Rhythmic arm cycling training improves walking and neurophysiological integrity in chronic stroke: the arms can give legs a helping hand in rehabilitation

Interactive Virtual Ankle Movement Controlled by Wrist sEMG Improves Motor Imagery: An Exploratory Study

Virtual reality (VR) techniques can significantly enhance motor imagery training by creating a strong illusion of action for central sensory stimulation. In this article, we establish a precedent by using surface electromyography (sEMG) of contralateral wrist movement to trigger virtual ankle movement through an improved data-driven approach with a continuous sEMG signal for fast and accurate intention recognition. Our developed VR interactive system can provide feedback training for stroke patients in the early stages, even if there is no active ankle movement. Our objectives are to evaluate: 1) the effects of VR immersion mode on body illusion, kinesthetic illusion, and motor imagery performance in stroke patients; 2) the effects of motivation and attention when utilizing wrist sEMG as a trigger signal for virtual ankle motion; 3) the acute effects on motor function in stroke patients. Through a series of well-designed experiments, we have found that, compared to the 2D condition, VR significantly increases the degree of kinesthetic illusion and body ownership of the patients, and improves their motor imagery performance and motor memory. When compared to conditions without feedback, using contralateral wrist sEMG signals as trigger signals for virtual ankle movement enhances patients' sustained attention and motivation during repetitive tasks. Furthermore, the combination of VR and feedback has an acute impact on motor function. Our exploratory study suggests that the sEMG-based immersive virtual interactive feedback provides an effective option for active rehabilitation training for severe hemiplegia patients in the early stages, with great potential for clinical application.

Influence of Pedal Interface During Pedaling With the Upper Versus Lower Limbs: A Pilot Analysis of Torque Performance and Muscle Synergies

Pedaling is a physical exercise practiced with either the upper or the lower limbs. Muscle coordination during these exercises has been previously studied using electromyography and synergy analysis, and three to four synergies have been identified for the lower and upper limbs. The question of synergy adaptabilities has not been investigated during pedaling with the upper limbs, and the impact of various modalities is yet not known. This study investigates the effect of pedal type (either clipped/gripped or flat) on the torque performance and the synergy in both upper and lower limbs. Torques applied by six participants while pedaling at 30% of their maximal power have been recorded for both upper and lower limbs. Electromyographic data of 11 muscles on the upper limbs and 11 muscles on the lower limbs have been recorded and synergies extracted and compared between pedal types. Results showed that the torques were not modified by the pedal types for the lower limbs while a deep adaptation is observable for the upper limbs. Participants indeed used the additional holding possibility by pulling the pedals on top of the pushing action. Synergies were accordingly modified for upper limbs while they remain stable for the lower limbs. In both limbs, the synergies showed a good reproducibility even if larger variabilities were observed for the upper limbs. This pilot study highlights the adaptability of muscle synergies according to the condition of movement execution, especially observed for the upper limbs, and can bring some new insights for the rehabilitation exercises.

Neuromechanical Differences between Pronated and Supinated Forearm Positions during Upper-Body Wingate Tests

Arm-cycling is a versatile exercise modality with applications in both athletic enhancement and rehabilitation, yet the influence of forearm orientation remains understudied. Thus, this study aimed to investigate the impact of forearm position on upper-body arm-cycling Wingate tests. Fourteen adult males (27.3 ± 5.8 years) underwent bilateral assessments of handgrip strength in standing and seated positions, followed by pronated and supinated forward arm-cycling Wingate tests. Electromyography (EMG) was recorded from five upper-extremity muscles, including anterior deltoid, triceps brachii lateral head, biceps brachii, latissimus dorsi, and brachioradialis. Simultaneously, bilateral normal and propulsion forces were measured at the pedal-crank interface. Rate of perceived exertion (RPE), power output, and fatigue index were recorded post-test. The results showed that a pronated forearm position provided significantly (p < 0.05) higher normal and propulsion forces and triceps brachii muscle activation patterns during arm-cycling. No significant difference in RPE was observed between forearm positions (p = 0.17). A positive correlation was found between seated handgrip strength and peak power output during the Wingate test while pronated (dominant: p = 0.01, r = 0.55; non-dominant: p = 0.03, r = 0.49) and supinated (dominant: p = 0.03, r = 0.51; don-dominant: p = 0.04, r = 0.47). Fatigue changed the force and EMG profile during the Wingate test. In conclusion, this study enhances our understanding of forearm position's impact on upper-body Wingate tests. These findings have implications for optimizing training and performance strategies in individuals using arm-cycling for athletic enhancement and rehabilitation.

Forelimb movements contribute to hindlimb cutaneous reflexes during locomotion in cats

During quadrupedal locomotion, interactions between spinal and supraspinal circuits and somatosensory feedback coordinate forelimb and hindlimb movements. How this is achieved is not clear. To determine whether forelimb movements modulate hindlimb cutaneous reflexes involved in responding to an external perturbation, we stimulated the superficial peroneal nerve in six intact cats during quadrupedal locomotion and during hindlimb-only locomotion (with forelimbs standing on stationary platform) and in two cats with a low spinal transection (T12-T13) during hindlimb-only locomotion. We compared cutaneous reflexes evoked in six ipsilateral and four contralateral hindlimb muscles. Results showed similar occurrence and phase-dependent modulation of short-latency inhibitory and excitatory responses during quadrupedal and hindlimb-only locomotion in intact cats. However, the depth of modulation was reduced in the ipsilateral semitendinosus during hindlimb-only locomotion. Additionally, longer-latency responses occurred less frequently in extensor muscles bilaterally during hindlimb-only locomotion, whereas short-latency inhibitory and longer-latency excitatory responses occurred more frequently in the ipsilateral and contralateral sartorius anterior, respectively. After spinal transection, short-latency inhibitory and excitatory responses were similar to both intact conditions, whereas mid- or longer-latency excitatory responses were reduced or abolished. Our results in intact cats and the comparison with spinal-transected cats suggest that the absence of forelimb movements suppresses inputs from supraspinal structures and/or cervical cord that normally contribute to longer-latency reflex responses in hindlimb extensor muscles.NEW & NOTEWORTHY During quadrupedal locomotion, the coordination of forelimb and hindlimb movements involves central circuits and somatosensory feedback. To demonstrate how forelimb movement affects hindlimb cutaneous reflexes during locomotion, we stimulated the superficial peroneal nerve in intact cats during quadrupedal and hindlimb-only locomotion as well as in spinal-transected cats during hindlimb-only locomotion. We show that forelimb movement influences the modulation of hindlimb cutaneous reflexes, particularly the occurrence of long-latency reflex responses.

Efficacy of arm crank ergometry on individuals with spinal cord injury: A systematic review of randomized controlled trials

OBJECTIVES

To investigate the efficacy of arm crank ergometry (ACE) on physical, psychological, and quality of life outcomes in individuals with spinal cord injury (SCI).

LITERATURE SURVEY

A comprehensive search was conducted on PubMed, Scopus, MEDLINE, Physiotherapy Evidence Database (PEDro), Web of Science, REHABDATA, and Embase from inception until July 2023.

METHODOLOGY

Studies were included if the sample was composed of individuals with SCI, the intervention followed an ACE intervention, and the study was a randomized controlled trial including at least one outcome measure evaluating physical, psychological, or quality of life. The PEDro scale was used to assess the methodological quality of the included studies. The meta-analysis was not feasible due to the heterogeneity in the treatment protocols and outcome measures among the selected studies.

SYNTHESIS

Of 1013 articles, seven studies (n = 200), with 16% of participants being female, were included in this review. The scores on the PEDro scale ranged from 6 to 8, with a median score of 7. There were variations in treatment protocols and outcome measures, resulting in heterogeneous findings. The effects of the ACE interventions on physical, psychological, and quality of life outcomes showed inconsistency.

CONCLUSIONS

ACE training proves to be a suitable and safe intervention for individuals with traumatic SCI. Nevertheless, the existing evidence concerning its effects on physical, psychological, and quality of life outcomes in individuals with SCI is limited. Further trials are required to investigate the effects of various ACE training protocols on SCI populations.

Effect of using an 8-figure shoulder brace on arm swing angle and gait parameters in chronic stroke patients: a pilot randomized controlled study

BACKGROUND

The 8-figure shoulder brace during treadmill training (8-FSBTT) intervention can stabilize the shoulder joint, improve the upright of the thoracic spine, induces a change in the angle of the arm during walking, and consequently improve walking ability in stroke patients.

OBJECTIVES

Our objective is to compare the effects of a 4-week program of 8-FSBTT with those of only treadmill training (OT) on arm swing angle, and gait parameters (gait speed, cadence, and both side stride lengths) in chronic stroke patients.

METHODS

Participants were randomized to either the 8-FSBTT (n = 11) or OT (n = 11) group. Patients in both groups underwent standard physiotherapy for 30 min per session. In addition, 8-FSBTT and OT interventions were performed 10 min, 5 times per week for 4 weeks. Arm swing angle, gait speed, cadence, and both side stride lengths were measured after 4 weeks of training.

RESULTS

After 4 weeks of training, the 8-FSBTT group showed significant improvement in all outcome measures compared with baseline (p < 0.05). Furthermore, Arm swing angle, gait speed, cadence, and both side stride lengths showed greater improvement in the 8-FSBTT group compared to the OT group (p < 0.05).

CONCLUSIONS

This study demonstrated that 8-FSBTT training, combined with standard physiotherapy, improved Arm swing angle, gait speed, cadence, and both side stride lengths in the chronic stroke patients.

Combined contralateral C7 to C7 and L5 to S1 cross nerve transfer for treating limb hemiplegia after stroke

BACKGROUND

Contralateral C7 to C7 cross nerve transfer has been proved to be safe and effective for patients with spastic arm paralysis due to stroke and traumatic brain injury. For the lower limb, contralateral L5 to S1 cross nerve transfer serves as a novel surgical approach. In many cases, patients with hemiplegia have both upper and lower limb dysfunction and hope to restore all limb functions within one operation. To cope with this demand, we performed combined contralateral C7 to C7 and L5 to S1 cross nerve transfer in two cases successfully.

CASE DESCRIPTION

Two patients were enrolled in this study. The first patient is a 36-year-old woman who had spasticity and hemiplegia in both upper and lower limbs on the left side after a right cerebral hemorrhage 14 years prior. The second patient is a 64-year-old man who suffered from permanent muscle weakness in his right limbs, especially the leg, after a left cerebral hemorrhage 7 years prior. Both patients underwent the combined nerve transfer to improve upper and lower limb motor functions simultaneously. During the 10-month follow-up after surgery, the limb functions of both patients improved significantly.

CONCLUSIONS

This study demonstrates the safety and benefits of combined contralateral C7 to C7 and L5 to S1 cross nerve transfer for hemiplegic patients after stroke. This novel combined surgical approach could provide an optimal choice for patients suffering from both upper and lower limb dysfunction, to reduce hospital stay while reducing financial burden.

Measuring Neuroplasticity in Response to Cardiovascular Exercise in People With Stroke: A Critical Perspective

BACKGROUND

Rehabilitative treatments that promote neuroplasticity are believed to improve recovery after stroke. Animal studies have shown that cardiovascular exercise (CE) promotes neuroplasticity but the effects of this intervention on the human brain and its implications for the functional recovery of patients remain unclear. The use of biomarkers has enabled the assessment of cellular and molecular events that occur in the central nervous system after brain injury. Some of these biomarkers have proven to be particularly valuable for the diagnosis of severity, prognosis of recovery, as well as for measuring the neuroplastic response to different treatments after stroke.

OBJECTIVES

To provide a critical analysis on the current evidence supporting the use of neurophysiological, neuroimaging, and blood biomarkers to assess the neuroplastic response to CE in individuals poststroke.

RESULTS

Most biomarkers used are responsive to the effects of acute and chronic CE interventions, but the response appears to be variable and is not consistently associated with functional improvements. Small sample sizes, methodological variability, incomplete information regarding patient's characteristics, inadequate standardization of training parameters, and lack of reporting of associations with functional outcomes preclude the quantification of the neuroplastic effects of CE poststroke using biomarkers.

CONCLUSION

Consensus on the optimal biomarkers to monitor the neuroplastic response to CE is currently lacking. By addressing critical methodological issues, future studies could advance our understanding of the use of biomarkers to measure the impact of CE on neuroplasticity and functional recovery in patients with stroke.

Effects of shoulder brace usage on postural stability in stroke survivors: A pilot randomized controlled trial

BACKGROUND

Despite advances in stroke rehabilitation, challenges in upper limb motor recovery and postural stability persist, negatively affecting overall well-being. Arm slings and shoulder braces have been proposed to address these issues, but their efficacy in promoting postural stability remains unclear.

OBJECTIVE

This pilot randomized controlled study aimed to evaluate the impact of a new shoulder brace (N1-Neurosling) on trunk postural stability during walking, pain, and upper limb muscle strength in chronic stroke survivors.

METHODS

Twenty-four adult chronic stroke patients were involved and randomly assigned to the shoulder brace group (SBg) or control group (CTRLg). Were assessed at baseline (T0) and after 4 weeks (T1) through the Trunk Control Test, the Numerical Rating Scale, the Motricity Index, Manual Muscle Test, and instrumental wearable-based assessment.

RESULTS

After 4 weeks, the SBg showed significant improvement in Trunk Control Test scores (p = 0.020) and smoothness of gait measured by log dimensionless jerk along the Antero-Posterior axis (- 5.31±0.25 vs. - 5.18±0.27, p = 0.018) compared to the CTRLg. The SBg also demonstrated a reduction in pain in the shoulder girdle and enhanced upper limb muscle strength.

CONCLUSION

The use of the N1-Neurosling shoulder brace led to improvements in postural stability and smoothness of gait in stroke patients.

Functional Near-Infrared Spectroscopy-Based Evidence of the Cerebral Oxygenation and Network Characteristics of Upper Limb Fatigue

OBJECTIVE

The objective of this research is to better understand the effects of upper limb fatigue on the cerebral cortex. The aim of this study was to investigate the characteristics of cerebral oxygenation and cortical functional connectivity in healthy adults after upper limb fatigue using functional near-infrared spectroscopy (fNIRS).

METHODS

Nineteen healthy adults participated in this study. The participants began exercising on an arm crank ergometer with no load, which was then increased by 0.2 kg per minute, maintaining a speed of at least 90 revolutions per minute during the exercise. Functional near-infrared spectroscopy covering the prefrontal cortex and motor area was used to monitor brain activity during rest and exercise. Heart rate and RPE were monitored during exercise to evaluate the degree of fatigue. Paired-sample t-tests were used to examine differences in the concentration of oxygenated hemoglobin (HbO2) and functional connectivity before and after fatigue.

RESULTS

All participants completed the exercise test that induced fatigue. We observed a significant decrease in HbO2 levels in the prefrontal and motor areas after exercise. In addition, brain network features showed a significant decrease in functional connectivity between the left and right motor cortices, between the motor and prefrontal cortices, and between both prefrontal cortices after fatigue.

CONCLUSION

This study demonstrates that, in healthy adults, exercise-induced fatigue in the upper limbs significantly affects brain function. In particular, it leads to reduced functional connectivity between the motor cortex and the prefrontal cortex.

Smartwatch gait coordination index: New measure for human gait utilizing smartwatch sensor

Human walking reflects the state of human health. Numerous medical studies have been conducted to analyze walking patterns and to diagnose disease progression. However, this process requires expensive equipment and considerable time and manpower. Smartwatches are equipped with gyro sensors to detect human movements and graph-walking patterns. To measure the abnormality in walking using this graph, we developed a smartwatch gait coordination index (SGCI) and examined its usefulness. The phase coordination index was applied to analyze arm movements. Based on previous studies, the phase coordination index formula was applied to graphs obtained from arm movements, showing that arm and leg movements during walking are correlated with each other. To prove this, a smartwatch was worn on the arms and legs of 8 healthy adults and the difference in arm movements was measured. The SGCI values with abnormal walking patterns were compared with the SGCI values obtained during normal walking. In the first experiment, the measured leg SGCI in normal walking averaged 9.002 ± 3.872 and the arm SGCI averaged 9.847 ± 6.115. The movements of both arms and legs showed stable sinusoidal waves. In fact, as a result of performing a paired t test of both exercise phases measured by the strike point using the maximum and minimum values, it was confirmed that the 2 exercises were not statistically different, as it yielded a P value of 0.469 (significance level α = 0.05). The arm SGCI measured after applying the 3 kg weight impairment on 1 leg was 22.167 ± 4.705. It was confirmed that the leg SGCI and 3 kg weight arm SGCI were statistically significant, as it yielded a P value of 0.001 (significance level α = 0.05). The SCGI can be automatically and continuously measured with the gyro sensor of the smartwatch and can be used as an indirect indicator of human walking conditions.

Disinhibition of short-latency but not long-latency afferent inhibition of the lower limb during upper-limb muscle contraction

Research has demonstrated that motor and sensory functions of the lower limbs can be modulated by upper-limb muscle contractions. However, whether sensorimotor integration of the lower limb can be modulated by upper-limb muscle contractions is still unknown. [AQ: NR Original articles do not require structured abstracts. Hence, abstract subsections have been deleted. Please check.]Human sensorimotor integration has been studied using short- or long-latency afferent inhibition (SAI or LAI, respectively), which refers to inhibition of motor-evoked potentials (MEPs) elicited via transcranial magnetic stimulation by preceding peripheral sensory stimulation. In the present study, we aimed to investigate whether upper-limb muscle contractions could modulate the sensorimotor integration of the lower limbs by examining SAI and LAI. Soleus muscle MEPs following electrical tibial nerve stimulation (TSTN) during rest or voluntary wrist flexion were recorded at inter-stimulus intervals (ISIs) of 30 (i.e. SAI), 100, and 200 ms (i.e. LAI). The soleus Hoffman reflex following TSTN was also measured to identify whether MEP modulation occurred at the cortical or the spinal level. Results showed that lower-limb SAI, but not LAI, was disinhibited during voluntary wrist flexion. Furthermore, the soleus Hoffman reflex following TSTN during voluntary wrist flexion was unchanged when compared with that during the resting state at any ISI. Our findings suggest that upper-limb muscle contractions modulate sensorimotor integration of the lower limbs and that disinhibition of lower-limb SAI during upper-limb muscle contractions is cortically based.

Evolution of muscle coordination and mechanical output following four weeks of arm cranking submaximal training

Muscle synergies is extensively studied to understand how the neuromusculoskeletal system deals with abundancy. The synergies represent covariant muscles that acts as building blocks for movement production. Nevertheless, little is known on how those synergies evolve following training, learning and expertise. This study reports the influence a 4-weeks submaximal training of arm-cranking on novice participants' muscle synergies.

METHODS

12 participants performed 8 sessions of submaximal training for 4 weeks. One session consisted in two 30-second-maximal power tests followed by six 2-minutes-bouts at 30% of maximal recorded power. Cranking torque and EMG of 11 muscles were recorded during the entire protocol. After EMG normalization, muscle synergies were extracted using NNMF. Similarity was computed using cross-correlation and cosine similarities and statistical evolution across training was tested using repeated measured ANOVA.

RESULTS

While maximal power increased across training days nor torque management, EMG or muscle synergies were significantly affected by submaximal training. Nevertheless, results suggest slights modifications of muscle synergies across day despite to non-significant differences.

DISCUSSION

Despite the strong complexity of the upper limbs anatomy, our results showed that training didn't induce significant changes in movement realization (mechanical and coordination level). A low-dimensional organization of muscle synergies is selected from the first day and kept through the following training days, despite slight but non-significant modifications.This study supports the hypothesis that motor control for movement production could be simplify using low-dimensional building blocks (muscle synergies). Such building blocks allow stability in movement execution and are slightly adjusted to fit movement requirements with training.

Effects of Aerobic Training in Patients with Subacute COVID-19: A Randomized Controlled Feasibility Trial

Many clinical practice recommendations indicate rehabilitation as essential for patients with sequelae of severe or critical COVID-19 and suggest the prompt initiation of a multicomponent rehabilitation program focused on aerobic and endurance training. However, randomized controlled trials (RCTs) regarding aerobic exercise are lacking. Therefore, we aimed to assess the feasibility and effectiveness of the addition of aerobic training to standard rehabilitation in subjects with subacute COVID-19. Participants were 32/214 patients with the sequelae of severe or critical COVID-19 in the acute phase who were eligible and agreed to participate in the study (eligibility = 15%, recruitment = 100%). After randomization and assessment with functional and strength tests, all the participants underwent an inpatient-tailored rehabilitation program (50 min/day, 5 days/week, 10 sessions); in addition, the experimental group performed a low- to moderate-intensity aerobic exercise (30 min/day, 10 sessions). No dropouts or severe adverse events were reported, with an attendance rate of 95.6%. Most of the secondary outcomes significantly improved in both groups, but the improvement in the Functional Independence Measure and Cumulated Ambulation Score-Italian version was significantly greater in the experimental group (at least, p < 0.05). This RCT showed that aerobic exercise is feasible and safe in subacute COVID-19. Moreover, it appears to be beneficial and useful in improving patients' independence and mobility.

A protocol to analyze the global literature on the clinical benefit of interlimb-coordinated intervention in gait recovery and the associated neurophysiological changes in patients with stroke

Background

Stroke is among the leading causes of disability of worldwide. Gait dysfunction is common in stroke survivors, and substantial advance is yet to be made in stroke rehabilitation practice to improve the clinical outcome of gait recovery. The role of the upper limb in gait recovery has been emphasized in the literature. Recent studies proposed that four limbs coordinated interventions, coined the term "interlimb-coordinated interventions," could promote gait function by increasing the neural coupling between the arms and legs. A high-quality review is essential to examine the clinical improvement and neurophysiological changes following interlimb-coordinated interventions in patients with stroke.

Methods

Systematic review and meta-analysis will be conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The literature will be retrieved from the databases of OVID, MEDLINE, PubMed, Web of Science, EMBASE, and PsycINFO. Studies published in English over the past 15 years will be included. All of the clinical studies (e.g., randomized, pseudorandomized and non-randomized controlled trials, uncontrolled trials, and case series) that employed interlimb intervention and assessed gait function of patients with stroke will be included. Clinical functions of gait, balance, lower limb functions, and neurophysiologic changes are the outcome measures of interest. Statistical analyses will be performed using the Comprehensive Meta-Analysis version 3.

Discussion

The findings of this study will provide insight into the clinical benefits and the neurophysiological adaptations of the nervous system induced by interlimb-coordinated intervention in patients with stroke. This would guide clinical decision-making and the future development of targeted neurorehabilitation protocol in stroke rehabilitation to improve gait and motor function in patients with stroke. Increasing neuroplasticity through four-limb intervention might complement therapeutic rehabilitation strategies in this patient group. The findings could also be insightful for other cerebral diseases.

Five weeks of Yuishinkai karate training improves balance and neuromuscular function in older adults: a preliminary study

Background

Martial arts training has shown positive impacts on balance and physiological measurements. Further investigation of the contents and feasibility of an effective therapeutic assessment of martial arts is needed in older adults, mainly for future applications and real-world implementation.

Methods

Sixteen older adults (8 male, 8 female, age 59–90 years), with or without chronic conditions, participated in a preliminary study using 5-weeks of karate training and a triple baseline control procedure. Group and single subject data analyses were conducted for dynamic balance, Timed Up and Go (TUG), hand grip, ankle plantarflexion force, and spinal cord excitability (via the soleus H-reflex) pre- and post-training.

Results

On average, participants completed a total of 2437 steps, 1762 turns, 3585 stance changes, 2047 punches, 2757 blocks, and 1253 strikes. Karate training improved dynamic balance performance such that the group average time was reduced (time to target (−13.6%, p = 0.020) and time to center (−8.3%, p = 0.010)). TUG was unchanged when considering the entire group (p = 0.779), but six participants displayed significant changes. Left handgrip (7.9%, p = 0.037), and plantarflexion force in the right (28.8%, p = 0.045) and left leg (13.3%, p = 0.024) increased for the group. Spinal cord excitability remained unchanged in group data analysis but 5 individuals had modulated H_max/M_max ratios.

Conclusion

5-weeks of karate training delivered in a fashion to mimic generally accessible community-level programs improved balance and strength in older adults. Whole-body movement embodied in karate training enhanced neuromuscular function and postural control. We met the overriding goal of this preliminary study to emphasize and assess feasibility and safety for the generalizability of martial arts interventions to real-world communities to impact health outcomes. Further quantitative work should explore threshold dose and development of martial arts training interventions as potential “exercise is medicine” functional fitness for older adults.

Subject specific muscle synergies and mechanical output during cycling with arms or legs

Background

Upper (UL) and lower limb (LL) cycling is extensively used for several applications, especially for rehabilitation for which neuromuscular interactions between UL and LL have been shown. Nevertheless, the knowledge on the muscular coordination modality for UL is poorly investigated and it is still not known whether those mechanisms are similar or different to those of LL. The aim of this study was thus to put in evidence common coordination mechanism between UL and LL during cycling by investigating the mechanical output and the underlying muscle coordination using synergy analysis.

Methods

Twenty-five revolutions were analyzed for six non-experts' participants during sub-maximal cycling with UL or LL. Crank torque and muscle activity of eleven muscles UL or LL were recorded. Muscle synergies were extracted using nonnegative matrix factorization (NNMF) and group- and subject-specific analysis were conducted.

Results

Four synergies were extracted for both UL and LL. UL muscle coordination was organized around several mechanical functions (pushing, downing, and pulling) with a proportion of propulsive torque almost 80% of the total revolution while LL muscle coordination was organized around a main function (pushing) during the first half of the cycling revolution. LL muscle coordination was robust between participants while UL presented higher interindividual variability.

Discussion

We showed that a same principle of muscle coordination exists for UL during cycling but with more complex mechanical implications. This study also brings further results suggesting each individual has unique muscle signature.

Neural Substrates of Transcutaneous Spinal Cord Stimulation: Neuromodulation across Multiple Segments of the Spinal Cord

Transcutaneous spinal cord stimulation (tSCS) has the potential to promote improved sensorimotor rehabilitation by modulating the circuitry of the spinal cord non-invasively. Little is currently known about how cervical or lumbar tSCS influences the excitability of spinal and corticospinal networks, or whether the synergistic effects of multi-segmental tSCS occur between remote segments of the spinal cord. The aim of this review is to describe the emergence and development of tSCS as a novel method to modulate the spinal cord, while highlighting the effectiveness of tSCS in improving sensorimotor recovery after spinal cord injury. This review underscores the ability of single-site tSCS to alter excitability across multiple segments of the spinal cord, while multiple sites of tSCS converge to facilitate spinal reflex and corticospinal networks. Finally, the potential and current limitations for engaging cervical and lumbar spinal cord networks through tSCS to enhance the effectiveness of rehabilitation interventions are discussed. Further mechanistic work is needed in order to optimize targeted rehabilitation strategies and improve clinical outcomes.

Mechanical Design and Control System Development of a Rehabilitation Robotic System for Walking With Arm Swing

Background: Interlimb neural coupling implies that arm swing should be included during gait training to improve rehabilitation outcomes. We previously developed several systems for production of walking with arm swing, but the reaction forces on the foot sole during usage of the systems were not satisfactory and there was potential to improve control system performance. This work aimed to design and technically evaluate a novel system for producing walking with synchronised arm and leg movement and with dynamic force loading on the foot soles.

Methods: The robotic system included a passive curved treadmill and a trunk frame, upon which the rigs for the upper and lower limbs were mounted. Ten actuators and servocontrollers with EtherCAT communication protocol controlled the bilateral shoulder, elbow, hip, knee and ankle joints. Impedance control algorithms were developed and ran in an industrial PC. Flexible pressure sensors recorded the plantar forces on the foot soles. The criteria of implementation and responsiveness were used to formally evaluate the technical feasibility of the system.

Results: Using impedance algorithms, the system produced synchronous walking with arm swing on the curved treadmill, with mean RMS angular tracking error <2° in the 10 joint profiles. The foot trajectories relative to the hip presented similar shapes to those during normal gait, with mean RMS displacement error <1.5 cm. A force pattern that started at the heel and finished at the forefoot was observed during walking using the system, which was similar to the pattern from overground walking.

Conclusion: The robotic system produced walking-like kinematics in the 10 joints and in the foot trajectories. Integrated with the curved treadmill, the system also produced walking-like force patterns on the foot soles. The system is considered feasible as far as implementation and responsiveness are concerned. Future work will focus on improvement of the mechanical system for future clinical application.

The Efficacy of Interlimb-Coordinated Intervention on Gait and Motor Function Recovery in Patients with Acute Stroke: A Multi-Center Randomized Controlled Trial Study Protocol

BACKGROUND

The efficacy of interlimb-coordinated training on gait and upper limb functional improvement remains unclear. The latest published randomized controlled trials have supported the potential benefits of interlimb-coordinated training to enhance gait function. Upper limb functional recovery may also benefit from interlimb-coordinated training since most everyday activities require the coordinated use of both hands to complete a task. This study investigates the efficacy of interlimb-coordinated training on gait and upper limb functional recovery over a short-medium term period.

METHODS

A total of 226 acute stroke patients will be recruited from four centres over four years. Patients will be randomly allocated to either conventional therapy or conventional therapy plus interlimb-coordinated training. Outcomes will be recorded at baseline, after 2 weeks of intervention, and at 3- and 6-months post-intervention. Gait speed is the primary outcome measure. Secondary outcome measures include Fugl-Meyer Assessment of Motor Recovery, Berg Balance Scale, Timed Up and Go test, Action Research Arm Test, electroencephalography, and magnetic resonance imaging.

CONCLUSION

The results of this trial will provide an in-depth understanding of the efficacy of early interlimb-coordinated intervention on gait and upper functional rehabilitation and how it may relate to the neural plasticity process.

The effects of arm crank training on aerobic capacity, physical performance, quality of life, and health-related disability in patients with Parkinson's disease

BACKGROUND

Aerobic exercise training contributes to improvement of cardiopulmonary capacity, mobility, neurological function, and quality of life.

AIMS

To investigate the effects of arm crank ergometer training on aerobic capacity, quality of life, and Parkinson's disease (PD)-related disability METHODS: Seventeen patients with PD were recruited to study. Assessments were performed at baseline and at the end of an 8-week arm crank ergometer (ACE) training program (3 days/week; 1 h per session, 50-70% VO_2peak) with patients acting as their own control. Outcome measures included aerobic capacity assessment, 6-min walk test (6MWT), timed up and go test (TUG), Unified Parkinson's Disease Rating Scale (UPDRS), Parkinson's Disease Questionnaire-39 (PDQ-39), Beck Depression Index (BDI), the Falls Efficacy Scale (FES), and Montreal Cognitive Assessment (MoCA).

RESULTS

At the end of the study, an increase of 30.49% in aerobic capacity was observed. Statistically significant improvements were found for the 6MWT (p = 0.001), TUG test (p = 0.001), UPDRS total score (p = 0.002), quality of life assessed with PDQ-39 (p = 0.006), BDI (p = 0.001), and FES scores (p = 0.002) after an 8-week ACE training. No significant effect on MoCA was found (p = 0.264).

CONCLUSION

An 8-week ACE training led to significant improvement in aerobic capacity, physical performance, and PD-related disabilities.

[Botulinum therapy of spastic forms of cerebral palsy in various locomotor patterns]

Spasticity in patients with cerebral palsy (CP) is the main impediment to normal locomotion. The function of the Central Pattern Generator (CPG), i.e. a group of neural chains in the spinal cord, stands at the core of any rhythmical movement. CPG can generate locomotion patterns without supraspinal control, which can have both positive and negative impact on the ability to move. Performing the motor tasks such as walking, running and swimming, creates the consistent rhythmical movement of legs and arms through interaction between CPGs of upper and lower extremities. This interaction can cause the activation of pathological movement patterns in lower extremities in response to upper limb spasticity. Thus, neural chains in the spinal cord become the generator of pathologically increased excitation which has developed as a result of a focal lesion in the CNS. All the statements described above show the importance of introducing the upper limb injections of bFotulinum toxin A in the protocol in order to develop normal locomotion. The PUL study approved the optimal level of efficacy and favourable safety profile of botulinum toxin A in children with CP and upper limb muscle spasticity.

Moving forward: methodological considerations for assessing corticospinal excitability during rhythmic motor output in humans

The use of transcranial magnetic stimulation to assess the excitability of the central nervous system to further understand the neural control of human movement is expansive. The majority of the work performed to-date has assessed corticospinal excitability either at rest or during relatively simple isometric contractions. The results from this work are not easily extrapolated to rhythmic, dynamic motor outputs, given that corticospinal excitability is task-, phase-, intensity-, direction-, and muscle-dependent (Power KE, Lockyer EJ, Forman DA, Button DC. Appl Physiol Nutr Metab 43: 1176-1185, 2018). Assessing corticospinal excitability during rhythmic motor output, however, involves technical challenges that are to be overcome, or at the minimum considered, when attempting to design experiments and interpret the physiological relevance of the results. The purpose of this narrative review is to highlight the research examining corticospinal excitability during a rhythmic motor output and, importantly, to provide recommendations regarding the many factors that must be considered when designing and interpreting findings from studies that involve limb movement. To do so, the majority of work described herein refers to work performed using arm cycling (arm pedaling or arm cranking) as a model of a rhythmic motor output used to examine the neural control of human locomotion.

Predictive Value of Upper Extremity Outcome Measures After Stroke-A Systematic Review and Metaregression Analysis

A better understanding of motor recovery after stroke requires large-scale, longitudinal trials applying suitable assessments. Currently, there is an abundance of upper limb assessments used to quantify recovery. How well various assessments can describe upper limb function change over 1 year remains uncertain. A uniform and feasible standard would be beneficial to increase future studies' comparability on stroke recovery. This review describes which assessments are common in large-scale, longitudinal stroke trials and how these quantify the change in upper limb function from stroke onset up to 1 year. A systematic search for well-powered stroke studies identified upper limb assessments classifying motor recovery during the initial year after a stroke. A metaregression investigated the association between assessments and motor recovery within 1 year after stroke. Scores from nine common assessments and 4,433 patients were combined and transformed into a standardized recovery score. A mixed-effects model on recovery scores over time confirmed significant differences between assessments (P < 0.001), with improvement following the weeks after stroke present when measuring recovery using the Action Research Arm Test (β = 0.013), Box and Block test (β = 0.011), Fugl–Meyer Assessment (β = 0.007), or grip force test (β = 0.023). A last-observation-carried-forward analysis also highlighted the peg test (β = 0.017) and Rivermead Assessment (β = 0.011) as additional, valuable long-term outcome measures. Recovery patterns and, thus, trial outcomes are dependent on the assessment implemented. Future research should include multiple common assessments and continue data collection for a full year after stroke to facilitate the consensus process on assessments measuring upper limb recovery.

Using a simple rope-pulley system that mechanically couples the arms, legs, and treadmill reduces the metabolic cost of walking

BACKGROUND

Emphasizing the active use of the arms and coordinating them with the stepping motion of the legs may promote walking recovery in patients with impaired lower limb function. Yet, most approaches use seated devices to allow coupled arm and leg movements. To provide an option during treadmill walking, we designed a rope-pulley system that physically links the arms and legs. This arm-leg pulley system was grounded to the floor and made of commercially available slotted square tubing, solid strut channels, and low-friction pulleys that allowed us to use a rope to connect the subject's wrist to the ipsilateral foot. This set-up was based on our idea that during walking the arm could generate an assistive force during arm swing retraction and, therefore, aid in leg swing.

METHODS

To test this idea, we compared the mechanical, muscular, and metabolic effects between normal walking and walking with the arm-leg pulley system. We measured rope and ground reaction forces, electromyographic signals of key arm and leg muscles, and rates of metabolic energy consumption while healthy, young subjects walked at 1.25 m/s on a dual-belt instrumented treadmill (n = 8).

RESULTS

With our arm-leg pulley system, we found that an assistive force could be generated, reaching peak values of 7% body weight on average. Contrary to our expectation, the force mainly coincided with the propulsive phase of walking and not leg swing. Our findings suggest that subjects actively used their arms to harness the energy from the moving treadmill belt, which helped to propel the whole body via the arm-leg rope linkage. This effectively decreased the muscular and mechanical demands placed on the legs, reducing the propulsive impulse by 43% (p < 0.001), which led to a 17% net reduction in the metabolic power required for walking (p = 0.001).

CONCLUSIONS

These findings provide the biomechanical and energetic basis for how we might reimagine the use of the arms in gait rehabilitation, opening the opportunity to explore if such a method could help patients regain their walking ability.

TRIAL REGISTRATION

 Study registered on 09/29/2018 in ClinicalTrials.gov (ID-NCT03689647).

Augmented efficacy of intermittent theta burst stimulation on the virtual reality-based cycling training for upper limb function in patients with stroke: a double-blinded, randomized controlled trial

Background

Virtual reality and arm cycling have been reported as effective treatments for improving upper limb motor recovery in patients with stroke. Intermittent theta burst stimulation (iTBS) can increase ipsilesional cortical excitability, and has been increasingly used in patients with stroke. However, few studies examined the augmented effect of iTBS on neurorehabilitation program. In this study, we investigated the augmented effect of iTBS on virtual reality-based cycling training (VCT) for upper limb function in patients with stroke.

Methods

In this randomized controlled trial, 23 patients with stroke were recruited. Each patient received either 15 sessions of iTBS or sham stimulation in addition to VCT on the same day. Outcome measures were assessed before and after the intervention. Primary outcome measures for the improvement of upper limb motor function and spasticity were Fugl-Meyer Assessment-Upper Extremity (FMA-UE) and Modified Ashworth Scale Upper-Extremity (MAS-UE). Secondary outcome measures for activity and participation were Action Research Arm Test (ARAT), Nine Hole Peg Test (NHPT), Box and Block Test (BBT) and Motor Activity Log (MAL), and Stroke Impact Scale (SIS). Wilcoxon signed-rank tests were performed to evaluate the effectiveness after the intervention and Mann–Whitney U tests were conducted to compare the therapeutic effects between two groups.

Results

At post-treatment, both groups showed significant improvement in FMA-UE and ARAT, while only the iTBS + VCT group demonstrated significant improvement in MAS-UE, BBT, NHPT, MAL and SIS. The Mann–Whitney U tests revealed that the iTBS + VCT group has presented greater improvement than the sham group significantly in MAS-UE, MAL-AOU and SIS. However, there were no significant differences in the changes of the FMA-UE, ARAT, BBT, NHPT and MAL-QOM between groups.

Conclusions

Intermittent TBS showed augmented efficacy on VCT for reducing spasticity, increasing actual use of the affected upper limb, and improving participation in daily life in stroke patients. This study provided an integrated innovative intervention, which may be a promising therapy to improve upper limb function recovery in stroke rehabilitation. However, this study has a small sample size, and thus a further larger-scale study is warranted to confirm the treatment efficacy.

Trial registration This trial was registered under ClinicalTrials.gov ID No. NCT03350087, retrospectively registered, on November 22, 2017

Simultaneous Cervical and Lumbar Spinal Cord Stimulation Induces Facilitation of Both Spinal and Corticospinal Circuitry in Humans

Coupling between cervical and lumbar spinal networks (cervico-lumbar coupling) is vital during human locomotion. Impaired cervico-lumbar coupling after neural injuries or diseases can be reengaged via simultaneous arm and leg cycling training. Sensorimotor circuitry including cervico-lumbar coupling may further be enhanced by non-invasive modulation of spinal circuity using transcutaneous spinal cord stimulation (tSCS). This project aimed to determine the effect of cervical, lumbar, or combined tSCS on spinal reflex (Hoffmann [H-]) and corticospinal (motor evoked potential [MEP]) excitability during a static or cycling cervico-lumbar coupling task. Fourteen neurologically intact study participants were seated in a recumbent leg cycling system. H-reflex and MEP amplitudes were assessed in the left flexor carpi radialis (FCR) muscle during two tasks (Static and Cycling) and four conditions: (1) No tSCS, (2) tSCS applied to the cervical enlargement (Cervical); (3) tSCS applied to the lumbar enlargement (Lumbar); (4) simultaneous cervical and lumbar tSCS (Combined). While cervical tSCS did not alter FCR H-reflex amplitude relative to No tSCS, lumbar tSCS significantly facilitated H-reflex amplitude by 11.1%, and combined cervical and lumbar tSCS significantly enhanced the facilitation to 19.6%. Neither cervical nor lumbar tSCS altered MEP amplitude alone (+4.9 and 1.8% relative to legs static, No tSCS); however, combined tSCS significantly increased MEP amplitude by 19.7% compared to No tSCS. Leg cycling alone significantly suppressed the FCR H-reflex relative to static, No tSCS by 13.6%, while facilitating MEP amplitude by 18.6%. When combined with leg cycling, tSCS was unable to alter excitability for any condition. This indicates that in neurologically intact individuals where interlimb coordination and corticospinal tract are intact, the effect of leg cycling on cervico-lumbar coupling and corticospinal drive was not impacted significantly with the tSCS intensity used. This study demonstrates, for the first time, that tonic activation of spinal cord networks through multiple sites of tSCS provides a facilitation of both spinal reflex and corticospinal pathways. It remains vital to determine if combined tSCS can influence interlimb coupling after neural injury or disease when cervico-lumbar connectivity is impaired.

Ipsilateral motor pathways to the lower limb after stroke: Insights and opportunities

Stroke-related damage to the crossed lateral corticospinal tract causes motor deficits in the contralateral (paretic) limb. To restore functional movement in the paretic limb, the nervous system may increase its reliance on ipsilaterally descending motor pathways, including the uncrossed lateral corticospinal tract, the reticulospinal tract, the rubrospinal tract, and the vestibulospinal tract. Our knowledge about the role of these pathways for upper limb motor recovery is incomplete, and even less is known about the role of these pathways for lower limb motor recovery. Understanding the role of ipsilateral motor pathways to paretic lower limb movement and recovery after stroke may help improve our rehabilitative efforts and provide alternate solutions to address stroke-related impairments. These advances are important because walking and mobility impairments are major contributors to long-term disability after stroke, and improving walking is a high priority for individuals with stroke. This perspective highlights evidence regarding the contributions of ipsilateral motor pathways from the contralesional hemisphere and spinal interneuronal pathways for paretic lower limb movement and recovery. This perspective also identifies opportunities for future research to expand our knowledge about ipsilateral motor pathways and provides insights into how this information may be used to guide rehabilitation.

Effects of gravity and kinematic constraints on muscle synergies in arm cycling

Arm cycling is a bimanual motor task used in medical rehabilitation and in sports training. Understanding how muscle coordination changes across different biomechanical constraints in arm cycling is a step toward improved rehabilitation approaches. This exploratory study aims to get new insights on motor control during arm cycling. To achieve our main goal, we used the muscle synergies analysis to test three hypotheses: 1) body position with respect to gravity (sitting and supine) has an effect on muscle synergies; 2) the movement size (crank length) has an effect on the synergistic behavior; 3) the bimanual cranking mode (asynchronous and synchronous) requires different synergistic control. Thirteen able-bodied volunteers performed arm cranking on a custom-made device with unconnected cranks, which allowed testing three different conditions: body position (sitting vs. supine), crank length (10 cm vs. 15 cm), and cranking mode (synchronous vs. asynchronous). For each of the eight possible combinations, subjects cycled for 30 s while electromyography of eight muscles (four from each arm) were recorded: biceps brachii, triceps brachii, anterior deltoid, and posterior deltoid. Muscle synergies in this eight-dimensional muscle space were extracted by nonnegative matrix factorization. Four synergies accounted for over 90% of muscle activation variances in all conditions. Results showed that synergies were affected by body position and cranking mode but practically unaffected by movement size. These results suggest that the central nervous system may employ different motor control strategies in response to external constraints such as cranking mode and body position during arm cycling.NEW & NOTEWORTHY Recent studies analyzed muscle synergies in lower limb cycling. Here, we examine upper limb cycling and specifically the effect of body position with respect to gravity, movement size, and cranking mode on muscle coordination during arm cranking tasks. We show that altered body position and cranking mode affects modular organization of muscle activities. To our knowledge, this is the first study assessing motor control through muscle synergies framework during upper limb cycling with different constraints.

Effects of Robot-Assisted Rehabilitation on Hand Function of People With Stroke: A Randomized, Crossover-Controlled, Assessor-Blinded Study

IMPORTANCE

The effects of robot-assisted task-oriented training with tangible objects among patients with stroke remain unknown.

OBJECTIVE

To investigate the effects of robot-assisted therapy (RT) with a Gloreha device on sensorimotor and hand function and ability to perform activities of daily living (ADLs) among patients with stroke.

DESIGN

Randomized, crossover-controlled, assessor-blinded study.

SETTING

Rehabilitation clinic.

PARTICIPANTS

Patients (N = 24) with moderate motor and sensory deficits.

INTERVENTION

Patients participated in 12 RT sessions and 12 conventional therapy (CT) sessions, with order counterbalanced, for 6 wk, with a 1-mo washout period.

OUTCOMES AND MEASURES

Performance was assessed four times: before and after RT and before and after CT. Outcomes were measured using the Fugl-Meyer Assessment-Upper Extremity (FMA-UE), Box and Block Test, electromyography of the extensor digitorum communis (EDC) and brachioradialis, and a grip dynamometer for motor function; Semmes-Weinstein hand monofilament and the Revised Nottingham Sensory Assessment for sensory function; and the Modified Barthel Index (MBI) for ADL ability.

RESULTS

RT resulted in significantly improved FMA-UE proximal (p = .038) and total (p = .046) and MBI (p = .030) scores. Participants' EDC muscles exhibited higher efficacy during the small-block grasping task of the Box and Block Test after RT than after CT (p = .050).

CONCLUSIONS AND RELEVANCE

RT with the Gloreha device can facilitate whole-limb function, leading to beneficial effects on arm motor function, EDC muscle recruitment efficacy, and ADL ability for people with subacute and chronic stroke.

WHAT THIS ARTICLE ADDS

The evidence suggests that a task-oriented approach combined with the Gloreha device can facilitate engagement in whole-limb active movement and efficiently promote functional recovery.

The Effect of Crank Resistance on Arm Configuration and Muscle Activation Variances in Arm Cycling Movements

Arm cycling on an ergometer is common in sports training and rehabilitation protocols. The hand movement is constrained along a circular path, and the user is working against a resistance, maintaining a cadence. Even if the desired hand trajectory is given, there is the flexibility to choose patterns of joint coordination and muscle activation, given the kinematic redundancy of the upper limb. With changing external load, motor noise and changing joint stiffness may affect the pose of the arm even though the endpoint trajectory is unchanged. The objective of this study was to examine how the crank resistance influences the variances of joint configuration and muscle activation. Fifteen healthy participants performed arm cranking on an arm-cycle ergometer both unimanually and bimanually with a cadence of 60 rpm against three crank resistances. Joint configuration was represented in a 3-dimensional joint space defined by inter-segmental joint angles, while muscle activation in a 4-dimensional "muscle activation space" defined by EMGs of 4 arm muscles. Joint configuration variance in the course of arm cranking was not affected by crank resistance, whereas muscle activation variance was proportional to the square of muscle activation. The shape of the variance time profiles for both joint configuration and muscle activation was not affected by crank resistance. Contrary to the prevailing assumption that an increased motor noise would affect the variance of auxiliary movements, the influence of noise doesn't appear at the joint configuration level even when the system is redundant. Our results suggest the separation of kinematic- and force-control, via mechanisms that are compensating for dynamic nonlinearities. Arm cranking may be suitable when the aim is to perform training under different load conditions, preserving stable and secure control of joint movements and muscle activations.

Addition of aerobic training to conventional rehabilitation after hip fracture: a randomized, controlled, pilot feasibility study

OBJECTIVES

To determine the feasibility and safety of aerobic training with an arm crank ergometer and its effectiveness in improving functional capacity and gait in patients with recent hip fracture.

DESIGN

Randomized, controlled, assessor-blinded pilot study, with intention-to-treat analysis.

SETTING

Inpatients, rehabilitation department.

SUBJECTS

40 patients with hip fracture surgically treated.

INTERVENTIONS

Training group performed aerobic exercise with an arm crank ergometer (15 sessions, 30 minutes/day) at an intensity of 64% to 76% of maximum heart rate, in addition to conventional inpatient rehabilitation.

MAIN MEASURES

Primary outcome was the feasibility (including eligibility rate, recruitment rate, number of drop-outs and adverse events, adherence). Secondary measures were the Timed Up and Go test, ability to walk independently, muscle torque of knee extensors of fractured and non-fractured leg, Functional Independence Measure.

RESULTS

Mostly due to pre-existing disability and fracture type, only 40/301 (13%) patients were eligible (age 84.6 ± 7.6 years, 75% female); all agreed to participate and 90% completed the trial, without adverse events. Adherence to aerobic exercise was good, with high attendance at sessions (93%), a strong compliance to exercise duration (95%) but lower compliance to the prescribed intensity (73%). After the program, more patients were able to walk independently in the training group (n = 18) compared to control (n = 13) (P < 0.05). Also the muscle torque of fractured leg knee extensors was higher in the training group (P < 0.05).

CONCLUSION

Aerobic training in addition to conventional rehabilitation after a hip fracture is feasible and safe and it was effective in improving gait performance and strength of fractured leg.

TRIAL REGISTRATION

NCT04025866.

Changes in muscle activity during the flexion and extension phases of arm cycling as an effect of power output are muscle-specific

Arm cycling is commonly used in rehabilitation settings for individuals with motor impairments in an attempt to facilitate neural plasticity, potentially leading to enhanced motor function in the affected limb(s). Studies examining the neural control of arm cycling, however, typically cycle using a set cadence and power output. Given the importance of motor output intensity, typically represented by the amplitude of electromyographic (EMG) activity, on neural excitability, surprisingly little is known about how arm muscle activity is modulated using relative workloads. Thus, the objective of this study was to characterize arm muscle activity during arm cycling at different relative workloads. Participants (n = 11) first completed a 10-second maximal arm ergometry sprint to determine peak power output (PPO) followed by 11 randomized trials of 20-second arm cycling bouts ranging from 5–50% of PPO (5% increments) and a standard 25 W workload. All submaximal trials were completed at 60 rpm. Integrated EMG amplitude (iEMG) was assessed from the biceps brachii, brachioradialis, triceps brachii, flexor carpi radialis, extensor carpi radialis and anterior deltoid of the dominant arm. Arm cycling was separated into two phases, flexion and extension, relative to the elbow joint for all comparisons. As expected, iEMG amplitude increased during both phases of cycling for all muscles examined. With the exception of the triceps brachii and extensor carpi radialis, iEMG amplitudes differed between the flexion and extension phases. Finally, there was a linear relationship between iEMG amplitude and the %PPO for all muscles during both elbow flexion and extension.

Age-related differences in interlimb coordination during typical gait: An observational study

BACKGROUND

Arm movements during gait are known to alter with increasing age during the slow maturation phase (>3years). It is unclear whether coordination between the arms and legs (i.e. interlimb coordination), which is a measure of gait quality, shows a similar pattern.

RESEARCH QUESTION

to investigate age-related differences in interlimb coordination during gait in typically developing children and adults.

METHODS

In this observational study, 98 typically developing participants were divided into five age-groups: preschool children (G1; 2.9-5.9 years[n = 18]), children (G2; 6.0-9.9 years[n = 22]), pubertal children (G3; 10.0-13.9 years[n = 26]), adolescents (G4; 14.0-18.9 years[n = 14]) and adults (G5; 19.0-35.2 years[n = 18]). Participants walked barefoot at a self-selected walking speed along a 10-m walkway during three-dimensional total-body gait analysis. To examine interlimb coordination, mean continuous relative phase over the gait cycle (MRP) and its variability (sdMRP) were calculated for each combination of limb pairs in the sagittal plane.

RESULTS

MRP increased towards more anti-phase coordination with increasing age in following limb pair combinations: left arm-right arm (median[interquartile range]; G1: 152.0°[126.6;160.7°]-G5: 171.5°[170.0;175.3°]), left arm-left leg (G1: 155.0°[131.3;167.6°]-G5: 170.8°[165.3;173.5°]) and right arm-right leg (G1: 155.7°[135.5;166.0°]-G5: 170.0°[166.4;173.5°]). MRP decreased towards more in-phase coordination from G1 to G5 in left arm-right leg (G1: 24.4°[15.3;45.8°]-G5: 10.5°[6.1;15.6°]) and right arm-left leg (G1: 25.0°[13.7;41.1°]-G5: 9.7°[5.2;16.8°]). sdMRP decreased from G1 to G5 for all limb pair combinations.

SIGNIFICANCE

Interlimb coordination altered with increasing age. First, coordination between the legs and right arm-left leg appeared mature in G1 (aged 2.9-5.9 years). Next, coordination between the ipsilateral limbs seemed mature at 9.9 years, followed by a mature coordination between left arm-right leg at 13.9years. Coordination between the two arms showed ongoing differences until adulthood. These data provide an age-related framework and normative dataset to distinguish age-related differences from pathology in children with neuromotor disorders in clinical practice.

Interlimb neural interactions in corticospinal and spinal reflex circuits during preparation and execution of isometric elbow flexion

We found that upper limb muscle contractions facilitated corticospinal circuits controlling lower limb muscles even during motor preparation, whereas motor execution of the task was required to facilitate spinal circuits. We also found that facilitation did not depend on whether contralateral or ipsilateral hands were contracted or if they were contracted bilaterally. Overall, these findings suggest that training of unaffected upper limbs may be useful to enhance facilitation of affected lower limbs in paraplegic individuals.

Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

BACKGROUND

Body weight support systems with three or more degrees of freedom (3-DoF) are permissive and safe environments that provide unloading and allow unrestricted movement in any direction. This enables training of walking and balance control at an early stage in rehabilitation. Transparent systems generate a support force vector that is near vertical at all positions in the workspace to only minimally interfere with natural movement patterns. Patients with impaired balance, however, may benefit from additional mediolateral support that can be adjusted according to their capacity. An elegant solution for providing balance support might be by rendering viscous damping along the mediolateral axis via the software controller. Before use with patients, we evaluated if control-rendered mediolateral damping evokes the desired stability enhancement in able-bodied individuals.

METHODS

A transparent, cable-driven robotic body weight support system (FLOAT) was used to provide transparent body weight support with and without mediolateral damping to 21 able-bodied volunteers while walking at preferred gait velocity on a treadmill. Stability metrics reflecting resistance to small and large perturbations were derived from walking kinematics and compared between conditions and to free walking.

RESULTS

Compared to free walking, the application of body weight support per-se resulted in gait alterations typically associated with body weight support, namely increased step length and swing phase. Frontal plane dynamic stability, measured by kinematic variability and nonlinear dynamics of the center of mass, was increased under body weight support, indicating reduced balance requirements in both damped and undamped support conditions. Adding damping to the body weight support resulted in a greater increase of frontal plane stability.

CONCLUSION

Adding mediolateral damping to 3-DoF body weight support systems is an effective method of increasing frontal plane stability during walking in able-bodied participants. Building on these results, adjustable mediolateral damping could enable therapists to select combinations of unloading and stability specifically for each patient and to adapt this in a task specific manner. This could extend the impact of transparent 3-DoF body weight support systems, enabling training of gait and active balance from an early time point onwards in the rehabilitation process for a wide range of mobility activities of daily life.

Preliminary development and technical evaluation of a belt-actuated robotic rehabilitation platform

BACKGROUND:

To provide effective rehabilitation in the early post-injury stage, a novel robotic rehabilitation platform is proposed, which provides full-body arm-leg rehabilitation via belt actuation to severely disabled patients who are restricted to bed rest.

OBJECTIVE:

To design and technically evaluate the preliminary development of the rehabilitation platform, with focus on the generation of various leg movements.

METHODS:

Two computer models were developed by importing the components from SolidWorks into Simscape Multibody in MATLAB. This allowed simulation of various stepping movements in supine-lying and side-lying positions. Two belt-actuated test rigs were manufactured and automatic control programs were developed in TIA Portal. Finally, the functionality of the test rigs was technically evaluated.

RESULTS:

Computer simulation yielded target positions for the generation of various stepping movements in the experimental platforms. The control system enabled the two-drive test rig to provide three modes of stepping in a supine position. In addition, the four-drive test rig produced walking-like stepping in a side-lying position.

CONCLUSIONS:

This work confirmed the feasibility of the mechanical development and control system of the test rigs, which are deemed applicable for further development of the overall novel robotic rehabilitation platform.

Exposure to impacts across a competitive rugby season impairs balance and neuromuscular function in female rugby athletes

Objectives

We used objective assessment tools to detect subtle neurological deficits that accompany repetitive and mild head impacts in contact sport across a season.

Methods

Female participants (n=13, 21±1.8 years old; 167.6±6.7 cm; 72.8±6.1 kg) completed assessments pre and post the varsity rugby season. A commercial balance board was used to assess static balance and response to dynamic postural challenge. Spinal cord excitability via the soleus H-reflex was assessed in both legs. Video analysis was used to identify head impact exposures.

Results

A total of 172 potential concussive events were verified across 11 athletes (15.6±11; 95% CI: 6.5 to 19.8). Balance performance was worse at post-season for total centre of pressure which increased by 26% in the double stance on a stable surface (t(12)=-2.33; p=0.03; d=0.6) and by 140% in the tandem stance on a foam surface (t(12)=-3.43; p<0.01; d=0.9). Despite that, dynamic postural performance was improved after the season (p<0.01). Spinal cord excitability in rugby athletes did not change across the season but deviated from normative values at baseline.

Conclusion

Quantitative measures revealed that exposure to impacts across a competitive rugby season impair balance in two specific stances in female rugby athletes. Tandem-leg stance on an unstable surface and double-leg stance on firm surface are useful assessment conditions when performed over a low-cost balance board, even without clinically diagnosed concussion.

Treadmill-Based Locomotor Training With Robotic Pelvic Assist and Visual Feedback: A Feasibility Study

BACKGROUND AND PURPOSE

Gait asymmetries are common after stroke, and often persist despite conventional rehabilitation. Robots provide training at a greater practice frequency than conventional approaches. However, prior studies of have found the transfer of learned skills outside of the device to be inadequate. The tethered pelvic assist device (TPAD) promotes weight shifting, yet allows users to independently navigate spatiotemporal aspects of gait. The purpose of this study was to evaluate feasibility and preliminary efficacy of a 5-day intervention combining TPAD training with visual feedback and task-specific overground training to promote improved force and stance symmetry in individuals after stroke.

METHODS

After baseline assessments, 11 participants chronically after stroke received 1 hour of practice for 5 consecutive days. Training sessions included visual feedback during TPAD treadmill training followed by overground gait training. Safety, perceived exertion, and adherence were recorded as measures of feasibility. Load and stance symmetry were reassessed after the intervention (posttraining) and again 1 week later.

RESULTS

No adverse events were reported. Mean (SD) perceived exertion (3.61 (0.23)) was low and did not significantly change throughout the intervention. Overall adherence was 96.4%. Load asymmetry was not significantly reduced on the treadmill from baseline to posttraining (P = 0.075). Overground stance symmetry significantly improved on posttraining (F = 8.498, P = 0.002), but was not sustained at follow-up. (See the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A311, which summarizes the study background, methods, and results.) DISCUSSION AND CONCLUSIONS:: Results demonstrate this combined interventional approach was feasible and improved stance symmetry overground, yet further work should consider increasing training intensity and/or duration to induce gains lasting through follow-up.

Changing coupling between the arms and legs with slow walking speeds alters regulation of somatosensory feedback

Arm swing movement is coordinated with movement of the legs during walking, where the frequency of coordination depends on walking speed. At typical speeds, arm and leg movements, respectively, are frequency locked in a 1:1 ratio but at slow speeds this changes to a 2:1 ratio. It is unknown if the changes in interlimb ratio that accompany slow walking speeds alters regulation of somatosensory feedback. To probe the neural interactions between the arms and legs, somatosensory linkages in the form of interlimb cutaneous reflexes were examined. It was hypothesized that different interlimb frequencies and walking speeds would result in changes in the modulation of cutaneous reflexes between the arms and legs. To test this hypothesis, participants walked in four combinations of walking speed (typical, slow) and interlimb coordination (1:1, and 2:1), while cutaneous reflexes and background muscle activity were evaluated with stimulation applied to the superficial peroneal nerve at the ankle and superficial radial nerve at the wrist. Results show main effects of interlimb coordination and walking speed on cutaneous reflex modulation, effects are largest in the swing phase, and a directional coupling was observed, where changes in the frequency of arm movements had a greater effect on muscle activity in the legs compared to the reverse. Task-dependent modulation was also revealed from stimulation at local and remote sources. Understanding the underlying neural mechanisms for the organization of rhythmic arm movement, and its coordination with the legs in healthy participants, can give insight into pathological walking, and will facilitate the development of effective strategies for the rehabilitation of walking.

Corticospinal excitability to the biceps and triceps brachii during forward and backward arm cycling is direction- and phase-dependent

The purpose of this study was to evaluate corticospinal excitability to the biceps and triceps brachii during forward (FWD) and backward (BWD) arm cycling. Corticospinal and spinal excitability were assessed using transcranial magnetic stimulation and transmastoid electrical stimulation to elicit motor evoked potentials (MEPs) and cervicomedullary evoked potentials (CMEPs), respectively. MEPs and CMEPs were recorded from the biceps and triceps brachii during FWD and BWD arm cycling at 2 positions, 6 and 12 o’clock. The 6 o’clock position corresponded to mid-elbow flexion and extension during FWD and BWD cycling, respectively, while 12 o’clock corresponded to mid-elbow extension and flexion during FWD and BWD cycling, respectively. During the flexion phase, MEP and CMEP amplitudes of the biceps brachii were higher during FWD cycling. However, during the extension phase, MEP and CMEP amplitudes were higher during BWD cycling. For the triceps brachii, MEP amplitudes were higher during FWD cycling regardless of phase. However, CMEP amplitudes were phase-dependent. During the flexion phase, CMEPs of the triceps brachii were higher during FWD cycling compared with BWD, but during the extension phase CMEPs were higher during BWD cycling compared with FWD. The data suggest that corticospinal and spinal excitability to the biceps brachii is phase- and direction-dependent. In the triceps brachii, spinal, but not corticospinal, excitability is phase-dependent when comparing FWD and BWD cycling.

Novelty This is the first study to assess corticospinal excitability during FWD and BWD locomotor output. Corticospinal excitability during arm cycling depends on the direction, phase, and muscle being assessed.

Transcutaneous spinal cord stimulation of the cervical cord modulates lumbar networks

It has been established that coordinated arm and leg (A&L) cycling facilitates corticospinal drive and modulation of cervico-lumbar connectivity and ultimately improves overground walking in people with incomplete spinal cord injury or stroke. This study examined the effect of noninvasive transcutaneous spinal cord stimulation (tSCS) on the modulation of cervico-lumbar connectivity. Thirteen neurologically intact adults participated in the study. The excitability of the Hoffmann (H) reflex elicited in the soleus muscle was examined under multiple conditions involving either the arms held in a static position or rhythmic arm cycling while tSCS was applied to either the cervical or lumbar cord. As expected, soleus H-reflex amplitude was significantly suppressed by 19.2% during arm cycling (without tSCS) relative to arms static (without tSCS). Interestingly, tSCS of the cervical cord with arms static significantly suppressed the soleus H-reflex (−22.9%), whereas tSCS over the lumbar cord did not suppress the soleus H-reflex (−3.8%). The combination of arm cycling with cervical or lumbar tSCS did not yield additional suppression of the soleus H-reflex beyond that obtained with arm cycling alone or cervical tSCS alone. The results demonstrate that activation of the cervical spinal cord through both rhythmic arm cycling and tonic tSCS significantly modulates the activity of lumbar networks. This highlights the potential for engaging cervical spinal cord networks through tSCS during rehabilitation interventions to enhance cervico-lumbar connectivity. This connectivity is influential in facilitating improvements in walking function after neurological impairment.

NEW & NOTEWORTHY This is the first study to investigate the modulatory effects of transcutaneous spinal cord stimulation (tSCS) on cervico-lumbar connectivity. We report that both rhythmic activation of the cervical spinal cord through arm cycling and tonic activation of the cervical cord through tSCS significantly modulate the activity of lumbar networks. This suggests that engaging cervical spinal cord networks through tSCS during locomotor retraining interventions may not only enhance cervico-lumbar connectivity but also further improve walking capacity.

Contralateral seventh cervical nerve transfer can affect the pennation angle of the lower limb in spastic hemiplegia patients: An observational case series study

INTRODUCTION

We previously reported transferring seventh cervical (C7) nerve from unaffected side to affected side in patients with spastic hemiplegia due to chronic cerebral injury, to improve function and reduce spasticity of paralyzed upper limb. In the clinics, some patients also reported changes of spasticity in their lower limb, which could not be detected by routine physical examinations. Pennation angle of muscle can indirectly reflect the condition of spasticity. The purpose of this study was to evaluate whether this upper limb procedure may affect spasticity of lower limb, using ultrasonography to detect changes of muscle pennation angle (PA).

METHODS

Twelve spastic hemiplegia patients due to cerebral injury including stroke, cerebral palsy, and traumatic brain injury, who underwent C7 nerve transfer procedure, participated in this study. B-mode ultrasonography was used to measure PA of the gastrocnemius medialis (GM) muscle at rest preoperatively and postoperatively. The plantar load distribution of the lower limbs was evaluated using a Zebris FDM platform preoperatively and postoperatively.

RESULTS

The PA of the GM was significantly smaller on the affected side than that of unaffected side before surgery. On the affected side, the postoperative PA was significantly larger than preoperative PA. On the unaffected side, the postoperative PA was not significantly different compared to preoperative PA. The postoperative plantar load distribution of the affected forefoot was significantly smaller than preoperative load distribution, which was consistent with ultrasonography results.

CONCLUSIONS

This study indicates that C7 nerve transfer surgery for improving upper limb function can also affect muscle properties of lower limb in spastic hemiplegia patients, which reveals a link between the upper and lower limbs. The interlimb interactions should be considered in rehabilitation physiotherapy, and the regular pattern and mechanism need to be further studied.

Interlimb coupling in poststroke rehabilitation: a pilot randomized controlled trial

Background: The interlimb coupling, coordination between the limbs, gets hampered in post-stroke hemiparesis. Most of the poststroke motor regimes primarily focus on the more affected limb.Objectives: To develop an interlimb coupling protocol and assess its feasibility and effect on motor recovery, gait and disability among post-stroke subjects.Design: A pilot randomized controlled, doubled blinded trialSetting: A rehabilitation instituteMethods: 50 post-stroke (> 6 months) hemiparetic subjects (Brunnstrom recovery stage ≥ 3) were randomly divided into experimental (n=26) and control (n=24) groups. The 8-week experimental intervention (3 sessions of 1 hour each, per week) comprised activities demanding coordinated, alternate, and rhythmic use of the affected as well as the less-affected limbs. The outcome measures were feasibility of activities, Fugl-Meyer assessment (FMA), Rivermead visual gait assessment (RVGA), Functional ambulation category (FAC) and modified Rankin scale (mRS).Results: The experimental protocol was found to be feasible by the participants. Post intervention, the experimental group exhibited highly significant difference for FMA (mean difference = 7.12, 95% CI = 5.71 - 8.53, p < 0.001), RVGA reduction (mean difference = - 6.32, 95% CI = 7.51 - 5.13, p < 0.001), and median FAC enhancement (p < 0.001) in comparison to the controls. However, the median mRS level of experimental group did not change significantly (p = 0.056) when compared with the controls.Conclusions: The interlimb coupling training, a feasible program may enhance recovery of the upper and lower limbs and gait in stroke. Further definitive randomized trials are warranted to validate the present findings.

Harnessing the Power of a Novel Program for Dynamic Balance Perturbation with Supported Body Weight

Self-initiated postural adjustments commonly occur in daily life. To accessibly measure this type of dynamic balance, we developed a simple computer program to induce virtual perturbations and combined it with a commercially available balance board and portable EMG system to measure resulting self-initiated postural adjustments. When performing perturbed balance tests, safety harness with body weight support (BWS) is often used. However, influences of these harnesses on postural reactions are not well known. This study investigated the sensitivity of our assessment tool under different BWS conditions and muscle responses during postural adjustments following perturbation at different directions. Fifteen neurologically intact participants performed self-initiated postural adjustments under conditions with: (1) no harness; (2) harness with no BWS; and (3) harness with 10% BWS. Postural adjustment time and muscle activities of the lower leg were measured. We observed significant increases in postural adjustment time in the harness with no BWS condition and differneces in lower leg muscles response to virtual perturbation. Our findings suggest that the combination of our customized program with EMG is a sensitive and convenient tool to measure postural adjustments that approximate real-world scenarios. This method can be used with light body weight support to ensure safety without influencing muscle synergies.

Robot controlled, continuous passive movement of the ankle reduces spinal cord excitability in participants with spasticity: a pilot study

Spasticity of the ankle reduces quality of life by impeding walking and other activities of daily living. Robot-driven continuous passive movement (CPM) is a strategy for lower limb spasticity management but effects on spasticity, walking ability and spinal cord excitability (SCE) are unknown. The objectives of this experiment were to evaluate (1) acute changes in SCE induced by 30 min of CPM at the ankle joint, in individuals without neurological impairment and those with lower limb spasticity; and, (2) the effects of 6 weeks of CPM training on SCE, spasticity and walking ability in those with lower limb spasticity. SCE was assessed using soleus Hoffmann (H-) reflexes, collected prior to and immediately after CPM for acute assessments, whereas a multiple baseline repeated measures design assessed changes following 18 CPM sessions. Spasticity and walking ability were assessed using the Modified Ashworth Scale, the 10 m Walk test, and the Timed Up and Go test. Twenty-one neurologically intact and nine participants with spasticity (various neurological conditions) were recruited. In the neurologically intact group, CPM caused bi-directional modulation of H-reflexes creating 'facilitation' and 'suppression' groups. In contrast, amongst participants with spasticity, acute CPM facilitated H-reflexes. After CPM training, H-reflex excitability on both the more-affected and less-affected sides was reduced; on the more affected side H@Thres, H@50 and H@100 all significantly decreased following CPM training by 96.5 ± 7.7%, 90.9 ± 9.2%, and 62.9 ± 21.1%, respectively. After training there were modest improvements in walking and clinical measures of spasticity for some participants. We conclude that CPM of the ankle can significantly alter SCE. The use of CPM in those with spasticity can provide a temporary period of improved walking, but efficacy of treatment remains unknown.

Training-Induced Neural Plasticity and Strength Are Amplified After Stroke

Following stroke, sensorimotor brain networks and descending regulation are compromised but spinal interlimb neural connections remain morphologically intact. After cross-education strength and locomotion training, amplified neural plasticity and functional responses are observed in chronic stroke compared with neurologically intact participants. We hypothesize that poststroke neuroplasticity is amplified because of the involvement of interlimb neural connections that persist from our quadrupedal ancestry.

Unilateral vs Bilateral Hybrid Approaches for Upper Limb Rehabilitation in Chronic Stroke: A Randomized Controlled Trial

OBJECTIVE

To investigate the effects of unilateral hybrid therapy (UHT) and bilateral hybrid therapy (BHT) compared with robot-assisted therapy (RT) alone in patients with chronic stroke.

DESIGN

A single-blind, randomized controlled trial.

SETTING

Four hospitals.

PARTICIPANTS

Outpatients with chronic stroke and mild to moderate motor impairment (N=44).

INTERVENTION

UHT combined unilateral RT (URT) and modified constraint-induced therapy. BHT combined bilateral RT (BRT) and bilateral arm training. The RT group received URT and BRT. The intervention frequency for the 3 groups was 90 min/d 3 d/wk for 6 weeks.

MAIN OUTCOME MEASURES

Fugl-Meyer Assessment (FMA, divided into the proximal and distal subscale) and Stroke Impact Scale (SIS) version 3.0 scores before, immediately after, and 3 months after treatment and Wolf Motor Function Test (WMFT) and Nottingham Extended Activities of Daily Living (NEADL) scale scores before and immediately after treatment.

RESULTS

The results favored BHT over UHT on the FMA total score and distal score at the posttest (P=.03 and .04) and follow-up (P=.01 and .047) assessment and BHT over RT on the follow-up FMA distal scores (P=.03). At the posttest assessment, the WMFT and SIS scores of the 3 groups improved significantly without between-group differences, and the RT group showed significantly greater improvement in the mobility domain of NEADL compared with the BHT group (P<.01).

CONCLUSIONS

BHT was more effective for improving upper extremity motor function, particularly distal motor function at follow-up, and individuals in the RT group demonstrated improved functional ambulation post intervention.

Exploiting cervicolumbar connections enhances short-term spinal cord plasticity induced by rhythmic movement

Arm cycling causes suppression of soleus (SOL) Hoffmann (H-) reflex that outlasts the activity period. Arm cycling presumably activates propriospinal networks that modulate Ia presynaptic inhibition. Interlimb pathways are thought to relate to the control of quadrupedal locomotion, allowing for smooth, coordinated movement of the arms and legs. We examined whether the number of active limb pairs affects the amount and duration of activity-dependent plasticity of the SOL H-reflex. On separate days, 14 participants completed 4 randomly ordered 30 min experimental sessions: (1) quiet sitting (CTRL); (2) arm cycling (ARM); (3) leg cycling (LEG); and (4) arm and leg cycling (A&L) on an ergometer. SOL H-reflex and M-wave were evoked via electrical stimulation of the tibial nerve. M-wave and H-reflex recruitment curves were recorded, while the participants sat quietly prior to, 10 and 20 min into, immediately after, and at 2.5, 5, 7.5, 10, 15, 20, 25, and 30 min after each experimental session. Normalized maximal H-reflexes were unchanged in CTRL, but were suppressed by > 30% during the ARM, LEG, and A&L. H-reflex suppression outlasted activity duration for ARM (≤ 2.5 mins), LEG (≤ 5 mins), and A&L (≤ 30 mins). The duration of reflex suppression after A&L was greater than the algebraic summation of ARM and LEG. This non-linear summation suggests that using the arms and legs simultaneously-as in typical locomotor synergies-amplifies networks responsible for the short-term plasticity of lumbar spinal cord excitability. Enhanced activity of spinal networks may have important implications for the implementation of locomotor training for targeted rehabilitation.