Spinal cord injury level and the circulating cytokine response to strenuous exercise

Med Sci Sports Exerc. 2013 Sep;45(9):1649-55. doi: 10.1249/MSS.0b013e31828f9bbb.


Purpose: A complete spinal cord injury (SCI) above the sixth 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 6 (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], and 8 = non-spinal-cord-injured controls [NON-SCI]) performed a submaximal exercise test followed by a graded exercise to exhaustion on a motorized treadmill. Blood samples were taken preexercise, postexercise, and 30 min postexercise and analyzed for concentrations of IL-6, IL-10, IL-1 receptor antagonist (IL-1ra), tumor necrosis factor α (TNF-α), epinephrine, and cortisol.

Results: The circulating IL-6 concentration was significantly elevated at postexercise and 30 min postexercise (post30; approximately fivefold) in NON-SCI and PARA (P = 0.003), whereas concentrations in TETRA did not change significantly from preexercise 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 NON-SCI (P = 0.001). At postexercise, epinephrine concentrations were significantly higher than preexercise and post30 concentrations in NON-SCI (approximately threefold) and PARA (approximately twofold) (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 postexercise and post30 compared with preexercise (P < 0.001). Total exercise time was similar between groups (NON-SCI = 38 ± 6; PARA = 35 ± 5; TETRA = 36 ± 5 min).

Conclusions: These findings suggest that 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Medulla / innervation
  • Adult
  • Case-Control Studies
  • Cervical Vertebrae
  • Cytokines / blood*
  • Epinephrine / blood*
  • Exercise Test
  • Heart Rate
  • Humans
  • Hydrocortisone / blood*
  • Interleukin 1 Receptor Antagonist Protein / blood
  • Interleukin-10 / blood
  • Interleukin-6 / blood
  • Male
  • Oxygen Consumption
  • Paraplegia / blood
  • Paraplegia / etiology
  • Physical Exertion / physiology*
  • Quadriplegia / blood
  • Quadriplegia / etiology
  • Spinal Cord Injuries / blood*
  • Spinal Cord Injuries / complications
  • Spinal Cord Injuries / physiopathology
  • Thoracic Vertebrae
  • Tumor Necrosis Factor-alpha / blood
  • Young Adult


  • Cytokines
  • IL1RN protein, human
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-6
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • Hydrocortisone
  • Epinephrine