Welcome to SCIRE Professional
 

Functional Electrical Stimulation (FES)

[link_block url=”https://scireproject.com/community/topic/functional-electrical-stimulation/” title=”Click here for patient information”][/link_block]

Computer-assisted FES during leg cycling has been shown to be an important and practical means of exercising a relatively large muscle mass in persons with SCI (Hooker et al. 1992). These devices also permit the activation of the skeletal muscle pump during leg cycling. For these reasons, FES training has been advocated widely as an effective treatment strategy for SCI. It is important to note, that the physiological responses to FES training appear to be distinct from arm ergometry training. For instance, arm exercise has been shown to lead to faster VO2 kinetics (oxygen metabolism/uptake) (at a constant workload), greater changes in HR, and lower post-exercise blood lactates than FES leg cycling (Barstow et al. 2000).

We identified one longitudinal (Berry et al. 2012), one prospective experimental (Fornusek et al. 2014), one post (Hakansson et al. 2012), and 13 pre-post (Ragnarsson et al. 1988, Faghri et al. 1992, Hooker et al. 1992, Barstow et al. 1996, Hjeltnes et al. 1997, Mohr et al. 1997, Gerrits et al. 2001, Hopman et al. 2002, Crameri et al. 2004, Janssen and Pringle 2008, Zbogar et al. 2008, Griffin et al. 2009, Kahn et al. 2010) studies that examined the effectiveness of FES leg cycle ergometry on indices of cardiovascular fitness and/or health in SCI. We also identified 7 pre-post (Pollack et al. 1989, Krauss et al. 1993, Mutton et al. 1997, Gurney et al. 1998, Thijssen et al. 2005, Thijssen et al. 2006, Brurok et al. 2011), 1 RCT (Bakkum et al. 2015) and 1 cross-sectional (Bakuum et al. 2014) investigations that examined hybrid FES (combined leg and arm) on cardiovascular fitness in SCI.

There was one further prospective cohort study (Carty et al. 2012), and 11 pre-post (Jacobs et al. 1997, Nash et al. 1997, Solomonow et al. 1997, Wheeler et al. 2002, de Groot et al. 2005, Sabatier et al. 2006, Stoner et al. 2007, Berry et al. 2008, Jeon et al. 2010, Taylor et al. 2011, Ryan et al. 2013) investigations that examined the effects of other electrically assisted training programs on cardiovascular fitness and/or health.

Table 6 : Effects of Functional Electrical Stimulation on Cardiovascular Fitness

Author, Year; Country

Score

Research Design

Sample Size

MethodsOutcomes
Berry et al. 2012;

UK

Longitudinal study

Level 2

N=11

Population: N=11 (9M;2F) participantswith T3-T9 SCI; mean(SD) age: 41.8(7.6) yrs old; at least 2 yrs since injury; all AIS A.

Treatment: Participants completed a 12-month, home-based progressive FES cycle training programme (up to 5x60min sessions per wk).

Outcome Measures: Stimulation cost, oxygen cost, efficiency and markers of anaerobic metabolism were determined before and after 6 and 12 months of training, during constant work-rate tests.

1.   Oxygen cost and efficiency did not significantly change after training.

2.   Total stimulation cost and blood lactate values reduced overall. The high metabolic cost of FES cycling is a result of non-physiological recruitment of predominantly fast muscle fibres. The electrical cost of cycling reduced by 37%, probably due to motor unit hypertrophy, and lactate oxidation capacity improved.

3.   Respiratory exchange ratios remained relatively high.

1.

Fornusek et al.

2014

Australia

Pre-post

Level 4

N=8

Population: 8 individuals with chronic paraplegia (T4- T11). 7 with complete SCI (AIS- A) and 1 with incomplete SCI (AIS- C)

 

Treatment: Participants performed electrical stimulation (ES) on 2 separate sessions one week apart. The first day consists of 5 min of rest followed by 35 min of FES cycling and 15 min intermittent isometric exercise where the pedals were locked in a fixed position using the same ES parameters. The second day, the order and durations of the ES isometric and FES cycling were swapped.

 

Outcome Measure: Cardiorespiratory activity (oxygen consumption- VO2, ventilation, tidal volume), heart rate, power output during FES cycling

2.      No differences during the first 35 minutes of isometric exercise on each day when comparing the 2 modes of exercise for average rate of oxygen consumption, average heart rate, isometric or minute ventilation.

3.      No differences between exercise modes for any peak cardiorespiratory values recorded during the initial 35 minute of exercise or the following 15-minute crossover exercise phase.

4.      Both FES cycling and isometric ES induced significant increases from rest values for all cardio respiratory measures.

Kahn et al. 2010;

USA

Pre-post

Level 4

N = 12

Population: 14 participants with paraplegia (T1-T10) or tetraplegia (C4-C8); >1 year post injury. 12 participants completed the trial.

Treatment: FES-leg cycle ergometry  training (2 sessions per week for 4 weeks). Each training session consisted of multiple exercise bouts (total 30 min, with 5-min rest period between boots). Stimulation was applied to quadriceps, hamstrings and gluteal muscle groups bilaterally

Outcome Measures: Thrombin activity, antithrombin III activity, fibrinogen level, coagulation factor levels, cyclic adenosine monophosphate (cAMP) level and platelet aggregation in blood.

1.    After the 1st session, significant increase were found for Antithrombin III (103.8 ± 8.9% to 110 ± 6.9%) and camp levels (9.9 ± 2.5% to 15.8 ± 3%)

2.    After the eight session, significant increase were found in antithrombine III activity, cAMP levels (17.8 ± 4.2% to 36.5 ± 7.6%) and coagulation factors V and X (respectively 88 ± 27 to 103 ± 23% and 100 ± 40 to 105 ± 7%). In addition, thrombine levels decreased (pre: 12.5 ± 2.0 s to post: 11.1 ± 1.7s) and platelet aggregation was inhibited by 40%.

 

Griffin et al. 2009;

USA

Pre-Post

Level 4

N = 18

Population: 18 SCI participants (age 40 +  2.4, YPI 11 + 3.1) with no cardiovascular disease

Treatment: FES cycling 2-3 times per week for 10 weeks

Outcome Measures: Cycling power; body composition; ASIA impairment scale (AIS)

1.   Cycling power and work done were greater during weeks 8, 9, and 10 compared to week 1

2.   Total body mass and lean muscle mass increased significantly after training.

3.   Lower extremity total AIS scores and the motor and sensory components of the AIS tests were all significantly higher after training.

Janssen & Pringle 2008;

The Netherlands

Pre-Post

Level 4

N = 12

Population: 12 men with SCI (6 tetraplegia and 6 paraplegia), including 4 participants (age 44 + 14, YPI 13 + 8) who had previous training on ES-LCE

Treatment: Computer controlled electrical stimulation induced leg cycle ergometry (ES-LCE); total of 18 training sessions with each session lasting 25-30 minutes

Outcome Measures: Heart rate; power output; oxygen uptake (VO2); Carbon dioxide production; minute ventilation (volume of gas into lungs)

1.   Significantly higher heart rate (+16%) and power output (+57%) after training, compared to baseline

2.   Significantly higher peak values for VO2 (+29%), carbon dioxide production (+22%), and minute ventilation (+19%)

Zbogar et al. 2008;

Canada

Pre-Post

Level 4

N = 4

Population: 4 SCI participants, all female, age 19-51, lesion level C4-T7

Treatment: 30-min sessions of FES leg cycle ergometry, 3 times per week for 12 weeks

Outcome Measures: Large and small artery compliance

1.   There was no significant change in large artery compliance.

2.   All participants demonstrated increased small artery compliance after training, an average of 63% increase (from 4.2 + 1.8 to 6.9 + 3.2 mL∙mmHg-1 × 100)

Crameri et al. 2004;

Denmark

Pre-post

Level 4

N = 6

Population: Paraplegia, complete, C6-T7, ages 26–54 yrs, 3–21 yrs post-injury.

Treatment: FES training 45 min/d, 3 d/wk, 10 wks. One leg: dynamic cycle ergometry involved bilateral quadriceps and hamstring stimulation; contralateral leg: isometric contractions.

Outcome Measures: muscle biopsies, capillary-to-muscle fibre ratio, muscle proteins, and oxygenation, citrate synthase activity (marker of intact mitochondria).

1.   The isometric-trained leg showed larger mean increases in force, increase in type 1 fibres, fibre cross-sectional area, capillary-to-fibre ratio, citrate synthase activity, and relative oxygenation after static training in comparison to baseline and the dynamically trained leg.
Hopman et al. 2002;

The Netherlands

Pre-post

Level 4

N = 9

Population: 9 males; Level of injury: thoracic and cervical; Type of injury: AIS A; Time since injury: range 1-22 years. Mean age (including 2 other participants not included in this part of the study) = 40.7±7.2 yrs.

Treatment: Cycle training was performed by using a computer-controlled leg cycle ergometer with electrodes placed over hamstring, gluteal, and quadriceps muscles. Participants trained for 30 minutes, 3x/week for 6 wks.

Outcome Measures: Mean arterial pressure, resting blood flow in femoral artery

1. Mean arterial pressure was similar after training compared with values before training.

2. Larger resting blood flow in the femoral artery was found after training. Peak systolic blood flow increased from 1330 ± 550 to 1710 ± 490 mL∙min-1 and mean blood flow increased from 270 ± 120 to 370 ± 160 mL∙min-1.

3.   Calculated vascular resistance decreased by 30% after 6 weeks of training.

Gerrits et al. 2001;

The Netherlands

Pre-post

Level 4

N = 9

 

Population: 9 males; Age: mean 39.2 yrs, range 26-61; Level of injury: C4-T6, 4 cervical and 5 thoracic; Time since injury: mean 11.1 yrs, range 2-27; Type of injury: 3 AIS  B, 5 AIS A, 1 AIS C

Treatment: All participants trained for 6 weeks, 3 d/wk. A training session consisted of a 30-minute FES-leg cycle ergometry (LCE) exercise.

Outcome Measures: Longitudinal images and simultaneous velocity spectra of the common carotid and femoral arteries (capturing blood flow); arterial diameters, peak systolic inflow volumes, mean inflow volume, velocity index

1.   Increased work output (300%).

2.   No change HR and systolic BP.

3.   Six weeks of FES-LCE training resulted in an increase in diameter of the femoral artery (pre-training 7.5±1.5 mm vs. post-raining 8.1±1.5 mm) whereas the diameter of the common carotid artery remained unchanged.

4.   Velocity index, an indicator for peripheral resistance, decreased from 1.24±0.11 to 1.14±0.12 in the femoral artery; unchanged in common carotid

5.   Larger resting inflow volumes of the femoral artery were found after training as peak systolic inflow increased from 1330 ± 550 to 1710 ± 490 mL∙min-1 and mean inflow volume increased from 270 ± 120 to 370 ± 160 mL∙min-1.

6.   After training, hyperaemic response is augmented.

Hjeltnes et al. 1997;

Norway

Pre-post

Level 4

N = 5

Population: 5 males, complete chronic lesions, 2 C5, 2 C6, 1 C7, 4 AIS  A, 1 AIS  A/B, age 35 yrs, 10.2 yrs post-injury.

Treatment: FES leg cycling, 7 x/wk, 8 wks.

Outcome Measures: DXA (Body composition), VO2peak.

1.   VO2peak increased (70%) during FES leg cycling but not during arm exercise.

2.   Increase in lean body mass (3.0%) and muscle cross-sectional area (21.3%).

3.   Decrease in body fat (6.4%).

Mohr et al. 1997;

Denmark

Pre-post

Level 4

N = 10

Population: 6 tetraplegia at C6, 4 paraplegia at T4, all complete, ages 27–45 yrs, 3–23 yrs post-injury.

Treatment: 1-yrs exercise training using an FES cycle ergometer (30 min/d, 3 d/wk). Outcome Measures: VO2max, total work output, blood lactate, muscle properties.

 

1.   4-fold increase in work output and 12% increase in thigh muscle mass with FES.

2.   VO2max increased 17.5% (6 months) and 19.2% (12 months).

3.   Shift toward more fatigue-resistant contractile proteins and a doubling of citric synthase activity.

Barstow et al. 1996;

USA

Pre-post

Level 4

N = 9

Population: 9 males, 2 tetraplegia, 7 paraplegia, all AIS  A, age 34.4 yrs, 10.1 yrs post-injury.

Treatment: FES leg-cycle exercise, 30 min (minimum of 24 sessions, 3d/wk).

Outcome Measures: Work rate, VO2peak, oxygen pulse.

1.   Training significantly increased VO2peak (10.9%), peak work rate (46.5%), and peak oxygen pulse (12.6%).
Faghri et al. 1992;

USA

Pre-post

Level 4

N = 13

Population: 6 paraplegics (5 complete), 7 tetraplegics (all incomplete), C4-C7 and T4-T10, age 30.5 yrs, 8 yrs post-injury.

Treatment: FES leg cycle, 3 d/wk, 12 wks. Outcome Measures: BP, power output, HR, VO2peak, stroke volume, and cardiac output.

1.   Increased resting HR and systolic blood pressure in the tetraplegics, while decreased systolic, diastolic, and mean arterial BP in the paraplegics after training.

2.   In both groups, decreased submaximal exercise HR and BP and increased stroke volume after training.

3.   After training, submaximal cardiac output increased significantly in the paraplegic group.

 

Hooker et al. 1992;

USA

Pre-post

Level 4

N = 18

 

Population: 17 males, 1 female, 10 tetraplegia (C5-C7), 8 paraplegia (T4-T11), 7 incomplete, age 30.6 yrs, 6.1 yrs post-injury.

Treatment: FES leg-cycle training 10–30 min/d, 2–3 d/wk, 12–16 wks.

Outcome Measures: VO2peak, power output, cardiac output, stroke volume, total peripheral resistance, and HR.

1.   Increase in power output (45%), VO2peak (23%), cardiac output (13%), HR (11%), and a reduction in total peripheral resistance (-14%) during peak FES leg cycle.

2.   No changes in stroke volume (6%), mean arterial BP (-5%), or arteriovenous oxygen difference (+10%).

3.   No differences during peak arm cranking exercise for any of the cardiovascular variables.

Janssen and Pringle 2008;

The Netherlands

Pre-Post

Level 4

N = 12

Population: All participantst are male, 6 participants with tetraplegia and 6 with paraplegia, including 4 participants (mean (SD) age 44 (14), yrs post-injury 13 (8)) who had previous training on ES-LCE.

Treatment: Computer controlled ES-LCE; total of 18 training sessions with each session lasting 25-30 minutes.

Outcome Measures: Heart rate; power output; oxygen uptake (VO2); Carbon dioxide production (VCO2); pulmonary ventilation (Ve); peak torque.

1.      Significantly higher heart rate (+16%) and power output (+57%) after training, compared to baseline

2.      Significantly higher peak values for VO2 (+29%), VCO2 (+22%), and Ve (+19%)

3.      Peak torques were significantly higher for most of the relevant muscles

Ragnarsson et al. 1988;

USA

Pre-post

Level 4

N = 19

Population: 16 male, 3 females (7 paraplegics T4-T10, 12 tetraplegics C4-C7), ages 19–47 yrs, 2–17 yrs post-injury.

Treatment: Phase I: quadriceps stimulation with dynamic knee extensions against increasing resistance, 3 d/wk, 4 wks; Phase II: leg-cycle FES, 15-30 min/d, 3 d/wk for 12 wks.

Outcome Measures: HR, work, BP, and VO2peak.

1.   Most showed an increase in strength and endurance.

2.   VO2peak increased nonsignificantly (14.9%) after training.

 

 

Hakansson et al. 2012;

USA

Post-test

Level 4

N=9

Population: N = 11 participants (8M;3F) with T4-T12 SCI; mean (SD) age: 28(9) yr old; DOI: 1.25-17 yr; all AIS A

Treatment: Participants pedaled the ergometer 3x/wk (30 min/session) during the first 3 weeks and once per week during the last 5 weeks. The last 4 weeks (used in analysis) were divided into two 2-week time blocks of StimErg and Stim3, which were randomly assigned.

Outcome Measures:  Work, VO2, blood lactate

1.    Participants performed 11% more work pedaling with Stim3 than with existing stimulation patterns (StimErg).

2.    Average VO2 and blood lactate concentrations were not significantly different between Stim3 (442 mL∙min-1; 5.9 mmoL∙L-1) and StimErg (417 mL∙min-1; 5.9 mmoL∙L-1).

 

Table 7 : Effects of Hybrid FES Training on Cardiovascular Fitness and Health

Author, Year;

Country

Score

Research Design

Sample Size

MethodsOutcomes
Bakkum et al.

2015

Netherlands

PEDro =6

RCT

Level 1

N=19

 

 

Population: 19 participants (18 males, 1 female, C2-L2) with SCI for more than 10 years.

 

Treatment: Participants were randomized to the hybrid or hand cycle group. 9 participants on hybrid cycle and 10 participants on hand cycle during 32 individual training sessions within a period of 16 weeks. The duration of each training session increased from 18 to 32 minutes during the program.

 

Outcome Measures: Metabolic syndrome (waist circumference, systolic/diastolic blood pressure, high density lipoprotein cholesterol, triglycerides, and insulin resistance), inflammatory status (C-reactive protein, interleukin -6 & -10), and visceral adiposity (trunk and android fat).

1.    For all metabolic components, inflammatory markers, and visceral adiposity, there were no differences over time between the 2 training groups.

2.    Overall reductions were found for waist circumference, diastolic blood pressure, insulin resistance, CRP, IL-6, trunk and android fat percentage.

 

 

 

 

 

Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data
Brurok et al. 2011;

Norway

Pre-Post

Level 4

N = 6

Population: 6 men with SCI in stable neurologic recovery (5 participants – paraplegic AIS A, 1 participant – tetraplegic AIS A)

Treatment: Aerobic high-intensity hybrid exercise training 3X/week for 8 wks preceded by a 7-wk control period of regular daily activity. Peak tests were performed at three different time points: 1, baseline; 2, control; and 3, post-training.

Outcome measures: peak stroke volume during hybrid cycling and peak oxygen consumption during hybrid cycling, arm cycle ergometry, and FES leg cycling.

1.   Between the control and post training test, there was a significant increase in Hybrid VO2 peak (25.3%) and VO2Peak during arm cycle ergometry (25.9%), and VO2 Peak during FES cycle (25.8%).
Thijssen et al. 2006;

The Netherlands

Pre-post

Level 4

N = 9

Population: 8 males, 1 female, C5-T12, 8 complete AIS A, 1 incomplete AIS C, age 39 yrs, 11 yrs post-injury.

Treatment: Simultaneous FES cycle ergometry and arm ergometry, 25 min/d, 2 d/wk, 6 wks followed by 6-wks detraining.

Outcome Measures: Blood flow of thigh, diameter of the femoral artery and flow-mediated dilation.

1.   After 2 wks of training, there was a significant increase in baseline and peak blood flow, an increase in femoral artery diameter, and a decrease in femoral artery flow-mediated dilation.

2.   Detraining lead to a reversal of baseline and peak thigh blood flow, vascular resistance, and femoral diameter.

3.   Detraining did not restore femoral artery flow mediated dilation.

Thijssen et al. 2005;

The Netherlands

Pre-post

Level 4

N = 10

Population: 9 males, 1 female, T1-T12, 9 complete, age 39.2 yrs, 1–20 yrs post-injury.

Treatment: Simultaneous FES cycle ergometry and arm ergometry, 30 min/d, 2–3 d/wk, 4 wks.

Outcome Measures: VO2peak, blood flow and vascular resistance, and echo Doppler (diameter and flow-mediated dilation after 13 min of ischemia).

1.   Training resulted in increased thigh resting (43.5%) and peak blood flow (17.1%), decreased thigh resting vascular resistance (31.8%), and increased femoral artery diameter.

2.   After training, there was an increase in maximal workload (6.8%), VO2peak (6.1%), and resistance to fatigue.

Gurney et al. 1998;

USA

Pre-post

Level 4

N = 6

Population: All male, C4-T10, 4 paraplegia, 2 tetraplegia, ages 23–41 yrs, 5–24 yrs post-injury.

Treatment: Phase I: FES leg cycle, 3 d/wk, 6 wks; Phase II: FES leg cycle with simultaneous, voluntary arm ergometry, 3 d/wk, 6 wks; Phase III: 8-wks detraining.

Outcome Measures: VO2peak, submaximal and maximal HR.

1.   Increased VO2peak (81.7%) and workload with FES leg cycle.

2.   After an 8-wk detraining period, peak workload returned to baseline; VO2peak remained higher.

Mutton et al. 1997;

USA

Pre-post

Level 4

N = 11

Population: All male, complete AIS A, C5-6 to T12-L1, age 35.6 yrs, 9.7 yrs post-injury.

Treatment: 3 phases of exercise training (FES leg-cycle ergometry). Phase I progressive FES leg-cycle exercise  to 30 min of exercise; Phase II ~35 sessions of FES-leg cycle ergometry; and Phase III ~41 sessions (30 min each) of combined FES-leg and arm ergometry.

Outcome Measures: VO2peak and submaximal physiological parameters (VO2, HR, blood lactate).

1.   In response to FES-leg cycle ergometry training both VO2peak and peak work rate during graded FES leg exercise (but not graded arm ergometry) testing improved.

2.   With hybrid training, VO2peak (13%) and peak power output (28%) were increased during graded hybrid testing, but not during graded arm or graded FES leg testing alone.

Krauss et al. 1993;

USA

Pre-post

Level 4

N = 8

Population: 7 male, 1 female, 7 paraplegia, 1 tetraplegia, age 32 yrs, 13 yrs post-injury.

Treatment: 2 phase program. Phase I: FES leg cycling 3 d/wk, 6 wks; Phase II: FES leg cycle plus simultaneous arm ergometry for 6 wks.

Outcome Measures: VO2peak, HR, workload, peak lactate.

1.   After Phase I, arm ergometer VO2peak (21.9%) and FES leg ergometer VO2peak (62.7%) increased.

2.   After Phase II, the hybrid exercise VO2peak increased 13.7%.

3.   Peak HR only increased with training during FES leg ergometry.

Pollack et al. 1989;

USA

Pre-post

Level 4

N = 11

Population: 7 male and 4 female, C4-C6 and T2-T6, complete motor lesions, ages 18–54 yrs, 6–132 months post-injury.

Treatment: 3 phase program over 13–28 wks. Phase I: quadriceps stimulation (knee extension); Phase II: FES leg cycle with 0–1 kp resistance; Phase III: loaded FES leg cycle, 3 d/wk, 3 wks.

Outcome Measures: BP, HR, oxygen consumption.

1.   There were significant increases in endurance time (288%), VO2peak (95.9%), and HR (16.8%) and decreases in diastolic BP (31.5%) with training.
Bakkum et al.

2014

Netherlands

Cross-sectional study

Level 5

N=9

 

Population: Nine individuals (8 males, 1 female, mean age of 40) with motor complete paraplegia or tetraplegia (6 AIS A, 4 AIS C)

 

Treatment: In Session 1, participants performed two 5 minute bouts of Hybrid Cycling at Rate of Perceived Exertions 3 (Light-Moderate) and 6 (Moderate-Vigorous). Hybrid cycling combines handcycling with FES-induced leg cycling. After 48-72 hours of rest, the same participants completed the exact same protocol but with Hand Cycling.

 

Outcome Measures: Metabolic rate, cardiorespiratory response (heart rate, oxygen pulse, ventilation)

1.      Metabolic rate was higher during hybrid cycling than during hand cycling at equal perceived exertion levels.

2.      When compared to Hand Cycling, heart rate and ventilation were higher during hybrid cycling, while oxygen pulse was the same.

3.      Heart rate also varied by perceived exercise intensity.

Table 8 : Effects of Other Electrically Assisted Training Programs on Cardiovascular Fitness and Health

Author, Year;

Country

Score

Research Design

Sample Size

MethodsOutcomes
Other forms of electrically assisted training
 

 

 

 

 

Menendez et al. 2016

Spain

PEDro=7

RCT

Level 1

N=10

Population: 10 individuals- 8 males and 2 females; all wheelchair users; AIS A or B; mean age =46.3 ± 12.9y; years post injury= 12.4 ± 7.8y

Treatment: All participants received 10 2-h rehabilitation sessions per month, which consisted of standing (tilted) position, passive movements, low-intensity resistance training or electrotherapy and physiotherapy treatment. Ten participants with SCI were assessed in five different sessions. After a familiarization session, four interventions were applied in random order; Whole body vibration (WBV), Electromyostimulation (ES), simultaneous WBV and ES (WBV+ES), and 30 s of WBV followed by 30 s of ES (WBV30/ES30). Each intervention consisted of 10 sets × 1 min ON+1 min OFF. Participants were seated on their own wheelchairs with their feet on the vibration platform (10 Hz, 5 mm peak-to-peak), and ES was applied on the gastrocnemius muscle of both legs (8 Hz, 400 μs).

Outcome Measures:  Popliteal artery blood velocity (BV) and skin temperature (ST) of the calf

1.      The simultaneous application (WBV+ES) produced the greatest increase in mean BV (MBV; 36% and 42%, respectively) and peak BV (PBV; 30% and 36%, respectively) during the intervention.

2.      This intervention produced the greatest mean increases in MBV (21%) and PBV (19%) during the recovery period. Last, this intervention produced the highest increase in ST during the intervention (2.1 °C).

Carty et al. 2012;

Ireland

Prospective cohort

Level 2

N=14

Population: N = 14 participants with T2-T11 SCI (11M;3F); 11 AIS A, 3 AIS B; mean (SD) age: 45.08 (7.92); mean (SD) yr since injury: 11.22 (11.23).

Treatment: Four electrodes were placed bilaterally on the quadriceps and hamstrings muscle groups, and subtetanic contractions were elicited using a neuromuscular electrical stimulation device. Training was undertaken for 1 hr, 5d/wk for 8 weeks. Participants increased the stimulation intensity on an incremental wheelchair exercise test of increasing speed and incline as quickly as tolerable to bring them to the desired training intensity as recorded on the Borg scale of rating of perceived exertion (RPE) (between 13 and 15 on RPE).

Outcome Measures: Incremental treadmill wheelchair propulsion exercise test with simultaneous cardiopulmonary gas exchange analysis to determine VO2peak and HRpeak.

1.       A significant increase in VO2peak and HRpeak between baseline and follow-up was observed. Changes in VO2peak ranged from -1.1% to 57.2%.

2.       There was no significant difference in the mean VO2peak change between the 2 groups based on the level of injury (above T6, T6 and below).

Asselin et al. 2015

USA

Pre-Post

Level 4

N= 8

 

 

 

 

 

 

Population: 8 individuals; non-ambulatory persons with paraplegia.

Treatment: 8 non-ambulatory persons with paraplegia were trained to ambulate with a powered exoskeleton. Once the participant was fitted properly in the device, he or she participated in three training sessions per week.

Outcome Measures: Measurements of oxygen uptake (VO2) and heart rate (HR) were recorded for 6 min each during each maneuver while sitting, standing, and walking.

1.      The average value of VO2 during walking was significantly higher than for sitting and standing.

2.      The HR response during walking was significantly greater than that of either sitting or standing.

Persons with paraplegia were able to ambulate efficiently using the powered exoskeleton for overground ambulation, providing the potential for functional gain and improved fitness.

Ryan et al. 2013;

USA

Pre-post

Level 4

N=14

Population: N = 14 Participants(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.

Treatment:  Participants performed 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.

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

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

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

 

Taylor et al. 2011;

USA

Pre-post

Level 4

N = 6

Population: Six male patients with SCI (T4-T9, ASIA A, within 18 years of injury, and younger than 40 years)

Treatment: Arms-only rowing and FES rowing. A sub-group (n = 3) completed at least 6 months of a progressive FES row training exercise program with graded exercise tests every 6 months.

Outcome measures: VO2peak, peak ventilation, peak respiratory exchange ratio, peak heart rate, and peak oxygen pulse.

1.     VO2peak was greater for FES rowing (20.0 ± 1.9 mL∙kg-1∙min-1, P=.01) than for arms-only rowing (15.7 ± 1.5 mL∙kg-1∙min-1)

2.    For 5 participants, the increase in aerobic capacity ranged from 12 to more than 50%.

3.    Peak respiratory exchange ratio was higher for arms-only rowing than FES rowing (1.28 ± 0.16 vs. 1.17 ± 0.03, P = 0.14)

4.    Peak heart rate was higher for FES rowing than arms-only rowing (179 vs. 170, P = 0.19).

5.    Peak oxygen pulse was 35% greater during FES rowing than arms-only rowing (6.90 vs. 9.08, P = 0.0007).

Jeon et al. 2010;

Canada

Pre-post

Level 4

N = 6

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

Treatment: Twelve 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.

1.    VO2peak increased from 21.4 ± 1.2 to 23.1 ± 0.8 mL∙kg-1∙min-1 (P = 0.048).

2.    Plasma glucose levels were reduced in all 6 patients after the training (pre: 103 ± 7.4 vs. post: 92.5±3.7 mg∙dL-1); however, this did not reach statistical significance.

3.    Plasma leptin levels were significantly decreased after the training (pre: 6.91 ± 1.82 ng∙dL-1 vs. post: 4.72 ± 1.04 ng∙dL-1; P = 0.046).

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

5.    Whole-body percent body fat decreased by 5% (pre: 25.5 ±1.8 vs. post: 24.4 ± 1.6%); however, this did not reach statistical significance (P = 0.074)

6.    A trend toward fat mass reduction was seen in 4 of the 6 participants; this change did not reach statistical significance (P = 0.08).

Berry et al. 2008

UK

Pre-Post

Level 4

N = 11

Population: 12 SCI participants(10 male, 2 female), with motor and sensory complete T3 to T12 lesion (AIS – A)

Treatment: Electrically stimulated (ES) cycling training, 236 sessions over 52 weeks

Outcome Measures: heart rate; O2 pulse; power output

1.    Peak heart rate increased by 13% after 6 months

2.    Peak O2 pulse increased significantly after 6 months

3.    Peak power output increased significantly after 3 months and 6 months

Stoner et al. 2007;

USA

Pre-post

Level 4

N = 5

Population: 5 males; Age: mean 35.6±4.9 yrs; Level of injury: range C5-T10; Time since injury: mean 13.4±6.5 yrs; Type of injury: AIS A.

Treatment: Neuromuscular electric stimulation-induced resistance training; the quadriceps femoris muscle group of both legs were trained 2x/week with 4×10 repetitions of unilateral, dynamic knee extensions for 18 weeks.

Outcomes measures: FMD and resting diameter and arterial range of the posterior tibial artery.

1.    FMD improved from 0.08 ± 0.11 (2.7%) to 0.18 ± 0.15 (6.6%) and arterial range improved from 0.36 ± 0.28 mm to 0.94 ± 0.40 mm. Resting diameter did not change.
Sabatier et al. 2006;

USA

Pre-post

Level 4

N = 5

Population: All male, complete AIS A, C5-T10, age 35.6 yrs, 13.4 yrs post-injury.

Treatment: Home-based electrical stimulation 2 d/wk, 18 wks.

Outcome Measures: Femoral artery diameter and blood flow, weight lifted, muscle mass, and muscle fatigue.

1.    Training resulted in significant increases in weight lifted and muscle mass and a decrease in muscle fatigue.

2.    There was no change in femoral artery diameter with training.

3.    Resting, reactive hyperaemia, and exercise blood flow did not change significantly with training.

de Groot et al. 2005;

The Netherlands

Pre-post

Level 4

N = 6

Population: SCI: 3 male, 3 female, T4-L2, all complete AIS A/B, age 43 yrs, 14.5 yrs post-injury; Controls: 8 able-bodied individuals (4 male, 4 female), age 41 yrs.

Treatment: Unilateral surface stimulation of the quadricep, tibial anterior, and gastrocnemius muscles, 30 min/d, daily, 4 wks.

Outcome Measures: Leg circumference, total limb volume, resting mean red blood cell velocity and vessel diameter and blood pressure.

1.    An increase in arterial compliance and a decrease in the flow-mediated dilation in the femoral artery of the trained leg, with no changes in these vascular parameters in the femoral artery of the untrained leg, the carotid artery, and the brachial artery.

2.    There were no significant training-related changes in resting vessel diameter, blood flow, or shear rate in the femoral, carotid, and brachial arteries.

Wheeler et al. 2002;

Canada

Pre-post

Level 4

N = 6

Population: C7-T12, 5 AIS A, 1 AIS C, age 42.5 yrs, 13.8 yrs post-injury.

Treatment: FES (quadriceps) with arm rowing (70%–75%VO2peak) 30 min/d, 3 d/wk, 12 wks.

Outcome Measures: Total rowing distance, VO2peak, and peak oxygen pulse.

1.    Training resulted in significant increases in rowing distance (25%), VO2peak (11.2%), and peak oxygen pulse (11.4%).

 

Jacobs et al. 1997;

USA

Pre-post

Level 4

N = 15

Population: 12 males and 3 females; Age: mean 28.2 ± 6.8 yrs, range 21.1-45.2 yrs; Time since injury: mean 3.7 ± 3.0 yrs, range 7-8.8 yrs; Type of injury: all AIS A paraplegia; Level of injury: T4-T11

Treatment: 32 sessions of functional neuromuscular stimulation ambulation training using a 6-channel system (Parastep ® 1). Participants trained 3 days/week. Typically, three walking trials were completed during each training session. Participants chose ambulation pace and duration.

Outcome measures: HR, peak VO2

1.    Heart rate was lower throughout sub-peak levels of arm ergometry after the ambulation training.

2.    Peak VO2 increased from 20.0 ± 3.3 mL∙kg-1∙min-1 to 23.0 ±3.6 mL∙kg-1∙min-1 post-training.

Nash et al. 1997;

USA

Pre–post

Level 4

N = 12

Population: SCI: T4–T11

Intervention: Parastep training (FES with aid of walker), 3 times per week for 12 weeks. Duration based on comfort of the participant.

Outcome measures: Femoral artery end-diastolic diameter and flow velocity profiles at rest and after 5 min thigh occlusion.

1.    Increased resting common femoral cross-sectional area, computed pulse volume, and arterial inflow volume.

2.    Peak systolic velocity was not significantly different.

3.    After 5-min thigh occlusion, femoral pulse volume, flow velocity integral and arterial inflow volume increased after training.

Solomonow et al. 1997;

USA

Pre-post

Level 4

N = 70

Population: All paraplegia, no other details given.

Treatment: Reciprocating gait orthosis (RGO) 3 hr/wk, 14 wks.

Outcome Measures: Cardiac output, stroke volume, vital capacity, knee extensor torque, and heart rate at the end of a 30 m walk.

1.    There was a non-significant increase in cardiac output (7.1%) and stroke volume (5.0%) after training.

2.    There was a significant increase in knee extensor torque (78.2%).

Discussion

There is a growing body of literature indicating that FES exercise training is an effective way of improving cardiovascular health, peak power output, and exercise tolerance/capacity in persons with SCI (Table 6). These studies generally employ a cycling motion, although rowing and bipedal ambulation have also been evaluated. It appears that moderate-to-vigorous intensity FES training (relative to baseline capacity) may be effective in enhancing cardiovascular fitness in persons with SCI. The majority of the investigations are pre-post designs (level 4) with investigators reporting marked changes in VO2max or VO2peak after FES training. Similar to aerobic training, 20–40% changes in aerobic capacity are often observed after FES training. However, improvements in excess of 70% are not uncommon (Faghri et al. 1992). Hakansson et al. (2012) tested new electrical stimulation timing patterns (Stim3, designed using a forward dynamic simulation to minimize the muscle stress-time integral) to determine whether SCI participants could increase work and metabolic responses when pedaling a commercial FES ergometer, and found that subjects performed 11% more work pedalling with Stim3 than with existing stimulation patterns.

Investigations with FES training have also shown an improvement in musculoskeletal fitness. Similar to arm exercise training, limited investigations have shown an improvement in cardiac function after FES training. An investigation has also revealed that the degree of muscular adaptation that can be achieved via FES exercise is dependent upon the load that is applied to the paralyzed muscle (Crameri et al. 2004).

Researchers have also shown that hybrid exercise training (FES leg cycling combined with arm ergometry) may elicit greater changes in peak work rates and VO2peak/VO2max than FES leg- cycling exercise alone (Krauss et al. 1993, Mutton et al. 1997). Moreover, it appears that the physiological adaptations to combined FES leg cycling and arm ergometry training are partially maintained after eight weeks of detraining (Gurney et al. 1998). Other interventions (Table 8) that make use of hybrid FES training have also been shown to improve the exercise capacity and cardiovascular health of persons with SCI. It would appear that the potential adaptations with hybrid exercise may be greater than FES alone; however, further research is required to test this hypothesis.

A series of intrinsic muscle adaptations can also occur after FES training that enhance the ability for oxidative metabolism at the cellular level, which in turn facilitate improved endurance, exercise tolerance and functional capacity. Key intrinsic muscle adaptations that have been observed include an increase in the proportion of type 1 fibres, an enhancement in cross-sectional fibre area, an increase in capillary-to-fibre ratio, a shift towards more fatigue resistant contractile proteins, and an increase in citrate synthase activity (an enzyme important for metabolism). Given the importance of musculoskeletal fitness for health and functional status (Warburton et al. 2001a,b, Warburton et al. 2006, Warburton et al. 2010), further research is clearly warranted with persons with SCI. Accordingly, randomized, controlled exercise interventions (both arm and/or FES training) that evaluate concurrent changes in musculoskeletal fitness and health status are particularly needed.

Conclusion

There is level 4 evidence from multiple pre-post studies (Berry et al. 2012; Griffin et al. 2009; Zbogar et al. 2008; Crameri et al. 2004; Hjeltnes et al. 1997; Mohr et al. 1997; Barstow et al. 1996; Faghri et al. 1992; Hooker et al. 1992) that FES training performed for a minimum of three days per week for two months may be effective for improving musculoskeletal fitness, the oxidative potential of muscle, exercise tolerance, and cardiovascular fitness.

There is level 2 evidence (Fornusek et al., 2014) that there is no difference in cardiorespiratory responses or peak values between ES leg isometric exercise compared to FES leg cycling.

There is level 4 evidence from multiple pre-post studies (Hopman et al. 2002; Gerrits et al. 2001; Ragnarsson et al. 1988) that FES training may be effective in improving exercise cardiac function in persons with SCI.

There is level 1b evidence (Bakkum et al. 2015) that there there is no difference in metabolic components between the hybrid cycle group and hand cycle group. Both groups experienced beneficial effects on metabolic syndrome components, inflammatory status and visceral adiposity. Conversely, there is level 5 evidence (Bakkum et al. 2014) that metabolic rate, heart rate, and ventilation levels are higher during hybrid cycling than during hand cycling.

There is level 4 evidence (Taylor et al. 2011) that arm-cranking exercise assisted by FES increases peak power output, and may increase oxygen uptake.

There is level 4 evidence (Kahn et al. 2010) that FES leg cycle ergometry decreases platelet aggregation and blood coagulation in persons with SCI.

There is level 4 evidence (Hakansson et al. 2012) that the use of patterns that minimize the muscle stress-time integral can prolong FES pedaling.

  • Interventions that involve FES training a minimum of 3 days per week for 2 months may improve muscular endurance, oxidative metabolism, exercise tolerance, and cardiovascular fitness.