Hamlin, M. J., & Hellemans, J. (2004). Effects of intermittent normobaric hypoxia on blood parameters in multi-sport endurance athletes. Medicine and Science in Sports and Exercise, 36(5), Supplement abstract 2316.

This study investigated the effect of intermittent normobaric hypoxic exposure in a simulated-altitude training device on selected blood parameters. Multi-sport endurance athletes of mixed ability (N = 22) were randomly assigned to either a placebo (M = 8, F = 2) or hypoxic group (M = 5, F = 7). Ss were given an intermittent normobaric hypoxic gas or a placebo gas containing ambient room air (placebo) in a randomized double-blind manner. Ss breathed the gas mixtures in five-minute intervals interspersed with five-minute recovery periods of ambient room air for a total of 90 minutes per day, five days per week, for three weeks. The hypoxic gas was adjusted from 13% oxygen at the beginning of week 1 to 10% by the end of week 3. Venous blood samples were taken before, 2, and 12 days after the placebo and intermittent hypoxic training exposure.

Hemoglobin changes from intermittent hypoxic training occurred by day 12, but not at day 2. Hematocrit responded quickly and more markedly across the period of exposure. Serum iron and ferritin decreased in the normobaric hypoxic condition.

Implication. Intermittent hypoxic breathing can elicit changes in hematological indices that suggest an acceleration of erythropoiesis. Only breathing the appropriate gas is required to elicit the response. One does not have to invest in a tent or chamber to produce this effect.

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