The Effect of Aerobic Exercise on Neuroplasticity within the Motor Cortex following Stroke

Mechanisms and benefits of cardiac rehabilitation in individuals with stroke: emerging role of its impact on improving cardiovascular and neurovascular health

Human and animal studies have demonstrated the mechanisms and benefits of aerobic exercise for both cardiovascular and neurovascular health. Aerobic exercise induces neuroplasticity and neurophysiologic reorganization of brain networks, improves cerebral blood flow, and increases whole-body VO2peak (peak oxygen consumption). The effectiveness of a structured cardiac rehabilitation (CR) program is well established and a vital part of the continuum of care for people with cardiovascular disease. Individuals post stroke exhibit decreased cardiovascular capacity which impacts their neurologic recovery and extends disability. Stroke survivors share the same risk factors as patients with cardiac disease and can therefore benefit significantly from a comprehensive CR program in addition to neurorehabilitation to address their cardiovascular health. The inclusion of individuals with stroke into a CR program, with appropriate adaptations, can significantly improve their cardiovascular health, promote functional recovery, and reduce future cardiovascular and cerebrovascular events thereby reducing the economic burden of stroke.

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.

Moderate intensity aerobic exercise may enhance neuroplasticity of the contralesional hemisphere after stroke: a randomised controlled study

Upregulation of neuroplasticity might help maximize stroke recovery. One intervention that appears worthy of investigation is aerobic exercise. This study aimed to determine whether a single bout of moderate intensity aerobic exercise can enhance neuroplasticity in people with stroke. Participants were randomly assigned (1:1) to a 20-min moderate intensity exercise intervention or remained sedentary (control). Transcranial magnetic stimulation measured corticospinal excitability of the contralesional hemisphere by recording motor evoked potentials (MEPs). Intermittent Theta Burst Stimulation (iTBS) was used to repetitively activate synapses in the contralesional primary motor cortex, initiating the early stages of neuroplasticity and increasing excitability. It was surmised that if exercise increased neuroplasticity, there would be a greater facilitation of MEPs following iTBS. Thirty-three people with stroke participated in this study (aged 63.87 ± 10.30 years, 20 male, 6.13 ± 4.33 years since stroke). There was an interaction between Time*Group on MEP amplitudes (P = 0.009). Participants allocated to aerobic exercise had a stronger increase in MEP amplitude following iTBS. A non-significant trend indicated time since stroke might moderate this interaction (P = 0.055). Exploratory analysis suggested participants who were 2-7.5 years post stroke had a strong MEP facilitation following iTBS (P < 0.001). There was no effect of age, sex, resting motor threshold, self-reported physical activity levels, lesion volume or weighted lesion load (all P > 0.208). Moderate intensity cycling may enhance neuroplasticity in people with stroke. This therapy adjuvant could provide opportunities to maximize stroke recovery.

Moderate-intensity cardiovascular exercise performed before motor practice attenuates offline implicit motor learning in stroke survivors but not age-matched neurotypical adults

The acute impact of cardiovascular exercise on implicit motor learning of stroke survivors is still unknown. We investigated the effects of cardiovascular exercise on implicit motor learning of mild-moderately impaired chronic stroke survivors and neurotypical adults. We addressed whether exercise priming effects are time-dependent (e.g., exercise before or after practice) in the encoding (acquisition) and recall (retention) phases. Forty-five stroke survivors and 45 age-matched neurotypical adults were randomized into three sub-groups: BEFORE (exercise, then motor practice), AFTER (motor practice, then exercise), and No-EX (motor practice alone). All sub-groups practiced a serial reaction time task (five repeated and two pseudorandom sequences per day) on three consecutive days, followed 7 days later by a retention test (one repeated sequence). Exercise was performed on a stationary bike, (one 20-min bout per day) at 50% to 70% heart rate reserve. Implicit motor learning was measured as a difference score (repeated-pseudorandom sequence response time) during practice (acquisition) and recall (delayed retention). Separate analyses were performed on the stroke and neurotypical groups using linear mixed-effects models (participant ID was a random effect). There was no exercise-induced benefit on implicit motor learning for any sub-group. However, exercise performed before practice impaired encoding in neurotypical adults and attenuated retention performance of stroke survivors. There is no benefit to implicit motor learning of moderately intense cardiovascular exercise for stroke survivors or age-matched neurotypical adults, regardless of timing. Practice under a high arousal state and exercise-induced fatigue may have attenuated offline learning in stroke survivors.

Corticostriatal Projections Relying on GABA Levels Mediate Exercise-Induced Functional Recovery in Cerebral Ischemic Mice

Stroke is a neurological disorder characterized by high disability and death worldwide. The occlusion of the middle cerebral artery (MCAO) supplying the cortical motor regions and its projection pathway regions can either kill the cortical neurons or block their projections to the spinal cord and subcortical structure. The cerebral cortex is the primary striatal afferent, and the medium spiny neurons of the striatum have been identified as the major output neurons projecting to the substantia nigra and pallidum. Thus, disconnection of the corticostriatal circuit often occurs in the model of MCAO. In this study, we hypothesize that striatal network dysfunction in cerebral ischemic mice ultimately modulates the activity of striatal projections from cortical neurons to improve dysfunction during exercise training. In this study, we observed that the corticostriatal circuit originating from glutamatergic neurons could partially medicate the improvement of motor and anxiety-like behavior in mice with exercise. Furthermore, exercising or activating a single optogenetic corticostriatal circuit can increase the striatal gamma-aminobutyric acid (GABA) level. Using the GABA-A receptor antagonist, bicuculline, we further identified that the striatal glutamatergic projection from the cortical neurons relies on the GABAergic synapse's activity to modulate exercise-induced functional recovery. Overall, those results reveal that the dorsal striatum-projecting subpopulation of cortical glutamatergic neurons can influence GABA levels in the striatum, playing a critical role in modulating exercise-induced improvement of motor and anxiety-like behavior.

A Systematic Review on the Effects of Acute Aerobic Exercise on Neurophysiological, Molecular, and Behavioral Measures in Chronic Stroke

BACKGROUND

A single bout of aerobic exercise (AE) can produce changes in neurophysiological and behavioral measures in healthy individuals and those with stroke. However, the effects of AE-priming effects on neuroplasticity markers and behavioral measures are unclear.

OBJECTIVES

This systematic review aimed to examine the effects of AE on neuroplasticity measures, such as corticomotor excitability (CME), molecular markers, cortical activation, motor learning, and performance in stroke.

METHODS

A literature search was performed in MEDLINE, CINAHL, Scopus, and PsycINFO databases. Randomized and non-randomized studies incorporating acute AE in stroke were selected. Two reviewers independently assessed the risk of bias and methodological rigor of the studies and extracted data on participant characteristics, exercise interventions, and neuroplasticity related outcomes. The quality of transcranial magnetic stimulation reported methods was assessed using a standardized checklist.

RESULTS

A total of 16 studies were found suitable for inclusion. Our findings suggest mixed evidence for the effects of AE on CME, limited to no effects on intracortical inhibition and facilitation and some evidence for modulating brain derived neurotrophic factor levels, motor learning, and cortical activation. Exercise intensities in the moderate to vigorous range showed a trend towards better effects on neuroplasticity measures.

CONCLUSION

It appears that choosing a moderate to vigorous exercise paradigm for at least 20 to 30 minutes may induce changes in some neuroplasticity parameters in stroke. However, these findings necessitate prudent consideration as the studies were diverse and had moderate methodological quality. There is a need for a consensus on an exercise priming paradigm and for good-quality, larger controlled studies.

Intensity matters: protocol for a randomized controlled trial exercise intervention for individuals with chronic stroke

Rationale

Cardiovascular exercise is an effective method to improve cardiovascular health outcomes, but also promote neuroplasticity during stroke recovery. Moderate-intensity continuous cardiovascular training (MICT) is an integral part of stroke rehabilitation, yet it may remain a challenge to exercise at sufficiently high intensities to produce beneficial adaptations to neuroplasticity. High-intensity interval training (HIIT) could provide a viable alternative to achieve higher intensities of exercise by using shorter bouts of intense exercise interspersed with periods of recovery.

Methods and design

This is a two-arm, parallel-group multi-site RCT conducted at the Jewish Rehabilitation Hospital (Laval, Québec, Canada) and McMaster University (Hamilton, Ontario, Canada). Eighty participants with chronic stroke will be recruited at both sites and will be randomly allocated into a HIIT or MICT individualized exercise program on a recumbent stepper, 3 days per week for 12 weeks. Outcomes will be assessed at baseline, at 12 weeks post-intervention, and at an 8-week follow-up.

Outcomes

The primary outcome is corticospinal excitability, a neuroplasticity marker in brain motor networks, assessed with transcranial magnetic stimulation (TMS). We will also examine additional markers of neuroplasticity, measures of cardiovascular health, motor function, and psychosocial responses to training.

Discussion

This trial will contribute novel insights into the effectiveness of HIIT to promote neuroplasticity in individuals with chronic stroke.

Trial registration

ClinicalTrials.govNCT03614585. Registered on 3 August 2018

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06359-w.

Effects of transcranial magnetic stimulation in modulating cortical excitability in patients with stroke: a systematic review and meta-analysis

Background

Transcranial magnetic stimulation (TMS) has attracted plenty of attention as it has been proved to be effective in facilitating motor recovery in patients with stroke. The aim of this study was to systematically review the effects of repetitive TMS (rTMS) and theta burst stimulation (TBS) protocols in modulating cortical excitability after stroke.

Methods

A literature search was carried out using PubMed, Medline, EMBASE, CINAHL, and PEDro, to identify studies that investigated the effects of four rTMS protocols—low and high frequency rTMS, intermittent and continuous TBS, on TMS measures of cortical excitability in stroke. A random-effects model was used for all meta-analyses.

Results

Sixty-one studies were included in the current review. Low frequency rTMS was effective in decreasing individuals’ resting motor threshold and increasing the motor-evoked potential of the non-stimulated M1 (affected M1), while opposite effects occurred in the stimulated M1 (unaffected M1). High frequency rTMS enhanced the cortical excitability of the affected M1 alone. Intermittent TBS also showed superior effects in rebalancing bilateral excitability through increasing and decreasing excitability within the affected and unaffected M1, respectively. Due to the limited number of studies found, the effects of continuous TBS remained inconclusive. Motor impairment was significantly correlated with various forms of TMS measures.

Conclusions

Except for continuous TBS, it is evident that these protocols are effective in modulating cortical excitability in stroke. Current evidence does support the effects of inhibitory stimulation in enhancing the cortical excitability of the affected M1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-022-00999-4.

Effects of aerobic physical exercise on neuroplasticity after stroke: systematic review

BACKGROUND

Stroke is among the leading causes of death and disability worldwide. Interventions for stroke rehabilitation aim to minimize sequelae, promote individuals' independence and potentially recover functional damage. The role of aerobic exercise as a facilitator of post-stroke neuroplasticity in humans is still questionable.

OBJECTIVE

To investigate the impact of aerobic exercise on neuroplasticity in patients with stroke sequelae.

METHODS

A systematic review of randomized clinical trials and crossover studies was performed, with searches for human studies in the following databases: PUBMED, EMBASE, LILACS and PeDRO, only in English, following the PRISMA protocol. The keywords used for selecting articles were defined based on the PICO strategy.

RESULTS

This systematic review evaluated the impacts of aerobic exercise on neuroplasticity through assessment of neural networks and neuronal excitability, neurotrophic factors, or cognitive and functional assessment. Studies that evaluated the effects of aerobic exercise on neuroplasticity after stroke measured through functional resonance (fMRI) or cortical excitability have shown divergent results, but aerobic exercise potentially can modify the neural network, as measured through fMRI. Additionally, aerobic exercise combined with cognitive training improves certain cognitive domains linked to motor learning. Studies that involved analysis of neurotrophic factors to assess neuroplasticity had conflicting results.

CONCLUSIONS

Physical exercise is a therapeutic intervention in rehabilitation programs that, beyond the known benefits relating to physical conditioning, functionality, mood and cardiovascular health, may also potentiate the neuroplasticity process. Neuroplasticity responses seem more robust in moderate to high-intensity exercise training programs, but dose-response heterogeneity and non-uniform neuroplasticity assessments limit generalizability.

Large-scale analysis of interindividual variability in single and paired-pulse TMS data

OBJECTIVE

This study brought together over 60 transcranial magnetic stimulation (TMS) researchers to create the largest known sample of individual participant single and paired-pulse TMS data to date, enabling a more comprehensive evaluation of factors driving response variability.

METHODS

Authors of previously published studies were contacted and asked to share deidentified individual TMS data. Mixed-effects regression investigated a range of individual and study level variables for their contribution to variability in response to single and paired-pulse TMS data.

RESULTS

687 healthy participant's data were pooled across 35 studies. Target muscle, pulse waveform, neuronavigation use, and TMS machine significantly predicted an individual's single-pulse TMS amplitude. Baseline motor evoked potential amplitude, motor cortex hemisphere, and motor threshold (MT) significantly predicted short-interval intracortical inhibition response. Baseline motor evoked potential amplitude, test stimulus intensity, interstimulus interval, and MT significantly predicted intracortical facilitation response. Age, hemisphere, and TMS machine significantly predicted MT.

CONCLUSIONS

This large-scale analysis has identified a number of factors influencing participants' responses to single and paired-pulse TMS. We provide specific recommendations to minimise interindividual variability in single and paired-pulse TMS data.

SIGNIFICANCE

This study has used large-scale analyses to give clarity to factors driving variance in TMS data. We hope that this ongoing collaborative approach will increase standardisation of methods and thus the utility of single and paired-pulse TMS.

Transcranial Magnetic Stimulation to Assess Exercise-Induced Neuroplasticity

Aerobic exercise facilitates neuroplasticity and has been linked to improvements in cognitive and motor function. Transcranial magnetic stimulation (TMS) is a non-invasive technique that can be used to quantify changes in neurophysiology induced by exercise. The present review summarizes the single- and paired-pulse TMS paradigms that can be used to probe exercise-induced neuroplasticity, the optimal stimulation parameters and the current understanding of the neurophysiology underlying each paradigm. Further, this review amalgamates previous research exploring the modulation of these paradigms with exercise-induced neuroplasticity in healthy and clinical populations and highlights important considerations for future TMS-exercise research.

A Single Bout of High-intensity Interval Exercise Increases Corticospinal Excitability, Brain-derived Neurotrophic Factor, and Uncarboxylated Osteolcalcin in Sedentary, Healthy Males

Exercise induces neuroplasticity in descending motor pathways facilitating motor learning, and as such it could be utilized as an intervention in neurorehabilitation, for example when re-learning motor skills after stroke. To date, however, the neurophysiological and molecular mechanisms underlying exercise-induced neuroplasticity remain largely unknown impeding the potential utilization of exercise protocols as 'motor learning boosters' in clinical and non-clinical settings. Here, we assessed corticospinal excitability, intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI) using transcranial magnetic stimulation (TMS) and serum biochemical markers including brain-derived neurotrophic factor (BDNF), total and precursor cathepsin B (tCTSB, proCTSB), uncarboxylated and carboxylated osteocalcin (unOCN, cOCN) and irisin using ELISA. Measurements were carried out in sedentary, healthy males before and after a single session of high-intensity interval exercise (HIIE) or in individuals who rested and did not perform exercise (No Exercise). We found that HIIE increased corticospinal excitability, BDNF and unOCN, and decreased cOCN. We also determined that greater increases in BDNF were associated with increases in unOCN and irisin and decreases in cOCN only in participants who underwent HIIE, suggesting that unOCN and irisin may contribute to exercise-induced BDNF increases. Conversely, no changes other than a decrease in serum unOCN/tOCN were found in No Exercise participants. The present findings show that a single session of HIIE is sufficient to modulate corticospinal excitability and to increase BDNF and unOCN in sedentary, healthy males.

Evaluation of eight-style Tai chi on cognitive function in patients with cognitive impairment of cerebral small vessel disease: study protocol for a randomised controlled trial

INTRODUCTION

Cerebral small vessel disease (CSVD) is a critical factor that causes cognitive decline and progresses to vascular dementia and acute cerebrovascular events. Tai chi has been proven to improve nerve plasticity formation and directly improve cognitive function compared with other sports therapy, which has shown its unique advantages. However, more medical evidence needs to be collected in order to verify that Tai chi exercises can improve cognitive impairment due to CSVD. The main purposes of this study are to investigate the effect of Tai chi exercise on neuropsychological outcomes of patients with cognitive impairment related to CSVD and to explore its mechanism of action with neuroimaging, including functional MRI (fMRI) and event-related potential (P300).

METHODS AND ANALYSIS

The design of this study is a randomised controlled trial with two parallel groups in a 1:1 allocation ratio with allocation concealment and assessor blinding. A total of 106 participants will be enrolled and randomised to the 24-week Tai chi exercise intervention group and 24-week health education control group. Global cognitive function and the specific domains of cognition (memory, processing speed, executive function, attention and verbal learning and memory) will be assessed at baseline and 12 and 24 weeks after randomisation. At the same time, fMRI and P300 will be measured the structure and function of brain regions related to cognitive function at baseline and 24 weeks after randomisation. Recruitment is currently ongoing (recruitment began on 9 November 2020). The approximate completion date for recruitment is in April 2021, and we anticipate to complete the study by December 2021.

ETHICS AND DISSEMINATION

Ethics approval was given by the Medical Ethics Committee of the Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine (approval number: 2019-058-04). The findings will be disseminated through peer-reviewed publications and at scientific conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2000033176; Pre-results.

Combining transcranial direct current stimulation with aerobic exercise to optimize cortical priming in stroke

Aerobic exercise (AE) and transcranial direct current stimulation (tDCS) are priming techniques that have been studied for their potential neuromodulatory effects on corticomotor excitability (CME); however, the synergistic effects of AE and tDCS are not explored in stroke. Here we investigated the synergistic effects of AE and tDCS on CME, intracortical and transcallosal inhibition, and motor control for the lower limb in stroke. Twenty-six stroke survivors participated in 3 sessions: tDCS, AE, and AE+tDCS. AE included moderate-intensity exercise and tDCS included 1 mA of anodal tDCS to the lower limb motor cortex with or without AE. Outcomes included measures of CME, short-interval intracortical inhibition (SICI), ipsilateral silent period (iSP) (an index of transcallosal inhibition) for the tibialis anterior, and ankle reaction time. Ipsilesional CME significantly decreased for AE compared with AE+tDCS and tDCS. No differences were noted in SICI, iSP measures, or reaction time between all 3 sessions. Our findings suggest that a combination of exercise and tDCS, and tDCS demonstrate greater excitability of the ipsilesional hemisphere compared with exercise only; however, these effects were specific to the descending corticomotor pathways. No additive priming effects of exercise and tDCS over tDCS was observed. Novelty: An exercise and tDCS paradigm upregulated the descending motor pathways from the ipsilesional lower limb primary motor cortex compared with exercise. Exercise or tDCS administered alone or in combination did not affect intracortical or transcallosal inhibition or reaction time.

Impacts of Sleep Loss versus Waking Experience on Brain Plasticity: Parallel or Orthogonal?

Recent studies on the effects of sleep deprivation on synaptic plasticity have yielded discrepant results. Sleep deprivation studies using novelty exposure as a means to keep animals awake suggests that sleep (compared with wake) leads to widespread reductions in net synaptic strength. By contrast, sleep deprivation studies using approaches avoiding novelty-induced arousal (i.e., gentle handling) suggest that sleep can promote synaptic growth and strengthening. How can these discrepant findings be reconciled? Here, we discuss how varying methodologies for the experimental disruption of sleep (with differential introduction of novel experiences) could fundamentally alter the experimental outcome with regard to synaptic plasticity. Thus, data from experiments aimed at assessing the relative impact of sleep versus wake on the brain may instead reflect the quality of the waking experience itself. The highlighted work suggests that brain plasticity resulting from novel experiences versus wake per se has unique and distinct features.

Neuroplasticity Modifications Following a Lower-Limb Amputation: A Systematic Review

BACKGROUND

Although there are studies that have examined brain functional reorganization following upper-limb amputation, understanding of the brain changes that occur in people with lower-limb amputation is limited.

OBJECTIVE

To investigate modifications in the brain following lower-limb amputation.

METHODS

We included case-control studies that evaluate neuroplasticity in the central nervous system using neuroimaging techniques. A literature search was conducted using MEDLINE, CINAHL, Web of Science, Scopus, and Cochrane.

RESULTS

Eleven articles were included (total n = 204 people with unilateral lower-limb amputation). These studies showed an increase in cerebellar gray matter volume in prosthesis users, as well as a decrease in thickness of the premotor cortex, orbitofrontal cortex, temporo-occipital junction, precentral gyrus, visual areas, and somatosensory cortex. Regarding white matter, the trials observed a decrease in the integrity at the corona radiata, the connections between the premotor areas, the fronto-occipital fasciculus and the corpus callosum. In addition, a decreased functional connectivity between cortical and subcortical areas has been described.

CONCLUSIONS

Lower-limb amputation causes changes in several brain structures that may occur in the absence of pain and regardless of prosthesis use. The modifications observed include thinning or loss of gray matter volume, decrease in the integrity of the white matter connections between brain structures and changes in the functional connectivity between cortical and subcortical areas.

LEVEL OF EVIDENCE

I.

A short bout of high-intensity exercise alters ipsilesional motor cortical excitability post-stroke

Background: Acute exercise can increase motor cortical excitability and enhance motor learning in healthy individuals, an effect known as exercise priming. Whether it has the same effects in people with stroke is unclear. Objectives: The objective of this study was to investigate whether a short, clinically-feasible high-intensity exercise protocol can increase motor cortical excitability in non-exercised muscles of chronic stroke survivors. Methods: Thirteen participants with chronic, unilateral stroke participated in two sessions, at least one week apart, in a crossover design. In each session, they underwent either high-intensity lower extremity exercise or quiet rest. Motor cortical excitability of the extensor carpi radialis muscles was measured bilaterally with transcranial magnetic stimulation before and immediately after either exercise or rest. Motor cortical excitability changes (post-exercise or rest measures normalized to pre-test measures) were compared between exercise vs. rest conditions. Results: All participants were able to reach the target high-intensity exercise level. Blood lactate levels increased significantly after exercise (p < .001, d = 2.85). Resting motor evoked potentials from the lesioned hemisphere increased after exercise (mean 1.66; 95% CI: 1.19, 2.13) compared to the rest condition (mean 1.23; 95% CI: 0.64, 1.82), p = .046, d = 2.76, but this was not the case for the non-lesioned hemisphere (p = .406, d = 0.25). Conclusions: High-intensity exercise can increase lesioned hemisphere motor cortical excitability in a non-exercised muscle post-stroke. Our short and clinically-advantageous exercise protocol shows promise as a potential priming method in stroke rehabilitation.

Role of Rehabilitation in Neural Plasticity

AIM

Verifying if physical therapy, neurostimulation techniques, aerobic fitness and video games can induce neural plasticity making it possible for cortical reorganisation, motor recovery in patients, improvement of cognitive functions and transfer of spatial knowledge in the everyday living environment.

METHODS

There have been revised scientific articles respectively focused on the role of pain, the role of physical therapy, neurostimulation techniques and video games in cortical reorganisation. Articles related to the role of pain have taken in the study subjects with pain, to observe its role in cortical reorganisation. Studies related to physical therapy and neurostimulation techniques after cerebrovascular accident consisted of the involvement of these subjects which exposed to different neurostimulations. Also, related to cognition and video games subjects exposed to these interventions for cognitive benefits.

RESULTS

From all articles reviewed there have been effective results of neurostimulation techniques, aerobic fitness and video games in cortical reorganisation inducing neural plasticity (p < 0.05) toward motor recovery, improvement of executive functions and transfer of spatial knowledge.

CONCLUSION

Rehabilitation through locomotor training and neurostimulation techniques, improves mobility in subjects after a cerebrovascular accident due to cortical reorganisation. Also, through aerobic fitness and video games, there have been improvements in cognitive functions. This way, rehabilitation dedicated to the promotion of well-being and health urges beneficial neuroplastic changes in brain corresponding in functional improvement.

Acute Effects of Assisted Cycling Therapy on Post-Stroke Motor Function: A Pilot Study

Background

Stroke is the most common cause of long-term disability in the United States (US). Assisted Cycling Therapy (ACT) at cadences of about 80 rpm has been associated with improvements in motor and clinical function in other clinical populations. The acute effects of ACT on motor function of persons with stroke have not been investigated.

Objectives

The primary purpose of this cross-over trial was to compare the effects of ACT, voluntary cycling (VC), and no cycling (NC) on upper (Box and Blocks Test) and lower extremity motor function (Lower Extremity Motor Coordination Test) in adults with chronic stroke (age: 60 ± 16 years; months since stroke: 96 ± 85). The secondary purpose was to examine average cycling cadence and ratings of perceived exertion as predictors of change in motor function following the exercise session.

Methods

Twenty-two participants (female = 6, male = 16) completed one 20-min session each of ACT (mean cadence = 79.5 rpm, VC (mean cadence = 51.5 rpm), and NC on separate days in quasi-counterbalanced fashion).

Results

Main effects of intervention did not differ between ACT and VC. Within-intervention analyses revealed significant (p < 0.05) pre- to posttest changes in all outcome measures for ACT but only in the Lower Extremity Motor Coordination Test on the non-paretic side for VC. Trend analyses revealed a positive relationship between average ACT cadences and improvements in upper and lower extremity motor function (p < 0.05). A positive relationship between average VC cadences and lower extremity function was also revealed (p < 0.05).

Conclusion

ACT and VC produced similar acute improvements in paretic and non-paretic lower extremity motor function whereas changes in upper extremity motor function were more limited. Faster cycling cadences seem to be associated with greater acute effects.

Intensity of acute aerobic exercise but not aerobic fitness impacts on corticospinal excitability

Aerobic exercise (AE) modulates cortical excitability. It can alter both corticospinal excitability and intra-cortical networks, which has implications for its use as a tool to facilitate processes such as motor learning, where increased levels of excitability are conducive to the induction of neural plasticity. Little is known about how different intensities of AE modulate cortical excitability or how individual-level characteristics impact on it. Therefore, we investigated whether AE intensities, lower than those previously employed, would be effective in increasing cortical excitability. We also examined whether the aerobic fitness of individual participants was related to the magnitude of change in AE-induced cortical excitability. In both experiments we employed transcranial magnetic stimulation to probe corticospinal excitability before and after AE. We show that 20 min of continuous moderate- (40% and 50% of heart rate reserve, HRR), but not low- (30% HRR) intensity AE was effective at increasing corticospinal excitability. We also found that while we observed increased corticospinal excitability following 20 min of continuous moderate-intensity (50% HRR) AE, aerobic fitness was not related to the magnitude of change. Our results suggest that there is a lower bound intensity of AE that is effective at driving changes in cortical excitability, and that while individual-level characteristics are important predictors of response to AE, aerobic fitness is not. Overall these findings have implication for the way that AE is used to facilitate processes such as motor learning, where increased levels of cortical excitability and plasticity are favourable.

A Bout of High Intensity Interval Training Lengthened Nerve Conduction Latency to the Non-exercised Affected Limb in Chronic Stroke

Objective: Evaluate intensity-dependent effects of a single bout of high intensity interval training (HIIT) compared to moderate intensity constant-load exercise (MICE) on corticospinal excitability (CSE) and effects on upper limb performance in chronic stroke.

Design: Randomized cross-over trial.

Setting: Research laboratory in a tertiary rehabilitation hospital.

Participants: Convenience sample of 12 chronic stroke survivors.

Outcome measures: Bilateral CSE measures of intracortical inhibition and facilitation, motor thresholds, and motor evoked potential (MEP) latency using transcranial magnetic stimulation. Upper limb functional measures of dexterity (Box and Blocks Test) and strength (pinch and grip strength).

Results: Twelve (10 males; 62.50 ± 9.0 years old) chronic stroke (26.70 ± 23.0 months) survivors with moderate level of residual impairment participated. MEP latency from the ipsilesional hemisphere was lengthened after HIIT (pre: 24.27 ± 1.8 ms, and post: 25.04 ± 1.8 ms, p = 0.01) but not MICE (pre: 25.49 ± 1.10 ms, and post: 25.28 ± 1.0 ms, p = 0.44). There were no significant changes in motor thresholds, intracortical inhibition or facilitation. Pinch strength of the affected hand decreased after MICE (pre: 8.96 ± 1.9 kg vs. post: 8.40 ± 2.0 kg, p = 0.02) but not after HIIT (pre: 8.83 ± 2.0 kg vs. post: 8.65 ± 2.2 kg, p = 0.29). Regardless of type of aerobic exercise, higher total energy expenditure was associated with greater increases in pinch strength in the affected hand after exercise (R² = 0.31, p = 0.04) and decreases in pinch strength of the less affected hand (R² = 0.26 p = 0.02).

Conclusion: A single bout of HIIT resulted in lengthened nerve conduction latency in the affected hand that was not engaged in the exercise. Longer latency could be related to the cross-over effects of fatiguing exercise or to reduced hand spasticity. Somewhat counterintuitively, pinch strength of the affected hand decreased after MICE but not HIIT. Regardless of the structure of exercise, higher energy expended was associated with pinch strength gains in the affected hand and strength losses in the less affected hand. Since aerobic exercise has acute effects on MEP latency and hand strength, it could be paired with upper limb training to potentiate beneficial effects.

A Single Bout of High-Intensity Interval Training Improves Motor Skill Retention in Individuals With Stroke

BACKGROUND

One bout of high-intensity cardiovascular exercise performed immediately after practicing a motor skill promotes changes in the neuroplasticity of the motor cortex and facilitates motor learning in nondisabled individuals.

OBJECTIVE

To determine if a bout of exercise performed at high intensity is sufficient to induce neuroplastic changes and improve motor skill retention in patients with chronic stroke.

METHODS

Twenty-two patients with different levels of motor impairment were recruited. On the first session, the effects of a maximal graded exercise test on corticospinal and intracortical excitability were assessed from the affected and unaffected primary motor cortex representational area of a hand muscle with transcranial magnetic stimulation. On the second session, participants were randomly assigned to an exercise or a nonexercise control group. Immediately after practicing a motor task, the exercise group performed 15 minutes of high-intensity interval training while the control group rested. Twenty-four hours after motor practice all participants completed a test of the motor task to assess skill retention.

RESULTS

The graded exercise test reduced interhemispheric imbalances in GABA_A-mediated short-interval intracortical inhibition but changes in other markers of excitability were not statistically significant. The group that performed high-intensity interval training showed a better retention of the motor skill.

CONCLUSIONS

The performance of a maximal graded exercise test triggers only modest neuroplastic changes in patients with chronic stroke. However, a single bout of high-intensity interval training performed immediately after motor practice improves skill retention, which could potentially accelerate motor recovery in these individuals.

The Effect of Diabetes on Cortical Function in Stroke: Implications for Poststroke Plasticity

Diabetes may impair the capacity for neuroplasticity such that patients experience a slower and poorer recovery after stroke. The current study investigated changes in cortical function in stroke patients with diabetes to determine how this comorbidity may affect poststroke cortical plasticity and thereby functional recovery. From a cohort of 57 participants, threshold-tracking transcranial magnetic stimulation was used to assess cortical function over the ipsilateral and contralesional hemispheres in 7 patients with diabetes after an acute stroke compared with 12 stroke patients without diabetes. Cortical function was also assessed in 8 patients with diabetes without stroke and 30 normal control subjects. After acute stroke, short-interval intracortical inhibition (SICI) was reduced over both motor cortices in stroke patients without diabetes compared with normal control patients, while in stroke patients with diabetes, SICI was only reduced over the contralesional but not the ipsilesional cortex compared with control patients with diabetes. In addition, SICI was significantly reduced in the control patients with diabetes compared with normal control patients. These results have demonstrated the absence of ipsilesional cortical excitability change after diabetic strokes, suggesting impaired capacity for neuroplasticity over this hemisphere as a consequence of a "double-hit" phenomenon because of preexisting alterations in cortical function in nonstroke patients with diabetes. The reliance on reorganization over the contralesional cortex after stroke will likely exert influence on poststroke recovery in patients with diabetes.

Acute Exercise and Motor Memory Consolidation: The Role of Exercise Intensity

A single bout of high intensity aerobic exercise (~90% VO_2peak) was previously demonstrated to amplify off-line gains in skill level during the consolidation phase of procedural memory. High intensity exercise is not always a viable option for many patient groups or in a rehabilitation setting where low to moderate intensities may be more suitable. The aim of this study was to investigate the role of intensity in mediating the effects of acute cardiovascular exercise on motor skill learning. We investigated the effects of different exercise intensities on the retention (performance score) of a visuomotor accuracy tracking task. Thirty six healthy male subjects were randomly assigned to one of three groups that performed either a single bout of aerobic exercise at 20 min post motor skill learning at 45% (EX45), 90% (EX90) maximal power output (W_max) or rested (CON). Randomization was stratified to ensure that the groups were matched for relative peak oxygen consumption (ml O₂/min/kg) and baseline score in the tracking task. Retention tests were carried out at 1 (R1) and 7 days (R7) post motor skill learning. At R1, changes in performance scores were greater for EX90 compared to CON (p<0.001) and EX45 (p = 0.011). The EX45 and EX90 groups demonstrated a greater change in performance score at R7 compared to the CON group (p = 0.003 and p<0.001, respectively). The change in performance score for EX90 at R7 was also greater than EX45 (p = 0.049). We suggest that exercise intensity plays an important role in modulating the effects that a single bout of cardiovascular exercise has on the consolidation phase following motor skill learning. There appears to be a dose-response relationship in favour of higher intensity exercise in order to augment off-line effects and strengthen procedural memory.