Peripheral vascular changes after electrically stimulated cycle training in people with spinal cord injury

Twelve-Week Daily Gluteal and Hamstring Electrical Stimulation Improves Vascular Structure and Function, Limb Volume, and Sitting Pressure in Spinal Cord Injury: A Pilot Feasibility Study

OBJECTIVE

We examined the long-term effects of low-intensity electrical stimulation on (micro)vasculature and sitting pressure of a home-based, wearable electrical stimulation device in a pilot feasibility study.

DESIGN

In a cohort observation before-after trial, nine middle-aged male (n = 8) and female (n = 1) individuals (48 ± 15 yrs) with American Spinal Injury Association A-C classified chronic (1-24 yrs) spinal cord injury underwent 12 wks of self-administered daily, low-intensity gluteal and hamstring electrical stimulation (50 Hz, 6 hrs [30-min electrical stimulation, 15-min rest]). Common femoral artery diameter and blood blow were determined with ultrasound, skin vascular function during local heating was assessed using Laser-Doppler flowmetry, thigh volume was estimated using leg circumferences and skinfolds, and interface sitting pressure was measured using pressure mapping.

RESULTS

Resting common femoral artery diameter increased (0.73 ± 0.20 to 0.79 ± 0.22 cm, P < 0.001) and baseline common femoral artery blood flow increased (0.28 ± 0.12 to 0.40 ± 0.15 l/min, P < 0.002). Gluteal cutaneous vascular conductance showed a time*temperature interaction (P = 0.01) with higher conductance at 42°C after 12 wks. Ischial peak pressure decreased (P = 0.003) by 32 ± 23 mm Hg and pressure gradient decreased (23 ± 7 to 16 ± 6 mm Hg, P = 0.007). Thigh volume increased (+19%, P = 0.01).

CONCLUSIONS

Twelve-week daily home-based gluteal and hamstring electrical stimulation is feasible and effective to improve (micro)vasculature and sitting pressure, and electrical stimulation may have clinical implications for ameliorating pressure ulcers and (micro)vascular complications in spinal cord injury.

Does aerobic exercise benefit persons with tetraplegia from spinal cord injury? A systematic review

CONTEXT

This review synthesizes the findings of previous research studies on the cardiovascular and metabolic benefits of aerobic exercise for individuals with tetraplegia secondary to spinal cord injury. They are often less active due to muscular paralysis, sensory loss, and sympathetic nervous system dysfunction that result from injury. Consequently, these persons are at higher risk for exercise intolerance and secondary health conditions.

OBJECTIVE

To evaluate the evidence concerning efficacy of aerobic exercise training for improving health and exercise performance in persons with tetraplegia from cervical injury.

METHODS

The search engines PubMed and Google Scholar were used to locate published research. The final 75 papers were selected on the basis of inclusion criteria. The studies were then rank-ordered using Physiotherapy Evidence Database.

RESULTS

Studies combining individuals with tetraplegia and paraplegia show that voluntary arm-crank training can increase mean peak power output by 33%. Functional electrical stimulation leg cycling was shown to induce higher peak cardiac output and stroke volume than arm-crank exercise. A range of peak oxygen uptake (VO_2peak) values have been reported (0.57-1.32 L/min). Both VO_2peak and cardiac output may be enhanced via increased muscle pump in the legs and venous return to the heart. Hybrid exercise (arm-crank and functional electrical stimulation leg cycling) can result in greater peak oxygen uptake and cardiovascular responses.

CONCLUSION

Evidence gathered from this systematic review of literature is inconclusive due to the lack of research focusing on those with tetraplegia. Higher power studies (level 1-3) are needed with the focus on those with tetraplegia.

Safety and preliminary efficacy of functional electrical stimulation cycling in an individual with cervical cord injury, autonomic dysreflexia, and a pacemaker: Case report

Context: Functional electric stimulation (FES) cycling is a commonly used therapeutic exercise modality after spinal cord injury (SCI); however, additional precautions must be taken in certain situations. The purpose of this study was to develop and apply a safety monitoring protocol for autonomic dysreflexia (AD) during FES cycling and to determine if an interval-FES cycling program can be safe and beneficial to an individual with cervical SCI, a history of AD, and a non-dependent cardiac pacemaker.The participant was a 36-year-old male with C6 AIS-C SCI sustained 9 years earlier, intermittent AD, and implanted cardiac pacemaker. Ten sessions of interval-FES cycling were performed twice weekly for 5 weeks. Rating of perceived exertion (RPE), blood pressure (BP), oxygen saturation (O2sat), and heart rate (HR) were monitored before, after, and every 5 min during cycling. ECG and cardiac pacemaker were evaluated by a cardiologist after ending the program.Findings: The participant reported self-limited chills 27 times over 10 sessions (19 "light", 3 "moderate", 5 "sharp"). Chills coincided with BP increases 59% of the time and their magnitudes moderately correlated (r = 0.32). The ECG was determined to be normal and the pacemaker fully functional at the end of the study, while blood glucose decreased (111-105 mg/dl), HbA1c levels increased (5.5-5.9%), and resting BP decreased (118/84-108/66 mmHg).Conclusion/Clinical Relevance: A person with cervical SCI, symptomatic AD, and a non-dependent pacemaker can safely participate and benefit from the interval-FES cycling program provided adequate monitoring of symptoms and vital signs.

Vascular adaptations in nonstimulated areas during hybrid cycling or handcycling in people with a spinal cord injury: a pilot study of 10 cases

STUDY DESIGN

Sub-study of a randomized controlled trial.

OBJECTIVES

To examine if hybrid cycling (cycling with the legs via electrical stimulation combined with voluntary handcycling) compared to handcycling leads to different systemic vascular adaptations in individuals with a long-term spinal cord injury (SCI).

SETTING

Two rehabilitation centers in the Netherlands.

METHODS

Ten individuals with a SCI trained on a hybrid bicycle (N = 5) or a handcycle (N = 5) for 16 weeks twice a week. Prior to and following the training the intima media thickness (IMT) of the common coronary artery (CCA) and superficial femoral artery (SFA) were measured and the flow-mediated dilation (FMD) of the brachial artery (BA) was analyzed.

RESULTS

Before training, there were no significant differences in any of the outcome measures between the groups. We found no change in CCA IMT (pre: 0.616 mm, post: 0.586 mm), or in SFA (pre: 0.512 mm, post: 0.520 mm) after hybrid cycling. We also found no change in FMD % of BA after hybrid cycling (pre: 9.040%, post: 9.220%). There were no changes in CCA IMT, SFA IMT, and FMD% after handcycling either.

CONCLUSIONS

It appears that 16 weeks of twice-weekly training of up to 30 min on a hybrid bicycle or handcycle does not lead to systemic vascular adaptations. A larger sample size and training protocol with more frequent and higher intensity training (which might involve a home-based setting and an adapted period prior to the training) might show different results.

Functional electrical stimulation cycling exercise after spinal cord injury: a systematic review of health and fitness-related outcomes

OBJECTIVES

The objective of this review was to summarize and appraise evidence on functional electrical stimulation (FES) cycling exercise after spinal cord injury (SCI), in order to inform the development of evidence-based clinical practice guidelines.

METHODS

PubMed, the Cochrane Central Register of Controlled Trials, EMBASE, SPORTDiscus, and CINAHL were searched up to April 2021 to identify FES cycling exercise intervention studies including adults with SCI. In order to capture the widest array of evidence available, any outcome measure employed in such studies was considered eligible. Two independent reviewers conducted study eligibility screening, data extraction, and quality appraisal using Cochranes' Risk of Bias or Downs and Black tools. Each study was designated as a Level 1, 2, 3 or 4 study, dependent on study design and quality appraisal scores. The certainty of the evidence for each outcome was assessed using GRADE ratings ('High', 'Moderate', 'Low', or 'Very low').

RESULTS

Ninety-two studies met the eligibility criteria, comprising 999 adults with SCI representing all age, sex, time since injury, lesion level and lesion completeness strata. For muscle health (e.g., muscle mass, fiber type composition), significant improvements were found in 3 out of 4 Level 1-2 studies, and 27 out of 32 Level 3-4 studies (GRADE rating: 'High'). Although lacking Level 1-2 studies, significant improvements were also found in nearly all of 35 Level 3-4 studies on power output and aerobic fitness (e.g., peak power and oxygen uptake during an FES cycling test) (GRADE ratings: 'Low').

CONCLUSION

Current evidence indicates that FES cycling exercise improves lower-body muscle health of adults with SCI, and may increase power output and aerobic fitness. The evidence summarized and appraised in this review can inform the development of the first international, evidence-based clinical practice guidelines for the use of FES cycling exercise in clinical and community settings of adults with SCI. Registration review protocol: CRD42018108940 (PROSPERO).

Effects of a Tailored Physical Activity Intervention on Cardiovascular Structure and Function in Individuals With Spinal Cord Injury

Background

Spinal cord injury (SCI) leads to a loss of descending motor and sympathetic control below the level of injury (LOI), which ultimately results in chronically altered cardiovascular function and remodeling. While supervised, laboratory-based exercise training can generate cardiovascular adaptations in people with SCI, it is unknown whether behavioral community-based interventions effectively generate such adaptations for individuals with SCI.

Objective

Examine the effects of a tailored behavioral physical activity (PA) intervention on cardiac and vascular structure and function in individuals with SCI.

Methods

In this randomized controlled trial, 32 participants with SCI (18-65 years, SCI >1 year) were assigned to PA (8-week behavioral intervention) or control (CON) groups. At baseline and postintervention, measures of resting left ventricular (LV) structure and function, carotid intima-media thickness and pulse-wave velocity were assessed with ultrasound and tonometry.

Results

Twenty-eight participants completed the study (n = 14/group). Across the full study cohort there were no significant changes in indices of LV or vascular structure and function, despite notable improvements in peak power and oxygen uptake in the PA group. However, in a subanalysis for LOI, individuals in the PA group with LOIs below T6 had evidence of altered LV geometry (ie, increased LV internal diameter, reduced sphericity index and relative wall thickness; group × time P < 0.05 for all), which was not seen in individuals with higher LOIs at or above T6.

Conclusion

An 8-week behavioral PA intervention appears to promote adaptations in cardiac geometry more readily in individuals with lower level SCI than those with higher-level SCI.

Feasibility of overnight electrical stimulation-induced muscle activation in people with a spinal cord injury. A Pilot study

Study Design

We investigated whether overnight ES is a feasible method to activate gluteal, quadriceps, and hamstrings muscles in a two-week experiment. Electrical stimulation (ES) induced muscle contractions have proven positive effects on risk factors for developing pressure ulcers in people with a spinal cord injury (SCI). Therefore prolonged overnight ES-induced muscle activation is interesting, but has never been studied.

Objective

To study feasibility of ES-induced leg muscle activation. In eight participants with motor complete SCI gluteal, hamstrings and quadriceps muscles were activated with a 2-weeks overnight stimulation protocol, 8 h per night, using specially developed ES-shorts.

Setting

The Netherlands.

Methods

Muscle fatigue was determined with a muscle contraction sensor. Questionnaires on sleep quality (SQ) and the ES-shorts usability were taken.

Results

After 8 h of activation muscles still contracted, although fatigue occurred, and mean contraction size was lower at the end of a cycle (p = 0.03). SQ (0-100) after intervention was 75, and 66 after 4 weeks without overnight ES (p = 0.04) indicating ES improves sleep quality. The usability of the ES-shorts was good.

Conclusions

This study shows that overnight ES-induced muscle activation using ES-shorts in SCI is a new, feasible method that does not interfere with sleep. The nightly use of the ES-shorts might be considered as an important part of the daily routine in SCI.

Is Technology for Orthostatic Hypotension Ready for Primetime?

Spinal cord injury (SCI) often results in the devastating loss of motor, sensory, and autonomic function. After SCI, the interruption of descending sympathoexcitatory pathways disrupts supraspinal control of blood pressure (BP). A common clinical consequence of cardiovascular dysfunction after SCI is orthostatic hypotension (OH), a debilitating condition characterized by rapid profound decreases in BP when assuming an upright posture. OH can result in a diverse array of insidious and pernicious health consequences. Acute effects of OH include decreased cardiac filling, cerebral hypoperfusion, and associated presyncopal symptoms such as lightheadedness and dizziness. Over the long term, repetitive exposure to OH is associated with a drastically increased prevalence of heart attack and stroke, which are leading causes of death in those with SCI. Current recommendations for managing BP after SCI primarily include pharmacologic interventions with prolonged time to effect. Because most episodes of OH occur in less than 3 minutes, this delay in action often renders most pharmacologic interventions ineffective. New innovative technologies such as epidural and transcutaneous spinal cord stimulation are being explored to solve this problem. It might be possible to electrically stimulate sympathetic circuitry caudal to the injury and elicit rapid modulation of BP to manage OH. This review describes autonomic control of the cardiovascular system before injury, resulting cardiovascular consequences after SCI such as OH, and the clinical assessment tools for evaluating autonomic dysfunction after SCI. In addition, current approaches for clinically managing OH are outlined, and new promising interventions are described for managing this condition.

Temporal analysis of cardiovascular control and function following incomplete T3 and T10 spinal cord injury in rodents

Spinal cord injury (SCI) is a devastating condition that results in whole‐body dysfunction, notably cardiovascular (CV) disruption and disease. Injury‐induced destruction of autonomic pathways in conjunction with a progressive decline in physical fitness contribute to the poor CV status of SCI individuals. Despite the wide use of exercise training as a therapeutic option to reduce CV dysfunction, little is known about the acute hemodynamic responses to the exercise itself. We investigated CV responses to an exercise challenge (swimming) following both high and low thoracic contusion to determine if the CV system is able to respond appropriately to the challenge of swimming. Blood pressure (BP) telemetry and echocardiography were used to track the progression of dysfunction in rodents with T3 and T10 SCI (n = 8 each) for 10 weeks postcontusion. At 1 week postinjury, all animals displayed a drastic decline in heart rate (HR) during the exercise challenge, likely a consequence of neurogenic shock. Furthermore, over time, all groups developed a progressive inability to maintain BP within a narrow range during the exercise challenge despite displaying normal hemodynamic parameters at rest. Echocardiography of T10 animals revealed no persistent signs of cardiac dysfunction; T3 animals exhibited a transient decline in systolic function that returned to preinjury levels by 10 weeks postinjury. Novel evidence provided here illustrates that incomplete injuries produce hemodynamic instability that only becomes apparent during an exercise challenge. Further, this dysfunction lasts into the chronic phase of disease progression despite significant recovery of hindlimb locomotion and cardiac function.

The Effect of Electrically Induced Cycling and Nutritional Counseling on Cardiometabolic Health in Upper and Lower Motor Neuron Chronic Spinal Cord Injury: Dual Case Report

Introduction:

Various therapies have been utilized to improve cardiometabolic health after spinal cord injury (SCI), including Functional Electrical Stimulation (FES) cycling. Typically, FES is used in SCI cases resulting from Upper Motor Neuron Injury (UMN-SCI). However, it has been reported that FES may improve muscle torque and functional mobility in individuals with Lower Motor Neuron Injuries (LMN-SCI) but potential effects on cardiometabolic health have not been studied before. Thus, this study examined the cardiometabolic health response to FES cycling combined with nutritional counseling in two individuals with chronic SCI; one person with LMN-SCI and one with UMN-SCI.

Case Presentation:

Body composition, vascular stiffness, and glucose deposition were assessed before and after participation in the FES cycling and nutritional counseling program. Despite the decrease in body mass in the case of LMN-SCI but not UMN-SCI, the fat mass-to-lean mass ratio in the lower limbs and trunk increased +4% and +8% respectively, in the former and decreased −10% and −8% respectively in the latter. Both subjects decreased markers of central vascular stiffness (AIx@75, reflection magnitude) as well as blood glucose and HbA1c levels, however, the changes were greater in the case of UMN-SCI.

Discussion:

This dual case study provides only a partial support for the use of FES cycling alone or in combination with nutritional counseling for improving cardio metabolic health in LMN-SCI, however modest decreases in glucose and vascular stiffness warrant further investigations.

Intermittent mild negative pressure applied to the lower limb in patients with spinal cord injury and chronic lower limb ulcers: a crossover pilot study

STUDY DESIGN

Randomized, assessor-blinded crossover pilot study.

OBJECTIVES

To explore the use of an intermittent negative pressure (INP) device for home use in addition to standard wound care (SWC) for patients with spinal cord injury (SCI) and chronic leg and foot ulcers before conducting a superiority trial.

SETTING

Patient homes and outpatient clinic.

METHODS

A 16-week crossover trial on 9 SCI patients (median age: 57 years, interquartile range [IQR] 52-66), with leg ulcers for 52 of weeks (IQR: 12-82) duration. At baseline, patients were allocated to treatment with INP + SWC or SWC alone. After 8 weeks, the ulcers were evaluated. To assess protocol adherence, the patients were then crossed over to the other group and were evaluated again after another 8 weeks. Lower limb INP treatment consisted of an airtight pressure chamber connected to an INP generator (alternating 10 s -40mmHg/7 s atmospheric pressure) used 2 h/day at home. Ulcer healing was assessed using a photographic wound assessment tool (PWAT) and by measuring changes in wound surface area (WSA).

RESULTS

Seven of nine recruited patients adhered to a median of 90% (IQR: 80-96) of the prescribed 8-week INP-protocol, and completed the study without side effects. PWAT improvement was observed in 4/4 patients for INP + SWC vs. 2/5 patients for SWC alone (P = 0.13). WSA improved in 3/4 patients allocated to INP + SWC vs. 3/5 patients in SWC alone (P = 0.72).

CONCLUSIONS

INP can be used as a home-based treatment for patients with SCI, and its efficacy should be tested in an adequately sized, preferably multicenter randomized trial.

Time Course of Flow-Mediated Dilation and Vascular Endothelial Growth Factor following Acute Stroke

OBJECTIVES

People after stroke demonstrate alterations in vascular endothelial function measured by flow-mediated dilation. Limited information is available in the literature on possible protective factors following stroke. The aims of the secondary analysis were (1) to characterize the time course of vascular endothelial function using flow-mediated dilation at 72 hours after stroke and 1 week later during inpatient stroke rehabilitation and (2) to determine whether flow-mediated dilation was related to vascular endothelial growth factor, brain-derived neurotrophic factor, or estimated prestroke peak oxygen uptake.

METHODS

Flow-mediated dilation using Doppler ultrasound was assessed in bilateral brachial arteries at the defined time points. Flow-mediated dilation and blood draws occurred on the same day between 7:30 am and 9:00 am following an overnight fast. Enzyme-linked immunosorbent assay was used to quantify plasma vascular endothelial growth factor and brain-derived neurotrophic factor values. A nonexercise estimate was used to calculate prestroke peak oxygen uptake.

RESULTS

We have shown that between-limb differences are evident within 72 hours after stroke and remain 1 week later during inpatient rehabilitation. Higher values for vascular endothelial growth factor were associated with increased flow-mediated dilation at both time points. Higher estimated prestroke peak oxygen uptake was related to flow-mediated dilation. Brain-derived neurotrophic factor was not related to any outcome measures.

CONCLUSIONS

Unique vascular adaptations start early after stroke in the stroke-affected limb and remain through inpatient stroke rehabilitation. Vascular endothelial growth factor and prestroke physical activity may have a protective role in vascular function following stroke. Future work should focus on mechanistic pathways for preservation of vascular health.

Effects of Electrical Stimulation on Risk Factors for Developing Pressure Ulcers in People with a Spinal Cord Injury: A Focused Review of Literature

Pressure ulcers (PUs) are a common and serious problem for wheelchair users, such as individuals with a spinal cord injury (SCI), resulting in great discomfort, loss of quality of life, and significant medical care costs. Therefore, it is of utmost importance to prevent PUs. In this literature overview, the effects of electrical stimulation (ES) on the risk factors for developing PUs in people with an SCI are examined and synthesized from January 1980 to January 2015. Thirty-four relevant studies of PU prevention in SCI were identified. Four were randomized clinical trials, 24 were case series, 6 had other designs. Three types of ES modalities were identified. The methodological quality varied from poor to fairly strong, with a large variety in used ES parameters. Twenty-three studies were identified describing short-term effects of ES on interface pressure, oxygenation, and/or blood flow, and 24 studies described the long-term effects of ES on muscle volume, muscle strength, and histology. Whereas there is a lack of controlled studies on the effects of ES on PU incidence, which disallows definite conclusions, there is moderate evidence to suggest that ES-induced muscle activation has a positive influence on several risk factors for developing PUs in people with an SCI.

Effects of Testosterone and Evoked Resistance Exercise after Spinal Cord Injury (TEREX-SCI): study protocol for a randomised controlled trial

INTRODUCTION

Individuals with spinal cord injury (SCI) are at a lifelong risk of obesity and chronic metabolic disorders including insulin resistance and dyslipidemia. Within a few weeks of injury, there is a significant decline in whole body fat-free mass, particularly lower extremity skeletal muscle mass, and subsequent increase in fat mass (FM). This is accompanied by a decrease in anabolic hormones including testosterone. Testosterone replacement therapy (TRT) has been shown to increase skeletal muscle mass and improve metabolic profile. Additionally, resistance training (RT) has been shown to increase lean mass and reduce metabolic disturbances in SCI and other clinical populations.

METHODS AND ANALYSIS

26 individuals with chronic, motor complete SCI between 18 and 50 years old were randomly assigned to a RT+TRT group (n=13) or a TRT group (n=13). 22 participants completed the initial 16-week training phase of the study and 4 participants withdrew. 12 participants of the 22 completed 16 weeks of detraining. The TRT was provided via transdermal testosterone patches (4-6 mg/day). The RT+TRT group had 16 weeks of supervised unilateral progressive RT using surface neuromuscular electrical stimulation with ankle weights. This study will investigate the effects of evoked RT+TRT or TRT alone on body composition (muscle cross-sectional area, visceral adipose tissue, %FM) and metabolic profile (glucose and lipid metabolism) in individuals with motor complete SCI. Findings from this study may help in designing exercise therapies to alleviate the deterioration in body composition after SCI and decrease the incidence of metabolic disorders in this clinical population.

ETHICS AND DISSEMINATION

The study is currently approved by the McGuire VA Medical Center and Virginia Commonwealth University. All participants read and signed approved consent forms. Results will be submitted to peer-reviewed journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

Pre-result, NCT01652040.

The relationship of pro-inflammatory markers to vascular endothelial function after acute stroke

Purpose/Aim: Data from chronic stroke studies have reported reduced blood flow and vascular endothelial function in the stroke-affected limb. It is unclear whether these differences are present early after stroke. First, we investigated whether vascular endothelial function in the stroke-affected limb would be different from healthy adults. Second, we examined whether between-limb differences in vascular endothelial function existed in the stroke-affected arm compared to the non-affected arm. Last, we tested whether reduced vascular endothelial function was related to pro-inflammatory markers that are present early after stroke.

MATERIALS AND METHODS

Vascular endothelial function was assessed by flow-mediated dilation (FMD) in the brachial artery within 72 h post-stroke. All participants withheld medications from midnight until after the procedure. Ultrasound scans and blood draws for pro-inflammatory markers occurred on the same day between 7:30 am and 9:00 am.

RESULTS

People with acute stroke had significantly lower FMD (4.2% ± 4.6%) than control participants (8.5% ± 5.2%, p = 0.037). Stroke participants had between-limb differences in FMD (4.2% ± 4.6% stroke-affected vs. 5.3% ± 4.4% non-affected, p = 0.02), whereas, the control participants did not. Of the pro-inflammatory markers, only vascular cell adhesion molecule-1(VCAM-1) had a significant relationship to FMD (stroke-affected limb, r = -0.62, p = 0.03; non-affected limb, r = -0.75, p = 0.005), but not tumor necrosis factor alpha nor interleukin-6.

CONCLUSIONS

Vascular endothelial function is reduced starting in the early stage of stroke recovery. People with higher levels of VCAM-1 had a lower FMD response.

Effects of a Functional Electrical Stimulation-Assisted Cycling Program on Immune and Cardiovascular Health in Persons with Spinal Cord Injury

Background: Spinal cord injury (SCI) is associated with both a state of chronic inflammation and an increased prevalence of cardiovascular disease (CVD). These disorders are closely linked and have been shown to negatively influence one another. Participation in regular exercise has been shown to be an effective intervention strategy in the treatment of each of these disorders. For individuals with SCI who may lack the lower limb motor capabilities to perform certain traditional exercise modalities, functional electrical stimulation (FES) cycling may provide an effective alternative. Objective: The purpose of this study was to examine the effects of 12 weeks of FES training performed 3 times per week on physiological indices of cardiovascular function as well as molecular indices of inflammation and cardiovascular health. Methods: Ten individuals with chronic SCI were included. Measures of central and peripheral cardiovascular function as well as hematological and immunological markers were assessed before and after the 12-week exercise program. Results: Enhancements in exercise performance as well as a corresponding increase in peripheral cardiovascular function were achieved, as shown by a significant 34% increase in pulse volume (P = .04) and trends toward increases in cross-sectional area (P = .09) and arterial inflow volume (P = .11) of the common femoral artery. Despite this, no change in any hematological or immunological markers was evident. Conclusion: Although the efficacy of FES exercise in enhancing exercise performance (time and distance to fatigue) and peripheral cardiovascular function has been reaffirmed, no alterations in any molecular indices of cardiovascular risk were achieved.

Functional electrical stimulation: cardiorespiratory adaptations and applications for training in paraplegia

Regular exercise can be broadly beneficial to health and quality of life in humans with spinal cord injury (SCI). However, exercises must meet certain criteria, such as the intensity and muscle mass involved, to induce significant benefits. SCI patients can have difficulty achieving these exercise requirements since the paralysed muscles cannot contribute to overall oxygen consumption. One solution is functional electrical stimulation (FES) and, more importantly, hybrid training that combines volitional arm and electrically controlled contractions of the lower limb muscles. However, it might be rather complicated for therapists to use FES because of the wide variety of protocols that can be employed, such as stimulation parameters or movements induced. Moreover, although the short-term physiological and psychological responses during different types of FES exercises have been extensively reported, there are fewer data regarding the long-term effects of FES. Therefore, the purpose of this brief review is to provide a critical appraisal and synthesis of the literature on the use of FES for exercise in paraplegic individuals. After a short introduction underlying the importance of exercise for SCI patients, the main applications and effects of FES are reviewed and discussed. Major findings reveal an increased physiological demand during FES hybrid exercises as compared with arms only exercises. In addition, when repeated within a training period, FES exercises showed beneficial effects on muscle characteristics, force output, exercise capacity, bone mineral density and cardiovascular parameters. In conclusion, there appears to be promising evidence of beneficial effects of FES training, and particularly FES hybrid training, for paraplegic individuals.

Four weeks of functional electrical stimulated cycling after spinal cord injury: a clinical cohort study

The aim of this study was to determine the efficacy and the effects of functional electrical stimulated cycling (FES cycling) in patients with spinal cord injury during their rehabilitation in a special acute care unit. Thirty patients [10 with American Spinal Injury Association Impairment Scale (AIS) grade A, three with AIS grade B, 15 with AIS grade C, two with AIS grade D] aged 44±15.5 years and 2 (median) (interquartile range, 1.0-4.25) months after spinal cord injury were included in the study. The patients participated in a 20-min FES-cycling program 2 days per week for 4 weeks during their acute inpatient rehabilitation. The influence on muscle cross-section, muscle and leg circumference, spasticity, and the walking ability parameter (distance, time, aids) was measured. Muscle stimulation intensity and output parameters (pedalling time and distance) were also recorded. Spasticity decreased during hip abduction and adduction (70 and 98.1%, respectively). Spasticity during knee flexion and knee extension decreased by 66.8 and 76.6%, and a decrease was found during dorsal foot extension (67.8%; for all, P<0.05). Presession-postsession comparisons showed that after 4 weeks of FES cycling, an increase in the circumference of the cross-sectional area of 15.3% on the left and of 17% on the right m. rectus femoris could be observed in group AIS A+B. In the AIS C+D group, the circumference of the left m. rectus femoris increased by 25% and that of the right m. rectus femoris by 21% (for all, P<0.05). The results of the study show that FES cycling in combination with function-oriented physiotherapy and occupational therapy can have a positive influence on spasticity, walking ability, and muscular reactivation. It seems to support circulatory processes within the rehabilitation of paraplegics already after a 4-week intervention.

Accommodation of wheelchair-reliant individuals by community fitness facilities

BACKGROUND

Adhering to the recommended healthy physical activity guidelines can be difficult for individuals with spinal cord injury (SCI), stroke or other paralytic conditions. Ordinary community structures such as curbs, stairs and narrow passageways can present as major obstacles for individuals who are reliant on wheelchairs. The Americans with Disabilities Act (ADA) of 1990 mandates that public facilities, including community fitness centers, should be accessible to everyone.

STUDY DESIGN

Analysis of compliance of the ADA and accommodation of wheelchair-reliant individuals.

OBJECTIVES

To determine the level of compliance with ADA and the degree of accommodation of wheelchair-reliant individuals.

SETTING

Community fitness centers in the Hattiesburg, Mississippi metropolitan area.

METHODS

Ten fitness centers consented to unfettered access for evaluation of ADA compliance and accommodation of wheelchair-reliant individuals using an 82-item checklist.

RESULTS

All surveyed facilities were found to be partially compliant, with none of the facilities being 100% compliant. The areas of least compliance were access to and free movement around exercise equipment and full access to restrooms. Beyond ADA accessibility, only 20% of the participating facilities provided suitable adaptive equipment, and no facilities employed staff trained for the special needs of those with paralytic conditions.

CONCLUSION

Beyond mandated physical accessibility, accommodation of individuals who are reliant on wheelchairs because of SCI or other paralytic conditions was found to be lacking. It remains important for health-care professionals and other advocacy groups to stress the need for inclusion and accommodation of individuals with disabilities to community fitness facilities allowing wellness needs to be met.

Metabolic rate and cardiorespiratory response during hybrid cycling versus handcycling at equal subjective exercise intensity levels in people with spinal cord injury

OBJECTIVE

To compare the metabolic rate and cardiorespiratory response during hybrid cycling versus handcycling at equal subjective exercise intensity levels in people with spinal cord injury (SCI).

DESIGN

Cross-sectional study.

SETTING

Amsterdam Rehabilitation Research Centre | Reade, Amsterdam, The Netherlands.

METHODS

On separate days, nine individuals with a motor complete paraplegia or tetraplegia (eight men, age 40 ± 13 years, time since injury 12 ± 10 years) performed 5-minute bouts of hybrid cycling (day 1) and handcycling (day 2) at moderate (level 3 on a 10-point rating of perceived exertion (RPE) scale) and vigorous (RPE level 6) subjective exercise intensity, while respiratory gas exchange was measured by open-circuit spirometry and heart rate was monitored using radiotelemetry.

OUTCOME MEASURES

Metabolic rate (calculated with the Weir equation) and cardiorespiratory response (heart rate, oxygen pulse, and ventilation).

RESULTS

Overall, the metabolic rate during hybrid cycling was 3.4 kJ (16%) higher (P = 0.006) than during handcycling. Furthermore, compared with handcycling, the overall heart rate and ventilation during hybrid cycling was 11 bpm (11%) and 5.3 l/minute (18%) higher (P = 0.004 and 0.024), respectively, while the oxygen pulse was the same (P = 0.26).

CONCLUSION

Hybrid cycling induces a higher metabolic rate and cardiorespiratory response at equal RPE levels than handcycling, suggesting that hybrid cycling is more suitable for fighting obesity and increasing cardiorespiratory fitness in individuals with SCI.

Gluteal blood flow and oxygenation during electrical stimulation-induced muscle activation versus pressure relief movements in wheelchair users with a spinal cord injury

BACKGROUND

Prolonged high ischial tuberosities pressure (IT pressure), decreased regional blood flow (BF) and oxygenation (%SO2) are risk factors for developing pressure ulcers (PUs) in patients with spinal cord injury (SCI). Electrical stimulation (ES)-induced gluteal and hamstring muscle activation may improve pressure distribution by changing the shape of the buttocks while sitting and also increase BF and %SO2.

OBJECTIVE

To compare acute effects of ES-induced gluteal and hamstring muscle activation with pressure relief movements (PRMs) on IT pressure, BF and %SO2.

PARTICIPANTS AND METHODS

Twelve men with SCI performed PRMs - push-ups, bending forward and leaning sideward - and received surface ES (87±19 mA) to the gluteal and hamstring muscles while sitting in their wheelchair. Ischial tuberosities pressure was measured using a pressure mapping system; (sub)cutaneous BF and %SO2 were measured using reflection spectroscopy and laser Doppler, respectively.

RESULTS

Compared with rest (156±26 mm Hg), IT pressure was significantly lower during all other conditions (push-ups 19±44; bending forward 56±33; leaning sideward 44±38; ES 67±45 mm Hg). For the whole group, all PRMs significantly augmented BF (+39 to -96%) and %SO2 (+6.0 to -7.9%-point), whereas ES-induced muscle activation did only for peak BF. In all, 63% of the participants showed an increased BF (average 52%) with ES.

CONCLUSION

PRMs acutely reduced IT pressure and improved oxygenation and BF in SCI. The currently used ES method cannot replace PRMs, but it may be used additionally. ES-induced muscle activation is not as effective for acute pressure relief, but the frequency of stimulation is much higher than the performance of PRMs and can therefore be more effective in the long term.

Exercise pressor reflex function following acute hemi-section of the spinal cord in cats

Cardiovascular disease is a leading cause of morbidity and mortality in patients post spinal cord injury (SCI). The prescription of exercise as a therapeutic modality for disease prevention in this population is promising. It is logical to suggest that the sooner an exercise program can begin the more benefit the patient will receive from the therapy. However, the time point after injury at which the requisite circulatory responses needed to support exercise are viable remains largely unknown. The skeletal muscle exercise pressor reflex (EPR) significantly contributes to cardiovascular control during exercise in healthy individuals. Experiments in patients with a chronic lateral hemi-section of the spinal cord (Brown-Séquard syndrome) suggest that the EPR, although blunted, is operational when examined months to years post injury. However, whether this critically important reflex remains functional immediately after lateral SCI or, in contrast, experiences a period of reduced capacity due to spinal shock has not been established. This study was designed to assess EPR function after acute lateral transection of the spinal cord. The EPR was selectively activated in seven decerebrate cats via electrically stimulated static contraction of the triceps surae muscles of each hindlimb before and after lateral hemi-section of the T₁₃–L₂ region of the spinal cord. Compared to responses prior to injury, increases in mean arterial pressure (MAP) were significantly decreased when contracting the hindlimb either ipsilateral to the lesion (MAP = 17 ± 3 mmHg before and 9 ± 2 mmHg after) or contralateral to the lesion (MAP = 22 ± 5 mmHg before and 12 ± 4 mmHg after). The heart rate (HR) response to stimulation of the EPR was largely unaffected by induction of acute SCI. The findings suggest that the EPR maintains the ability to importantly contribute to cardiovascular regulation during exercise immediately following a Brown-Séquard-like injury.

Expression of genes involved in fatty acid transport and insulin signaling is altered by physical inactivity and exercise training in human skeletal muscle

Physical deconditioning is associated with the development of chronic diseases, including type 2 diabetes and cardiovascular disease. Exercise training effectively counteracts these developments, but the underlying mechanisms are largely unknown. To gain more insight into these mechanisms, muscular gene expression levels were assessed after physical deconditioning and after exercise training of the lower limbs in humans by use of gene expression microarrays. To exclude systemic effects, we used human models for local physical inactivity (3 wk of unilateral limb suspension) and for local exercise training (6 wk of functional electrical stimulation exercise of the extremely deconditioned legs of individuals with a spinal cord injury). The most interesting subset of genes, those downregulated after deconditioning as well as upregulated after exercise training, contained 18 genes related to both the "insulin action" and "adipocytokine signaling" pathway. Of these genes, the three with strongest up/downregulation were the muscular fatty acid-binding protein-3 (FABP3), the fatty acid oxidizing enzyme hydroxyacyl-CoA dehydrogenase (HADH), and the mitochondrial fatty acid transporter solute carrier 25 family member A20 (SLC25A20). The expression levels of these genes were confirmed using RT-qPCR. The results of the present study indicate an important role for a decreased transport and metabolism of fatty acids, which provides a link between physical activity levels and insulin signaling.

Can the efficacy of electrically stimulated pedaling using a commercially available ergometer BE improved by minimizing the muscle stress-time integral?

INTRODUCTION

The cardiorespiratory and muscular strength benefits of functional electrical stimulation (FES) pedaling for spinal cord injury (SCI) subjects are limited because the endurance of electrically stimulated muscle is low.

METHODS

We tested new electrical stimulation timing patterns (Stim3, designed using a forward dynamic simulation to minimize the muscle stress-time integral) to determine whether SCI subjects could increase work and metabolic responses when pedaling a commercial FES ergometer. Work, rate of oxygen uptake (VO(2)), and blood lactate data were taken from 11 subjects (injury level T4-T12) on repeated trials.

RESULTS

Subjects performed 11% more work pedaling with Stim3 than with existing stimulation patterns (StimErg) (P = 0.043). Average (VO(2)) and blood lactate concentrations were not significantly different between Stim3 (442 ml/min, 5.9 mmol/L) and StimErg (417 ml/min, 5.9 mmol/L).

CONCLUSION

The increased mechanical work performed with Stim3 supports the use of patterns that minimize the muscle stress-time integral to prolong FES pedaling.

Reduced cardiorespiratory fitness after stroke: biological consequences and exercise-induced adaptations

Evidence from several studies consistently shows decline in cardiorespiratory (CR) fitness and physical function after disabling stroke. The broader implications of such a decline to general health may be partially understood through negative poststroke physiologic adaptations such as unilateral muscle fiber type shifts, impaired hemodynamic function, and decrements in systemic metabolic status. These physiologic changes also interrelate with reductions in activities of daily living (ADLs), community ambulation, and exercise tolerance, causing a perpetual cycle of worsening disability and deteriorating health. Fortunately, initial evidence suggests that stroke participants retain the capacity to adapt physiologically to an exercise training stimulus. However, despite this evidence, exercise as a therapeutic intervention continues to be clinically underutilized in the general stroke population. Far more research is needed to fully comprehend the consequences of and remedies for CR fitness impairments after stroke. The purpose of this brief review is to describe some of what is currently known about the physiological consequences of CR fitness decline after stroke. Additionally, there is an overview of the evidence supporting exercise interventions for improving CR fitness, and associated aspects of general health in this population.

Blood redistribution during exercise in subjects with spinal cord injury and controls

INTRODUCTION/PURPOSE

During exercise, redistribution of blood takes place to enhance blood flow to exercising muscles. To examine the role of sympathetic control in blood redistribution, we assessed blood flow in inactive regions (leg-splanchnic area) during arm-crank exercise in controls and in subjects with spinal cord injury (SCI) who lack central sympathetic control.

METHODS

SCI with a low lesion (< or = T7; SCI-L) have no leg sympathetic control and SCI with high lesion (> or = T6; SCI-H) lack sympathetic control in the legs and splanchnic area. This enables us to compare inactive regions between subjects with (controls, SCI-L; splanchnic) and without sympathetic innervation (SCI-L: leg, SCI-H: leg-splanchnic). Before and every 5 min during a 25-min arm-crank exercise bout at 50% of the individual maximal capacity, portal vein and femoral artery blood flow were measured.

RESULTS

Before exercise, portal vein blood flow was not different among groups. Arm-crank exercise induced a significant decrease in portal vein blood flow in subjects with splanchnic sympathetic control (able-bodied controls + SCI-L; ANOVA, P < 0.05), whereas SCI-H showed no change in portal vein blood flow. Baseline femoral artery blood was significantly lower in SCI compared with able-bodied controls. Exercise increased femoral artery blood flow in subjects with leg sympathetic control (controls; ANOVA, P < 0.05) but not in persons lacking sympathetic control in the leg (SCI). Leg vascular conductance did not change during exercise in both groups.

CONCLUSIONS

In summary, portal vein blood flow decreases in subjects with sympathetic control of the splanchnic area, whereas exercise-induced changes in femoral artery hemodynamics did not differ between groups. These observations primarily indicate the presence of regional differences regarding the magnitude of exercise-induced blood redistribution in vivo in humans.

Effects of co-administration of clenbuterol and testosterone propionate on skeletal muscle in paraplegic mice

Spinal cord injury (SCI) is generally associated with a rapid and significant decrease in muscle mass and corresponding changes in skeletal muscle properties. Although beta(2)-adrenergic and androgen receptor agonists are anabolic substances clearly shown to prevent or reverse muscle wasting in some pathological conditions, their effects in SCI patients remain largely unknown. Here we studied the effects of clenbuterol and testosterone propionate administered separately or in combination on skeletal muscle properties and adipose tissue in adult CD1 mice spinal-cord-transected (Tx) at the low-thoracic level (i.e., induced complete paraplegia). Administered shortly post-Tx, these substances were found to differentially reduce loss in body weight, muscle mass, and muscle fiber cross-sectional area (CSA) values. Although all three treatments induced significant effects, testosterone-treated animals were generally less protected against Tx-related changes. However, none of the treatments prevented fat tissue loss or muscle fiber type conversion and functional loss generally found in Tx animals. These results provide evidence suggesting that clenbuterol alone or combined with testosterone may constitute better clinically-relevant treatments than testosterone alone to decrease muscle atrophy (mass and fiber CSA) in SCI subjects.

The effects of stimulating lower leg muscles on the mechanical work and metabolic response in functional electrically stimulated pedaling

Functional electrical stimulation (FES) pedaling with the muscles of the upper leg has been shown to provide benefit to spinal cord injured (SCI) individuals. FES pedaling with electrical stimulation timing patterns that minimize the stress-time integral of activated muscles has been shown to increase the work individuals can perform during the exercise compared to existing FES stimulation timing patterns. Activation of the lower leg muscles could further enhance the benefit of FES pedaling by increasing the metabolic response to the exercise. For SCI individuals, the objectives of this study were to experimentally determine whether FES pedaling with the upper and lower leg muscles would affect the work generated and increase the physiological responses compared to pedaling with the upper leg muscles alone. Work, rate of oxygen consumption ·VO₂, and blood lactate data were measured from nine SCI subjects (injury level T4-T12) as they pedaled using upper leg and upper and lower leg muscle groups on repeated trials. The subjects performed 6% more work with the upper and lower legs than with the upper legs alone, but the difference was not significant (p = 0.2433). The average rate of oxygen consumption associated with the upper leg muscles (441 ±231 mL/min) was not significantly different from the corresponding average for the upper and lower legs (473 ±213 mL/min) (p = 0.1176). The blood lactate concentration associated with the upper leg muscles (5.9 ±2.3 mmoles/L) was significantly lower than the corresponding average for the upper and lower legs (6.8 ±2.3 mmoles/L) (p = 0.0049). The results indicate that electrical stimulation timing patterns that incorporate the lower leg muscles do increase the blood lactate concentrations. However, there was not enough evidence to reject the null hypothesis that stimulating the lower leg muscles affected the work accomplished or increased the rate of oxygen consumption. In conclusion, incorporating the lower leg muscles in the exercise does not lead to negative effects and could result in enhanced exercise outcomes in the long term.

Single limb exercise induces femoral artery remodeling and improves blood flow in the hemiparetic leg poststroke

BACKGROUND AND PURPOSE

After stroke, individuals have decreased mobility of the hemiparetic leg, which demands less muscle oxygen consumption; thus, blood flow decreases. The purpose of this study was to determine the effect of single limb exercise (SLE) on femoral artery blood flow, diameter, and peak flow velocity in the hemiparetic leg after stroke.

METHODS

Twelve individuals (60.6+/-14.5 years of age; 5 male) with chronic stroke (69.1+/-82.2 months; 5 with right-sided hemiparesis) participated in the study. The intervention consisted of a SLE knee extension/flexion protocol 3 times per week for 4 weeks. Using Doppler ultrasound, bilateral femoral artery blood flow, diameter, and peak flow velocity were assessed at baseline, after 2 weeks, and after 4 weeks of SLE.

RESULTS

Using repeated-measures analysis of variance, femoral artery blood flow, arterial diameter, and blood flow velocity in the hemiparetic limb were significantly improved (P<0.0001) after the SLE. No significant changes occurred in the nontrained limb for any outcome measures.

CONCLUSIONS

These data suggest that a 4-week SLE training program that increases muscular activity in the hemiparetic limb improves femoral artery blood flow, diameter, and peak velocity. SLE may be an important training strategy in stroke rehabilitation to minimize the vascular changes that occur poststroke due to decreased activity of the hemiparetic limb.

Muscle stimulation waveform timing patterns for upper and lower leg muscle groups to increase muscular endurance in functional electrical stimulation pedaling using a forward dynamic model

Functional electrical stimulation (FES) of pedaling provides a means by which individuals with spinal cord injury can obtain cardiorespiratory exercise. However, the early onset of muscle fatigue is a limiting factor in the cardiorespiratory exercise obtained while pedaling an FES ergometer. One objective of this study was to determine muscle excitation timing patterns to increase muscle endurance in FES pedaling for three upper leg muscle groups and to compare these timing patterns to those used in a commercially available FES ergometer. The second objective was to determine excitation timing patterns for a lower leg muscle group in conjunction with the three upper leg muscle groups. The final objective was to determine the mechanical energy contributions of each of the muscle groups to drive the crank. To fulfill these objectives, we developed a forward dynamic simulation of FES pedaling to determine electrical stimulation on and off times that minimize the muscle stress-time integral of the stimulated muscles. The computed electrical stimulation on and off times differed from those utilized by a commercially available FES ergometer and resulted in 17% and 11% decrease in the muscle stress-time integral for the three upper leg muscle groups and four upper and lower leg muscle groups, respectively. Also, the duration of muscle activation by the hamstrings increased by 5% over a crank cycle for the computed stimulation on and off times, and the mechanical energy generated by the hamstrings increased by 20%. The lower leg muscle group did not generate sufficient mechanical energy to reduce the energy contributions of the upper leg muscle groups. The computed stimulation on and off times could prolong FES pedaling, and thereby provide improved cardiorespiratory and muscle training outcomes for individuals with spinal cord injury. Including the lower leg muscle group in FES pedaling could increase cardiorespiratory demand while not affecting the endurance of the muscles involved in the pedaling task.

Effect of functional electrostimulation on impaired skin vasodilator responses to local heating in spinal cord injury

Spinal cord injury (SCI) induces vascular adaptations below the level of the lesion, such as impaired cutaneous vasodilation. However, the mechanisms underlying these differences are unclear. The aim of this study is to examine arm and leg cutaneous vascular conductance (CVC) responses to local heating in 17 able-bodied controls (39 +/- 13 yr) and 18 SCI subjects (42 +/- 8 yr). SCI subjects were counterbalanced for functional electrostimulation (FES) cycling exercise (SCI-EX, n = 9) or control (SCI-C, n = 9) and reanalyzed after 8 wk. Arm and leg skin blood flow were measured by laser-Doppler flowmetry during local heating (42 degrees C), resulting in an axon-reflex mediated first peak, nadir, and a primarily nitric oxide-dependent plateau phase. Data were expressed as a percentage of maximal CVC (44 degrees C). CVC responses to local heating in the paralyzed leg, but also in the forearm of SCI subjects, were lower than in able-bodied controls (P < 0.05 and 0.01, respectively). The 8-wk intervention did not change forearm and leg CVC responses to local heating in SCI-C and SCI-EX, but increased femoral artery diameter in SCI-EX (P < 0.05). Interestingly, findings in skin microvessels contrast with conduit arteries, where physical (in)activity contributes to adaptations in SCI. The lower CVC responses in the paralyzed legs might suggest a role for inactivity in SCI, but the presence of impaired CVC responses in the normally active forearm suggests other mechanisms. This is supported by a lack of adaptation in skin microcirculation after FES cycle training. This might relate to the less frequent and smaller magnitude of skin blood flow responses to heat stimuli, compared with controls, than physical inactivity per se.

The effects of functional electrical stimulation leg cycle ergometry training on arterial compliance in individuals with spinal cord injury

STUDY DESIGN

A prospective intervention of functional electrical stimulation leg cycle ergometry (FES-LCE) of four women with spinal cord injury (SCI).

OBJECTIVE

To evaluate the effect of FES-LCE training on arterial compliance in individuals with chronic SCI of traumatic origin.

SETTING

Tertiary rehabilitation center in Canada.

METHODS

Large and small artery compliance were measured at the radial artery before and after a 3-month training program using FES-LCE.

RESULTS

There was no significant change in large artery compliance after FES-LCE (16.0+/-4.2 to 16.8+/-6.1 ml mm Hg(-1) x 10, P=NS). There was a marked (63%) increase in small artery compliance after the FES training program (4.2+/-1.8 to 6.9+/-3.2 ml mm Hg(-1) x 100, P<0.05).

CONCLUSION

It appears that FES-LCE is effective in improving small artery compliance in females with SCI.

FES cycling

Spinal cord injury (SCI) leads to a partial or complete disruption of motor, sensory, and autonomic nerve pathways below the level of the lesion. In paraplegic patients, functional electrical stimulation (FES) was originally widely considered as a means to restore walking function but this was proved technically very difficult because of the numerous degrees of freedom involved in walking. FES cycling was developed for people with SCI and has the advantages that cycling can be maintained for reasonably long periods in trained muscles and the risk of falls is low. In the article, we review research findings relevant to the successful application of FES cycling including the effects on muscle size, strength and function, and the cardiovascular and bone changes. We also describe important practical considerations in FES cycling regarding the application of surface electrodes, training and setting up the stimulator limitations, implanted stimulators and FES cycling including FES cycling in groups and other FES exercises such as FES rowing.

Cardiovascular Health and Exercise Rehabilitation in Spinal Cord Injury

There appears to be an increased prevalence and earlier onset of cardiovascular disease (CVD) in persons with SCI. Physical inactivity is thought to be a key factor in the increased risk for CVD. Physical inactivity is highly prevalent in persons with SCI and it appears that activities of daily living are not sufficient to maintain cardiovascular fitness and health. This systematic review examines the current literature regarding the risk for CVD and the effectiveness of varied exercise rehabilitation programs in attenuating the risk for CVD in SCI.

Effects of Graduated Compression Stockings on Cardiovascular and Metabolic Responses to Exercise and Exercise Recovery in Persons With Spinal Cord Injury

OBJECTIVE

To investigate whether reporting blood redistribution by means of graduated elastic stockings affects exercise and postexercise responses in people with spinal cord injury (SCI).

DESIGN

Crossover trial.

SETTING

Physical medicine and rehabilitation department in France.

PARTICIPANTS

Fourteen men with traumatic SCI, grouped according to their level of injury.

INTERVENTIONS

Subjects performed 2 maximal wheelchair exercise tests 1 week apart, in random order and under a counter-balanced design. One test was done with and the other without graduated elastic stockings (21 mmHg).

MAIN OUTCOME MEASURES

Blood lactate, blood pressure, heart rate, maximal power output, and oxygen consumption (Vo2).

RESULTS

Postexercise venous lactate concentration was reduced in SCI subjects with lesion levels below T6 while wearing graduated elastic stockings during both exercise and recovery (10.9+/-3.9 mmol/L vs 12.5+/-4.6 mmol/L, P<.05). There were no significant differences in submaximal and maximal values (heart rate, Vo2, power output) between subjects tested with and without graduated elastic stockings.

CONCLUSIONS

Wearing elastic stockings affects postexercise responses by decreasing lactate concentration in well-trained, low-level paraplegic patients after a maximal exercise. The relatively low pressure generated by the stockings may not, however, influence the venous system enough to produce improved performance and cardiovascular responses.

Acute peripheral blood flow response induced by passive leg cycle exercise in people with spinal cord injury

OBJECTIVE

To determine the acute femoral artery hemodynamic response in paraplegic subjects during a passive leg cycle exercise.

DESIGN

Case series.

SETTING

Department of physical medicine and rehabilitation in a university in France.

PARTICIPANTS

A volunteer sample of 15 people with traumatic spinal cord injury.

INTERVENTION

Subjects performed a 10-minute session of passive leg cycle exercise in the sitting position.

MAIN OUTCOME MEASURES

We measured heart rate, maximal (Vmax), and minimal femoral artery blood flow velocity at rest and immediately after the passive leg cycle exercise, using quantitative duplex Doppler ultrasound. We calculated mean blood flow velocity (Vmean) and velocity index, representing the peripheral resistance, for each condition.

RESULTS

Vmax and Vmean increased (from .80+/-.18 m/s to .96+/-.24 m/s, P<.01; and from .058+/-.02 m/s to .076+/-.03 m/s, P<.01; respectively) after 10 minutes of passive leg cycle exercise. Heart rate did not change. The velocity index decreased from 1.23+/-0.15 to 1.16+/-0.21 (P=.038).

CONCLUSIONS

The results of this study suggest that acute passive leg cycle exercise increases vascular blood flow velocity in paralyzed legs of people with paraplegia. This exercise could have clinical implications for immobilized persons.

Electrically stimulated resistance training in SCI individuals increases muscle fatigue resistance but not femoral artery size or blood flow

STUDY DESIGN

Longitudinal.

OBJECTIVES

The purpose of this study was to evaluate the effect of lower extremity resistance training on quadriceps fatigability, femoral artery diameter, and femoral artery blood flow.

SETTING

Academic Institution.

METHODS

Five male chronic spinal cord injury (SCI) individuals (American Spinal Injury Association (ASIA): A complete; C5-T10; 36+/-5 years old) completed 18 weeks of home-based neuromuscular electrical stimulation (NMES) resistance training. Subjects trained the quadriceps muscle group twice a week with four sets of 10 dynamic knee extensions against resistance while in a seated position. All measurements were made before training and after 8, 12, and 18 weeks of training. Ultrasound was used to measure femoral artery diameter and blood flow. Blood flow was measured before and after 5 and 10 min of distal cuff occlusion, and during a 4-min isometric electrical stimulation fatigue protocol.

RESULTS

Training resulted in significant increases in weight lifted and muscle mass, as well as a 60% reduction in muscle fatigue (P = 0.001). However, femoral arterial diameter did not increase. The range was 0.44+/-0.03 to 0.46+/-0.05 cm over the four time points (P = 0.70). Resting, reactive hyperemic, and exercise blood flow did not appear to change with training.

CONCLUSION

NMES resistance training improved muscle size and fatigue despite an absence of response in the supplying vasculature. These results suggest that the decreases in arterial caliber and blood flow seen with SCI are not tightly linked to muscle mass and fatigue resistance. In addition, muscle fatigue in SCI patients can be improved without increases in arterial diameter or blood flow capacity.