Dose-Response Outcomes Associated with Different Forms of Locomotor Training in Persons with Chronic Motor-Incomplete Spinal Cord Injury

Outcomes of training are thought to be related to the amount of training (training dose). Although various approaches to locomotor training have been used to improve walking function in persons with spinal cord injury (SCI), little is known about the relationship between dose of locomotor training and walking outcomes. This secondary analysis aimed to identify the relationship between training dose and improvement in walking distance and speed associated with locomotor training in participants with chronic motor-incomplete spinal cord injury (MISCI). We compared the dose-response relationships associated with each of four different locomotor training approaches. Participants were randomized to either: treadmill-based training with manual assistance (TM=17), treadmill-based training with stimulation (TS=18), overground training with stimulation (OG=15), and treadmill-based training with locomotor robotic device assistance (LR=14). Subjects trained 5 days/week for 12 weeks, with a target of 60 training sessions. The distance-dose and time-dose were calculated based on the total distance and total time, respectively, participants engaged in walking over all sessions combined. Primary outcome measures included walking distance (traversed in 2min) and walking speed (over 10m). Only OG training showed a good correlation between distance-dose and change in walking distance and speed walked over ground (r=0.61, p=0.02; r=0.62, p=0.01). None of the treadmill-based training approaches were associated with significant correlations between training dose and improvement of functional walking outcome. The findings suggest that greater distance achieved over the course of OG training is associated with better walking outcomes in the studied population. Further investigation to identify the essential elements that determine outcomes would be valuable for guiding rehabilitation.