Cardiovascular Responses and Postexercise Hypotension After Arm Cycling Exercise in Subjects With Spinal Cord Injury
Abstract
Claydon VE, Hol AT, Eng JJ, Krassioukov AV. Cardiovascular responses and postexercise hypotension after arm cycling exercise in subjects with spinal cord injury.
Objective
To examine postexercise hypotension and contributing factors in subjects with spinal cord injury (SCI).
Design
Prospective clinical research study.
Setting
Rehabilitation center.
Participants
Subjects with chronic cervical-level (n=19) and thoracic-level (n=8) SCI.
Interventions
Not applicable.
Main Outcome Measures
Subjects underwent graded arm-cycling with electrocardiogram and oxygen uptake monitoring to exhaustion. Heart rates and blood pressures were measured before and after exercising. Injury to motor and sensory pathways was determined by American Spinal Injury Association grade, and to autonomic pathways by sympathetic skin responses (SSRs) (n=16).
Results
Resting blood pressures and heart rates were lower in cervical than thoracic SCI (mean arterial pressure [MAP]: cervical, 76.6±2mmHg; thoracic, 93.5±3mmHg; P<.001). Following exercise, heart rate responses were greater in thoracic than cervical SCI; MAP increased in thoracic SCI (8.4±5mmHg) and markedly decreased in cervical SCI (−9.3±2mmHg) (P<.001). No subject had significant electrocardiographic abnormalities at rest or during exercise. There were correlations between SSR and heart rate and blood pressure responses to exercise; the correlation between the SSR and blood pressure response was due to an interaction between the heart rate and blood pressure responses.
Conclusions
Abnormal cardiovascular responses to exercise and transient postexercise hypotension were common in cervical, but not thoracic SCI. This may be partly related to loss of descending sympathetic nervous control of the heart and vasculature following high SCI.
aInternational Collaboration On Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
bSchool of Rehabilitation Sciences, University of British Columbia, Vancouver, BC, Canada
cGF Strong Rehabilitation Centre, Vancouver, BC, Canada.
Correspondence to Andrei V. Krassioukov, MD, PhD, International Collaboration On Repair Discoveries (ICORD), 6270 University Blvd, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
Supported by the Rick Hansen Man In Motion Research Foundation (grant no. 05-0747), the Canadian Institutes of Health Research (career scientist award), and Michael Smith Foundation of Health Research.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.
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