Comparison of 1- Versus 3-Minute Stage Duration During Arm Ergometry in Individuals With Spinal Cord Injury

Therapeutic Lifestyle Intervention Targeting Enhanced Cardiometabolic Health and Function for Persons with Chronic Spinal Cord Injury in Caregiver/Care-Receiver Co-Treatment: A Study Protocol of a Multisite Randomized Controlled Trial

BACKGROUND

Chronic spinal cord injury (SCI) significantly accelerates morbidity and mortality, partly due to the increased risk of cardiometabolic diseases (CMD), including neurogenic obesity, dyslipidemia, and impaired glucose metabolism. While exercise and dietary interventions have shown some transient benefits in reducing CMD risk, they often fail to improve clinically relevant disease markers and cardiovascular events. Moreover, SCI also places caregiving demands on their caregivers, who themselves experience health and functional decline. This underscores the need for more substantial interventions that incorporate appropriate physical activity, heart-healthy nutrition, and behavioral support tailored to the SCI population.

OBJECTIVES

This randomized clinical trial (RCT) protocol will (1) assess the health and functional effects, user acceptance, and satisfaction of a 6-month comprehensive therapeutic lifestyle intervention (TLI) adapted from the National Diabetes Prevention Program (DPP) for individuals with chronic SCI and (2) examine the impact of a complementary caregiver program on the health and function of SCI caregivers and evaluate user acceptance and satisfaction. Caregivers (linked with their partners) will be randomized to 'behavioral support' or 'control condition'.

METHODS

Dyadic couples comprise individuals with SCI (18-65 years, >1-year post-injury, ASIA Impairment Scale A-C, injury levels C5-L1) and non-disabled SCI caregivers (18-65 years). Both groups undergo lock-step circuit resistance training, a calorie-restricted Mediterranean-style diet, and 16 educational sessions focused on diet/exercise goals, self-monitoring, psychological and social challenges, cognitive behavioral therapy, and motivational interviewing. The outcome measures encompass the cardiometabolic risks, cardiorespiratory fitness, inflammatory stress, multidimensional function, pain, life quality, independence, self-efficacy, program acceptance, and life satisfaction for SCI participants. The caregiver outcomes include multidimensional function, pain, quality of life, independence, and perceived caregiver burden.

DISCUSSION/CONCLUSIONS

This study evaluates the effects and durability of a structured, multi-modal intervention on health and function. The results and intervention material will be disseminated to professionals and consumers for broader implementation.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02853149 Registered 2 August 2016.

Effect of wheelchair-modified rowing exercise on cardiometabolic risk factors in spinal cord injured wheelchair users: protocol for a randomised controlled trial

INTRODUCTION

Cardiovascular and metabolic diseases are a growing concern for individuals with spinal cord injury (SCI). Physical inactivity contributes to cardiometabolic morbidity and mortality in the SCI population. However, previous studies have shown mixed results regarding the effects of exercise on cardiometabolic risk factors in individuals with SCI. This discrepancy could be influenced by insufficient exercise stimuli. Recent guidelines recommend 30 min of moderate-to-vigorous intensity aerobic exercise, three times per week, for improvement in cardiometabolic health in individuals with SCI. However, to date, no studies have implemented an exercise intervention matching the new recommendations to examine the effects on cardiometabolic risk factors. Therefore, the primary objective of this study is to determine the effects of 12 weeks of wheelchair user-modified upper-body rowing exercise on both traditional (constituents of the metabolic syndrome) and novel (eg, vascular structure and function) cardiometabolic risk factors in manual wheelchair users with SCI.

METHODS AND ANALYSIS

A randomised controlled trial will compare 12 weeks of upper-body rowing exercise, 30 min three times per week, with a control group continuing their normal lifestyle. Outcome measurements will be performed immediately before (baseline), after 6 weeks (halfway), 12 weeks of training (post) and 6 months after the termination of the intervention period (follow-up). Outcomes will include inflammatory (eg, C reactive protein) and metabolic biomarkers determined from venous blood (with serum fasting insulin as primary outcome), body composition, arterial blood pressure, cardiorespiratory fitness level, brachial artery vascular structure and function and autonomic nervous system function.

ETHICS AND DISSEMINATION

This trial is reported to the Danish Data Protection Agency (J.nr. 2019-899/10-0406) and approved by the Committees on Health Research Ethics in The North Denmark Region on 12 December 2019 (J.nr. N-20190053). The principal investigator will collect written informed consent from all participants prior to inclusion. Irrespective of study outcomes, the results will be submitted to peer-reviewed scientific journals for publication.

TRIAL REGISTRATION NUMBER

NCT04390087.

Feasibility, acceptability, and preliminary efficacy of a handcycling high-intensity interval training program for individuals with spinal cord injury

Study Design:

Pilot non-randomized clinical trial

Objectives:

To examine the feasibility, acceptability and preliminary efficacy of performing handcycling high intensity interval training (HIIT) for six weeks in wheelchair users with spinal cord injury.

Setting:

Participant’s home

Methods:

Participants completed pre and post graded exercise stress tests, exercise surveys and six weeks of handcycling HIIT. The HIIT program consisted of two weekly, 25 minute supervised at-home sessions (2-3 min warm-up, then 10 intervals of cycling with a ratio of 1 minute work at 90% peak power output (PPO) to 1 minute recovery at 0-20% PPO, then 2-3 min cool-down). Real-time power output and heart rate were recorded via sensors and a bike computer. The sensor data were analyzed to evaluate training efficacy.

Results:

Seven of the 10 enrolled participants (70%) completed the study. All but one completed the required 12 sessions. The participants met at least one of the HIIT target intensity criteria in 76 out of 89 total sessions (85.4%) performed. Participants expressed a high level of enjoyment on the Physical Activity Enjoyment Scale, mean (SD) = 114.8 (11.3), and satisfaction with the overall experience. Five of the seven participants (71%) who completed the study felt an increase in endurance, function and health. Objective physiological changes showed mixed results.

Conclusions:

Six weeks of handcycling HIIT appears to be safe, feasible and acceptable. A longer HIIT work interval may be needed to elicit significant physiological responses. Future investigation of the feasibility and efficacy of differing HIIT parameters is needed.

Development and deployment of an at-home strength and conditioning program to support a phase I trial in persons with chronic spinal cord injury

STUDY DESIGN

Nonrandomized clinical trial (NCT02354625).

OBJECTIVES

As a part of a Phase I clinical trial to assess the safety of autologous human Schwann cells (ahSC) in persons with chronic spinal cord injury (SCI), participants engaged in a multimodal conditioning program pre- and post-ahSC transplantation. The program included a home-based strength and endurance training program to prevent lack of fitness and posttransplantation detraining from confounding potential ahSC therapeutic effects. This paper describes development, deployment, outcomes, and challenges of the home-based training program.

SETTING

University-based laboratory.

METHODS

Development phase: two men with paraplegia completed an 8-week laboratory-based 'test' of the home-based program. Deployment phase: the first four (two males, two females) participant cohort of the ahSC trial completed the program at home for 12 weeks pre and 20 weeks post ahSC transplant.

RESULTS

Development phase: both participants improved their peak aerobic capacity (VO_2peak) (≥17%), peak power output (PO_peak) (≥8%), and time to exhaustion (TTE) (≥7%). Deployment phase: pretransplant training minimally increased fitness in the two male participants (≥6% PO_peak and ≥9% TTE). The two women had no PO_peak changes and slight TTE changes (+2.6 and -1.2%, respectively.) All four participants detrained during the posttransplant recovery period. After posttransplant retraining, all four participants increased TTE (4-24%), three increased VO_2peak (≥11%), and two increased PO_peak (≥7%)_. CONCLUSIONS: Home-based strength and condition programs can be effective and successfully included in therapeutic SCI trials. However, development of these programs requires substantial content knowledge and experience.

Modulation of left ventricular diastolic filling during exercise in persons with cervical motor incomplete spinal cord injury

PURPOSE

To characterize left ventricular diastolic function during an exertional challenge in adults with incomplete cervical spinal cord Injury (icSCI).

METHODS

In this cross-sectional study, a two-group convenience sample was used to compare left ventricular LV diastolic performance during a 5-10 W·min-1 incremental arm ergometer exercise protocol, using bioimpedance cardiography. Subjects were eight males with cervical incomplete spinal cord injury (icSCI; C5-C7: age 39 ± 14 years) versus eight able-bodied males (CON: age 38 ± 13 years). Left ventricular (LV) diastolic indices included end-diastolic volume (EDV) and early diastolic filling ratio (EDFR). LV ejection time (LVET), inotropic index (dZ/dT2) and stroke volume (SV) were compared between the groups at peak exercise, and maximum workload for the icSCI group (isomax).

RESULTS

EDV (at peak exercise:131.4 ± 7.3 vs 188.78 ± 9.4, p < 0.001; at isomax: 131.4 ± 7.3 vs 169 ± 23, p = 0.0009) and EDFR (at peak exercise 73 ± 14% vs 119 ± 11%, p = 0.006; at isomax 94 ± 10; p = 0.009) were significantly reduced in icSCI compared to CON, respectively. Significant differences in LVET (icSCI: 273 ± 48 vs CON: 305 ± 68; p = 0.1) and dZ/dT2 (icSCI: 0.64 ± 0.11 vs CON: 0.85 ± 0.31; p = 0.1) were not observed at isomax, despite a significant decrease in SV in the subjects with icSCI (77.1 ± 6.05 mL vs 105.8 ± 9.2 mL, p < 0.00) CONCLUSION: Left ventricular filling was impaired in the subjects with icSCI as evidenced at both peak exercise and isomax. It is likely that restrictions on the skeletal muscle pump mechanized the impairment but increased left ventricular wall stiffness could not be excluded as a mediator.

Differences in Acute Metabolic Responses to Bionic and Nonbionic Ambulation in Spinal Cord Injured Humans and Controls

OBJECTIVES

To (1) compare energy expenditure during seated rest, standing, and prolonged bionic ambulation or bipedal ambulation in participants with spinal cord injury (SCI) and noninjured controls, respectively, and (2) test effects on postbionic ambulation glycemia in SCI.

DESIGN

Two independent group comparison of SCI and controls.

SETTING

Academic Medical Center.

PARTICIPANTS

Ten participants with chronic SCI (C7-T1, American Spinal Injury Association Impairment Scale A-C) and 10 controls (N=20).

INTERVENTIONS

A commercial bionic exoskeleton.

MAIN OUTCOME MEASURES

Absolute and relative (to peak) oxygen consumption, perceived exertion, carbohydrate/fat oxidation, energy expenditure, and postbionic ambulation plasma glucose/insulin.

RESULTS

Average work intensity accompanying 45 minutes of outdoor bionic ambulation was <40% peak oxygen consumption, with negligible drift after reaching steady state. Rating of perceived exertion (RPE) did not differ between groups and reflected low exertion. Absolute energy costs for bionic ambulation and nonbionic ambulation were not different between groups despite a 565% higher ambulation velocity in controls and 3.3× higher kilocalorie per meter in SCI. Fuel partitioning was similar between groups and the same within groups for carbohydrate and fat oxidation. Nonsignificant (9%) lowering of the area under a glucose tolerance curve following bionic ambulation required 20% less insulin than at rest.

CONCLUSION

Work intensity during prolonged bionic ambulation for this bionic exoskeleton is below a threshold for cardiorespiratory conditioning but above seated rest and passive standing. Bionic ambulation metabolism is consistent with low RPE and unchanged fuel partitioning from seated rest. Bionic ambulation did not promote beneficial effects on glycemia in well-conditioned, euglycemic participants. These findings may differ in less fit individuals with SCI or those with impaired glucose tolerance. Observed trends favoring this benefit suggest they are worthy of testing.

A cross-sectional comparison between cardiorespiratory fitness, level of lesion and red blood cell distribution width in adults with chronic spinal cord injury

OBJECTIVES

To assess; (1) differences in red blood cell distribution width between individuals with chronic (>1year), motor-complete cervical (n=21), upper-thoracic (n=27) and thoracolumbar (n=15) spinal cord injury and, (2) associations between red blood cell distribution width and cardiorespiratory fitness.

DESIGN

Prospective multi-center, cross-sectional study.

METHODS

Peak oxygen uptake was determined using an upper-body arm-crank exercise test to volitional exhaustion and red blood cell distribution width was measured using an automated hematology system.

RESULTS

There were significant (p<0.009) differences between groups classified by level of injury in absolute and relative peak oxygen uptake, peak power output and red blood cell distribution width. A significant (p<0.001) large negative association (r = -0.524) was found between relative peak oxygen uptake and red blood cell distribution width. Unbiased recursive partitioning, while revealing study site specific differences in red blood cell distribution width, identified homogenous subgroups based specifically on cardiorespiratory fitness irrespective of additional demographic and injury characteristics.

CONCLUSION

The strong negative association between cardiorespiratory fitness and red blood cell distribution width in individuals with paraplegia parallel those previously observed in non-disabled individuals. Higher red blood cell distribution width values are an independent risk factor for increased cardiovascular mortality, heart failure, and coronary heart disease and may reflect several underlying exacerbated metabolic responses such as oxidative stress and systemic inflammation. These data emphasize the importance of maintaining a high aerobic capacity following spinal cord injury.

The influence of protocol design on the identification of ventilatory thresholds and the attainment of peak physiological responses during synchronous arm crank ergometry in able-bodied participants

Purpose

To examine the effects of stage duration on power output (PO), oxygen uptake (VO₂), and heart rate (HR) at peak level and ventilatory thresholds during synchronous arm crank ergometry.

Methods

Nineteen healthy participants completed a ramp, 1-min stepwise, and 3-min stepwise graded arm crank exercise test. PO, VO_2, and HR at the first and second ventilatory threshold (VT1, VT2) and peak level were compared among the protocols: a repeated measures analysis of variance was performed to test for systematic differences, while intraclass correlation coefficients (ICC) and Bland–Altman plots were calculated to determine relative and absolute agreement.

Results

Systematic differences among the protocols were found for PO at VT1, VT2, and peak level. At peak level, PO differed significantly among all protocols (ramp: 115 ± 37 W; 1-min stepwise: 108 ± 34 W; 3-min stepwise: 94 ± 31 W, p ≤ 0.01). No systematic differences for HR or VO₂ were found among the protocols. VT1 and VT2 were identified at 52% and 74% of VO₂peak, respectively. The relative agreement among protocols varied (ICC 0.02–0.97), while absolute agreement was low with small-to-large systematic error and large random error.

Conclusions

PO at VTs and peak level was significantly higher in short-stage protocols compared with the 3-min stepwise protocol, whereas HR and VO₂ showed no differences. Therefore, training zones based on PO determined in short-stage protocols might give an overestimation. Moreover, due to large random error in HR at VTs between the protocols, it is recommended that different protocols should not be used interchangeably within individuals.

Good association between sprint power and aerobic peak power during asynchronuous arm-crank exercise in people with spinal cord injury

PURPOSE

To (1) investigate the association between sprint power and aerobic power output (POpeak_GXT) during a graded peak exercise test (GXT); and (2) validate the prediction models of POpeak_GXT based on sprint power and personal and lesion characteristics.

MATERIALS AND METHODS

Wheelchair users with tetraplegia (N = 35) and paraplegia (N = 58) performed a 30 s-Wingate test and GXT on an asynchronous arm-crank ergometer. Data were split into samples to develop and validate the model. Sprint power (POmean_Wingate and POpeak_Wingate, respectively) and POpeak_GXT were determined. Regression analyses were performed to develop POpeak_GXT prediction models. Candidate independent variables included POmean_Wingate or POpeak_Wingate, age (years), sex, body mass (kg) or BMI (kg/m²), time since injury (TSI, years) and lesion level (tetraplegia/paraplegia). The best model was validated by comparing the predicted POpeak_GXT with measured POpeak_GXT.

RESULTS

The best model (R ² = 0.76) to predict POpeak_GXT included POmean_Wingate, BMI and all other independent variables. No significant difference was found between measured (68 ± 35 W) and predicted POpeak_GXT (68 ± 30 W, p = 0.97). The ICC was excellent (0.89 with 95% confidence intervals: 0.75-0.95). The 95% limits of agreement for the Bland-Altman plots were wide (-30 to 31 W).

CONCLUSIONS

Strong associations were found between POmean_Wingate and POpeak_GXT. Although relative agreement was excellent, absolute agreement was low. Implications for rehabilitation There is a strong relationship between peak aerobic power output and sprint power output, both tested on an arm-crank ergometer, in people with spinal cord injury. A prediction model for peak aerobic power output, based on sprint power output and personal and lesion characteristics, showed a high explained variance. The predictive model can give a guideline for choosing the right graded exercise test protocol but should be used with caution.

Interrater and intrarater reliability of ventilatory thresholds determined in individuals with spinal cord injury

STUDY DESIGN

Cross-sectional.

OBJECTIVES

Individualized training regimes are often based on ventilatory thresholds (VTs). The objectives were to study: (1) whether VTs during arm ergometry could be determined in individuals with spinal cord injury (SCI), (2) the intrarater and interrater reliability of VT determination.

SETTING

University research laboratory.

METHODS

Thirty graded arm crank ergometry exercise tests with 1-min increments of recreationally active individuals (tetraplegia (N = 11), paraplegia (N = 19)) were assessed. Two sports physicians assessed all tests blinded, randomly, in two sessions, for VT1 and VT2, resulting in 240 possible VTs. Power output (PO), heart rate (HR), and oxygen uptake (VO₂) at each VT were compared between sessions or raters using paired samples t-tests, Wilcoxon signed-rank tests, intraclass correlation coefficients (ICC, relative agreement), and Bland-Altman plots (random error, absolute agreement).

RESULTS

Of the 240 VTs, 217 (90%) could be determined. Of the 23 undetermined VTs, 2 (9%) were VT1 and 21 (91%) were VT2; 7 (30%) among individuals with paraplegia, and 16 (70%) among individuals with tetraplegia. For the successfully determined VTs, there were no systematic differences between sessions or raters. Intrarater and interrater ICCs for PO, HR, and VO₂ at each VT were high to very high (0.82-1.00). Random error was small to large within raters, and large between raters.

CONCLUSIONS

For VTs that could be determined, relative agreement was high to very high, absolute agreement varied. For some individuals, often with tetraplegia, VT determination was not possible, thus other methods should be considered to prescribe exercise intensity.

Peak power output in handcycling of individuals with a chronic spinal cord injury: predictive modeling, validation and reference values

Purpose: To develop and validate predictive models for peak power output to provide guidelines for individualized handcycling graded exercise test protocols for people with spinal cord injury (SCI); and to define reference values.Materials and methods: Power output was measured in 128 handcyclists with SCI during a synchronous handcycling exercise test. Eighty percent of the data was used to develop four linear regression models: two theoretical and two statistical models with peak power output (in W and W/kg) as dependent variable. The other 20% of the data was used to determine agreement between predicted versus measured power output. Reference values were based on percentiles for the whole group.Results: Lesion level, handcycling training hours and sex or body mass index were significant determinants of peak power output. Theoretical models (R² = 42%) were superior to statistical models (R²=39% for power output in W, R² = 30% for power output in W/kg). The intraclass correlation coefficients varied between 0.35 and 0.60, depending on the model. Absolute agreement was low.Conclusions: Both models and reference values provide insight in physical capacity of people with SCI in handcycling. However, due to the large part of unexplained variance and low absolute agreement, they should be used with caution. Implications for rehabilitationIndividualization of the graded exercise test protocol is very important to attain the true peak physical capacity in individuals with spinal cord injury.The main determinants to predict peak power output during a handcycling graded exercise test for individuals with a spinal cord injury are lesion level, handcycling training hours and sex or body mass index.The predictive models for peak power output should be used with caution and should not replace a graded exercise test.

Quantifying cardiorespiratory responses resulting from speed and slope increments during motorized treadmill propulsion among manual wheelchair users

BACKGROUND

Cardiorespiratory fitness assessment and training among manual wheelchair (MW) users are predominantly done with an arm-crank ergometer. However, arm-crank ergometer biomechanics differ substantially from MW propulsion biomechanics. This study aimed to quantify cardiorespiratory responses resulting from speed and slope increments during MW propulsion on a motorized treadmill and to calculate a predictive equation based on speed and slope for estimating peak oxygen uptake (VO_2peak) in MW users.

METHODS

In total, 17 long-term MW users completed 12 MW propulsion periods (PP), each lasting 2min, on a motorized treadmill, in a random order. Each PP was separated by a 2-min rest. PPs were characterized by a combination of 3 speeds (0.6, 0.8 and 1.0m/s) and 4 slopes (0°, 2.7°, 3.6° and 4.8°). Six key cardiorespiratory outcome measures (VO₂, heart rate, respiratory rate, minute ventilation and tidal volume) were recorded by using a gas-exchange analysis system. Rate of perceived exertion (RPE) was measured by using the modified 10-point Borg scale after each PP.

RESULTS

For the 14 participants who completed the test, cardiorespiratory responses increased in response to speed and/or slope increments, except those recorded between the 3.6^o and 4.8^o slope, for which most outcome measures were comparable. The RPE was positively associated with cardiorespiratory response (r_s≥0.85). A VO₂ predictive equation (R²=99.7%) based on speed and slope for each PP was computed. This equation informed the development of a future testing protocol to linearly increase VO₂ via 1-min stages during treadmill MW propulsion.

CONCLUSIONS

Increasing speed and slope while propelling a MW on a motorized treadmill increases cardiorespiratory response along with RPE. RPE can be used to easily and accurately monitor cardiorespiratory responses during MW exercise. The VO₂ can be predicted to some extent by speed and slope during MW propulsion. A testing protocol is proposed to assess cardiorespiratory fitness during motorized MW propulsion.