Intermittent Hypoxia and Locomotor Training Enhances Dynamic but Not Standing Balance in Patients With Incomplete Spinal Cord Injury

Abstract

ObjectiveTo test the effect of combined intermittent hypoxia (IH) and body weight–supported treadmill training (BWSTT) on standing and dynamic balance in persons with incomplete spinal cord injury (iSCI). DesignRandomized, triple-blind, placebo-controlled study. SettingRehabilitation medical centers. ParticipantsStudy participants (N=35) with chronic iSCI with American Spinal Injury Association grades C and D (>1y postinjury) were randomly assigned to either IH plus BWSTT (n=18) or continued normoxia (placebo) plus BWSTT protocol (n=17). InterventionsParticipants received either IH (alternating 1.5min 9% inspired O2 with 1.5min 21% inspired O2, 15 cycles per day) or continued normoxia (21% O2) combined with 45 minutes of BWSTT for 5 consecutive days, followed by 3 times per week IH or normoxia plus BWSTT, for 3 additional weeks. Main Outcome MeasuresStanding balance (normalized jerk and root-mean-square [RMS]) and dynamic balance (turning duration, cadence in a turn, and turn-to-sit duration) were assessed before and after IH and normoxia protocol by means of instrumented sway and instrumented timed Up and Go test. ResultsThere was no significant difference in standing balance between interventions for both normalized jerk and RMS instrumented sway components (both P>.05). There was a significantly faster cadence (P<.001), turning duration (P<.001), and turn-to-sit duration (P=.001) in subjects receiving IH plus BWSTT, compared with placebo. ConclusionsA 4-week protocol of IH combined with locomotor training improves dynamic, but not standing, balance in persons with iSCI.