title: Spinal cord injury level and the circulating cytokine response to strenuous exercise.
abstract: OBJECTIVE
  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.
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UK.
authors.forename: Thomas A W
authors.initials: TA
authors.lastname: Paulson
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Goosey-Tolfrey
authors.forename: John P
authors.initials: JP
authors.lastname: Lenton
authors.forename: Christof A
authors.initials: CA
authors.lastname: Leicht
authors.forename: Nicolette C
authors.initials: NC
authors.lastname: Bishop
mesh_terms: D000313:Adrenal Medulla / Q000294:innervation; D000328:Adult; D016022:Case-Control Studies; D002574:Cervical Vertebrae; D016207:Cytokines / Q000097:blood*; D004837:Epinephrine / Q000097:blood*; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D053590:Interleukin 1 Receptor Antagonist Protein / Q000097:blood; D016753:Interleukin-10 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D010101:Oxygen Consumption; D010264:Paraplegia / Q000097:blood / Q000209:etiology; D005082:Physical Exertion / Q000502:physiology*; D011782:Quadriplegia / Q000097:blood / Q000209:etiology; D013119:Spinal Cord Injuries / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D013904:Thoracic Vertebrae; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D055815:Young Adult
chemical_list: D016207:Cytokines; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D006854:Hydrocortisone; D004837:Epinephrine