Functional electrical stimulation assisted cycling of patients with subacute stroke: kinetic and kinematic analysis

The effect of robot-assisted walking in different modalities on cardiorespiratory responses and energy consumption in patients with subacute stroke

OBJECTIVES

The aim of our study was to evaluate the effect of robot-assisted walking in different modalities on cardiorespiratory responses and energy consumption in subacute stroke patients.

METHODS

Our study consisted of 16 individuals between the ages of 18-65 years. Individuals diagnosed with hemiplegia after unilateral ischemic or haemorrhagic stroke constitute the stroke group. Eight subacute stroke individuals were included in the experimental group, and eight healthy individuals were included in the control group. Each participant tested on the Lokomat in three consecutive days in random sequence, with three tests: the first test: 100% guiding strength (GF)and 100% body weight support (BWS); the second test 80% GF, 50% BWS; the third test 60% GF, 30% BWS was achieved. Gas analyzer (Cosmed, Quark CPET, Italy) measurements were made with the help of a mask to evaluate the cardiorespiratory responses of the participants during all tests.

RESULTS

In the comparison of the three test results of the two groups separately, the stroke group's oxygen consumption (VO2), carbon dioxide production (VCO2), tidal volume (VT), pulse reserve (HRR), calories burned per hour (EEh), Borg dyspnea values, control group's VO2, VCO2, VE, HR, HRR, and EEh, Borg values were statistically significantly different (p < 0.005). It was seen that the third test results were significantly greater than the first and second test results (p < 0.005).

DISCUSSION

By decreasing GF and BWS values during robot-assisted walking, adequate cardio-metabolic and energy response in both subacute stroke patients and healthy individuals could be achieved. These results show us that it is important to consider the cardiorespiratory function of the patient when choosing training protocols.

Short-term effects of pedaling exercise combined with integrated volitional control electrical stimulation in an older patient hospitalized for subacute stroke: ABA single-case design

[Purpose] The purpose of this study was to examine effects on gait indices produced by a short-term intervention of pedaling combined with integrated volitional control electric stimulation in an older patient with stroke. [Participant and Methods] This study was a single-case ABA (A-control, B-treatment) design. Each phase lasted four consecutive days (12 days total). Ten minutes of pedaling were performed daily. In Phase B, pedaling was combined with integrated volitional control electric stimulator on the rectus femoris of the affected side. The primary outcomes were the coefficient of variation, a measure of stride time homogeneity during gait; and the root mean square, a measure of trunk sway in the triaxial direction (mediolateral, vertical, anteroposterior) during gait. Assessments were measured before the intervention (day 0) and after the end of each phase (days 4, 8, and 12). [Results] Changes from the previous coefficient of variation were +1.13%, -3.95%, and +0.82% in Phases A, B, and A', respectively, with the greatest improvement occurring after Phase B. The root mean square improved the most with -5.13 for mediolateral after Phase B, -3.33 for vertical, and -6.99 for anteroposterior after Phase A. [Conclusion] A short-term intervention consisting of pedaling combined with integrated volitional control electric stimulation may contribute to the improvement of gait abnormalities.

Muscle Electrical Impedance Properties and Activation Alteration After Functional Electrical Stimulation-Assisted Cycling Training for Chronic Stroke Survivors: A Longitudinal Pilot Study

Electrical impedance myography (EIM) is a sensitive assessment for neuromuscular diseases to detect muscle inherent properties, whereas surface electromyography (sEMG) is a common technique for monitoring muscle activation. However, the application of EIM in detecting training effects on stroke survivors is relatively few. This study aimed to evaluate the muscle inherent properties and muscle activation alteration after functional electrical stimulation (FES)-assisted cycling training to chronic stroke survivors. Fifteen people with chronic stroke were recruited for 20 sessions of FES-assisted cycling training (40 min/session, 3–5 sessions/week). The periodically stimulated and assessed muscle groups were quadriceps (QC), tibialis anterior (TA), hamstrings (HS), and medial head of gastrocnemius (MG) on the paretic lower extremity. EIM parameters [resistance (R), reactance (X), phase angle (θ), and anisotropy ratio (AR)], clinical scales (Fugl-Meyer Lower Extremity (FMA-LE), Berg Balance Scale (BBS), and 6-min walking test (6MWT)] and sEMG parameters [including root-mean square (RMS) and co-contraction index (CI) value] were collected and computed before and after the training. Linear correlation analysis was conducted between EIM and clinical scales as well as between sEMG and clinical scales. The results showed that motor function of the lower extremity, balance, and walking performance of subjects improved after the training. After training, θ value of TA (P = 0.014) and MG (P = 0.017) significantly increased, and AR of X (P = 0.004) value and AR of θ value (P = 0.041) significantly increased on TA. The RMS value of TA decreased (P = 0.022) and a significant reduction of CI was revealed on TA/MG muscle pair (P < 0.001). Significant correlation was found between EIM and clinical assessments (AR of X value of TA and FMA-LE: r = 0.54, P = 0.046; X value of TA and BBS score: 0.628, P = 0.016), and between sEMG and clinical scores (RMS of TA and BBS score: r = −0.582, P = 0.029). This study demonstrated that FES-assisted cycling training improved lower limb function by developing coordinated muscle activation and facilitating an orderly myofiber arrangement. The current study also indicated that EIM can jointly evaluate lower extremity function alteration with sEMG after rehabilitation training.

Clinical Trail Registration: The study was registered on the Clinical Trial Registry (trial registration number: NCT 03208439, https://clinicaltrials.gov/ct2/show/NCT03208439).

Effect of cycling and functional electrical stimulation with linear and interval patterns of timing on gait parameters in patients after stroke: a randomized clinical trial

OBJECTIVE

Patients in the chronic phase after a stroke are an underrepresented group in the literature. Therefore, the aim of this study was to compare the effects of cycling and functional electrical stimulation with linear versus interval patterns of timing on gait parameters in patients after stroke.

DESIGN

A double blinded, parallel, randomized clinical trial.

SETTING

Neuroscience Institute.

PARTICIPANTS

Patients with lower limb disability due to stroke (N = 30) with a stroke onset >6 months and <18 months.

INTERVENTIONS

Twenty-eight minutes of leg cycling with functional electrical stimulation with linear or interval patterns of timing applied to the peroneal and biceps femoris muscles, 3 times/week for 4 weeks.

MAIN MEASURES

Timed 10-Meter Walk Test and Functional Ambulation Classification were the primary outcome measures. The Modified Modified Ashworth scale, active range of motion, Timed Up and Go Test, and Single Leg Stance Test were the secondary outcome measures. Evaluation was performed at baseline, after 4, and after 8 weeks.

RESULTS

Thirty participants completed the 4-week intervention (interval group, n = 16; linear group, n = 14). The Functional Ambulation Classification, Timed 10-Meter Walk Test, and the Timed Up and Go Test improved significantly in both groups. The Modified Modified Ashworth scale scores for quadriceps and plantar flexion statistically decreased after 4-weeks in the interval group. Significant group-by-time interaction was shown for Timed Up and Go Test (p = 0.003, np²=0.228), knee flexion active range of motion (p < 0.001, np²=0.256) and dorsiflexion active range of motion (p < 0.001, np²=0.359). Modified Modified Ashworth scale and active range of motion in both the ankle and knee improved significantly in the interval group.

CONCLUSIONS

The functional electrical stimulation with cycling protocols improved the Functional Ambulation Classification, Timed 10-Meter Walk Test, active range of motion, Timed Up and Go Test, and Modified Modified Ashworth scale. An interval protocol of timing was more effective than the linear protocol in terms of spasticity and active range of motion.Implications for rehabilitationCycling + functional electrical stimulation training with an interval pattern of timing seems superior to cycling + functional electrical stimulation training with a linear pattern.Interval protocol has positive effects on spasticity and range of motion after 12 sessions in patients post stroke.Cycling + functional electrical stimulation improves functional mobility and speed in stroke survivors and the effects of this intervention lasted in follow-up assessment after one month.

Oxygen Consumption While Walking With Multijoint Neuromuscular Electrical Stimulation After Stroke

This case study evaluated the effect of implanted multijoint neuromuscular electrical stimulation gait assistance on oxygen consumption relative to walking without neuromuscular electrical stimulation after stroke. The participant walked slowly with an asymmetric gait pattern after stroke. He completed repeated 6-min walk tests at a self-selected walking speed with and without hip, knee, and ankle stimulation assistance. His walking speed with neuromuscular electrical stimulation more than doubled from 0.28 ± 0.01 m/sec to 0.58 ± 0.04 m/sec, whereas average step length and cadence increased by 0.12 m and 24 steps/min, respectively. As a result, energy cost of walking with neuromuscular electrical stimulation decreased by 0.19 ml O2/kg per meter as compared with walking without stimulation while oxygen consumption increased by 1.1 metabolic equivalent of tasks (3.9 ml O2/kg per minute). These metabolic demands are similar to those reported for stroke survivors capable of walking at equivalent speeds without stimulation, suggesting the increase in oxygen consumption and decreased energy cost result from improved efficiency of faster walking facilitated by neuromuscular electrical stimulation. Although the effect of neuromuscular electrical stimulation on gait economy has implications for community walking within the user's metabolic reserves, this case study's results should be interpreted with caution and the hypothesis that multijoint neuromuscular electrical stimulation improves metabolic efficiency should be tested in a wide population of stroke survivors with varied deficits.

FES-assisted Cycling Improves Aerobic Capacity and Locomotor Function Postcerebrovascular Accident

PURPOSE

After a cerebrovascular accident (CVA) aerobic deconditioning contributes to diminished physical function. Functional electrical stimulation (FES)-assisted cycling is a promising exercise paradigm designed to target both aerobic capacity and locomotor function. This pilot study aimed to evaluate the effects of an FES-assisted cycling intervention on aerobic capacity and locomotor function in individuals post-CVA.

METHODS

Eleven individuals with chronic (>6 months) post-CVA hemiparesis completed an 8-wk (three times per week; 24 sessions) progressive FES-assisted cycling intervention. V˙O2peak, self-selected, and fastest comfortable walking speeds, gait, and pedaling symmetry, 6-min walk test (6MWT), balance, dynamic gait movements, and health status were measured at baseline and posttraining.

RESULTS

Functional electrical stimulation-assisted cycling significantly improved V˙O2peak (12%, P = 0.006), self-selected walking speed (SSWS, 0.05 ± 0.1 m·s, P = 0.04), Activities-specific Balance Confidence scale score (12.75 ± 17.4, P = 0.04), Berg Balance Scale score (3.91 ± 4.2, P = 0.016), Dynamic Gait Index score (1.64 ± 1.4, P = 0.016), and Stroke Impact Scale participation/role domain score (12.74 ± 16.7, P = 0.027). Additionally, pedal symmetry, represented by the paretic limb contribution to pedaling (paretic pedaling ratio [PPR]) significantly improved (10.09% ± 9.0%, P = 0.016). Although step length symmetry (paretic step ratio [PSR]) did improve, these changes were not statistically significant (-0.05% ± 0.1%, P = 0.09). Exploratory correlations showed moderate association between change in SSWS and 6-min walk test (r = 0.74), and moderate/strong negative association between change in PPR and PSR.

CONCLUSIONS

These results support FES-assisted cycling as a means to improve both aerobic capacity and locomotor function. Improvements in SSWS, balance, dynamic walking movements, and participation in familial and societal roles are important targets for rehabilitation of individuals after CVA. Interestingly, the correlation between PSR and PPR suggests that improvements in pedaling symmetry may translate to a more symmetric gait pattern.

Variations of ankle-foot orthosis-constrained movements increase ankle range of movement while maintaining power output of recumbent cycling

Previous research investigated recumbent cycle power output (PO) from the perspective of knee and hip joint biomechanics. However, ankle-foot biomechanics and, in particular, the effect of ankle-foot orthosis (AFO)-constrained movements on cycle PO has not been widely explored. Therefore, the purpose of this study was to determine whether AFOs of a fixed position (FP) and in dorsi-plantarflexion (DPF)-, dorsiflexion (DF)- and plantarflexion (PF)-constrained movements might influence PO during voluntary recumbent cycling exercises. Twenty-five healthy individuals participated in this study. All underwent 1-min cycling at a fixed cadence for each of the AFOs. The peak and average PO of each condition were analyzed. The peak and average PO were 27.2±12.0 W (range 6-60) and 17.2±9.0 W (range 2-36), respectively, during voluntary cycling. There were no significant differences in the peak PO generated by the AFOs (p=0.083). There were also no significant differences in the average PO generated using different AFOs (p=0.063). There were no significant differences in the changes of the hip and knee joint angles with different AFOs (p=0.974 and p=1.00, respectively). However, there was a significant difference in the changes of the ankle joint angle (p<0.00). The present study observed that AFO-constrained movements did not have an influence in altering PO during voluntary recumbent cycling in healthy individuals. This finding might serve as a reference for future rehabilitative cycling protocols.

Improved lower extremity pedaling mechanics in individuals with stroke under maximal workloads

Background Individuals with stroke present with motor control deficits resulting in the abnormal activation and timing of agonist and antagonist muscles and inefficient movement patterns. The analysis of pedaling biomechanics provides a window into understanding motor control deficits, which vary as a function of workload. Understanding the relationship between workload and motor control is critical when considering exercise prescription during stroke rehabilitation. Objectives To characterize pedaling kinematics and motor control processes under conditions in which workload was systematically increased to an eventual patient-specific maximum. Methods A cohort study was conducted in which 18 individuals with chronic stroke underwent a maximal exertion cardiopulmonary exercise test on a stationary cycle ergometer, during which pedaling torque was continuously recorded. Measures of force production, pedaling symmetry, and pedaling smoothness were obtained. Results Mean Torque increased significantly (p < 0.05) for both legs from initial to terminal workloads. Mean torque Symmetry Index, calculated for down and upstroke portions of the pedaling action, improved from 0.37(0.29) to 0.29(0.35) during downstroke (p = 0.007), and worsened during the upstroke: -0.37(0.38) to -0.62(0.46) (p < 0.001) from initial to terminal workloads. Low Torque Duration improved from initial to terminal workloads, decreasing from 121.1(52.9) to 58.1(39.6) degrees (p < 0.001), respectively. Smoothness of pedaling improved significantly from initial to terminal workloads (p < 0.001). Conclusions Improved pedaling kinematics at terminal workloads indicate that individuals with stroke demonstrate improved motor control with respect to the timing, sequencing, and activation of hemiparetic lower extremity musculature compared to lower workloads. Therapeutic prescription involving higher resistance may be necessary to sufficiently engage and activate the paretic lower extremity.

Cadence Tracking and Disturbance Rejection in Functional Electrical Stimulation Cycling for Paraplegic Subjects: A Case Study

Functional electrical stimulation cycling has been proposed as an assistive technology with numerous health and fitness benefits for people with spinal cord injury, such as improvement in cardiovascular function, increase in muscular mass, and reduction of bone mass loss. However, some limitations, for example, lack of optimal control strategies that would delay fatigue, may still prevent this technology from achieving its full potential. In this work, we performed experiments on a person with complete spinal cord injury using a stationary tadpole trike when both cadence tracking and disturbance rejection were evaluated. In addition, two sets of experiments were conducted 6 months apart and considering activation of different muscles. The results showed that reference tracking is achieved above the cadence of 25 rpm with mean absolute errors between 1.9 and 10% when only quadriceps are activated. The disturbance test revealed that interferences may drop the cadence but do not interrupt a continuous movement if the cadence does not drop below 25 rpm, again when only quadriceps are activated. When other muscle groups were added, strong spasticity caused larger errors on reference tracking, but not when a disturbance was applied. In addition, spasticity caused the last experiments to result in less smooth cycling.

Robot-assisted gait training improves brachial-ankle pulse wave velocity and peak aerobic capacity in subacute stroke patients with totally dependent ambulation: Randomized controlled trial

OBJECTIVE

Brachial-ankle pulse wave velocity (baPWV) evaluates arterial stiffness and also predicts early outcome in stroke patients. The objectives of this study were to investigate arterial stiffness of subacute nonfunctional ambulatory stroke patients and to compare the effects of robot-assisted gait therapy (RAGT) combined with rehabilitation therapy (RT) on arterial stiffness and functional recovery with those of RT alone.

METHOD

The RAGT group (N = 30) received 30 minutes of robot-assisted gait therapy and 30 minutes of conventional RT, and the control group (N = 26) received 60 minutes of RT, 5 times a week for 4 weeks. baPWV was measured and calculated using an automated device. The patients also performed a symptom-limited graded exercise stress test using a bicycle ergometer, and parameters of cardiopulmonary fitness were recorded. Clinical outcome measures were categorized into 4 categories: activities of daily living, balance, ambulatory function, and paretic leg motor function and were evaluated before and after the 4-week intervention.

RESULTS

Both groups exhibited significant functional recovery in all clinical outcome measures after the 4-week intervention. However, peak aerobic capacity, peak heart rate, exercise tolerance test duration, and baPWV improved only in the RAGT group, and the improvements in baPWV and peak aerobic capacity were more noticeable in the RAGT group than in the control group.

CONCLUSION

Robot-assisted gait therapy combined with conventional rehabilitation therapy represents an effective method for reversing arterial stiffness and improving peak aerobic capacity in subacute stroke patients with totally dependent ambulation. However, further large-scale studies with longer term follow-up periods are warranted to measure the effects of RAGT on secondary prevention after stroke.

An automatic identification procedure to promote the use of FES-cycling training for hemiparetic patients

Cycling induced by Functional Electrical Stimulation (FES) training currently requires a manual setting of different parameters, which is a time-consuming and scarcely repeatable procedure. We proposed an automatic procedure for setting session-specific parameters optimized for hemiparetic patients. This procedure consisted of the identification of the stimulation strategy as the angular ranges during which FES drove the motion, the comparison between the identified strategy and the physiological muscular activation strategy, and the setting of the pulse amplitude and duration of each stimulated muscle. Preliminary trials on 10 healthy volunteers helped define the procedure. Feasibility tests on 8 hemiparetic patients (5 stroke, 3 traumatic brain injury) were performed. The procedure maximized the motor output within the tolerance constraint, identified a biomimetic strategy in 6 patients, and always lasted less than 5 minutes. Its reasonable duration and automatic nature make the procedure usable at the beginning of every training session, potentially enhancing the performance of FES-cycling training.

The application of cycling and cycling combined with feedback in the rehabilitation of stroke patients: a review

Stroke is a leading cause of long-term disabilities, such as hemiparesis, inability to walk without assistance, and dependence of others in the activities of daily living. Motor function rehabilitation after stroke demands for methods oriented to the recovery of the walking capacity. Because of the similarities with walking, cycling leg exercise may present a solution to this problem. The aim of this article is to review the state of the art applications of cycling leg exercise as a (1) motor function rehabilitation method and an (2) aerobic training method for stroke patients as well as the commonly used (3) assessment tools. The cycling characteristics and applications, the applied test protocols as well as the tools used to assess the state and the recovery of patients and types of cycling devices are presented. In addition, the potential benefits of the use of other therapies, like feedback, together with cycling are explored. The application of cycling leg exercise alone and combined with feedback in stroke rehabilitation approaches has shown promising results. Positive effects on motor abilities were found in subacute and chronic patients. However, larger and normalized studies and assessments are needed because there is a high heterogeneity in the patients' characteristics, protocols and metrics. This wil allow the comparison between different studies related with cycling.

Leg general muscle moment and power patterns in able-bodied subjects during recumbent cycle ergometry with ankle immobilization

Rehabilitation of persons with pareses commonly uses recumbent pedalling and a rigid pedal boot that fixes the ankle joint from moving. This study was performed to provide general muscle moments (GMM) and joint power data from able-bodied subjects performing recumbent cycling at two workloads. Twenty-six able-bodied subjects pedalled a stationary recumbent tricycle at 60 rpm during passive cycling and at two workloads (low 15 W and high 40 W per leg) while leg kinematics and pedal forces were recorded. GMM and power were calculated using inverse dynamic equations. During the high workload, the hip and knee muscles produced extensor/flexor moments throughout the extensions/flexions phases of the joints. For low workload, a prolonged (crank angle 0-258°) hip extension moment and a shortened range (350-150°) of knee extension moment were observed compared to the corresponding extension phases of each joint. The knee and hip joints generated approximately equal power. At the high workload the hip and knee extensors generated increased power in the propulsion phase. For the first time, this study provides GMM and power patterns for able-bodied subjects performing recumbent cycling with an immobilized ankle. The patterns showed greater similarities to upright cycling with a free ankle, than previously supposed.

The effects of assisted ergometer training with a functional electrical stimulation on exercise capacity and functional ability in subacute stroke patients

OBJECTIVE

To determine if assistive ergometer training can improve the functional ability and aerobic capacity of subacute stroke patients and if functional electrical stimulation (FES) of the paretic leg during ergometer cycling has additional effects.

METHODS

Sixteen subacute stroke patents were randomly assigned to the FES group (n=8) or the control group (n=8). All patients underwent assistive ergometer training for 30 minutes (five times per week for 4 weeks). The electrical stimulation group received FES of the paretic lower limb muscles during assistive ergometer training. The six-minute walk test (6MWT), Berg Balance Scale (BBS), and the Korean version of Modified Barthel Index (K-MBI) were evaluated at the beginning and end of treatment. Peak oxygen consumption (Vo2peak), metabolic equivalent (MET), resting and maximal heart rate, resting and maximal blood pressure, maximal rate pressure product, submaximal rate pressure product, submaximal rate of perceived exertion, exercise duration, respiratory exchange ratio, and estimated anaerobic threshold (AT) were determined with the exercise tolerance test before and after treatment.

RESULTS

At 4 weeks after treatment, the FES assistive ergometer training group showed significant improvements in 6MWT (p=0.01), BBS (p=0.01), K-MBI (p=0.01), Vo2peak (p=0.02), MET (p=0.02), and estimated AT (p=0.02). The control group showed improvements in only BBS (p=0.01) and K-MBI (p=0.02). However, there was no significant difference in exercise capacity and functional ability between the two groups.

CONCLUSION

This study demonstrated that ergometer training for 4 weeks improved the functional ability of subacute stroke patients. In addition, aerobic capacity was improved after assisted ergometer training with a FES only.

Effects of Lower Limb Reciprocal Pedalling Exercise on Motor Function after Stroke: A Systematic Review of Randomized and Nonrandomized Studies

This review systematically synthesized current evidence on the effects of lower limb reciprocal pedalling exercise on motor function poststroke. Detailed analysis of single studies in the review revealed multiple instances of heterogeneity including outcome measures; therefore we decided to avoid undertaking a single, potentially misleading meta-analysis. We found that despite beneficial (although nondefinitive) effects on balance, functional independence, and muscle strength, it is not possible to make clinical recommendations that support or refute the use of reciprocal pedalling exercise to enhance recovery of motor function after stroke. Our findings provide proof-of-concept for pedalling interventions and provide a foundation for subsequent research, suggesting a need for further standardized, controlled clinical trials of clearly described pedalling interventions for stroke survivors and with subsequent transparent reported findings.

Design of a symmetry controller for cycling induced by electrical stimulation: preliminary results on post-acute stroke patients

This study deals with the design of a controller for cycling induced by functional electrical stimulation. The controller will be exploitable in the rehabilitation of hemiparetic patients who need to recover motor symmetry. It uses the pulse width as the control variable in the stimulation of the two legs in order to nullify the unbalance between the torques produced at the two crank arms. It was validated by means of isokinetic trials performed both by healthy subjects and stroke patients. The results showed that the controller was able to reach, and then maintain, a symmetrical pedaling. In the future, the controller will be validated on a larger number of stroke patients.

Force-pain relationship in functional magnetic and electrical stimulation of subjects with paresis and preserved sensation

OBJECTIVE

Using "painless" magnetic stimulation (FMS) to support the cycling of paretic subjects with preserved sensation is possible and potentially superior to electrical stimulation (FES). We investigated the dependence of the torque and the pain evoked by FMS and FES on stimulation conditions in order to optimize magnetic stimulation.

METHODS

Torque and pain induced by quadriceps stimulation in 13 subjects with paresis and preserved sensation (due to multiple sclerosis) were compared under the conditions: (1) small vs large stimulated surfaces of the thigh, (2) varying contraction velocities of the muscle (isometric vs 15 and 30 rpm isokinetic speed), (3) FMS vs FES modalities, and (4) varying magnetic coil locations.

RESULTS

Torque and pain significantly depended on the amount of surface and location of stimulation during FMS, on the stimulation modality, and on the muscle contraction velocity during FES and FMS. FMS with a saddle-shaped coil produced more torque (p<0.05) than any other stimulation modality, even at 30 rpm velocity.

CONCLUSIONS

To support leg cycling of subjects with preserved sensation, the application of FMS stimulation with a large-surface saddle-shaped coil and the focusing of stimulation on the lateral-frontal surface of the thigh produces greater torque and less pain than FES.

SIGNIFICANCE

Optimized magnetic stimulation is a superior alternative to electrical stimulation in the rehabilitation of subjects with preserved sensation.

A comparison of functional electrical and magnetic stimulation for propelled cycling of paretic patients

OBJECTIVE

To compare isometric torque and cycling power, smoothness and symmetry using repetitive functional magnetic stimulation (FMS) and functional electrical stimulation (FES) in patients with paretic legs with preserved sensibility and in patients without sensibility.

DESIGN

Repeated-measures design.

SETTING

Laboratory setting.

PARTICIPANTS

Eleven subjects with complete spinal cord injury (SCI) and 29 subjects with chronic hemiparesis (16.6+/-5.5mo poststroke) volunteered.

INTERVENTIONS

Using a tricycle testbed, participants were exposed to isometric measurements and ergometric cycling experiments, performed during both 20Hz FMS and FES stimulation. Subjects with hemiparesis and with complete SCI were stimulated at maximally tolerable level and maximal intensity, respectively.

MAIN OUTCOME MEASURES

Maximal isometric pedaling torque and mean ergometric power, smoothness, and symmetry were recorded for voluntary, FES, and FMS conditions.

RESULTS

Two different patterns of the efficacy of FMS were identified. (1) Patients with complete SCI did not benefit (less torque and power was evoked with FMS than with FES, P<.003 and 10(-4) respectively). (2) Patients with hemiplegia and preserved sensibility could improve their torque output (P<.05), smoothness, and symmetry of pedaling (P<.05) with FMS more than with FES.

CONCLUSIONS

FMS is a potential alternative to surface FES of the large thigh musculature in stimulation-supported cycling of patients with partially or completely preserved sensibility.