Neya, M., Maegawa, T., Kumai, Y., Enoki, T., & Kawahara, T. (2006). The effects of nightly normobaric hypoxia on running economy and hemoglobin mass. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 2728.

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This study investigated the effects of nightly intermittent hypoxia on total hemoglobin mass, maximum oxygen consumption, and running economy. College-level distance runners were assigned to a hypoxic group (N = 10) who rested and slept in hypoxic accommodation (O2 concentration = 14.5%; altitude = 3000 m) for ~10-12 hours per night and trained at sea level, or to a control group (N = 6) who slept and trained at sea level. The hypoxic period was 29 nights. Maximum oxygen consumption and total hemoglobin mass were measured before and 5-7 days after. Submaximal running economy was measured on a motorized treadmill at 12, 14, 16 and 18 km/h with four minutes at each speed.

Total hemoglobin mass and maximum oxygen consumption did not change in the “live simulated high, train sea level” condition. These results indicate that this duration of intermittent exposure to hypoxia was insufficient stimulate increased red blood cell production. The hypoxic group improved running economy at 18 km/hour.

Implication. This study showed that hypoxic sleeping was related to an improvement in running economy. Why the two would be associated is a mystery.

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