Iron insufficiency diminishes the erythropoietic response to moderate altitude exposure

Kazunobu Okazaki, James Stray-Gundersen, Robert F. Chapman, Benjamin D. Levine

Research output: Contribution to journalArticle

Abstract

The effects of iron stores and supplementation on erythropoietic responses to moderate altitude in endurance athletes were examined. In a retrospective study, red cell compartment volume (RCV) responses to 4 wk at 2,500 m were assessed in athletes with low (n = 9, ≤20 and ≤30 ng/mL for women and men, respectively) and normal (n = 10) serum ferritin levels ([Ferritin]) without iron supplementation. In a subsequent prospective study, the same responses were assessed in athletes (n = 26) with a protocol designed to provide sufficient iron before and during identical altitude exposure. The responses to a 4-wk training camp at sea level were assessed in another group of athletes (n = 13) as controls. RCV and maximal oxygen uptake (VO2max) were determined at sea level before and after intervention. In the retrospective study, athletes with low [Ferritin] did not increase RCV (27.0 ± 2.9 to 27.5 ± 3.8 mL/kg, mean ± SD, P = 0.65) or VO2 max (60.2 ± 7.2 to 62.2 ± 7.5 mL•kg-1•min-1, P = 0.23) after 4 wk at altitude, whereas athletes with normal [Ferritin] increased both (RCV: 27.3 ± 3.1 to 29.8 ± 2.4 mL/kg, P = 0.002; V O2max: 62.0 ± 3.1 to 66.2 ± 3.7 mL•kg-1•min-1, P = 0.003). In the prospective study, iron supplementation normalized low [Ferritin] observed in athletes exposed to altitude (n = 14) and sea level (n = 6) before the altitude/sea-level camp and maintained [Ferritin] within normal range in all athletes during the camp. RCV and VO2max increased in the altitude group but remained unchanged in the sea-level group. Finally, the increase in RCV correlated with the increase in VO2 max [(r = 0.368, 95% confidence interval (CI): 0.059-0.612, P = 0.022]. Thus, iron deficiency in athletes restrains erythropoiesis to altitude exposure and may preclude improvement in sea-level athletic performance. NEW & NOTEWORTHY Hypoxic exposure increases iron requirements and utilization for erythropoiesis in athletes. This study clearly demonstrates that iron deficiency in athletes inhibits accelerated erythropoiesis to a sojourn to moderate high altitude and may preclude a potential improvement in sea-level athletic performance with altitude training. Iron replacement therapy before and during altitude exposure is important to maximize performance gains after altitude training in endurance athletes.

Original languageEnglish (US)
Pages (from-to)1569-1578
Number of pages10
JournalJournal of applied physiology
Volume127
Issue number6
DOIs
StatePublished - Jan 1 2019

Keywords

  • Anemia
  • Ferritin
  • Long-distance running
  • Red cell mass

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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