Exercise and executive function in individuals with chronic stroke: a pilot study

Application of principles of exercise training in sub-acute and chronic stroke survivors: a systematic review

BACKGROUND

There is increasing evidence for the beneficial effects of exercise training in stroke survivors. In order to reach the desired training effects, exercise training principles must be considered as this ensures the prescription of adequate exercises at an adequate dose. Moreover, exercise training interventions must be designed in a way that maximizes patients' adherence to the prescribed exercise regimen. The objectives of this systematic review were (1) to investigate whether training principles for physical exercise interventions are reported in RCTs for sub-acute and chronic stroke survivors, (2) to evaluate whether the RCTs reported the prescription of the FITT components of the exercise interventions as well as (3) patients' adherence to this prescription, and (4) to assess the risk of bias of the included studies.

METHODS

We performed a systematic review of RCTs with exercise training as the primary intervention and muscular strength and/or endurance as primary outcomes. The Cochrane library's risk of bias (ROB) tool was used to judge the methodological quality of RCTs.

RESULTS

Thirty-seven RCTs were included in this systematic review. Eighteen studies (48.7%) focused on aerobic, 8 (21.6%) on resistance and 11 (29.7%) on combined interventions of aerobic and resistive strength exercise. Twenty-nine studies (78.4%) included only chronic stroke survivors, 5 studies (13.5%) only sub-acute stroke survivors whilst 3 studies (8.1%) included both. In terms of principle of exercise training, 89% reported specificity, 75.7% progression, 48.7% overload, 37.8% initial values, 32.4% reversibility and 13.5% diminishing returns. One RCT described all principles of physical exercise training and 19 (51.4%) all FITT components. Patients' adherence to exercise prescription was accounted for in 3 studies (8.1%). Failure to report blinding in patients and participants and failure to report allocation concealment were the most prevalent methodological shortcomings.

CONCLUSIONS

Incomplete and inconsistent reporting of (1) training components, (2) underlying exercise training principles and (3) patient adherence together with (4) a broad variation in the methodological quality of the included RCTs limit both the utility and reproducibility of physical exercise programs in stroke patients.

Phase I/II randomized trial of aerobic exercise in Parkinson disease in a community setting

OBJECTIVES

To (1) investigate effects of aerobic walking on motor function, cognition, and quality of life in Parkinson disease (PD), and (2) compare safety, tolerability, and fitness benefits of different forms of exercise intervention: continuous/moderate intensity vs interval/alternating between low and vigorous intensity, and individual/neighborhood vs group/facility setting.

METHODS

Initial design was a 6-month, 2 × 2 randomized trial of different exercise regimens in independently ambulatory patients with PD. All arms were required to exercise 3 times per week, 45 minutes per session.

RESULTS

Randomization to group/facility setting was not feasible because of logistical factors. Over the first 2 years, we randomized 43 participants to continuous or interval training. Because preliminary analyses suggested higher musculoskeletal adverse events in the interval group and lack of difference between training methods in improving fitness, the next 17 participants were allocated only to continuous training. Eighty-one percent of 60 participants completed the study with a mean attendance of 83.3% (95% confidence interval: 77.5%-89.0%), exercising at 46.8% (44.0%-49.7%) of their heart rate reserve. There were no serious adverse events. Across all completers, we observed improvements in maximum oxygen consumption, gait speed, Unified Parkinson's Disease Rating Scale sections I and III scores (particularly axial functions and rigidity), fatigue, depression, quality of life (e.g., psychological outlook), and flanker task scores (p < 0.05 to p < 0.001). Increase in maximum oxygen consumption correlated with improvements on the flanker task and quality of life (p < 0.05).

CONCLUSIONS

Our preliminary study suggests that aerobic walking in a community setting is safe, well tolerated, and improves aerobic fitness, motor function, fatigue, mood, executive control, and quality of life in mild to moderate PD.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that in patients with PD, an aerobic exercise program improves aerobic fitness, motor function, fatigue, mood, and cognition.

Examining cerebral angiogenesis in response to physical exercise

Capillary growth and expansion (angiogenesis) is a prerequisite for many forms of neural and behavioral plasticity. It is commonly observed in both brain and muscle of aerobically exercising animals. As such, several histological methods have been used to quantify capillary density, including perfusion with India ink, various Nissl stains, and immunohistochemistry. In this chapter, we will describe these histological procedures and describe the stereological analysis used to quantify vessel growth in response to aerobic exercise.

Promoting neuroplasticity for motor rehabilitation after stroke: considering the effects of aerobic exercise and genetic variation on brain-derived neurotrophic factor

Recovery of motor function after stroke involves relearning motor skills and is mediated by neuroplasticity. Recent research has focused on developing rehabilitation strategies that facilitate such neuroplasticity to maximize functional outcome poststroke. Although many molecular signaling pathways are involved, brain-derived neurotrophic factor (BDNF) has emerged as a key facilitator of neuroplasticity involved in motor learning and rehabilitation after stroke. Thus, rehabilitation strategies that optimize BDNF effects on neuroplasticity may be especially effective for improving motor function poststroke. Two potential poststroke rehabilitation strategies that consider the importance of BDNF are the use of aerobic exercise to enhance brain function and the incorporation of genetic information to individualize therapy. Converging evidence demonstrates that aerobic exercise increases BDNF production and consequently enhances learning and memory processes. Nevertheless, a common genetic variant reduces activity-dependent secretion of the BDNF protein. Thus, BDNF gene variation may affect response to motor rehabilitation training and potentially modulate the effects of aerobic exercise on neuroplasticity. This perspective article discusses evidence that aerobic exercise promotes neuroplasticity by increasing BDNF production and considers how aerobic exercise may facilitate the acquisition and retention of motor skills for poststroke rehabilitation. Next, the impact of the BDNF gene val66met polymorphism on motor learning and response to rehabilitation is explored. It is concluded that the effects of aerobic exercise on BDNF and motor learning may be better exploited if aerobic exercise is paired more closely in time with motor training. Additionally, information about BDNF genotype could provide insight into the type and magnitude of effects that aerobic exercise may have across individuals and potentially help guide an individualized prescription of aerobic exercise to enhance motor rehabilitation poststroke.

Submaximal and peak cardiorespiratory response after moderate-high intensity exercise training in subacute stroke

PURPOSE

Reduced cardiovascular fitness post-stroke may negatively impact recovery. There is little information regarding exercise testing performance and cardiorespiratory response to an aerobic exercise intervention in subacute stroke. The purpose of this study was to examine cardiorespiratory response in subacute stroke after an 8-week aerobic exercise intervention using a total body recumbent stepper (TBRS).

METHODS

Nine individuals with mean age 61.2 (SD 4.7) years and mean 66.7 (SD 41.5) days post-stroke completed the exercise intervention. Participants had a mean Fugl-Meyer score of 100.3 (SD 29.3). Outcome measures were obtained at baseline and postintervention. A peak exercise test using a TBRS assessed oxygen consumption, heart rate, and minute ventilation. Participants completed an 8-week exercise intervention on a recumbent stepper 3 times per week at a prescribed heart rate intensity.

RESULTS

Submaximal VO2 was significantly lower from baseline to postintervention with a main effect of Study Visit (F1,8 = 8.5, p = 0.02). Heart rate was not significantly different pre- to postintervention. Minute ventilation exhibited no main effect of Study Visit or Test Minute.

CONCLUSION

Moderate-high intensity aerobic exercise in subacute stroke appears to be beneficial for improving cardiovascular outcomes during submaximal performance of an exercise test.

Characteristics of exercise training interventions to improve cardiorespiratory fitness after stroke: a systematic review with meta-analysis

BACKGROUND

Cardiorespiratory fitness is low after stroke. Improving fitness has the potential to improve function and reduce secondary cardiovascular events.

OBJECTIVE

. This review with meta-analysis aims to identify characteristics and determine the effectiveness of interventions to improve cardiorespiratory fitness after stroke.

METHODS

A systematic search and review with meta-analysis was undertaken. Key inclusion criteria were the following: peer-reviewed articles published in English, adult stroke survivors, an intervention with the potential to improve cardiorespiratory fitness, and peak oxygen consumption (VO2peak) assessed preintervention and postintervention via a progressive aerobic exercise test.

RESULTS

From 3209 citations identified, 28 studies were included, reporting results for 920 participants. Studies typically included chronic, ambulant participants with mild to moderate deficits; used an aerobic or mixed (with an aerobic component) intervention; and prescribed 3 sessions per week for 30 to 60 minutes per session at a given intensity. Baseline VO2peak values were low (8-23 mL/kg/min). Meta-analysis of the 12 randomized controlled trials demonstrated overall improvements in VO2peak of 2.27 (95% confidence interval = 1.58, 2.95) mL/kg/min postintervention. A similar 10% to 15% improvement occurred with both aerobic and mixed interventions and in shorter (≤ 3 months) and longer (>3 months) length programs. Only 1 study calculated total dose received and only 1 included long-term follow-up.

CONCLUSIONS

The results demonstrate that interventions with an aerobic component can improve cardiorespiratory fitness poststroke. Further investigation is required to determine effectiveness in those with greater impairment and comorbidities, optimal timing and dose of intervention, whether improvements can be maintained in the longer term, and whether improved fitness results in better function and reduced risk of subsequent cardiovascular events.

Aerobic exercise in subacute stroke improves cardiovascular health and physical performance

BACKGROUND AND PURPOSE

Cardiovascular health is often impaired after stroke. Reduced exercise capacity ((Equation is included in full-text article.)VO(2peak)) and changes in the vascular system in the stroke-affected limb may impact performance of physical activities such as walking. There is little information regarding the role of prescribed moderate- to high-intensity exercise in subacute stroke. The purpose of this study was to examine whether an 8-week aerobic exercise intervention would improve cardiovascular health and physical performance in participants with subacute stroke.

METHODS

Ten subjects were enrolled in the study and 9 of them completed the intervention. Participants were aged 61.2 ± 4.7 years old, were 66.7 ± 41.5 days poststroke, and had minor motor performance deficits (Fugl-Meyer score, 100.3 ± 29.3). Outcome measures were taken at baseline, postintervention, and at 1-month follow-up. Brachial artery vasomotor reactivity (flow-mediated dilation [FMD]) of both arms was used to assess vascular health, and a peak exercise test was used to assess exercise capacity. The 6-minute walk test (6MWT) was used to assess physical performance. Participants exercised on a recumbent stepper 3 times per week for 8 weeks at a prescribed heart rate intensity.

RESULTS

At baseline, we identified between-limb differences in brachial artery FMD and low (Equation is included in full-text article.)VO(2peak) values. After the intervention, significant improvements were observed in the FMD in both arms, resting systolic blood pressure, and the 6MWT. Although we also observed improvements in the resting diastolic blood pressure, heart rate, and (Equation is included in full-text article.)VO(2peak) values, these changes were not significantly different.

DISCUSSION AND CONCLUSION

Aerobic exercise in participants with subacute stroke was beneficial for improving cardiovascular health, reducing cardiac risk, and improving physical performance (6MWT).

Long-term consequences of developmental alcohol exposure on brain structure and function: therapeutic benefits of physical activity

Developmental alcohol exposure both early in life and during adolescence can have a devastating impact on normal brain structure and functioning, leading to behavioral and cognitive impairments that persist throughout the lifespan. This review discusses human work as well as animal models used to investigate the effect of alcohol exposure at various time points during development, as well as specific behavioral and neuroanatomical deficits caused by alcohol exposure. Further, cellular and molecular mediators contributing to these alcohol-induced changes are examined, such as neurotrophic factors and apoptotic markers. Next, this review seeks to support the use of aerobic exercise as a potential therapeutic intervention for alcohol-related impairments. To date, few interventions, behavioral or pharmacological, have been proven effective in mitigating some alcohol-related deficits. Exercise is a simple therapy that can be used across species and also across socioeconomic status. It has a profoundly positive influence on many measures of learning and neuroplasticity; in particular, those measures damaged by alcohol exposure. This review discusses current evidence that exercise may mitigate damage caused by developmental alcohol exposure and is a promising therapeutic target for future research and intervention strategies.

On aerobic exercise and behavioral and neural plasticity

Aerobic exercise promotes rapid and profound alterations in the brain. Depending upon the pattern and duration of exercise, these changes in the brain may extend beyond traditional motor areas to regions and structures normally linked to learning, cognition, and emotion. Exercise-induced alterations may include changes in blood flow, hormone and growth factor release, receptor expression, angiogenesis, apoptosis, neurogenesis, and synaptogenesis. Together, we believe that these changes underlie elevations of mood and prompt the heightened behavioral plasticity commonly observed following adoption of a chronic exercise regimen. In the following paper, we will explore both the psychological and psychobiological literatures relating to exercise effects on brain in both human and non-human animals and will attempt to link plastic changes in these neural structures to modifications in learned behavior and emotional expression. In addition, we will explore the therapeutic potential of exercise given recent reports that aerobic exercise may serve as a neuroprotectant and can also slow cognitive decline during normal and pathological aging.

The effects of an aerobic and resistance exercise training program on cognition following stroke

BACKGROUND

Cognitive benefits obtained from exercise in healthy populations support the idea that aerobic and resistance training (AT+RT) would confer benefit for poststroke recovery. However, there is little evidence regarding the effectiveness of such programs.

OBJECTIVE

To evaluate the effects of a 6-month exercise program of AT+RT on cognition in consecutively enrolled patients with motor impairments ≥10 weeks poststroke.

METHODS

Outcomes were measured before and after 6 months of AT+RT on 41 patients. Cognition was measured by the Montreal Cognitive Assessment (MoCA). Secondary measures included evaluation of gas exchange anaerobic threshold (ATge), body composition by dual energy X-ray absorptiometry, and depressive symptoms by questionnaire.

RESULTS

There were significant improvements in overall MoCA scores (22.5 ± 4.5 to 24.0 ± 3.9, P < .001) as well as in the subdomains of attention/concentration (4.7 ± 1.7 to 5.2 ± 1.3, P = .03) and visuospatial/executive function (3.4 ± 1.1 to 3.9 ± 1.1, P = .002). There was a significant reduction in the proportion of patients meeting the threshold criteria for mild cognitive impairment (MCI) at baseline compared with posttraining (65.9% vs 36.6%, P < .001). In a linear regression model, there was a positive association between change in cognitive function and change in fat-free mass of the nonaffected limbs (β = .002; P = .005) and change in attention/concentration and change in ATge (β = .383; P ≤ .001), independent of age, sex, time from stroke, and change in fat mass and depression score.

CONCLUSION

A combined training model (AT+RT) resulted in improvements in cognitive function and a reduction in the proportion of patients meeting the threshold criteria for MCI. Change in cognition was positively associated with change in fat-free mass and ATge.

Stochastic resonance activity influences serum tryptophan metabolism in healthy human subjects

Background

Stochastic resonance therapy (SRT) is used for rehabilitation of patients with various neuropsychiatric diseases. An alteration in tryptophan metabolism along the kynurenine pathway has been identified in the central and peripheral nervous systems in patients with neuroinflammatory and neurodegenerative diseases and during the aging process. This study investigated the effect of SRT as an exercise activity on serum tryptophan metabolites in healthy subjects.

Methods

Serum L-tryptophan, L-kynurenine, kynurenic acid, and anthranilic acid levels were measured one minute before SRT and at one, 5, 15, 30, and 60 minutes after SRT. We found that SRT affected tryptophan metabolism. Serum levels of L-tryptophan, L-kynurenine, and kynurenic acid were significantly reduced for up to 60 minutes after SRT. Anthranilic acid levels were characterized by a moderate, non significant transient decrease for up to 15 minutes, followed by normalization at 60 minutes. Tryptophan metabolite ratios were moderately altered, suggesting activation of metabolism after SRT. Lowering of tryptophan would generally involve activation of tryptophan catabolism and neurotransmitter, protein, and bone biosynthesis. Lowering of kynurenic acid by SRT might be relevant for improving symptoms in patients with neuropsychiatric disorders, such as Parkinson’s disease, Alzheimer’s disease, schizophrenia, and depression, as well as certain pain conditions.