Stray-Gundersen, J., Karlsen, T., Resaland, G. K., Aasen, S., Lind, C., Birkelan, K., & Hallen, J. (2000). No difference in 3-day EPO response to 8, 12, or 16 hours/day intermittent hypoxia. Medicine and Science in Sports and Exercise, 32(5), Supplement abstract 1221.

"Intermittent normobaric hypoxia has been utilized to obtain an increase in red cell mass based on the "Living High, Training Low " model. Presumably, the mechanism for an increase in red cell mass is an hypoxia induced increase in circulating levels of erythropoietin (EPO)" (p. S251). The EPO responses to 8, 12, and 16 hours of normobaric hypoxia (2,440 m, 15.45% oxygen) were compared in male endurance athletes (N = 8).

EPO increased over baseline in each condition. There were no differences between conditions. There was considerable variation between Ss, with a minimal response in three of them. The highest concentration of EPO was recorded at four hours in the 8-hour trial.

It was concluded that intermittent normobaric hypoxia of as little as eight hours per day will increase EPO significantly over three days, provided the stimulus is sufficiently severe. Longer daily periods of exposure do not yield any further response. [No control group or control over extraneous factors was exhibited in this study. It is possible that resting in the tent environment allowed recovery to accelerate, which influenced EPO production. It is difficult to understand why EPO levels remained elevated when exposed to 20 hours of normobaric normoxia.]

Implication. The EPO response to normobaric hypoxia occurs quickly.

Return to Table of Contents for this issue.