PURPOSE: A complete spinal cord injury (SCI) above the 6th thoracic vertebra (T6) results in
the loss of sympathetic innervation of the adrenal medulla. This study examined the effect of
a complete SCI above and below T6 on plasma concentrations of epinephrine, circulating
interleukin (IL)-6 and other inflammatory cytokines in response to acute strenuous exercise.
METHODS: Twenty-six elite male wheelchair athletes (8=C6-C7 tetraplegic (TETRA); 10=T6-
L1 paraplegic (PARA); 8=non-spinal cord injured controls (NON-SCI)) performed a
submaximal exercise test followed by a graded exercise to exhaustion on a motorised
treadmill. Blood samples were taken pre-exercise, post-exercise and 30 min post-exercise
(post30) and analysed for concentrations of IL-6, IL-10, IL-1 receptor-antagonist (IL-1ra),
tumor necrosis factor-alpha (TNF-α), epinephrine and cortisol. RESULTS: Circulating IL-6
concentration was significantly elevated at post-exercise and post30 (~5-fold) in NON-SCI
and PARA (P=0.003) whereas concentrations in TETRA did not change significantly from
pre-exercise values. IL-10, IL-1ra and TNF-α were unaffected by exercise in all groups,
however both SCI groups presented elevated concentrations of IL-10 compared with NONSCI
(P=0.001). At post-exercise, epinephrine concentrations were significantly higher than
pre-exercise and post30 concentrations in NON-SCI (~3-fold) and PARA (~2-fold) (P=0.02).
Plasma epinephrine concentrations were unchanged in TETRA throughout exercise;
concentrations were significantly lower than NON-SCI and PARA at all-time points. Plasma
cortisol concentrations were significantly elevated in all groups at post-exercise and post30
compared with pre-exercise (P<0.001). Total exercise time was similar between groups
(NON-SCI= 38±6; PARA= 35±5; TETRA= 36±5 min). CONCLUSION: These findings suggest
the sympathetic nervous system plays an important regulatory role in the circulating IL-6
response to exercise and has implications for the metabolic and inflammatory responses to
exercise in individuals with injuries above T6.
Funding
A grant from the Coca-Cola Foundation was received for consumable costs during this research along with additional support provided by the corresponding institution.
History
School
Sport, Exercise and Health Sciences
Published in
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE
Volume
45
Issue
9
Pages
1649 - 1655 (7)
Citation
PAULSON, T.A.W. ... et al., 2013. Spinal cord injury level and the circulating cytokine response to strenuous exercise. Medicine and Science in Sports and Exercise, 45 (9), pp. 1649-1655.
This is a non-final version of an article published in final form in: PAULSON, T.A.W. ... et al., 2013. Spinal cord injury level and the circulating cytokine response to strenuous exercise. Medicine and Science in Sports and Exercise, 45 (9), pp. 1649-1655. URL: http://dx.doi.org/10.1249/MSS.0b013e31828f9bbb.