Wheelchair half-marathon race increases natural killer cell activity in persons with cervical spinal cord injury

Study design: Non-randomized study. Objective: We reported that individuals with cervical spinal cord injury (CSCI) showed no increase in natural killer cell activity (NKCA) in response to 20-min arm exercise. It could be argued that this lack of response was owing to the short duration and intensity of the exercise. Setting: The 29th Oita International wheelchair marathon race. Methods: The present study compared the effects of wheelchair half-marathon race on natural killer (NK) cell count, NKCA and other hematological and hormonal parameters in six subjects with CSCI and seven control subjects with spinal cord injury between T4 and L1 (SCI), before, immediately after and 2 h after recovery. Results: NK cell counts increased at both time points after the race in SCI, but not in CSCI, compared with before the race. NKCA increased immediately in both groups of subjects after the race, and then returned to the pre-race level at 2 h after the race. Plasma cortisol did not change in both groups throughout the study. Plasma adrenaline increased sharply in SCI after the race, then returned to the pre-race level at 2 h after the race, whereas no change was observed in CSCI throughout the study. Conclusion: The present study demonstrated that wheelchair half-marathon race increases NKCA despite the lack of increase in plasma adrenaline in CSCI, suggesting the activation of NKCA by mechanisms other than circulating adrenaline level. Spinal Cord (2012) 50, 533-537; doi: 10.1038/sc.2011.188; published online 17 January 2012