Military personnel frequently experience declines in iron status during training and when in the field, which may compromise performance. The overall purpose of this study is to determine why the decline in iron status occurs and potential countermeasures. Participants will be given an acute dose of erythropoietin (EPO) or placebo and will complete a 90-minute load carriage exercise test. Prior to the main trial, this pilot study will determine the optimal approach to assess iron absorption following exercise (red blood cell incorporation or plasma isotope appearance), the percentage of iron incorporated into red blood cells with EPO compared to placebo, and the timing of the intervention.