2.5. Erythropoietin Levels

Upon arrival to the laboratory on Visit 2, a venous blood draw was obtained for later analysis of EPO levels. Previous studies consistently reported EPO levels peaking 2–3 h following termination of hypoxic bouts [10,20,21,22,23,24]; therefore, another blood draw was performed 2 h following the completion of the intermittent hypoxia protocol or intermittent normoxia protocol. Following collection, blood was centrifuged and serum aliquoted and stored at −80 °C for subsequent analyses. EPO levels were determined using an enzyme-linked immunosorbent assay (Abcam, Cambridge, UK).