Impact of Intravenous Iron on Aerobic Capacity and Iron Metabolism in Elite Athletes

Purpose: Iron deficient athletes are often treated with long term, low dose iron therapy. Such treatments may be efficacious in correcting iron deficiency, however the effect on acute and chronic iron metabolism and subsequent endurance capacity is less clear. Methods: Fifteen national and international standard runners were identified as iron deficient non-anaemic (IDNA)and assigned to either an intravenous iron treatment or placebo group. Participants completed 3exercise tests to volitional exhaustion; before treatment, within 24 h and 4 weeks after treatment. Results: Serum ferritin, serum iron, transferrin saturation were significantly improved in the iron group following intervention and compared to placebo (p < 0.05). Hepcidin levels were significantly greater before and after exercise following the iron injection (p < 0.05) and this was independent of changes in interleukin-6. There were no differences between groups in red cell indices, total haemoglobin mass, V! O2max, sub-maximal blood lactate, running economy, ratings of perceived exertion or time to exhaustion (p > 0.05). Conclusion: A single 500 mg intravenous iron injection is effective for improving iron status for at least 4 weeks but this does not lead to an improved aerobic capacity. This investigation suggests that iron availability supersedes inflammation in the regulation of hepcidin in IDNA endurance athletes following acute intravascular iron injection treatment.