Walking endurance, muscle oxygen extraction, and perceived fatigability after overground locomotor training in incomplete spinal cord injury: A pilot study.

Objective: The purpose of this study was to examine the effects of overground locomotor training (OLT) on walking endurance and gastrocnemius oxygen extraction in people with chronic cervical motor-incomplete spinal cord injury (SCI). Design: Prospective single-arm pre-post pilot study. Setting: Human Performance Research Laboratory. Participants: Adult men with traumatic chronic cervical SCI ( n  = 6; age = 30.8 ± 12.5). Intervention: Twenty-four sessions of structured OLT. Outcome measures: Walking endurance was determined during a constant work-rate time-to-exhaustion treadmill test. Normalized perceived fatigability was calculated by dividing subjective ratings of tiredness by walking time. Cardiorespiratory outcomes and muscle oxygen extraction were analyzed using breath-by-breath gas-exchange and near-infrared spectroscopy. Results: OLT resulted in large effects on walking endurance (1232 ± 446 s vs 1645 ± 255 s; d  = 1.1; P  = 0.045) and normalized perceived fatigability (5.3 ± 1.5 a.u. vs 3.6 ± 0.9 a.u.; d  = 1.3; P  = 0.033). Small-to-medium effects on absolute (2.8 ± 2.5 a.u. vs 4.2 ± 3.5 a.u.; d  = 0.42; P  = 0.035) and isotime (2.8 ± 2.5 a.u. vs 3.8 ± 3.0 a.u.; d  = 0.33; P  = 0.023) muscle oxygen extraction were also observed after OLT. Conclusion: These findings provide preliminary data supporting the potential for improved walking endurance, enhanced muscle O ₂ extraction, and reduced perceived fatigability in people with chronic cervical motor-incomplete SCI following the OLT program described in this study.