Effects of Three Different Distance/Elevation Gain Ultra-Trail Races on Red Blood Cell Oxidative Stress and Senescence, and Blood Rheology.

Purpose: Red blood cell (RBC) senescence and blood rheology during ultraendurance running events appear to be affected differently depending on the race distance. The physiological mechanisms underlying these differences are poorly understood.

Methods: We investigated the effects of three different ultra-trail running races performed in La Reunion Island (Mascareignes, "the 70 km," 70 km/4000 m D+; Trail Du Bourbon, "the 100 km," 100 km/6090 m D+; Diagonale des Fous, "the 170 km," 170 km/10,500 m D+) on RBC oxidative stress, RBC senescence, and blood rheology in 66 finishers (18 "70 km," 24 "100 km," and 24 "170 km").

Results: We observed a decrease in RBC antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase, and catalase) positively related to the race distance and an increase in RBC H 2 O 2 and isoprostane levels after the three races. However, RBC H 2 O 2 and isoprostane levels were found to be higher after the 70-km race compared with the 170-km and the 100-km races. RBC phosphatidylserine externalization increased over baseline value after the 70-km race only. Chymotrypsin-like and trypsin-like activities of the RBC proteasome were decreased after all races compared with before. RBC-derived microparticles (RBC-MP) were increased after the 170-km and the 70-km races. Despite increased RBC senescence markers, RBC deformability increased after the three races. Blood viscosity was differently affected by the three races with a decrease at low shear rate after the two longest races (the 170 km and the 100 km) and an increase at high shear rate after the shortest one (the 70 km).

Conclusions: Our results confirm that ultraendurance running events differently affect RBC senescence markers and blood viscosity depending on the race distance and suggest that RBC oxidative stress could play a key role in the observed alterations.