Effect of repeated locomotor training on ventilatory measures, perceived exertion and walking endurance in persons with motor incomplete spinal cord injury

Abstract

Study design: Pre-Post, Repeated Measures. Objectives: To determine if a warm-up bout of exercise could elicit a phasic ventilatory response to constant work rate (CWR) exercise in individuals with incomplete spinal cord injury (iSCI) during unsupported CWR treadmill walking. Describe the changes in ventilatory kinetics, ventilatory variability and ratings of perceived exertion (RPE) before and after 12 and 24 weeks of overground locomotor training (OLT). Investigate the relationship among minute ventilation (VE) variability, RPE, and walking endurance. Setting: Laboratory. Methods: A 6-min CWR was used as a warm-up preceding a CWR, at the same walking speed, until volitional fatigue or 30 min. Breath-by-breath ventilatory data were examined during the second CWR using a mono-exponential model. VE variability was calculated as the difference between the observed and predicted values. Data were time-matched before and after 12 and 24 weeks of OLT. A Pearson’s correlation was used for VE variability, RPE, and walking endurance. Results: A warm-up CWR did elicit a phasic ventilatory response. OLT resulted in faster ventilatory kinetics. Ventilatory variability reduced after 12 weeks of OLT but returned to pre-OLT values after 24 weeks of training. The change in VE variability was correlated with the change in RPE throughout the study. 12 and 24 weeks of OLT resulted in significant improvements in treadmill walking time. Conclusions: SCI patients can achieve a phasic ventilatory response to walking if the exercise bout is preceded by a warm-up. OLT normalizes the ventilatory kinetics and improves walking endurance. The change in VE variability is correlated to RPE.