Key result
Higher levels of spinal cord injury resulted in lower resting epinephrine and norepinephrine and restricted cardioacceleration during exercise compared to lower lesions and able-bodied persons.
Why the study?
How do different levels of spinal cord injury affect catecholamine release, heart rate, and oxygen uptake during graded wheelchair exercise?
Cross-Sectional (n=68)
How do different levels of spinal cord injury affect catecholamine release, heart rate, and oxygen uptake during graded wheelchair exercise?
The level of spinal cord injury significantly dictates the catecholamine and cardiovascular response to exercise due to varying degrees of sympathetic nervous system interruption.
May guide lesion-level exercise testing in SCI; hypothesis-generating for autonomic-targeted interventions.
The purpose of this study was to investigate the influence of different injury levels in persons with spinal cord injury (SCI) on epinephrine (Epi) and norepinephrine (NE) at rest and during graded wheelchair exercise and the related changes in heart rate and O2 uptake (VO2). Twenty tetraplegics (Tetra), 10 high-lesion paraplegics (HLPara), 20 paraplegics with SCI below T5 (MLPara), and 18 able-bodied, nonhandicapped persons (AB) were examined. Because of the higher level of interruption of the sympathetic pathways, Tetra persons showed lower Epi and NE at rest and only slight increases during exercise compared with all other groups; the Tetra subjects' impaired cardiac sympathetic innervation caused restricted cardioacceleration and strongly reduced maximal VO2. When compared with AB persons, HLPara had comparable NE but lower Epi levels as a result of partial innervation of the noradrenergic system and denervation of the adrenal medulla. MLPara subjects showed an augmented basal and exercise-induced upper spinal thoracic sympathetic activity compared with AB subjects. The increase in heart rate in relation to VO2 was higher in HLPara because of a smaller stroke volume as a result of venous blood pooling. The different exercise response in persons with SCI is a result of the interruption of pathways in the spinal cord to the peripheral sympathetic nervous system in addition to the motor paralysis.
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Schmid et al. (1998) conducted a cross-sectional in Spinal cord injury (n=68). Spinal cord injury level vs. Able-bodied, nonhandicapped persons was evaluated on Epinephrine and norepinephrine levels at rest and during graded wheelchair exercise, and related changes in heart rate and O2 uptake. Higher levels of spinal cord injury resulted in lower resting epinephrine and norepinephrine and restricted cardioacceleration during exercise compared to lower lesions and able-bodied persons.
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