Time course of neopterin and cytokines after an extreme bicycle race at moderate altitude

Endurance exercise induces several alterations in the immune and hematological system. At present it is unknown whether exercise under hypoxic conditions can modulate these changes. We investigated the effects of a prolonged endurance bicycle exercise in 8 healthy athletes (Oetztal Bicycle Marathon, OEBM; distance 230 km; vertical displacement 5000 m) on serum concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-a (TNF-α), neopterin as well as erythropoietin (EPO). Blood was collected before (A), immediately after the race (B), one (C), two (D), three (E) as well as five (F) days after the OEBM. We could demonstrate that IL-6 was increased significantly after exercise termination, whereas IL-1β and TNF-α were unchanged. Neopterin was significantly elevated from B to D, indicating an activation of the cellular immune system. Serum EPO was significantly increased from day 1 to day 5 after exercise which might reflect the combination of hypoxia and postexercise hemodilution.