The inflammatory response to a wheelchair half-marathon in people with a spinal cord injury - the role of autonomic function.

This study investigates the relationship between autonomic function and the inflammatory response to a wheelchair half-marathon in people with a spinal cord injury (SCI). Seventeen wheelchair athletes with a cervical SCI (CSCI, N = 7) and without CSCI (NON-CSCI, N = 10) participated in a wheelchair half-marathon. Blood was taken prior, post and 1 h post-race to determine the concentrations of adrenaline, noradrenaline, extracellular heat shock protein 72 (eHsp72) and interleukin-6 (IL-6). A sit-up tilt test was performed to assess autonomic function at rest. CSCI showed a lower supine ratio of the low and high frequency power of the variability in RR intervals (LF/HF RRI, p = 0.038), total and low frequency power of the systolic blood pressure variability (TP SBP, p < 0.001; LF SBP, p = 0.005) compared to NON-CSCI. Following the race, catecholamine concentrations increased only in NON-CSCI ( p < 0.036). The increase in IL-6 post-race was larger in NON-CSCI ( p = 0.040). Post-race catecholamine levels explained 60% of the variance in the IL-6 response ( r = 0.77, p = 0.040), which was further increased when the resting autonomic function indices were added to the regression model (R2  > 81%, p < 0.012). In summary, the dampened acute inflammatory response to a wheelchair half-marathon in CSCI was strongly associated with the autonomic dysfunction present in this group.