Il-6, CRP And CK Responses To A 32.2-kilometer Trail Race In Experienced And Novice Runners

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In a preliminary study (n=8) we found that female runners with extensive mountain trail endurance racing experience had a more pronounced interleukin-6 (IL-6) response to a 32.2 km trail race with 2,073 m of ascent and 2,896 m of descent (Ed Anacker Bridger Ridge Run). We hypothesized that a protective effect related to the inflammatory response may occur with habituation to rigorous downhill running leading to a higher response of IL-6. The impact of this difference on C-reactive protein (CRP) and creatine kinase activity (CK) responses is unknown. PURPOSE To determine whether experienced runners differ in their IL-6, CRP, and CK responses following the Ed Anacker Bridger Ridge Run. METHODS Twenty-seven endurance-trained runners (14 male, 13 female) registered for a 32.2-kilometer trail race were divided according to history of at least three previous Ridge Runs or at least two ridge runs and at least one ultra (>42.2 kilometers) endurance event (experienced) or less (novice). Eighteen novice runners (mean ± SD: Age 30.9 ± 7.4 y, finish time 5.9 ± 1.2 h) and 9 veteran runners (Age 43.4 ± 13.4y, finish time 6.2 ± 1.3 h) Blood samples were collected on the afternoon before the run, and 0, 4, and 24 h post-race. Plasma and serum samples were analyzed for IL-6 (ELISA), CRP (EIA), and CK activity (enzymatic assay. Data were analyzed using a general linear model with group and time as main effects and race time and carbohydrate intake as covariates. RESULTS Interleukin-6 was increased pre- to 0-h post-race from 1.01 ± 0.55 to 32.22 ± 12.38 pg-ml1 for the experienced group and from 0.93 ± 1.05 to 33.26 ± 23.94 pg-ml1 for the novice group. No differences between groups were detected for IL-6. A significant group by time interaction (P <0.01) for CRP was measured, which increased (P <0.001) 24 h post-race. The increase from pre-race to 24 h post-race was 2.15 ± 1.95 to 36.27 ± 27.16 mg-1−1 for the experienced group and 0.69 ± 0.73 to 14.91 ± 7.49 mg-1−1 for the novice group. Creatine kinase activity increased (P <0.001) at 0, 4, and 24 h post-race, peaking at 4 h post-race for the novice runners (1515 ± 1094 IU-1−1) in the novice and at 24 h post-race for the experienced runners (1360 ±1106 IU-1−1). No differences in CK were detected between groups. CONCLUSION Using race time and carbohydrate intake as covariates, no difference in IL-6 was measured between experienced and novice runners. However, the systemic acute phase (CRP) response was more pronounced in experienced runners and the later peak in CK may be an indication that the kinetics of the inflammatory and muscle damage responses may differ between the groups. Supported by NIHP20RR-16455-03 from the BRIN Program of the NCRR to MPM.