Abstract
Increased risk of cardiovascular diseases and autonomic dysregulation are common health
concerns in individuals with spinal cord injury (SCI). Two therapies that may help
improve cardiovascular control are body-weight supported treadmill training (BWSTT)
and head-up tilt training (HUTT). The purpose of this study was to examine the effects
of short-term BWSTT and HUTT on cardiac autonomic function. Seven participants (6
male, 37.1±7.7 years) with SCI (C5-T10, ASIA A-C; 5.0±4.4 years post-injury) completed the study protocol. In this randomized cross-over
design, participants were required to complete 4 weeks of thrice-weekly BWSTT and
HUTT (i.e. 12 sessions each), separated by a 4 week detraining period. Cardiac autonomic
function was assessed at rest, before and after, each 4 week training period using
linear and non-linear measures (sample entropy and detrended fluctuation analysis
(α1)) of heart rate dynamics. Participants completed equivalent amounts of time performing
BWSTT and HUTT (453.7±27.3 min vs. 471.6±19.7 min, p=0.24). There were no significant differences in linear heart rate variability following
BWSTT or HUTT (p>0.05). In contrast, there was a significant change in sample entropy following BWSTT
(1.05±0.14 to 1.42±0.12, p<0.05). Due to the bi-directional pattern of α1 values, distance scores were calculated (│1−α1│) and demonstrated a significant reduction following BWSTT (0.54±0.06 to 0.26±0.05, p=0.001). In conclusion, 4 weeks of BWSTT but not HUTT training are sufficient to increase
sample entropy and reduce the fractal scaling distance score in participants with
SCI.
Keywords
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Article info
Publication history
Accepted:
March 30,
2009
Received:
February 26,
2009
Identification
Copyright
© 2009 Elsevier B.V. Published by Elsevier Inc. All rights reserved.
