The Feasibility of Blood Flow Restriction Exercise in Patients With Incomplete Spinal Cord Injury

Background: Blood flow restriction (BFR) exercise, which already has shown promise in the able-bodied population, may be a novel method for improving muscle function in the incomplete spinal cord injury (iSCI) population. However, the feasibility and tolerance for BFR exercise in this population is unknown. Objective: To determine the feasibility and safety of BFR exercise in the iSCI population, with special attention paid to acute hemodynamic changes and the risk of deep vein thrombosis (DVT). Design: Within-subjects repeated measures design. Setting: Outpatient SCI rehabilitation unit in a Veterans Affairs medical center. Participants: Nine individuals with varying levels of iSCI and varying functional abilities. Methods: Subjects performed a trial of unilateral BFR knee extension (3 x 10) with, and without, BFR (125% of venous occlusion pressure) in a counterbalanced order. Main Outcome Measurements: Acute autonomic dysreflexia risk, total work, pain, perceived difficulty, muscle activation, lactate, hemodynamics, and tissue oxygenation were compared between conditions. Each subject was screened for a DVT at baseline and returned for a quantitative D-dimer assessment 3-4 days after the protocol. Results: All subjects were able to complete each BFR trial without showing signs of autonomic dysreflexia or DVT formation. No differences were observed for pain, perceived effort, muscular activation, or lactate between BFR and control exercise. Mean arterial pressure and systolic pressure both increased with exercise (18.8% and 17.6% in BFR, and 19.4% and 19.6% in control, respectively; P < .05) but were not different between conditions. Oxyhemoglobin and deoxyhemoglobin saturation both increased during BFR exercise (+12.3 +/- 96.7 and +105.4 +/- 76.7, respectively), whereas tissue oxygenation index decreased (-6.5 +/- 3.0%; P < .05 for all comparisons). Conclusions: Results suggest that controlled BFR exercise can be safely performed by individuals with iSCI without added cardiovascular strain or heightened pain.