Austin, K. G., Daigle, K., Cowman, J., Bograd, B., & Haymes, E. (2004). Regulation of erythropoietin production and iron metabolism: Control by arterial oxyhemoglobin saturation vs. set altitude exposure. Medicine and Science in Sports and Exercise, 36(5), Supplement abstract 761.

"The rise in serum erythropoietin (Epo) concentration due to hypoxia has shown great individual variability. It has been proposed that the magnitude of Epo release is different due to varying magnitudes of hypoxic thresholds (as indicated by arterial oxyhemoglobin saturation [SaO2]). Prior studies have demonstrated an inverse relationship between Epo production and SaO2 , suggesting that the variation in Epo levels can be attributed to the variation in SaO2 " (p. S108).

College runners (N = 7) performed two experimental trials of continuous normobaric hypoxia (8 hours) for 5 consecutive nights. One condition simulated an altitude of 3,100 m with 14.2% oxygen content. The other employed arterial oxygen saturation of ~89%. Changes in blood characteristics were monitored.

There were no significant differences between the two conditions on all measures. Individual variations in responses were very noticeable.

Implication. Individual hypoxic thresholds need to be taken into account when examining responses to hypoxia.

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