Elevated urinary biopyrrin excretion and oxidative bilirubin metabolism during 24-hour ultramarathon running.

: The oxidative metabolite of bilirubin, biopyrrin, is considered a useful candidate marker of oxidative stress in vivo. The present study examines whether urinary biopyrrin excretion is elevated and how general laboratory parameters are changed by long-duration running such as that involved in ultramarathons. Fifteen volunteer runners (12 males and 3 females; aged 44 +/- 9 years; means +/- SD) provided written informed consent to participate in this study. The 24-h experimental run was not a race against time but rather to determine the effects of running around a track for 24 h without sleep and sufficient rest. Blood and urine samples were obtained before (0 h), during (16 h), and immediately after (24 h) running for 24 h. All of the participants completed the run. The mean (+/- SD) distance run was 162.6 +/- 18.3 km. Mean urinary biopyrrin excretion values at 0, 16, and 24 h were 1.23 +/- 0.73, 2.55 +/- 0.95, and 4.00 +/- 1.50 U/g creatinine, respectively. Urinary biopyrrin excretion was positively and significantly correlated with the serum bilirubin concentration (p<0.05) and distance run (p<0.05). These results suggest that urinary biopyrrin excretion could be a useful marker of oxygen stress incurred during a 24-h ultramarathon.