Serum biomarkers fluctuate as a result of running marathons, but their changes during ultramarathons have not been adequately studied. We collected blood samples from 20 participants before and 21 participants after the 161-km ultramarathon in Leadville, Colorado in August 2013. Using a portable analyzer, we measured cardiac troponin I (cTnl), hematologic, and metabolic biomarkers. Out of 10 runners for whom we collected both pre- and post-race samples, 8 were able to successfully complete the race. Mean cTnl increased from 0.001 to 0.047 ng/mL (p=0.005). Mean sodium decreased from 141 to 138 mmol/L (p <0.01). However, all runners had a sodium of ≥135 mmol/L post-race (reference range 138-146 mmol/L). Mean creatinine increased from 0.93 to 1.17 mg/dL (p <0.05). Only one out of 10 runners had an abnormal creatinine level of 1.8 mg/dL post-race (reference range 0.6-1.3 mg/dL). The other parameters did not reach statistical significance. Analyzing the samples from 21 runners after the race revealed that runners who finished the race in faster time had higher cTnl levels compared to those who finished the race close to the 30-hour cut-off finish time (P=0.005). Running an ultramarathon caused significant changes in cardiac and metabolic parameters. Ultramarathon running intensity and finish time may have effects on post-race cTnl level.
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