Citation

Onushko T, Mahtani G, Brazg G, Hornby TG, Schmit BD. J. Neurotrauma 2019; ePub(ePub): ePub.

Affiliation

Marquette University, Departmetn of Biomedical Engineering , 1515 West Wisconsin Avenue , Room 206 , Milwaukee, Wisconsin, United States , 53233 ; brian.schmit@marquette.edu.

Copyright

(Copyright © 2019, Mary Ann Liebert Publishers)

DOI

10.1089/neu.2018.5719

PMID

30696387

Abstract

The purpose of this study was to understand how high and low intensity locomotor training (LT) affects sympathetic-somatomotor coupling in people with incomplete spinal cord injury (SCI). Proper coupling between sympathetic and somatomotor systems allows controlled regulation of cardiovascular responses to exercise. In people with SCI, altered connectivity between descending pathways and spinal segments impairs sympathetic and somatomotor coordination, which may have deleterious effects during exercise and limit rehabilitation outcomes. We postulated that high-intensity LT, which repeatedly engages sympathetic-somatomotor systems, would alter sympathetic-somatomotor coupling. Thirteen individuals (50 ± 7.2 years) with motor incomplete spinal cord injuries (ASIA Impairment Scale C or D; injury level > T6) participated in a locomotor treadmill training program. Patients were randomized into either a high-intensity (high-LT; 70-85% of maximum predicted heart rate; n=6) group or a low-intensity (low-LT; 50-65% of maximum predicted heart rate; n=7) group and completed up to 20 LT training sessions over 4-6 weeks, 3-5 days/week. Prior to and following training, we tested sympathetic-somatomotor coupling by eliciting reflexive sympathetic activity via a cold stimulation, noxious stimulation and a mental math task while we measured tendon reflexes, blood pressure and heart rate. Participants who completed high vs low-LT exhibited significant decreases in reflex torques during triggered sympathetic activity (cold: -83 vs 13%, p < 0.01; pain: -65 vs 54%, p < 0.05; mental math: -43 vs 41%, p < 0.05). Mean arterial pressure responses to sympathetic stimuli were slightly higher following high- vs low LT (cold: 30 vs -1.5%; pain: 6 vs -12%; mental math: 5 vs 7%) although differences were not statistically significant. These results suggest that high-LT may be advantageous to low-LT to improve sympathetic-somatomotor coupling in people with incomplete SCI.

Language: en

Keywords

HUMAN STUDIES; REHABILITATION; spinal cord injury