Robotics-assisted Treadmill Exercise Research Articles

Efficacy of Feedback-Controlled Robotics-Assisted Treadmill Exercise to Improve Cardiovascular Fitness Early After Stroke: A Randomized Controlled Pilot Trial.

Cardiovascular fitness is greatly reduced after stroke. Although individuals with mild to moderate impairments benefit from conventional cardiovascular exercise interventions, there is a lack of effective approaches for persons with severely impaired physical function. This randomized controlled pilot trial investigated efficacy and feasibility of feedback-controlled robotics-assisted treadmill exercise (FC-RATE) for cardiovascular rehabilitation in persons with severe impairments early after stroke. Twenty individuals (age 61 ± 11 years; 52 ± 31 days poststroke) with severe motor limitations (Functional Ambulation Classification 0-2) were recruited for FC-RATE or conventional robotics-assisted treadmill exercise (RATE) (4 weeks, 3 × 30-minute sessions/wk). Outcome measures focused on peak cardiopulmonary performance parameters, training intensity, and feasibility, with examiners blinded to allocation. All 14 allocated participants (70% of recruited) completed the intervention (7/group, withdrawals unrelated to intervention), without serious adverse events occurring. Cardiovascular fitness increased significantly in both groups, with peak oxygen uptake increasing from 14.6 to 17.7 mL · kg · min (+17.8%) after 4 weeks (45.8%-55.7% of predicted maximal aerobic capacity; time effect P = 0.01; no group-time interaction). Training intensity (% heart rate reserve) was significantly higher for FC-RATE (40% ± 3%) than for conventional RATE (14% ± 2%) (P = 0.001). Substantive overall increases in the main cardiopulmonary performance parameters were observed, but there were no significant between-group differences when comparing FC-RATE and conventional RATE. Feedback-controlled robotics-assisted treadmill exercise significantly increased exercise intensity, but recommended intensity levels for cardiovascular training were not consistently achieved. Future research should focus on appropriate algorithms within advanced robotic systems to promote optimal cardiovascular stress.Video abstract available for more insights from the authors (Supplemental Digital Content 1, http://links.lww.com/JNPT/A107).

Cardiovascular rehabilitation soon after stroke using feedback-controlled robotics-assisted treadmill exercise: study protocol of a randomised controlled pilot trial.

BackgroundAfter experiencing a stroke, most individuals also suffer from cardiac disease, are immobile and thus have low endurance for exercise. Aerobic capacity is seriously reduced in these individuals and does not reach reasonable levels after conventional rehabilitation programmes. Cardiovascular exercise is beneficial for improvement of aerobic capacity in mild to moderate stroke. However, less is known about its impact on aerobic capacity, motor recovery, and quality-of-life in severely impaired individuals. The aim of this pilot study is to explore the clinical efficacy and feasibility of cardiovascular exercise with regard to aerobic capacity, motor recovery, and quality-of-life using feedback-controlled robotics-assisted treadmill exercise in non-ambulatory individuals soon after experiencing a stroke.Methods/DesignThis will be a single-centred single blind, randomised control trial with a pre-post intervention design. Subjects will be recruited early after their first stroke (≤20 weeks) at a neurological rehabilitation clinic and will be randomly allocated to an inpatient cardiovascular exercise programme that uses feedback-controlled robotics-assisted treadmill exercise (experimental) or to conventional robotics-assisted treadmill exercise (control). Intervention duration depends on the duration of each subject’s inpatient rehabilitation period. Aerobic capacity, as the primary outcome measure, will be assessed using feedback-controlled robotics-assisted treadmill-based cardiopulmonary exercise testing. Secondary outcome measures will include gait speed, walking endurance, standing function, and quality-of-life. Outcome assessment will be conducted at baseline, after each 4-week intervention period, and before clinical discharge. Ethical approval has been obtained.DiscussionWhether cardiovascular exercise in non-ambulatory individuals early after stroke has an impact on aerobic capacity, motor recovery, and quality-of-life is not yet known. Feedback-controlled robotics-assisted treadmill exercise is a relatively recent intervention method and might be used to train and evaluate aerobic capacity in this population. The present pilot trial is expected to provide new insights into the implementation of early cardiovascular exercise for individuals with severe motor impairment. The findings of this study may guide future research to explore the effects of early cardiovascular activation after severe neurological events.Trial registrationThis trial is registered with the Clinical Trials.gov Registry (NCT01679600).

Feedback-controlled robotics-assisted treadmill exercise to assess and influence aerobic capacity early after stroke: a proof-of-concept study

Purpose: The majority of post-stroke individuals suffer from low exercise capacity as a secondary reaction to immobility. The aim of this study was to prove the concept of feedback-controlled robotics-assisted treadmill exercise (RATE) to assess aerobic capacity and guide cardiovascular exercise in severely impaired individuals early after stroke. Method: Subjects underwent constant load and incremental exercise testing using a human-in-the-loop feedback system within a robotics-assisted exoskeleton (Lokomat, Hocoma AG, CH). Inclusion criteria were: stroke onset ≤8 weeks, stable medical condition, non-ambulatory status, moderate motor control of the lower limbs and appropriate cognitive function. Outcome measures included oxygen uptake kinetics, peak oxygen uptake (VO2peak), gas exchange threshold (GET), peak heart rate (HRpeak), peak work rate (Ppeak) and accuracy of reaching target work rate (P-RMSE). Results: Three subjects (18–42 d post-stroke) were included. Oxygen uptake kinetics during constant load ranged from 42.0 to 60.2 s. Incremental exercise testing showed: VO2peak range 19.7–28.8 ml/min/kg, GET range 11.6–12.7 ml/min/kg, and HRpeak range 115–161 bpm. Ppeak range was 55.2–110.9 W and P-RMSE range was 3.8–7.5 W. Conclusions: The concept of feedback-controlled RATE for assessment of aerobic capacity and guidance of cardiovascular exercise is feasible. Further research is warranted to validate the method on a larger scale.Implications for RehabilitationAerobic capacity is seriously reduced in post-stroke individuals as a secondary reaction to immobility.Robotics-assisted walking devices may have substantial clinical relevance regarding assessment and improvement of aerobic capacity early after stroke.Feedback-controlled robotics-assisted treadmill exercise represents a new concept for cardiovascular assessment and intervention protocols for severely impaired individuals.

Evaluation of exercise capacity after severe stroke using robotics-assisted treadmill exercise: A proof-of-concept study

Robotics-assisted treadmill exercise (RATE) with focus on motor recovery has become popular in early post-stroke rehabilitation but low endurance for exercise is highly prevalent in these individuals. This study aimed to develop an exercise testing method using robotics-assisted treadmill exercise to evaluate aerobic capacity after severe stroke. Constant load testing (CLT) based on body weight support (BWS) control, and incremental exercise testing (IET) based on guidance force (GF) control were implemented during RATE. Analyses focussed on step change, step response kinetics, and peak performance parameters of oxygen uptake. Three subjects with severe motor impairment 16-23 days post-stroke were included. CLT yielded reasonable step change values in oxygen uptake, whereas response kinetics of oxygen uptake showed low goodness of fit. Peak performance parameters were not obtained during IET. Exercise testing in post-stroke individuals with severe motor impairments using a BWS control strategy for CLT is deemed feasible and safe. Our approach yielded reasonable results regarding cardiovascular performance parameters. IET based on GF control does not provoke peak cardiovascular performance due to uncoordinated walking patterns. GF control needs further development to optimally demand active participation during RATE. The findings warrant further research regarding the evaluation of exercise capacity after severe stroke.

A software module for cardiovascular rehabilitation in robotics-assisted treadmill exercise

A new software module for cardiovascular rehabilitation in robotics-assisted treadmill exercise is described; it is designed to evaluate and improve aerobic capacity for individuals with different neurological diseases.The Lokomat device was used in conjunction with a breath-by-breath cardiopulmonary monitoring system and a heart rate monitoring module to quantify the subjects’ exercise intensity and capacity, managed by the new software module.The intensity of the individuals’ exercise participation was estimated by a novel method which respects passive stiffness of the lower limbs and was guided by a custom human-in-the-loop feedback control system. Severely affected individuals’ participation was controlled by modifying body weight support or guidance force of the Lokomat system.Standard assessment and testing protocols were implemented and adapted to the target populations for cardiovascular rehabilitation tasks. Further intensity-control mechanisms provided by the software are feedback control of heart rate, oxygen uptake and metabolic work rate.The results demonstrated the technical feasibility of the software module for cardiovascular assessment and training in robotics-assisted treadmill exercise. Using one of the intensity control methods, cardiovascular responses were activated and controlled in healthy people, moderately to severely affected individuals early after stroke and also in individuals with spinal cord injury.

Feedback control of heart rate during robotics-assisted treadmill exercise

Robotics-assisted treadmill exercise has potential for cardiovascular rehabilitation of patients with miscellaneous neurological deficits. A novel approach is presented here which suggests using heart rate to define and control exercise intensity during robotics-assisted treadmill exercise. The work delineates the design and provides technical validation of the new method. A feedback structure in conjunction with a human-in-the-loop feedback for volitional control of mechanical work rate is proposed which provides automatic regulation of heart rate. A controller computes the target mechanical work rate based on target and actual heart rates. An analytical model-based method was used to design the controller. The overall feedback design process is technically validated through a test series with different control tasks including square-wave tracking, disturbance rejection, ramp tracking and an open loop test. The feedback method and the heart rate control provide close to nominal performance for square-wave and ramp reference tracking tasks below and above the anaerobic threshold, which was estimated by the V-slope method. The controllers provide robust and stable performance as verified by calculation of the root mean square error of the tracked heart rate at different effort levels as well as with the disturbance test. Further work is required to evaluate the robustness of the approach across a group of subjects including neurological patients to show the potential for clinical implementation and to achieve a positive effect for the cardiovascular status of patients.

Feedback control of human metabolic work rate during robotics-assisted treadmill exercise

A novel approach is presented which suggests the use of human metabolic work rate to define and regulate exercise intensity during robotics-assisted treadmill training. The work describes the design and technical validation of the new method.A feedback structure is proposed which provides automatic regulation of metabolic work rate, in conjunction with an embedded feedback loop for volitional control of mechanical work rate. Human metabolic work rate was derived in real time from breath-by-breath measurements of oxygen uptake and carbon dioxide output.The results show that the feedback method provides close to nominal performance for square-wave and ramp reference tracking tasks and that good disturbance rejection properties are obtained. A collateral finding of this work is an estimate of 14.5% of the metabolic efficiency of robotics-assisted treadmill exercise.The use of feedback control of human metabolic work rate provides a direct measure of exercise intensity as perceived by the exercising human as it directly reflects the energy requirements of the working muscles. This complements previous approaches to guiding robotics-assisted treadmill training based on mechanical work rate, heart rate or oxygen uptake. The new approach based on metabolic work rate may have advantages in populations with compromised and widely varying exercise responses. This provides a new approach for driving and controlling active patient participation during robotics-assisted treadmill exercise.

The metabolic cost of passive walking during robotics-assisted treadmill exercise

We are investigating the potential of robotics-assisted treadmill technology as a mode of exercise in people with spinal cord injury (SCI). People with incomplete SCI can actively contribute to this form of exercise, but in the clinical setting they often walk passively in the system. It is not known whether in doing so they are meeting the recommended guidelines for increasing cardiopulmonary fitness. The aims of this study were twofold: to characterise the intensity of passive walking during robotics-assisted treadmill exercise (RATE) in incomplete SCI; and to determine if this intensity meets the recommended guidelines for cardiopulmonary training in this population. 10 subjects with incomplete SCI twice performed an exercise test on a robotics-assisted treadmill. The test comprised a period of passive walking and a ramp phase to the limit of tolerance. Oxygen uptake VO(2) heart rate (HR) were continuously measured. VO(2) during passive exercise was on average 1.4 times higher than resting VO(2R), but this was only 29% of peak VO(2) (VO(2 peak))(range 16-43%). Relative to rest, passive VO(2) (VO(2P) was only 12% of VO(2 peak). HR did not increase from rest to passive walking (81 ± 10 bpm to 81 ± 13 bpm respectively). The HR associated with passive walking was on average 50% of peak HR (HR(peak)) (161 ± 13 bpm). Test-retest reliability was moderate for VO(2R) (R=0.62) and resting HR (HR(R)) (R=0.68), high for VO(2P) (R=0.81), passive HR (HR(P)) (R=0.87) and HR(peak) (R=0.88), and very high (R=0.95) for VO(2 peak). Only HR(p) differed significantly between tests (p=0.029). The intensity of passive walking during RATE is low and is insufficient to increase cardiopulmonary fitness in people with SCI. Subjects must actively contribute to the exercise in order to achieve the recommended training intensity.

Comparison of peak cardiopulmonary performance parameters during robotics-assisted treadmill exercise and arm crank ergometry in incomplete spinal cord injury

(i) to compare cardiopulmonary performance parameters obtained from incremental exercise tests (IETs) performed using a robotics-assisted treadmill and an arm crank ergometer; (ii) to investigate test-retest reliability during both modes of exercise. Each participant performed two IETs to the limit of tolerance on both a robotics-assisted treadmill and an arm crank ergometer. A Spinal Injuries Unit in the United Kingdom. 10 people with an incomplete spinal cord injury (SCI). Not applicable. Peak oxygen uptake (VO(2peak)), the gas exchange threshold (GET), peak heart rate (HR(peak)) and peak lactate (Lactate(peak) were obtained for each mode of assessment. The mean responses and test-retest reliability of the main outcome measures were determined and compared between modes of assessment. VO(2peak) was 16% higher (p = 0.016) and the VO2 at the GET was 40% higher (p = 0.007) during the robotics-assisted treadmill exercise (RATE) IET. There was a trend for HR(peak) to be higher during arm crank ergometry (ACE) (p = 0.058). Lactate(peak) was 46% higher (p = 0.006) during the ACE IET. During robotics-assisted exercise, the test-retest reliability was very high for VO2(peak) (r = 0.95), high for the GET (r = 0.75) and HR(peak) (r = 0.88), and moderate for Lactate(peak) (r =0.58). For ACE, the test-retest reliability was very high for VO(2peak) (r = 0.93), high for HR(peak) (r = 0.81) and Lactate(peak) (r = 0.78), and low for the GET (r = 0.16). The results suggest that, when compared with ACE,RATE can be a highly effective stressor of the cardiopulmonary system, and may be a more appropriate mode of assessment to determine and monitor cardiopulmonary fitness in people with incomplete SCI.

Comparison of peak cardiopulmonary performance parameters during robotics-assisted treadmill exercise and arm crank ergometry in incomplete spinal cord injury

Objective: (i) to compare cardiopulmonary performance parameters obtained from incremental exercise tests (IETs) performed using a robotics-assisted treadmill and an arm crank ergometer; (ii) to in...

Characterisation of oxygen uptake response to linearly increasing work rate during robotics-assisted treadmill exercise in incomplete spinal cord injury

Background Robotics-assisted treadmill exercise (RATE) is a new mode of exercise available to people with an incomplete spinal cord injury (SCI) that allows them to utilise their lower limb muscles during stepping. Pilot data suggest that RATE elicits a non-linear oxygen uptake ( V ˙ O 2 ) response corresponding to a linear increase in work rate. However, a linear V ˙ O 2 response during an incremental exercise test (IET) may be important to enable accurate estimation of key cardiopulmonary performance parameters. Aim This study aims to characterise the linearity of the V ˙ O 2 response elicited by a linearly increasing work rate during robotics-assisted treadmill exercise in subjects with incomplete SCI. Methods Utilising the Lokomat system, 10 subjects each performed two IETs on a robotics-assisted treadmill to the limit of their tolerance. By employing work rate estimation algorithms, subjects were asked to use cognitive feedback and volitional control of their contribution to the exercise to follow a linearly increasing target work rate that was displayed on screen. Pulmonary gas exchange and ventilatory measurements (including V ˙ O 2 ) were continuously measured throughout the exercise using a breath-by-breath respiratory monitoring system. Linear and 3rd-order non-linear approximations with comparable R 2 values were computed for each subject’s V ˙ O 2 response to the linear increasing work rate. Results R 2 values for the non-linear approximations were 9% higher on average ( p = 0.015 ) than the corresponding R 2 values for the linear approximations. Conclusion The V ˙ O 2 response elicited by a linearly increasing work rate during robotics-assisted treadmill exercise in those with incomplete SCI is non-linear. To ensure the intensity of exercise increases linearly, a more appropriate IET may be implemented by employing feedback control of V ˙ O 2 to track a linear target.