OBJECTIVES: Previous studies have suggested that acute exercise-induced cardiac and kidney damage following ultra-distance running is low in Mexican Tarahumara even though C-reactive protein (CRP) remained elevated 24 hours post-race. We aimed to study if the plasma biomarker, soluble urokinase-type plasminogen activator receptor (suPAR), could replace or complement CRP as a systemic inflammation biomarker in Tarahumara men and women following ultra-distance running.

METHODS: Plasma samples were collected pre-race and at three to six different time points post-race in Mexican Tarahumara competing in three independent ultramarathons; men running 78 km (GroupI, n = 9), women running 52 km (GroupII, n = 3), and men running 63 km (GroupIII, n = 10). Baseline anthropometry, blood pressure, glycated hemoglobin, and hemoglobin were measured, aerobic fitness was estimated by submaximal step test, absolute and relative running intensity assessed using combined heart rate and accelerometry. Plasma was collected pre- and post-race to analyze concentrations of suPAR, and-for women only-a panel of inflammatory, cardiac and kidney plasma biomarkers. Mixed-effect models were used to evaluate the effect of ultramarathon running on plasma suPAR concentrations.

RESULTS: Compared to pre-race values, suPAR was significantly elevated in plasma <5 minutes after the three ultramarathon races (70%-109% increase of the mean for the three groups). Furthermore, plasma suPAR remained significantly elevated up to 6 hours post-race for all three groups of runners independent of running intensity.

CONCLUSIONS: The results suggest that suPAR can complement, but not replace CRP following ultra-distance running in Tarahumara men and women.