rate was considerably less than that previously reported during intermittent isometric tetanic stimulation, suggesting that subtetanic isometric NMES is more sustainable for exercise interventions aimed at accumulating a therapeutic aerobic exercise volume.

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

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

Variability in Muscle Adaptation to Electrical Stimulation

The aims were to investigate the plasticity of the myosin heavy chain (MHC) phenotype following neuromuscular electrical stimulation (NMES) and to assess the correlation between MHC isoform distribution and muscle fibre conduction velocity (MFCV).14 men were subjected to 24 sessions of quadriceps NMES. Needle biopsies were taken from the dominant vastus lateralis and neuromuscular tests were performed on the dominant thigh before and after training. NMES significantly increased the quadriceps maximal force by 14.4±19.7% (P=0.02), vastus lateralis thickness by 10.7±8.6% (P=0.01), vastus lateralis MFCV by 11.1±3.5% (P<0.001), vastus medialis MFCV by 8.4±1.8% (P<0.001). The whole spectrum of possible MHC isoform adaptations to training was observed: fast-to-slow transition (4 subjects), bi-directional transformation from MHC-1 and MHC-2X isoforms toward MHC-2A isoform (7 subjects), shift toward MHC-2X (2 subjects), no MHC distribution change (1 subject). No significant correlation was observed between MHC-2 relative content and vastus lateralis MFCV (pre-training: R2=0.04, P=0.46; post-training: R2=0.02, P=0.67). NMES elicited distinct adaptations in the MHC composition and increased force, muscle thickness, and MFCV. The MHC isoform distribution did not correlate with MFCV, thus implying that the proportion of different fibre types cannot be estimated from this electrophysiological variable.

Effects of Neuromuscular Electrical Stimulation and Aerobic Exercise Training on Arterial Stiffness and Autonomic Functions in Patients With Chronic Heart Failure

Neuromuscular electrical stimulation (NMES) of leg muscles has been introduced in clinical practice as a rehabilitation (RHB) method in patients with chronic heart failure (CHF); however, the role of NMES on the reduction of arterial stiffness and autonomic disbalance in these patients has not yet been studied. Sixty-one patients with stable CHF (mean age 58.9 [2.1] years; mean ejection fraction 31 [4.2]%, New York Heart Association II-III) were randomly assigned into two groups. Patients in (i) exercise training group (ET; n = 30) underwent 12 weeks of bicycle ET (3 × 40 min/week); (ii) group NMES (n = 31) performed 12 weeks of NMES of quadriceps and calf muscles (frequency 10 Hz, mode "20 s on-20 s off," intensity 60 mA), 2 × 60 min/day. Noninvasive assessment of arterial stiffness was done using the cardio-ankle vascular index (CAVI). CAVI and heart rate variability (HRV) and ·VO(2peak) were evaluated before and after RHB program. Both types of RHB reduced significantly CAVI (ET from 9.6 [0.2] to 8.9 [0.2], P < 0.012; NMES from 9.3 [0.2] to 8.7 [0.2], P < 0.013), increased high frequency (HF) component of HRV (+65.6%; P = 0.001) and decreased ratio of low frequency (LF) component with HF component (LF/HF ratio) in group ET (-39.8%; P < 0.001). Changes of HRV parameters in group NMES were not significant; however, a marked tendency to autonomic stabilization was present. Both types of RHB led also to significant increase of ·VO(2peak) (ET from 18.7 [0.7] to 20.8 [0.7] mL/kg/min, P < 0.004; NMES from 17.3 [0.7] to 19.0 [0.7] mL/kg/min, P < 0.001). ET or NMES has been shown to improve significantly arterial stiffness and to stabilize autonomic balance.