Effect of iron supplementation during high altitude training on haemoglobin and iron status of Sri Lankan middle- and long-distance athletes

Background: Literature reports significant disparities in the haematological response to altitude training among endurance athletes. The role of iron in determining the haematological response to altitude training is under-investigated.

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Objective: This study compared haematological parameters between Sri Lankan endurance athletes exposed to hypoxic and normoxic conditions, with and without iron supplementation.

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Method: Sri Lanka Army long and middle-distance male athletes were studied under four conditions; low altitude non-supplemented [LOW: n=14] and supplemented [LOW-S: n=7], high altitude non-supplemented [HIGH: n=6] and supplemented [HIGH-S: n=7]. High altitude groups lived at 2200 m and trained at 1800 m. Low altitude groups lived and trained at 40 or 120 m. All athletes underwent endurance training for five weeks. Pre and post intervention blood samples were obtained to determine haematological parameters.

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Results: A significant increase in haemoglobin concentration (0.67 g/dl) was observed in the two high altitude groups after five weeks of training (p=0.004). Serum ferritin decreased by 28.4% (p=0.05) and red cell distribution width increased (p=0.04) in HIGH while ferritin increased by 26.5% (p=0.08) and red cell distribution width decreased (p=0.01) in HIGH-S. No changes were observed in the low altitude groups.

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Conclusion: A substantial haematological response is observed when Sri Lankan endurance athletes are exposed to an adequate hypoxic dose. However, non-iron supplemented athletes are at a tendency to develop iron deficiency whilst supplemented athletes may accumulate iron even with previously recommended levels of pre-altitude ferritin