Locomotor step training with body weight support improves respiratory motor function in individuals with chronic spinal cord injury

Abstract

This prospective case-controlled clinical study was undertaken to investigate to what extent the manually assisted treadmill stepping locomotor training with body weight support (LT) can change respiratory function in individuals with chronic spinal cord injury (SCI). Pulmonary function outcomes (forced vital capacity /FVC/, forced expiratory volume one second /FEV1/, maximum inspiratory pressure /PImax/, maximum expiratory pressure /PEmax/) and surface electromyographic (sEMG) measures of respiratory muscles activity during respiratory tasks were obtained from eight individuals with chronic C3-T12 SCI before and after 62±10 (mean±SD) sessions of the LT. FVC, FEV1, PImax, PEmax, amount of overall sEMG activity and rate of motor unit recruitment were significantly increased after LT (p<0.05). These results suggest that these improvements induced by the LT are likely the result of neuroplastic changes in spinal neural circuitry responsible for the activation of respiratory muscles preserved after injury.

Keywords: Locomotor training; Motor control; Respiratory function; Spinal cord injury.

Copyright © 2013 Elsevier B.V. All rights reserved.

Figures

Fig. 1

Surface electromyography (sEMG) recorded during a Maximum Expiratory Pressure Task (MEPT) in a Non-injured individual and a person (C09) with C7, AIS-C SCI. Muscles shown are right and left pectoralis (RPEC/LPEC), 6th intercostals (RIC6/LIC6), rectus abdominus (RRA/LRA), oblique abdominus (ROBL/LOBL), and paraspinals (RPS/LPS). Arrows indicate volitional initiation of the task. Note the considerably reduced amount of sEMG activity (Mag) before LT and its increase with more rapid recruitment of motor units and improvement in similarity index (SI) value after LT.

Fig. 2

Surface electromyography (sEMG) recorded during a Coughing Task in a Non-injured individual and a person (C09) with C7, AIS-C (C7C) SCI. Muscles shown are right and left pectoralis (RPEC/LPEC), 6th intercostals (RIC6/LIC6), rectus abdominus (RRA/LRA), oblique abdominus (ROBL/LOBL), and paraspinals (RPS/LPS). Arrows indicate volitional initiation of the task. Note the improved ability to produce repeated coughs with more rapid recruitment of motor units after LT in the SCI subject.

Fig. 3

Group mean values for the speed of the sEMG raising slope from the onset to the peak of the muscle activity during MEPT and Cough. Note that prior to LT, the raising slope was significantly lower in the SCI group as compared to the control group (** p<.01 however the slope was significantly increased post-lt as compared to pre-lt values p>