Metabolic Intensity of Overground Robotic Exoskeleton Gait Training Among Patients with Subacute Spinal Cord Injury

Research Objectives: Gait training intensity plays a crucial role in the rehabilitation of persons with incomplete spinal cord injury (SCI). Identifying gait training modalities that can elicit higher absolute intensity and progress over time to meet the individual’s changing functional needs can promote physiological gains and reduce the risk of secondary complications following SCI. The objective of the present study was to assess the absolute metabolic intensity (MI) as well as the magnitude of change between two gait training approaches [overground robotic exoskeleton (ORE) or usual care (UC)] among patients with subacute SCI.

Design: Randomized controlled trial.

Setting: Inpatient rehabilitation (IPR) hospital.

Participants: Adults with SCI (ASIA Impairment Scale C or D) in the subacute recovery phase.

Interventions: Following randomization to ORE or UC, participants completed two assessments of MI during gait training (once within 1-week of IPR admission and once within 1-week preceding IPR discharge) using a metabolic cart (K5, COSMED, Rome, Italy).

Main Outcome Measures: MI was measured using average relative volume of oxygen consumption (VO2) categorized as metabolic equivalents (METs). Hedges’ g statistics were calculated to describe the magnitude of the difference in change in MI during IPR.

Results: Patients (n=10; ORE=5, UC=5) were predominantly male (n=9, 90%), White (n=6, 60%), and non-Hispanic (n=8, 80%) with an age (mean±SD) of 45.1±19.5 years and time since SCI of 30.7±17.8 days. Injury characteristics of the ORE group included 4 (80%) AIS C, 1 (20%) AIS D, 3 (60%) paraplegia, and 2 (40%) tetraplegia, with a median (Q1,Q3) IPR stay of 36 (35,37) days. For UC, 2 (40%) were classified AIS C, 3 (60%) AIS D, 1 (20%) paraplegia, and 4 (80%) tetraplegia, with a median (Q1,Q3) IPR stay of 28 (27,51) days. Mean ORE relative VO2 was 9.3±6.1 (admission) and 12.5±6.8 (discharge) mL/min/kg, and METs were 2.7±1.7 (admission) and 3.6±1.9 (discharge). Mean UC VO2 was 13.5±8.8 (admission) and 14.1±9.5 (discharge) mL/min/kg, and average METs were 3.6±1.9 (admission) and 4.0±2.7 (discharge). Large effect sizes were observed in the increase in MI [VO2 (g=0.82) and METs (g=0.91)] between ORE and UC.

Conclusions: Although higher absolute MI was observed with UC, the magnitude of MI change with ORE was significant at ~1 MET during IPR. Future research should consider examining the role of injury severity on absolute MI and potential for change.

Author(s) Disclosures: Dr. Chad Swank is the recipient of grant funding from NIDILRR (90IFRE0043) and DoD/CDMRP (W81XWH-2110922) to study the use of robotic exoskeletons in persons with SCI.