Neuromuscular Electrical Stimulation (NMES) Training

Our definition of neuromuscular electrical stimulation (NMES), and how we use the term “functional electrical stimulation (FES)”, can be found above in Section 3.0 on Cardiorespiratory Health and Endurance.

Author Year

Country
Research Design

Score
Total Sample Size

Methods

Outcome

Functional Electrical Stimulation Leg Cycling Exercise (FES-LCE)
Gorgey et al. (2016)

USA

Prospective Controlled Trial

N=11

Population: Gender: males=11, females=0; Level of injury: C1-T1=3, T2-L5=8; Level of severity: AIS A=8, AIS B=3, AIS C=0. Exercise group: Mean age: 40.5±7yr; Mean time since injury: 13.3±9.3yr. Control group: Mean age: 35±7.5yr; Mean time since injury: 4.7±4yr.

Intervention: Exercise group (n=6) received either: arm cycling ergometry (ACE), (n=3) or Functional electrical stimulation (FES)-LCE, (n=3). ACE was performed two to three times a week for 16 weeks with ten-minute warm-up, forty minutes of training, and with a ten-minute cool down. The workload was adjusted as the participant tolerated from 20 to 40 watts to maintain a peak HR at 75% of theirmaximum HR. The participant was encouraged to maintain an exercise rate of 50 revolutions per minute. FES cycling (n=3) was performed with bilateral stimulation of the quadriceps, hamstrings, and gluteal muscles. Muscles were stimulated sequentially at 60 Hz with current amplitude (140 mA) necessary to complete 40min of cycling at a cadence of 50 revolutions per min (RPM) with progressively greater resistance over the course of training. Each session included 10min of passive warm-up and cool down. Controls (n=5) did not receive any exercise intervention.

Outcome Measures: Anthropomorphic measurements, body composition, Basal Metabolic Rate (BMR) and blood lipid profiles for cholesterol, high-, low-density lipoproteins, triglycerides.

·         In a within group comparison there were significant ↑ in only thigh circumference; 48.5±8 to 52.6±10cm, p<0.05 for the exercise group. Measurements for waist, calf, and hip were all non significant. ·         In a between group comparison 2.5yr after the intervention, this thigh circumference was significantly larger in the exercise group. ·         Lean Mass (LM) ↑ by 8.4% and reverted back by 5.4% following 2.5yr of washout period. Whole body LM significantly ↓ at the follow-up visit compared to both the baseline visit (p=0.015) and the post-intervention visit (p=0.054) in the exercise group, with no changes in the control group. ·         Blood lipid profiles were all non significant in both within group comparison and between group comparison at 2.5yr follow up.
Van Duijnhoven et al. (2010)
Switzerland
Pre-PostN=9
Population: Mean age: 41yr; Gender: males=9, females=0; Level of injury: complete lesions C5-T11=7, incomplete lesion at C5=2; Level of severity: AIS A=7, AIS B=1, AIS D=1; Mean time since injury: >4yr.
Intervention:
Participants completed 8-week of Functional Electrical Stimulation (FES) exercise training. For FES a computer-controlled leg cycle ergometer was used and electrical stimulation (450µs, frequency 30Hz, 140mA), pedaling rate approximately 50rpm). A total of 20 sessions were completed (2/wk for 4wk then 3/wk for 4wk). Assessments were done at baseline and post intervention, as well as before and after first FES cycling session.
Outcome Measures:
Malondialdehyde levels (MDA), Superoxide dismutase (SOD) levels and Glutathione peroxidase enzyme (GPx) levels.
·         After a single FES training and after 8 weeks of FES training, there were no significant differences in MDA, SOD or GPx levels.
Jeon et al. (2002)

Canada

Pre-Post

N=7

Population: 5 male, 2 female, motor complete, C5-T10, ages 30-53yr, 3–40yr post-injury.

Intervention: FES leg-cycle training, 30 min/d, 3 d/wk, 8 wks.

Outcome Measures: oral glucose tolerance test (OGTT), glucose and insulin levels, glucose utilization, insulin sensitivity and levels.

·         There were significantly lower (14.3%) 2-hr OGTT glucose levels after 8wk of training.
Mohr et al. (2001)

Denmark

Pre-Post

N=10

Population: 8 male, 2 female, 6 tetraplegia, 4 paraplegia, C6-T4, age 35yr, 12yr post-injury.

Intervention: FES-LCE, 30 min/d, 3 d/wk, 12 months; 7 participants completed an additional 6 months (1 d/wk).

Outcome Measures: insulin-stimulated glucose uptake, oral glucose tolerance test (OGTT), GLUT 4 glucose transporter protein.

·         Insulin-stimulated glucose uptake rates ↑ after intensive training, suggesting improved insulin sensitivity.

·         With the reduction in training, insulin sensitivity ↓ to a similar level as before training. GLUT-4 content in the quadricep muscle significantly ↑ by 105% after intense training and ↓ again with the training reduction.

·         The participants had impaired glucose tolerance before and after training, and neither glucose tolerance nor insulin responses to OGTT were significantly altered by training.

Hjeltnes et al. (1998)

Sweden

Pre-Post

N=5

Population: 5 males, C5-C7, all complete AIS A, age 35yr, 10yr post-injury.

Intervention: Electrically stimulated leg cycling exercise, 7 d/wk, 8wk.

Outcome Measures: peripheral insulin sensitivity, whole body glucose utilization, glucose transport, phosphofructokinase, citrate synthase, hexokinase, glycogen synthase, blood glucose, plasma insulin.

·         After training, insulin-mediated glucose disposal was ↑ by 33%. There was a 2.1-fold ↑ in insulin-stimulated glucose transport.

·         Training led to marked ↑ in protein expression of GLUT4 (glucose transporter) (378%), glycogen synthase (526%), and hexokinase II (204%) in the vastus lateralis muscle.

·         Hexokinase II activity ↑ 25% after training.

FES Rowing (FES-ROW)
Jeon et al. (2010)

Canada

Pre-Post

N=6

Population: 6 male participants with paraplegia participated in the study (mean age, 48.6 ± 6.0 y; mean weight, 70.1 ± 3.3 kg; injury levels between T4-5 and T10).

Intervention: 12 weeks of FES-rowing exercise training 3 to 4 times a week (600–800 kcal).

Outcome measures: VO2peak, plasma leptin, insulin, and glucose levels, insulin sensitivity, body composition.

·         VO2peak ↑ from 21.4 ± 1.2 to 23.1 ± 0.8 mL/kg/min (P = 0.048).

·         Plasma leptin levels were significantly ↓ after the training (pre: 6.91 ± 1.82 ng/dL vs. post: 4.72 ± 1.04 ng/dL; P = 0.046).

·         Plasma glucose and leptin levels were significantly ↓ after exercise training by 10% and 28% (P = 0.028), respectively.

·         HOMA-IR did not reach statistical significance.

Solinsky et al. (2020)

USA

Pre-Post

N=40

Population: Mean age: 34.1±12.4yr; Gender: males=34, females=6; Level of injury: C1-T1=21, T2-L5=18 Unknown=1; Level of severity: AIS A=19, AIS B=8, AIS C=5, AIS D=2, AIS Unknown=6; Mean time since injury: 41.4±87.4mo.

Intervention: Hybrid Functional Electrical Stimulation (FES) on quadriceps and hamstrings during rowing exercise with a goal of 2-3 sessions/wk at a goal heart rate of over 75% of maximum, quantified during baseline. Individuals averaged 42.1± 22.0min of hybrid-FES rowing/wk, mean 1.69 sessions/wk for 6mo. Outcome Measures: VO2peak, Cardiometabolic Disease (CMD) indicator, SCI specific-Body Mass Index, A1C, free insulin, fasting glucose, LDL, HDL, total cholesterol, triglycerides.

·         VO2peak ↑ and AIC ↓ significantly, p<0.001 and p=0.01, respectively. ·         Non-significant ↓ in prevalence of cardiometabolic disease (p=0.70), BMI (p=0.27) Triglycerides (p=0.12), LDL (p=0.08), HDL (p= 0.48), cholesterol (p=0.11), except for A1C which was reduced over the 6 month period ·         Subdividing into those with para- or tetraplegia showed, neither group ↓ their prevalence of cardiometabolic disease to a significant degree (p>0.58 for both). The exception to this were ↑ in both LDL and insulin resistance (via HOMA-2) in the sub-group with paraplegia (p<0.05).
Neuromuscular Electrical Stimulation Resistance Training (NMES-RT)
Gorgey et al. (2019)

USA

RCT

PEDro=7

N=22

Population: Mean age: 37 ± 12 yr in experimental group (n=11), 35 ± 8 yr in control group (n=11); Gender: males=22, females=0; Level of injury: C1-T1=NR, T2-L5=NR; Level of severity: AIS A=16, AIS B=6, AIS C=0; Mean time since injury: 10 ± 9 in experimental group, 7 ± 6 in control group

Intervention: All subjects received 2–6 mg/day of testosterone (TRT) administered through transdermal testosterone patches. Experimental group (TRT-RT), received additional progressive resistance exercise of the knee extensor muscle groups and with neuromuscular electrical stimulation (NEMS). NMES was applied over thigh at Biphasic waveform, 30 Hz, 450 µs pulse width, current intensity enough to elicit full knee extension. RT was performed two times per week for the study duration of 16 weeks.

Outcomes: Body mass index (BMI) and body composition, Basal Metabolic Rate (BMR), lipid panel, serum testosterone, adiponectin, inflammatory (C-Reactive Protein, CRP, Tumour Necrosis Factor-α TNF-α, Free fatty Acids, FFA) and anabolic biomarkers (IGF-1 and IGFBP-3) glucose effectiveness (Sg) and insulin sensitivity (Si).

·         BMI and supine thigh circumference were significantly ↑ in the experimental group relative to the control, p=0.004 and p=0.01 respectively.

·         Total visceral adipose tissue, BMR, Si, IGF-1, IGFBP-1 demonstrated no significant group differences (p>0.05)

·         Neither intervention appeared to significantly influence any parameters of the lipid panel, CRP, TNF-α or FFA (p>0.05).

·         A significant interaction was noted in the circulating adiponectin between TRT+RT (n=8) and TRT (n=10) groups for both absolute (P=0.024) and adjusted (adiponectin adjusted to body weight: P= 0.022 & adiponectin adjusted to lean mass: P=0.036)

 

Ryan et al. (2013)

USA

Pre-Post

N=14

Population: 11M;3F with motor complete SCI C4-T7 level; AIS A or B; mean (SD) age: 26.7(4.7)yr; mean (SD) time post injury: 7.7 (6.5)yr.

Intervention:  Participants performed NMES resistance exercise training of the knee extensor muscles twice weekly for 16 weeks. Four sets of 10 knee extensions were performed using neuromuscular electrical stimulation. Legs were alternated after 10 repetitions, and training sets were separated by 2 min.

Outcome Measures: plasma glucose and insulin; thigh muscle and fat mass; quadriceps and hamstrings muscle size and composition; muscle oxidative metabolism.

·         Mean (SD) muscle mass ↑ in all participants (39(27)%). The mean change (SD) in intramuscular fat was 3(22)%.

·         Phosphocreatine mean recovery time constants (SD) were 102(24) and 77(18)s before and after electrical stimulation-induced resistance training, respectively.

·         No improvement in fasting blood glucose levels, homeostatic model assessment calculated insulin resistance, 2-hour insulin, or 2-hr glucose was observed.

Discussion

Seven studies have investigated the effect of FES cycling or rowing exercise training interventions on blood serum parameters. With the exception of one small prospective controlled trial (n=3), all studies utilized a simple pre to post-design. From the pre-post studies, there is level 4 evidence that FES improves glucose tolerance, as determined via either H1C or via oral glucose tolerance testing, but not markers of anti-oxidant function. Moreover, two studies have demonstrated that FES improves insulin sensitivity and Glut4 content in the leg muscles. Glut4 is responsible for insulin-mediated glucose in skeletal muscle cells. Of the 2 studies that have investigated Neuromuscular Electrical Stimulation Resistance Training (NMES-RT), one RCT demonstrated a positive impact of NMES-RT on adiponectin levels, but neither study found any change in glucose tolerance or insulin resistance.

Conclusion

There is level 1a evidence (Gorgey et al. 2019) that 16 weeks of 2d/wk of knee extensor resistance exercise with neuromuscular electrical stimulation in combination with testosterone patches does not improve markers of immune function or blood lipids, but does improve adiponectin in those with thoracic or lumbar SCI.

There is level 2 evidence (Gorgey & Lawrence 2016) that 16 weeks of 2-3d/wk FES-leg cycling exercise (40min of cycling at a cadence of 50 revolutions per min (RPM)) improves thigh lean mass but not blood lipids in individuals with various levels and severities of SCI

There is level 4 evidence (Van Duijnhoven et al. 2010) that 8 weeks of 2-3d/wk FES-leg cycling exercise (60 min/day, cycling at a cadence of 50 revolutions per min (RPM)) does not improve markers of anti-oxidant function in individuals with various levels and severities of SCI

There is level 4 evidence (Jeon et al. 2002) that 8 weeks of 3d/wk FES-leg cycling exercise (30min/day) improves glucose tolerance in individuals with various levels and severities of SCI

There is level 4 evidence (Mohr et al. 2001) that 12 months of 3d/wk FES-leg cycling exercise (30min/day) improves insulin-stimulated glucose uptake and GLUT-4 content in the quadriceps muscle in individuals with cervical or high-thoracic SCI

There is level 4 evidence (Hjeltnes et al. 1998) that 8 weeks of 7d/wk FES-leg cycling exercise improves insulin-mediated glucose disposal and GLUT-4 content in the quadriceps muscle in individuals with cervical SCI

There is level 4 evidence (Jeon et al. 2010) that 12 weeks of 3-4d/wk FES-rowing exercise (600–800 kcal) improves plasma leptin and glucose but not glucose tolerance in those with mid-to-low thoracic SCI

There is level 4 evidence (Solinsky et al. 2020) that 6 months of 1-2d/wk FES-rowing exercise (>75% peak heart rate) improves hemoglobin A1C but not blood lipids in those with various levels and severities of SCI.

There is level 4 evidence (Ryan et al. 2013) that 16 weeks of 2d/wk of NMES resistance exercise training of the knee extensor muscles do not improve insulin resistance or glucose tolerance.