Locomotor-respiratory coupling in ambulatory adults with incomplete spinal cord injury

Study design Observational, analytical cohort study. Objectives After incomplete spinal cord injury (iSCI), propriospinal pathways may remain intact enabling coupling between respiration and locomotion. This locomotor-respiratory coupling (LRC) may enable coordination between these two important behaviors and have implications for rehabilitation after iSCI. However, coordination between these behaviors is not well understood and it is unknown if iSCI disrupts LRC. The objective of this study was to compare LRC in ambulatory adults with iSCI to able-bodied controls. Setting Rehabilitation Research Center, Jacksonville, Florida, United States of America. Methods Adults with iSCI (4 males, 1 female) and able-bodied controls (2 males, 3 females) walked at their fastest comfortable speed for 6 min over ground, and on a treadmill with bodyweight support (10-20%) and as-needed assistance at a standardized fast speed (controls) or their fastest speed (iSCI) for 6 min. LRC was quantified as the percent of breaths that were coupled with steps at a consistent ratio during the last 4 min of each walking condition. Results Over ground, participants with iSCI demonstrated significantly more LRC than able-bodied controls (72.4 +/- 6.4% vs. 59.1% +/- 7.5, p = 0.016). During treadmill walking, LRC did not differ between groups (iSCI 67.5 +/- 15.8% vs. controls 66.3 +/- 4.0%, p > 0.05). Conclusions Adults with iSCI demonstrated similar or greater LRC compared to able-bodied controls. This suggests that pathways subserving coordination between these behaviors remain intact in this group of individuals who walk independently after iSCI.