Physical Activity: Cardiovascular Health and Fitness

Exoskeleton Training

Exoskeleton assist devices support body movements by containing the lower limbs within a rigid scaffold with motorized joints to support and assist limb movement during physical efforts. Modern exoskeleton systems are able to provide reactive support, only engaging mechanical joints to assist movement (i.e., active movement) rather than initiate joint movements (i.e., passive movement). Exoskeleton systems can be used to assist over-ground walking in individuals with preserved locomotor function or can be paired with treadmill or BWSTT systems to partially support body weight to accommodate non-weight bearing individuals. The available evidence supporting exoskeleton devices for improvement in cardiorespiratory fitness comes from a combination of over-ground and over-treadmill walking, summarized below.

Author Year

Country
Research Design

Score
Total Sample Size

 Methods

Outcome

Gorman et al. (2019)

USA

RCT Crossover

PEDro=7

NInitial=37, NFinal=31

Population: Mean age robotic group: 46.9 yrs. Mean age aquatic group: 45.4 yrs. Level of injury: C2-T12; Level of severity: AIS C, AIS D.

Intervention: Individuals were randomized to either robotic therapy (RT; n = 18) or aquatic therapy (AT; n = 15). RT used a robotic-assisted body-weight supported treadmill device. First session was 20min, then ↑ by 5min in subsequent visits until the duration reached 45min 3 days/wk for a total of 36 sessions. AT consisted of three, 45min sessions/wk. Water positioning (standing, sitting, horizontal, depth), floatation and resistance devices were used.

Outcome Measures: Heart rate (HR), peak oxygen consumption (VO2peak).

·         VO2peak measured with arm ergometry was not significantly different with either aquatic intervention (p=0.14) or robotic intervention (p=0.31).

·         VO2peak during robotic treadmill ergometry demonstrated a statistical increase (p=0.03).

·         Comparison between the two interventions demonstrated a trend favoring aquatic therapy for improving arm ergometry VO2peak (p=0.063).

Gorgey et al. (2017)

USA

Case Series

N=4

Population: SCI: Mean age: 44.75yr; Gender: males=4, females=0; Level of injury: C5=2, T4=2; Injury severity: AIS A=3, AIS D=1.

Intervention: Participants took part in a clinical rehabilitation program, in which they walked once weekly using an overground powered exoskeleton for approximately 1h for 10-15wk.

Outcome Measures: Walking time, stand up time, ratio of walking-to-stand up time, number of steps; oxygen uptake (VO2), energy expenditure, and body composition were measured in one participant after training.

·         Over the course of 10 to 15wk, the maximum walking time ↑ from 12 to 57 minutes, and the number of steps ↑ from 59 to 2,284 steps.

·         At the end of the training, all four participants were able to exercise for 26 to 59min.

·         For one participant, oxygen uptake ↑ from 0.27 L/min during rest to 0.55 L/min during walking.

·         Delta energy expenditure ↑ by 1.4 kcal/min during walking.

Hoekstra et al. (2013)

Netherlands

Pre-post

N=10

Population: Mean age: 49 yrs; Sex: males=4, females=6; Level of severity: AIS C=6, AIS D=4; Time since injury: <1yr=2, 1-5yr=3, >5yr=5.

Intervention: Participants received robot-assisted gait training using a robotic-assisted body-weight supported treadmill device (24 sessions total, 2-3 sessions/wk, 60min each) and physical therapy completed within 10 to 16wk.

Outcome Measures: Graded arm crank exercise test, Robotic walking test,  VO2 and O2 pulse.

·         No significant differences in submaximal VO2 between pre- and post-test were found, but submaximal HR was significantly lower after the training program.

·         Resting heart rate was significantly lower at post-test than pre-test.

·         No changes were found in VO2 robot and HR robot pre- to post-training.

Turiel et al. (2011)

Italy

Pre-Post

N=14

 

Population: SCI Group: Mean age 50.6 ± 17.1 yrs; Sex: males=10, females=4; 2-10 yrs post-injury; 9 paraplegia) with lost sensorimotor function caused by incomplete SCI.

Intervention: Robotic-assisted body-weight supported treadmill training for 60 min sessions, 5 days/wk, 6 wks, with 30-50% of body weight supported (reduced as tolerated).

Outcome Measures: Left ventricular function, coronary blood flow reserve (via dipyrsidamole stress echo), plasma asymmetric dimethylarginine (ADMA), and plasma inflammatory markers.

·         Significant improvement in left ventricular diastolic function (i.e., a reduction in isovolumic relaxation time and deceleration time was observed following the training).

·         Significant ↑ in coronary reserve flow and reduced plasma ADMA levels were observed in the follow-up.

·         Significant reduction in the inflammatory status (C-reactive protein and erythrocyte sedimentation rate).

Cheung et al. (2019)

Hong Kong

RCT

PEDro=8

N=16

Population: Incomplete SCI; Robotic-assisted body weight supported treadmill training (RABWSTT) Group (n=8): Mean age: 55.6 yrs; Sex: males=7, females=1; Level of injury: C1-L2; Mean time post injury: 17.0mo. Control Group (n=8): Mean age: 53.0 yrs; Sex: males=4, females=4; Level of injury: C3-L2; Mean time post-injury: 10.4 mos.

Intervention: Participants were randomly allocated into an intervention group or control group. The intervention group received 30 min of RABWSTT with EMG biofeedback system over the vastus lateralis muscle to enhance active participation. Training was 3 times/wk for 8 wks. Dose equivalent passive lower limbs mobilization exercise was provided to subjects in the control group.

Outcome Measures: Walking Index for Spinal Cord Injury version II (WISCI II), Spinal Cord Independence Measure version III (SCIM II), lower limb muscle strength (Lower Extremity Motor Score; LEMS), Isometric muscle strength of hips and knees, Modified Ashworth Scale, hip and knee flexors and extensors, joint stiffness, passive hip and knee joint movements in different speeds, resistive torque, quality of gait pattern, VO2peak, peak expiratory flow (PEF), forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC).

·         Significant time-group interaction was found in the WISCI II (p=0.02), SCIM III mobility sub-score (p < 0.001), bilateral symmetry (p=0.048), maximal oxygen consumption (p=0.014) and peak expiratory flow rate (p=0.048).

·         Compared to the control group, the intervention group showed significant improvements in the above-mentioned outcomes after the intervention (p<0.025), except WISCI II.

 

 

 

 

 

 

Gorman et al. (2016)

USA

RCT

PEDro=6

N=18

Population: Incomplete SCI: n=18; between C4 and L2; >1yr post injury.

Intervention: Participants were randomized to Robotic-Assisted Body-Weight Supported Treadmill Training (RABWSTT) or a home stretching program (HSP) 3 times per week for 3 mos. Those in the home stretching group were crossed over to three months of RABWSTT following completion of the initial 3 mo phase.

Outcome Measures: VO2peak was measured during both robotic treadmill walking and arm cycle ergometry: twice at baseline, once at 6wks (mid-training) and twice at 3mo (post-training). VO2peak values were normalized for body mass.

·         The RABWSTT group improved VO2peak by 12.3% during robotic treadmill walking (20.2 ± 7.4 to 22.7 ± 7.5 ml/kg/min, P = 0.018).

·         VO2peak during robotic treadmill walking and arm ergometry showed statistically significant differences.

Discussion

The general observations from the available exercise training studies indicate that exoskeleton-assisted exercise training primarily improves exercise capacity in exoskeleton-specific movements and its improvements do not largely translate to central cardiovascular fitness as determined by conventional arm cycling tests. Five studies employed over-treadmill exoskeleton-assisted walking, and one study used over-ground exoskeleton-assisted walking. By nature of the intervention, all participants engaged in active walking (i.e., the exercise was not passively guided).

In a case series, Gorgey, Wade et al. (2017) indicated that over-ground exoskeleton training was feasible in a small group of individuals undergoing a clinical rehabilitation program, providing support that mode-specific exercise capacity can improve with only one hour of exoskeleton training per week for greater than 10 weeks.

Conclusions

There is Level 1 evidence (Gorman et al. 2019; Gorman et al. 2016) that 3 months of exoskeleton exercise training can improve exoskeleton-specific exercise capacity.

There is Level 4 evidence (Gorgey, Wade et al. 2017) that 10 weeks of exoskeleton exercise training can increase exoskeleton walking time and walking duration.

There is Level 4 evidence (Hoekstra et al. 2013) that 10 weeks of exoskeleton exercise training can increase submaximal heart rate and lower resting heart rate.

Chapter Downloads
Patient Handouts
Outcome Measures
Toolkits
Videos
Active Clinical Trials