Relationship between pulmonary function and exercise capacity in individuals with spinal cord injury

Systemic and Pulmonary Inflammation/Oxidative Damage: Implications of General and Respiratory Muscle Training in Chronic Spinal-Cord-Injured Patients

Chronic spinal cord injury affects several respiratory-function-related parameters, such as a decrease in respiratory volumes associated with weakness and a tendency to fibrosis of the perithoracic muscles, a predominance of vagal over sympathetic action inducing airway obstructions, and a difficulty in mobilizing secretions. Altogether, these changes result in both restrictive and obstructive patterns. Moreover, low pulmonary ventilation and reduced cardiovascular system functionality (low venous return and right stroke volume) will hinder adequate alveolar recruitment and low O₂ diffusion, leading to a drop in peak physical performance. In addition to the functional effects described above, systemic and localized effects on this organ chronically increase oxidative damage and tissue inflammation. This narrative review describes both the deleterious effects of chronic spinal cord injury on the functional effects of the respiratory system as well as the role of oxidative damage/inflammation in this clinical context. In addition, the evidence for the effect of general and respiratory muscular training on the skeletal muscle as a possible preventive and treatment strategy for both functional effects and underlying tissue mechanisms is summarized.

Improved pulmonary function is associated with reduced inflammation after hybrid whole-body exercise training in persons with spinal cord injury

NEW FINDINGS

What is the central question of this study? Does 12 weeks of functional electrical stimulation (FES) rowing exercise training lead to suppressed systemic inflammation and an improvement in pulmonary function in persons with sub-acute spinal cord injury (SCI)? What is the main finding and its importance? Twelve weeks of FES rowing exercise improves pulmonary function and the magnitude of improvement is associated with reductions in inflammatory biomarkers. Thus, interventions targeting inflammation may lead to better pulmonary outcomes for person with sub-acute SCI.

ABSTRACT

The current study was designed to test the hypotheses that (1) reducing systemic inflammation via a 12-week functional electrical stimulation rowing exercise training (FESRT) prescription results in augmented pulmonary function, and (2) the magnitude of improvement in pulmonary function is inversely associated with the magnitude of systemic inflammation suppression in persons with sub-acute (≤2 years) spinal cord injury (SCI). We conducted a retrospective analysis of a randomized controlled trial (NCT#02139436). Twenty-one participants were enrolled (standard of care (SOC; n = 9) or FESRT (n = 12)). The exercise prescription was three sessions/week at 70-85% of peak heart rate. A two-way analysis of covariance and regression analysis was used to assess group differences and associations between pulmonary function, log transformed high-sensitivity C-reactive protein (hsCRPlog ) and white blood cell count (WBC). Following FESRT, clinically significant improvements in forced expiratory volume in 1 s (FEV1 ; 0.25 (0.08-0.43) vs. -0.06 (-0.26 to 0.15) litres) and forced vital capacity (0.22 (0.04-0.39) vs. 0.08 (-0.29 to 0.12) litres) were noted and systemic WBC (-1.45 (-2.48 to -0.50) vs. 0.41 (-0.74 to 1.56) μl) levels were suppressed compared to SOC (mean change (95% confidence interval); P < 0.05). Additionally, both ΔhsCRPlog and ΔWBC were predictors of ΔFEV1 (r2  = 0.89 and 0.43, respectively; P < 0.05). Twelve weeks of FESRT improves pulmonary function and reduces WBC in persons with sub-acute SCI. The potency of FESRT to augment pulmonary function may depend on adequate suppression of systemic inflammation.

Is there a role of pulmonary rehabilitation in extrapulmonary diseases frequently encountered in the practice of physical medicine and rehabilitation?

There is a group of diseases such as low back pain, osteoporosis, fibromyalgia and obesity for which pulmonary rehabilitation can be applied. Although these diseases do not directly impact the lungs, respiratory dysfunction occurs through various mechanisms during the disease process and complicates the underlying primary disease. Respiratory dysfunction and spirometric abnormalities have been observed from the early stages of these diseases, even without obvious signs and symptoms. These patients should be carefully evaluated for pulmonary problems as a sedentary lifestyle may hide the presence of respiratory symptoms. Once pulmonary problems have been detected, pulmonary rehabilitation should be added to the routine treatment of the primary disease.

Serotonin 1A Receptor Pharmacotherapy and Neuroplasticity in Spinal Cord Injury

Spinal cord injury is associated with damage in descending and ascending pathways between brainstem/cortex and spinal neurons, leading to loss in sensory-motor functions. This leads not only to locomotor reduction but also to important respiratory impairments, both reducing cardiorespiratory engagement, and increasing cardiovascular risk and mortality. Moreover, individuals with high-level injuries suffer from sleep-disordered breathing in a greater proportion than the general population. Although no current treatments exist to restore motor function in spinal cord injury (SCI), serotoninergic (5-HT) 1A receptor agonists appear as pharmacologic neuromodulators that could be important players in inducing functional improvements by increasing the activation of spared motoneurons. Indeed, single therapies of serotoninergic 1A (5-HT_1A) agonists allow for acute and temporary recovery of locomotor function. Moreover, the 5-HT_1A agonist could be even more promising when combined with other pharmacotherapies, exercise training, and/or spinal stimulation, rather than administered alone. In this review, we discuss previous and emerging evidence showing the value of the 5HT_1A receptor agonist therapies for motor and respiratory limitations in SCI. Moreover, we provide mechanistic hypotheses and clinical impact for the potential benefit of 5-HT_1A agonist pharmacology in inducing neuroplasticity and improving locomotor and respiratory functions in SCI.

Exoskeleton-assisted walking improves pulmonary function and walking parameters among individuals with spinal cord injury: a randomized controlled pilot study

BACKGROUND

Exoskeleton-assisted walking (EAW) is expected to improve the gait of spinal cord injury (SCI) individuals. However, few studies reported the changes of pulmonary function (PF) parameters after EAW trainings. Hence, we aimed to explore the effect of EAW on PF parameters, 6-min walk test (6MWT) and lower extremity motor score (LEMS) in individuals with SCI and to compare those with conventional trainings.

METHODS

In this prospective, single-center, single-blinded randomized controlled pilot study, 18 SCI participants were randomized into the EAW group (n = 9) and conventional group (n = 9) and received 16 sessions of 50-60 min training (4 days/week, 4 weeks). Pulmonary function parameters consisting of the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), forced expiratory flow (FEF), peak expiratory flow, and maximal voluntary ventilation, 6MWT with assisted devices and LEMS were reported pre- and post-training.

RESULTS

Values of FVC (p = 0.041), predicted FVC% (p = 0.012) and FEV₁ (p = 0.013) were significantly greater in EAW group (FVC: 3.8 ± 1.1 L; FVC% _pred = 94.1 ± 24.5%; FEV₁: 3.5 ± 1.0 L) compared with conventional group (FVC: 2.8 ± 0.8 L; FVC% _pred = 65.4 ± 17.6%; FEV₁: 2.4 ± 0.6 L) after training. Participants in EAW group completed 6MWT with median 17.3 m while wearing the exoskeleton. There was no difference in LEMS and no adverse event.

CONCLUSIONS

The current results suggest that EAW has potential benefits to facilitate PF parameters among individuals with lower thoracic neurological level of SCI compared with conventional trainings. Additionally, robotic exoskeleton helped walking.

TRIAL REGISTRATION

Registered on 22 May 2020 at Chinese Clinical Trial Registry (ChiCTR2000033166). http://www.chictr.org.cn/edit.aspx?pid=53920&htm=4 .

Serotonin 1A agonist and cardiopulmonary improvements with whole-body exercise in acute, high-level spinal cord injury: a retrospective analysis

PURPOSE

High-level spinal cord injury (SCI) can result in spinal and supraspinal respiratory control deficits leading to insufficient ventilatory responses to exercise and training-related adaptations. We hypothesized a serotonin agonist, known to improve respiratory function in animal models, would improve adaptations to whole-body functional electrical stimulation (FES) exercise training in patients with acute high-level SCI.

METHODS

We identified 10 patients (< 2 years of injury with SCI from C4 to T3) in our program who had performed 6 months of FES-row training while on Buspirone (29 ± 17 mg/day) between 2012 and 2018. We also identified well-matched individuals who trained for six months but not on Buspirone (n = 11). A peak incremental FES-rowing exercise test and resting pulmonary function test had been performed before and after training.

RESULTS

Those on Buspirone demonstrated greater increases in peak oxygen consumption (VO₂peak: + 0.24 ± 0.23 vs. + 0.10 ± 0.13 L/min, p = 0.08) and peak ventilation (VEpeak: + 6.5 ± 8.1 vs. - 0.7 ± 6.9 L/min, p < 0.05) compared to control. In addition, changes in VO₂peak and VEpeak were correlated across all patients (r = 0.63, p < 0.01), but most strongly in those on Buspirone (r = 0.85, p < 0.01). Furthermore, changes in respiratory function correlated with increased peak tidal volume in the Buspirone group (r > 0.66, p < 0.05).

CONCLUSION

These results suggest Buspirone improves cardiorespiratory adaptations to FES-exercise training in individuals with acute, high-level SCI. The strong association between increases in ventilatory and aerobic capacities suggests improved respiratory function is a mechanism; however, controlled studies are needed to determine if this preliminary finding is reproducible.

Gains in aerobic capacity with whole-body functional electrical stimulation row training and generalization to arms-only exercise after spinal cord injury

STUDY DESIGN

Longitudinal study in adults (n = 27; 19-40 years old) with tetraplegic or paraplegic spinal cord injury (SCI).

OBJECTIVES

Determine physiological adaptations and generalizable fitness effects of 6 months of whole-body exercise training using volitional arm and functional electrical stimulation (FES) leg rowing.

SETTING

Outpatient hospital-based exercise facility and laboratory.

METHODS

Participants enrolled in hybrid FES-row training (FESRT) and performed peak exercise tests with arms-only (AO; baseline and 6 months) and FES rowing (baseline, 3, 6 months).

RESULTS

Participants demonstrated increased aerobic capacity (VO_2peak) after FESRT (p < 0.001, n_p² = 0.56) that tended to be higher when assessed with FES than AO rowing tests (0.15 ± 0.20 vs. 0.04 ± 0.22 L/min; p = 0.10). Changes in FES and AO VO_2peak were significantly correlated (r = 0.55; p < 0.01), and 11 individuals demonstrated improvements (>6%) on both test formats. Younger age was the only difference between those who showed generalization of training effects and those who did not (mean age 26.6 ± 5.6 vs. 32.0 ± 5.7 years; p < 0.05) but changes in FES VO_2peak correlated to time since injury in individuals <2 years post-SCI (r = -0.51, p < 0.01, n = 24). Lastly, VO_2peak improvements were greater during the first 3 months vs. months 4-6 (+7.0% vs. +3.9%; p < 0.01) which suggests early training adaptations during FESRT.

CONCLUSIONS

Gains in aerobic capacity after whole-body FESRT are better reflected during FES-row testing format. They relate to high-intensity exercise and appear early during training, but they may not generalize to equivalent increases in AO exercise in all individuals with SCI.

Acute Ventilatory Support During Whole-Body Hybrid Rowing in Patients With High-Level Spinal Cord Injury: A Randomized Controlled Crossover Trial

BACKGROUND

High-level spinal cord injury (SCI) results in profound spinal and supraspinal deficits, leading to substantial ventilatory limitations during whole-body hybrid functional electrical stimulation (FES)-rowing, a form of exercise that markedly increases the active muscle mass via electrically induced leg contractions. This study tested the effect of noninvasive ventilation (NIV) on ventilatory and aerobic capacities in SCI.

METHODS

This blinded, randomized crossover study enrolled 19 patients with SCI (level of injury ranging from C4 to T8). All patients were familiar with FES-rowing and had plateaued in their training-related increases in aerobic capacity. Patients performed two FES-rowing peak exercise tests with NIV or without NIV (sham).

RESULTS

NIV increased exercise tidal volume (peak, 1.50 ± 0.31 L vs 1.36 ± 0.34 L; P < .05) and reduced breathing frequency (peak, 35 ± 7 beats/min vs 38 ± 6 beats/min; P < .05) compared with the sham test, leading to no change in alveolar ventilation but a trend toward increased oxygen uptake efficiency (P = .06). In those who reached peak oxygen consumption (Vo₂peak) criteria (n = 13), NIV failed to significantly increase Vo₂peak (1.73 ± 0.66 L/min vs 1.78 ± 0.59 L/min); however, the range of responses revealed a correlation between changes in peak alveolar ventilation and Vo₂peak (r = 0.89; P < .05). Furthermore, those with higher level injuries and shorter time since injury exhibited the greatest increases in Vo₂peak.

CONCLUSIONS

Acute NIV can successfully improve ventilatory efficiency during FES exercise in SCI but may not improve Vo₂peak in all patients. Those who benefit most seem to be patients with cervical SCI within a shorter time since injury.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT02865343 and NCT03267212; URL: www.clinicaltrials.gov.

Relationship of Spinal Cord Injury Level and Duration to Peak Aerobic Capacity With Arms-Only and Hybrid Functional Electrical Stimulation Rowing

OBJECTIVE

The aim of the study was to assess the relationship of spinal cord injury level and duration to peak aerobic capacities during arms-only rowing compared with hybrid Functional Electrical Stimulation (FES)-rowing.

DESIGN

Comparison of peak aerobic capacity (VO2), peak ventilation, peak respiratory exchange ratio, and peak heart rate were measured during arms-only rowing and FES-rowing obtained from graded exercise tests.

RESULTS

Peak aerobic values were strongly related to injury level and injury duration for both arms-only rowing (r = 0.67, P < 0.05) and FES-rowing (r = 0.61, P < 0.05). Peak aerobic capacities were greater across all injury levels and durations with FES-rowing compared with arms-only rowing. Differences in VO2 were inversely related to injury level (r = 0.55, P < 0.05) with greater increases in VO2 in higher level injuries. Injury durations of less than 2 yrs had greater percent increases in VO2 with FES-rowing.

CONCLUSIONS

FES-rowing acutely post injury may have the greatest effect to maintain function and improve VO2. This impact seems to be greatest in those with higher level injuries.

Exercise testing protocol using a roller system for manual wheelchair users with spinal cord injury

OBJECTIVE

Determine the validity and reliability of an exercise testing protocol to evaluate cardiorespiratory measures in manual wheelchair users (MWUs) with spinal cord injury (SCI) using a roller-based (RS) wheelchair system.

DESIGN

Repeated measures within-subject design.

SETTING

Community-based research laboratory.

PARTICIPANTS

Ten adults with SCI requiring the use of a manual wheelchair.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Cardiorespiratory measures (peak oxygen consumption [VO₂peak], respiratory exchange ratio [RER], pulmonary ventilation [VE], energy expenditure [EE], heart rate [HR], accumulated kilocalories [AcKcal]) and perceived exertion (RPE) were measured during three separate maximal exercise tests using an arm crank ergometer (ACE) and an RS.

RESULTS

At maximal exertion, there were no significant differences in variables between groups, with moderate-to-strong correlations (P < 0.05, r = 0.79-0.90) for VO₂, HR, RPE, AcKcal, and rate of EE between RS and ACE trials. Significant moderate-to-strong correlations existed between RS trials for VO₂, AcKcal, rate of EE, and peak power output (P < 0.01, r = 0.77-0.97).

CONCLUSIONS

VO_2peak was highly correlated between ACE and RS trials and between the two RS trials, indicating the RS protocol to be reliable and valid for MWUs with SCI. Differences in perceived exertion and efficiency at submaximal workloads and maximal pulmonary ventilation at peak workloads indicated potential advantages to using the RS.

Augmenting exercise capacity with noninvasive ventilation in high-level spinal cord injury

High-level spinal cord injury (SCI) results in a very limited innervated skeletal muscle mass that strongly reduces exercise capacity. Our recent work showed that when adding functional electrical stimulation (FES) of the paralyzed legs (hybrid FES-exercise) to produce higher exercise capacity, peak ventilation became a limiting factor to training-induced improvement in aerobic capacity. Our assumption was that the systemic adaptations to exercise training are delimited by the maximal ventilation that can be achieved. However, herein, we present a case showing an acute increase in aerobic capacity when using noninvasive ventilatory support (NIV) during FES-rowing test in an individual who had previously experimented a plateau in his aerobic capacity for 18 mo. An 18-yr-old man with C5 SCI trained with arms-only rowing for 6 mo and subsequently trained with hybrid FES-rowing for 18 mo. Peak minute ventilation (V̇e_peak) and peak oxygen consumption (V̇o_2peak) were increased after arms-only training and increased further with 6 mo of hybrid FES-row training. Despite continued intense and frequent, hybrid FES-row training, neither V̇e_peak nor V̇o_2peak increased further over the next year (1.94 and 66.0 l/min). However, when this individual performed a FES-rowing V̇o_2peak test with the addition of NIV, V̇e_peak increased by 5 l/min, resulting in an improved V̇o_2peak (2.23 l/min, +12%). This case demonstrates that noninvasive ventilation can overcome limitations to ventilation in high-level SCI and improve aerobic capacity during hybrid FES-exercise to a level not otherwise achievable. In addition, it broadly illustrates the intimate role of pulmonary function in determining the capacity to perform exercise.

Impact of neurological level and spinal curvature on pulmonary function in adults with spina bifida

PURPOSE

To describe pulmonary function and determine the impact of neurological level, scoliosis, and obesity on pulmonary function in people with spina bifida (SB).

METHODS

Participants with SB (N= 29) (15 females; age, 30 ± 12 years) completed spirometry and body plethysmographic lung volume testing. Univariate and multivariate regression analyses were used to describe the factors associated with pulmonary function in people with SB.

RESULTS

Distribution of category of impairment in pulmonary function was: 55% (n= 16) restricted, 6.9% (n= 2) spirometric restricted, 1 combined obstructed and restricted, and 35.5% (n= 10) normal. In univariate analyses, neurological level was negatively associated with pulmonary function parameters, i.e., forced vital capacity (FVC) (p= 0.005), forced expiratory volume in 1 second (FEV1) (p= 0.008), total lung capacity (TLC) (p= 0.001), and degree of scoliosis were inversely associated with FVC (p= 0.005), FEV1 (p= 0.003), and TLC (p= 0.004). In multivariate models, level of lesion and degree of scoliosis independently contributed to the degree of lung function impairment. Restrictive pulmonary function was observed in 9/10 (90%) of those with thoracic neurological levels and was associated with decreased inspiratory capacity (IC) and expiratory reserve volume (ERV). Lumbar level lesions were associated with either normal lung function or an isolated reduction in FVC due to reduction in only ERV and preserved TLC representing spirometric restriction.

CONCLUSIONS

High prevalence of restrictive pulmonary physiology is present in people with SB, with more rostral neurological levels and greater degree of scoliosis associated with a higher degree of pulmonary function impairment.

A chronic care model for spina bifida transition

Providing comprehensive transition care for adolescents and young adults with spina bifida (AYASB) requires a structured approach to addressing chronic condition management, self-management, care coordination, and health care navigation that is adaptable to the various levels of cognitive ability, physical function, and family/community environments within the population. This commentary (1) highlights AYASB transition program needs identified in the literature and within a local community, (2) analyzes advantages and limitations of published AYASB transition care models in addressing these needs, (3) demonstrates how a spina bifida (SB) transition clinic used the Chronic Care Model (CCM) to develop a comprehensive AYASB transition program, and (4) examines the potential feasibility in adapting this model to other SB clinics. A SB-specific transition clinic based on the CCM model facilitates the complex chronic care management and transition planning for AYASB. Further study is needed to evaluate health care outcomes using the CCM for SB transition.

Reliability and minimal detectable change of a new treadmill-based progressive workload incremental test to measure cardiorespiratory fitness in manual wheelchair users

BACKGROUND

Cardiorespiratory fitness training is commonly provided to manual wheelchair users (MWUs) in rehabilitation and physical activity programs, emphasizing the need for a reliable task-specific incremental wheelchair propulsion test.

OBJECTIVE

Quantifying test-retest reliability and minimal detectable change (MDC) of key cardiorespiratory fitness measures following performance of a newly developed continuous treadmill-based wheelchair propulsion test (WPT_Treadmill).

METHODS

Twenty-five MWUs completed the WPT_Treadmill on two separate occasions within one week. During these tests, participants continuously propelled their wheelchair on a motorized treadmill while the exercise intensity was gradually increased every minute until exhaustion by changing the slope and/or speed according to a standardized protocol. Peak oxygen consumption (VO_2peak), carbon dioxide production (VCO_2peak), respiratory exchange ratio (RER_peak), minute ventilation (VE_peak) and heart rate (HR_peak) were computed. Time to exhaustion (TTE) and number of increments completed were also measured. Intra-class correlation coefficients (ICC) were calculated to determine test-retest reliability. Standard error of measurement (SEM) and MDC_90% values were calculated.

RESULTS

Excellent test-retest reliability was reached for almost all outcome measures (ICC=0.91-0.76), except for RER_peak (ICC=0.58), which reached good reliability. TTE (ICC=0.89) and number of increments (ICC=0.91) also reached excellent test-retest reliability. For the main outcome measures (VO_2peak and TTE), absolute SEM was 2.27 mL/kg/min and 0.76 minutes, respectively and absolute MDC_90% was 5.30 mL/kg/min and 1.77 minutes, respectively.

CONCLUSION

The WPT_Treadmill is a reliable test to assess cardiorespiratory fitness among MWUs. TTE and number of increments could be used as reliable outcome measures when VO₂ measurement is not possible.

Ventilation Limits Aerobic Capacity after Functional Electrical Stimulation Row Training in High Spinal Cord Injury

PURPOSE

In the able-bodied, exercise training results in increased ventilatory capacity to meet increased aerobic demands of trained skeletal muscle. However, after spinal cord injury (SCI), peak ventilation can be limited by pulmonary muscle denervation. In fact, peak ventilation may restrict aerobic capacity in direct relation to injury level. Hybrid functional electrical stimulation (FES) exercise training results in increased aerobic capacity and dissociation between aerobic capacity and injury level in those with injuries at T3 and below. However, injuries above T3 have the greatest pulmonary denervation, and ventilatory capacity may restrict the increase in aerobic capacity with hybrid FES training.

METHODS

We assessed relationships among injury level, peak ventilation, and peak aerobic capacity and calculated oxygen uptake efficiency slope during hybrid FES exercise in 12 individuals (1 female) with SCI at level T2 to C4 (injury duration = 0.33-33 yr, age = 20-60 yr), before and after 6 months of FES-row training (FES-RT).

RESULTS

Training increased peak aerobic capacity by 12% (P = 0.02) with only a modest increase in peak ventilation (7 of 12 subjects, P = 0.09). Both before and after training, injury level was directly related to peak ventilation (R = 0.48 and 0.43) and peak aerobic capacity (R = 0.70 and 0.55). Before training, the relationship of peak aerobic capacity to peak ventilation was strong (R = 0.62), however, after training, this relationship became almost completely linearized (R = 0.84). In addition, oxygen uptake efficiency slope increased by 11% (P < 0.05) after FES-RT.

CONCLUSION

Despite the ability to increase exercise capacity via hybrid FES exercise, the inability to increase peak ventilation beyond limits set by SCI level in those with high-level injuries (above T3) appears to restrict aerobic capacity.

A comparative study of two protocols for treadmill walking exercise testing in ambulating subjects with incomplete spinal cord injury

STUDY DESIGN

This is a comparative study of two exercise testing protocols.

OBJECTIVES

The objective of this study was to compare maximal oxygen uptake (VO₂ max) and achieved criteria for maximal exercise testing between the Sunnaas Protocol-a newly designed treadmill exercise test protocol-and the Modified Bruce Protocol in persons with incomplete spinal cord injury (SCI).

SETTING

This study was conducted in Sunnaas Rehabilitation Hospital, Norway.

METHODS

Twenty persons (19 men) with incomplete SCI (AIS D) capable of ambulating without assistive devices performed two treadmill walking exercise tests (Sunnaas Protocol and Modified Bruce Protocol) until exhaustion 1-3 days apart. The key differences between the protocols are the smaller increments in speed and shorter duration on each workload in the Sunnaas Protocol. Cardiovascular responses were measured continuously throughout both tests.

RESULTS

The subjects exhibited statistically significantly higher VO₂ max when using the Sunnaas Protocol (37.1±9.9 vs 35.4±9.8 ml kg^-1 min^-1, P=0.01), with a mean between-test difference of 1.8 ml kg^-1 min^-1 (95% confidence interval: 0.49-3.16). There was no significant difference in mean maximal heart rate (HR max). Nineteen (95%) subjects achieved at least three of the four criteria for maximal oxygen uptake using the Sunnaas Protocol. Thirteen (65%) subjects achieved at least three of the criteria using a Modified Bruce protocol.

CONCLUSIONS

The small differences in both VO₂ max and achieved criteria in favor of the Sunnaas Protocol suggest that it could be a useful alternative treadmill exercise test protocol for ambulating persons with incomplete SCI.

Hybrid functional electrical stimulation exercise training alters the relationship between spinal cord injury level and aerobic capacity

OBJECTIVE

To test the hypothesis that hybrid functional electrical stimulation (FES) row training would improve aerobic capacity but that it would remain strongly linked to level of spinal cord lesion because of limited maximal ventilation.

DESIGN

Longitudinal before-after trial of 6 months of FES row training.

SETTING

Exercise for persons with disabilities program in a hospitaL.

PARTICIPANTS

Volunteers (N=14; age range, 21-63y) with complete spinal cord injury (SCI) (T3-11) who are >2 years postinjury.

INTERVENTION

Six months of FES row training preceded by a variable period of FES strength training.

MAIN OUTCOME MEASURES

Peak aerobic capacity and peak exercise ventilation before and after 6 months of FES row training.

RESULTS

FES row training significantly increased peak aerobic capacity and peak minute ventilation (both P<.05). Prior to FES row training, there was a close relation between level of SCI and peak aerobic capacity (adjusted R(2)=.40, P=.009) that was markedly reduced after FES row training (adjusted R(2)=.15, P=.10). In contrast, the relation between level of injury and peak minute ventilation was comparable before and after FES row training (adjusted R(2)=.38 vs .32, both P<.05).

CONCLUSIONS

The increased aerobic capacity reflects more than increased ventilation; FES row training effectively circumvents the effect of SCI on peak aerobic capacity by engaging more muscle mass for training, independent of the level of injury.