The effect of FES-rowing training on cardiac structure and function: pilot studies in people with spinal cord injury

Exercise and aerobic capacity in individuals with spinal cord injury: A systematic review with meta-analysis and meta-regression

BACKGROUND

A low level of cardiorespiratory fitness [CRF; defined as peak oxygen uptake ([Formula: see text]O2peak) or peak power output (PPO)] is a widely reported consequence of spinal cord injury (SCI) and a major risk factor associated with chronic disease. However, CRF can be modified by exercise. This systematic review with meta-analysis and meta-regression aimed to assess whether certain SCI characteristics and/or specific exercise considerations are moderators of changes in CRF.

METHODS AND FINDINGS

Databases (MEDLINE, EMBASE, CENTRAL, and Web of Science) were searched from inception to March 2023. A primary meta-analysis was conducted including randomised controlled trials (RCTs; exercise interventions lasting >2 weeks relative to control groups). A secondary meta-analysis pooled independent exercise interventions >2 weeks from longitudinal pre-post and RCT studies to explore whether subgroup differences in injury characteristics and/or exercise intervention parameters explained CRF changes. Further analyses included cohort, cross-sectional, and observational study designs. Outcome measures of interest were absolute (A[Formula: see text]O2peak) or relative [Formula: see text]O2peak (R[Formula: see text]O2peak), and/or PPO. Bias/quality was assessed via The Cochrane Risk of Bias 2 and the National Institute of Health Quality Assessment Tools. Certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Random effects models were used in all meta-analyses and meta-regressions. Of 21,020 identified records, 120 studies comprising 29 RCTs, 67 pre-post studies, 11 cohort, 7 cross-sectional, and 6 observational studies were included. The primary meta-analysis revealed significant improvements in A[Formula: see text]O2peak [0.16 (0.07, 0.25) L/min], R[Formula: see text]O2peak [2.9 (1.8, 3.9) mL/kg/min], and PPO [9 (5, 14) W] with exercise, relative to controls (p < 0.001). Ninety-six studies (117 independent exercise interventions comprising 1,331 adults with SCI) were included in the secondary, pooled meta-analysis which demonstrated significant increases in A[Formula: see text]O2peak [0.22 (0.17, 0.26) L/min], R[Formula: see text]O2peak [2.8 (2.2, 3.3) mL/kg/min], and PPO [11 (9, 13) W] (p < 0.001) following exercise interventions. There were subgroup differences for R[Formula: see text]O2peak based on exercise modality (p = 0.002) and intervention length (p = 0.01), but there were no differences for A[Formula: see text]O2peak. There were subgroup differences (p ≤ 0.018) for PPO based on time since injury, neurological level of injury, exercise modality, and frequency. The meta-regression found that studies with a higher mean age of participants were associated with smaller changes in A[Formula: see text]O2peak and R[Formula: see text]O2peak (p < 0.10). GRADE indicated a moderate level of certainty in the estimated effect for R[Formula: see text]O2peak, but low levels for A[Formula: see text]O2peak and PPO. This review may be limited by the small number of RCTs, which prevented a subgroup analysis within this specific study design.

CONCLUSIONS

Our primary meta-analysis confirms that performing exercise >2 weeks results in significant improvements to A[Formula: see text]O2peak, R[Formula: see text]O2peak, and PPO in individuals with SCI. The pooled meta-analysis subgroup comparisons identified that exercise interventions lasting up to 12 weeks yield the greatest change in R[Formula: see text]O2peak. Upper-body aerobic exercise and resistance training also appear the most effective at improving R[Formula: see text]O2peak and PPO. Furthermore, acutely injured, individuals with paraplegia, exercising for ≥3 sessions/week will likely experience the greatest change in PPO. Ageing seemingly diminishes the adaptive CRF responses to exercise training in individuals with SCI.

REGISTRATION

PROSPERO: CRD42018104342.

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.

Development of a Coaching System for Functional Electrical Stimulation Rowing: A Feasibility Study in Able-Bodied Individuals

Background: Functional electrical stimulation (FES) during rowing has substantial effects on cardiovascular health in individuals with spinal cord injuries. Currently, manual stimulation control where stimulation is operated by rowers is mostly utilized. However, it takes time to obtain the skill to initiate FES at the optimal timing. The purpose of this study was to develop a coaching system that helps rowers to initiate FES at the optimal timing. Methods: The optimal range for FES application was identified based on the electromyography of the left quadriceps in 10 able-bodied individuals (AB). Then, the effects of the coaching system on the timing of button-pressing, power, and work were investigated in 7 AB. Results: Vastus lateralis (VL) activation began consistently before the seat reached the anterior-most position. Therefore, seat position at the onset of VL was used as the variable to control the switch timing in the coaching system. The results revealed significantly higher power and work outputs in the coaching than the no-coaching condition (median power coaching: 19.10 W, power no-coaching: 16.48 W, p = 0.031; median work coaching: 109.74 J, work no-coaching: 65.25 J, p = 0.047). Conclusions: The coaching system can provide the optimal timing for FES, resulting in improved performance.

Effects of functional electrical stimulation on muscle health after spinal cord injury

Spinal cord injury is a devastating condition interrupting voluntary movement and motor control. In response to unloading, skeletal muscle undergoes numerous adaptations, including rapid and profound atrophy, intramuscular fat accumulation, impaired muscular glucose metabolism and decreased force generation and muscle performance. Functional electrical stimulation (FES) involves electrically stimulating affected muscles to contract in a coordinated manner to create a functional movement or task. Effects of FES-cycling, rowing and resistance training on muscle health are described here. Briefly, FES-cycling and resistance training may slow muscle atrophy or facilitate muscle hypertrophy, and all modalities benefit muscle composition and performance to some extent. These interventions show promise as future rehabilitative tools after spinal cord injury.

Reductions in Cardiac Structure and Function 24 Months After Spinal Cord Injury: A Cross-Sectional Study

OBJECTIVE

To determine the alterations in cardiac structure and function that occur in the months after spinal cord injury (SCI).

STUDY DESIGN

Cross-sectional SETTING: Rehabilitation Hospital PARTICIPANTS: Volunteers (N=29; 4 women, 25 men) between 3 and 24 months after SCI.

MAIN OUTCOME MEASURES

Transthoracic echocardiography was performed on each volunteer. The relationships between time since injury and neurologic and sensory levels of injury to cardiac structure and function were assessed via multiple linear regression.

RESULTS

Time since injury was most strongly associated with reductions in left ventricular end diastolic volume (r2=0.156; P=.034), end systolic volume (r2=0.141; P=.045), and mass (r2=0.138; P=.047). These structural changes were paralleled by reduced stroke volume (r2=0.143; P=.043) and cardiac output (r2=0.317; P=<.001). The reductions in left ventricular structure and systolic function were not differentially affected by neurologic or sensory levels of injury (P=.084-.921).

CONCLUSIONS

These results suggest progressive reductions in left ventricular structure and systolic function between 3 and 24 months after SCI that occur independent of neurologic and sensory levels of injury.

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.

Effects of NMES pulse width and intensity on muscle mechanical output and oxygen extraction in able-bodied and paraplegic individuals

PURPOSE

Neuromuscular Electrical Stimulation (NMES) is commonly used in neuromuscular rehabilitation protocols, and its parameters selection substantially affects the characteristics of muscle activation. Here, we investigated the effects of short pulse width (200 µs) and higher intensity (short-high) NMES or long pulse width (1000 µs) and lower intensity (long-low) NMES on muscle mechanical output and fractional oxygen extraction. Muscle contractions were elicited with 100 Hz stimulation frequency, and the initial torque output was matched by adjusting stimulation intensity.

METHODS

Fourteen able-bodied and six spinal cord-injured (SCI) individuals participated in the study. The NMES protocol (75 isometric contractions, 1-s on-3-s off) targeting the knee extensors was performed with long-low or short-high NMES applied over the midline between anterior superior iliac spine and patella protrusion in two different days. Muscle work was estimated by torque-time integral, contractile properties by rate of torque development and half-relaxation time, and vastus lateralis fractional oxygen extraction was assessed by Near-Infrared Spectroscopy (NIRS).

RESULTS

Torque-time integral elicited by the two NMES paradigms was similar throughout the stimulation protocol, with differences ranging between 1.4% (p = 0.877; able-bodied, mid-part of the protocol) and 9.9% (p = 0.147; SCI, mid-part of the protocol). Contractile properties were also comparable in the two NMES paradigms. However, long-low NMES resulted in higher fractional oxygen extraction in able-bodied (+ 36%; p = 0.006).

CONCLUSION

Long-low and short-high NMES recruited quadriceps femoris motor units that demonstrated similar contractile and fatigability properties. However, long-low NMES conceivably resulted in the preferential recruitment of vastus lateralis muscle fibers as detected by NIRS.

Clinical Benefits and System Design of FES-Rowing Exercise for Rehabilitation of Individuals with Spinal Cord Injury: A Systematic Review

OBJECTIVE

To comprehensively and critically appraise the clinical benefits and engineering designs of functional electrical stimulation (FES)-rowing for management of individuals with spinal cord injury (SCI).

DATA SOURCES

Electronic database searches were conducted in Cumulative Index to Nursing & Allied Health Literature, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Excerpta Medica database, Emcare, Medline, PubMed, Scopus, and Web of Science databases from inception to May 12, 2020.

STUDY SELECTION

Search terms used were synonyms of "spinal cord injury" for Population and "Electric Stimulation (Therapy)/ and rowing" for Intervention. Two reviewers independently assessed articles based on the following inclusion criteria: recruited individuals with SCI; had aerobic FES-rowing exercise as study intervention; reported cardiovascular, muscular, bone mineral density, or metabolic outcomes; and examined engineering design of FES-rowing systems. Of the 256 titles that were retrieved in the primary search, 24 were included in this study.

DATA EXTRACTION

Study characteristics, quality, participants' characteristics, test descriptions, and results were independently extracted by 2 reviewers. The quality of studies was assessed with the Downs and Black checklist.

DATA SYNTHESIS

Comparison of peak oxygen consumption (V̇_o2peak) rates showed that V̇_o2peak during FES-rowing was significantly higher than arm-only exercise; FES-rowing training improved V̇_o2peak by 11.2% on average (95% confidence interval, 7.25-15.1), with a 4.1% (95% confidence interval, 2.23-5.97) increase in V̇_o2peak per month of training. FES-rowing training reduced bone density loss with increased time postinjury. The rowing ergometer used in 2 studies provided motor assistance during rowing. Studies preferred manual stimulation control (n=20) over automatic (n=4).

CONCLUSIONS

Our results suggest FES-rowing is a viable exercise for individuals with SCI that can improve cardiovascular performance and reduce bone density loss. Further randomized controlled trials are needed to better understand the optimal set-up for FES-rowing that maximizes the rehabilitation outcomes.

Cardiac, Autonomic, and Cardiometabolic Impact of Exercise Training in Spinal Cord Injury: A QUALITATIVE REVIEW

INTRODUCTION

Direct and indirect effects of spinal cord injury lead to important cardiovascular (CV) complications that are further increased by years of injury and the process of "accelerated aging." The present review examines the current evidence in the literature for the potential cardioprotective effect of exercise training in spinal cord injury.

REVIEW METHODS

PubMed and Web of Science databases were screened for original studies investigating the effect of exercise-based interventions on aerobic capacity, cardiac structure/function, autonomic function, CV function, and/or cardiometabolic markers. We compared the effects in individuals <40 yr with time since injury <10 yr with those in older individuals (≥40 yr) with longer time since injury (≥10 yr), reasoning that the two can be considered individuals with low versus high CV risk factors.

SUMMARY

Studies showed similar exercise effects in both groups (n = 31 in low CV risk factors vs n = 15 in high CV risk factors). The evidence does not support any effect of exercise training on autonomic function but does support an increased peripheral blood flow, improved left ventricular mass, higher peak cardiac output, greater lean body mass, better antioxidant capacity, and improved endothelial function. In addition, some evidence suggests that it can result in lower blood lipids, systemic inflammation (interleukin-6, tumor necrosis factor α, and C-reactive protein), and arterial stiffness. Training intensity, volume, and frequency were key factors determining CV gains. Future studies with larger sample sizes, well-matched groups of subjects, and randomized controlled designs will be needed to determine whether high-intensity hybrid forms of training result in greater CV gains.

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.

Supporting front crawl swimming in paraplegics using electrical stimulation: a feasibility study

Background

Participation in physical and therapeutic activities is usually severely restricted after a spinal cord injury (SCI). Reasons for this are the associated loss of voluntary motor function, inefficient temperature regulation of the affected extremities, and early muscle fatigue. Hydrotherapy or swim training offer an inherent weight relief, reduce spasticity and improve coordination, muscle strength and fitness.

Methods

We present a new hybrid exercise modality that combines functional electrical stimulation (FES) of the knee extensors and transcutaneous spinal cord stimulation (tSCS) with paraplegic front crawl swimming. tSCS is used to stimulate the afferent fibers of the L2–S2 posterior roots for spasticity reduction. By activating the tSCS, the trunk musculature is recruited at a motor level. This shall improve trunk stability and straighten the upper body. Within this feasibility study, two complete SCI subjects (both ASIA scale A, lesion level Th5/6), who have been proficient front crawl swimmers, conducted a 10-week swim training with stimulation support. In an additional assessment swim session nine months after the training, the knee extension, hip extension, and trunk roll angles where measured using waterproof inertial measurement units (IMUs) and compared for different swimming conditions (no stimulation, tSCS, FES, FES plus tSCS).

Results

For both subjects, a training effect over the 10-week swim training was observed in terms of measured lap times (16 m pool) for all swimming conditions. Swimming supported by FES reduced lap times by 15.4% and 8.7% on average for Subject A and Subject B, respectively. Adding tSCS support yielded even greater mean decreases of 19.3% and 20.9% for Subjects A and B, respectively. Additionally, both subjects individually reported that swimming with tSCS for 30–45 minutes eliminated spasticity in the lower extremities for up to 4 hours beyond the duration of the session. Comparing the median as well as the interquartile range of all different settings, the IMU-based motion analysis revealed that FES as well as FES+tSCS improve knee extension in both subjects, while hip extension was only increased in one subject. Trunk roll angles were similar for all swimming conditions. tSCS had no influence on the knee and hip joint angles. Both subjects reported that stimulation-assisted swimming is comfortable, enjoyable, and they would like to use such a device for recreational training and rehabilitation in the future.

Conclusions

Stimulation-assisted swimming seems to be a promising new form of hybrid exercise for SCI people. It is safe to use with reusable silicone electrodes and can be performed independently by experienced paraplegic swimmers except for transfer to water. The study results indicate that swimming speed can be increased by the proposed methods and spasticity can be reduced by prolonged swim sessions with tSCS and FES. The combination of stimulation with hydrotherapy might be a promising therapy for neurologic rehabilitation in incomplete SCI, stroke or multiples sclerosis patients. Therefore, further studies shall incorporate other neurologic disorders and investigate the potential benefits of FES and tSCS therapy in the water for gait and balance.

Optimizing Neuromuscular Electrical Stimulation Pulse Width and Amplitude to Promote Central Activation in Individuals With Severe Spinal Cord Injury

Neuromuscular electrical stimulation (NMES) is one of the most effective treatments for counteracting the deleterious skeletal muscle adaptations that occur after spinal cord injury (SCI). Additionally, previous findings suggest that NMES can activate motor units via both peripheral and central mechanisms; however, this NMES-promoted central activation is not well understood. In this study, we aimed at investigating the effects of NMES on central activation in 10 individuals with motor complete SCI, focusing on understanding how to optimize NMES pulse width and amplitude for promoting central activation in this population. To this end, we used NMES to generate isometric contractions of the knee extensors and ankle plantarflexors while electromyographic (EMG) activity was recorded from the vastus lateralis and gastrocnemius medialis, respectively. We used EMG activity that persisted after the termination of NMES delivery (post-NMES) as a neurophysiological marker to assess central activation and explored differences in post-NMES EMG activity promoted by 500 and 1,000 μs pulse width NMES. Additionally, we explored the relationships between post-NMES EMG amplitude, torque output, and stimulation amplitude. Our results show that the higher pulse width (1,000 μs) demonstrated a greater effect on central activation as quantified by more frequent occurrences of post-NMES EMG activity (p = 0.002) and a 3.551 μV higher EMG amplitude (p = 0.003) when controlling for the torque output generated by 500 and 1,000 μs pulse width NMES. Importantly, we also found that the interplay among central activation, stimulation amplitude, and muscle torque output differs across SCI individuals, conceivably because of the individual-specific characteristics of the cord lesion and following plasticity of the spinal circuitry. These results suggest that NMES can be optimized to promote central activation, which may lead to novel opportunities for motor function recovery after SCI.

Garments for functional electrical stimulation: Design and proofs of concept

Introduction

Repeated use of functional electrical stimulation can promote functional recovery in individuals with neurological paralysis. We designed garments able to deliver functional electrical stimulation.

Methods

Shirts and pants containing electrodes knitted with a conductive yarn were produced. Electrodes were moistened with water before use. Stimulation intensity at four thresholds levels (sensory, movement, full range of motion, and maximal), stimulation comfort, and electrical properties of the interface were tested in one able-bodied subject with garment electrodes and size-matched conventional gel electrodes. The pants and shirt were then used to explore usability and design limitations.

Results

Compared to gel electrodes, fabric electrodes had a lower sensory threshold (on forearm muscles) but they had a higher maximal stimulation threshold (for all tested muscles). The stimulation delivery was comfortable when the garment electrodes were recently moistened; however, as the electrodes dried (within 9 to 18 min) stimulation became unpleasant. Inconsistent water content in the fabric electrodes caused inconsistent intensity thresholds and inconsistent voltage necessary to apply a desired stimulation current. Garments’ tightness and impracticality of electrode lead necessitate further design improvement.

Conclusions

Fabric electrodes offer a promising alternative to gel electrodes. Further work involving people with paralysis is required to overcome the identified challenges.

Energy Expenditure as a Function of Activity Level After Spinal Cord Injury: The Need for Tetraplegia-Specific Energy Balance Guidelines

The World Health Organization recognizes obesity as a global and increasing problem for the general population. Because of their reduced physical functioning, people with spinal cord injury (SCI) face additional challenges for maintaining an appropriate whole body energy balance, and the majority with SCI are overweight or obese. SCI also reduces exercise capacity, particularly in those with higher-level injury (tetraplegia). Tetraplegia-specific caloric energy expenditure (EE) data is scarce. Therefore, we measured resting and exercise-based energy expenditure in participants with tetraplegia and explored the accuracy of general population-based energy use predictors. Body composition and resting energy expenditure (REE) were measured in 25 adults with tetraplegia (C4/5 to C8) and in a sex-age-height matched group. Oxygen uptake, carbon dioxide production, heart rate, perceived exertion, and exercise intensity were also measured in 125 steady state exercise trials. Those with motor-complete tetraplegia, but not controls, had measured REE lower than predicted (mean = 22% less, p < 0.0001). REE was also lower than controls when expressed per kilogram of lean mass. Nine had REE below 1200 kcal/day. We developed a graphic compendium of steady state EE during arm ergometry, wheeling, and hand-cycling. This compendium is in a format that can be used by persons with tetraplegia for exercise prescription (calories, at known absolute intensities). EE was low (55–450 kcal/h) at the intensities participants with tetraplegia were capable of maintaining. If people with tetraplegia followed SCI-specific activity guidelines (220 min/week) at the median intensities we measured, they would expend 563–1031 kcal/week. Participants with tetraplegia would therefore require significant time (4 to over 20 h) to meet a weekly 2000 kcal exercise target. We estimated total daily EE for a range of activity levels in tetraplegia and compared them to predicted values for the general population. Our analysis indicated that the EE values for sedentary through moderate levels of activity in tetraplegia fall well below predicted sedentary levels of activity for the general population. These findings help explain sub-optimal responses to exercise interventions after tetraplegia, and support the need to develop tetraplegia-specific energy-balance guidelines that reflects their unique EE situation.