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The Science of Intermittent Hypoxic Exposure

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The research shows that there is wide individual variation in the response to IHE and altitude. This variation exists in both humans and animals, and appears to be due to mechanisms beyond simple iron insufficiency.
==Research from the USSR==A lot of research on IHE has come from the former USSR<ref name="USSR"/>==.
* Expose subjects to 15,000 feet for 1 hour per day over several days for 7 to 11 sessions showed increased blood O<sub>2</sub> saturation compared with initial exposure and the benefits were detectable for up to 4 weeks.
* Exposure of 30 min to 3 hours every 2 to 3 days for 9 exposures increased hemoglobin by 12% and red blood cells by 22%
* Recent studies indicate that IHE stimulates NO (Nitric Oxide) production, with the excess stored in the vascular walls. This improves blood pressure.
* Research indicates that there is a very wide variability in the response to altitude (IHE or other) and tolerance of extreme hypoxia. Future research may provide methods of overcoming the lack of response in some individuals.
==Western Other Research==
* Research<ref name="jack"/> using highly trained runners showed no running improvement with IHE. However, this study used IHE for 4 weeks and had O<sub>2</sub> saturation values of 89.9, 86.3, 85.9, and 81.4 for each week. The value of IHE is dependent upon the O<sub>2</sub> saturation levels, with little effect until values under 89%<ref name="HTI"/>. The athletes in the study therefore only received significant hypoxia for about one week. The athletes were given 5 min hypoxic, 5 min normal for 70 minutes total for five days per week, 4 weeks total.
* A similar research<ref name="junis"/> study showed a significant improvement in 3K running performance. This study used 90 minutes of IHE (5 hypoxic:5 normal) for 15 days over a three week period, using 13,000 feet at the start to 19,000 feet at the end.
* Subjects exposed hypoxia in a hypobaric chamber showed elevated EPO levels after 114 min at 9,000 feet and or after 84 minutes at 12,000 feet. EPO levels continued to rise with longer exposure. <ref name="acu"/>
* Research using the [[AltoLab]] system showed a significant improvement in sprint speed. The study used 6 min hypoxia (10,000 to 18,000 ft) with 4 min recovery for an hour a day for 15 days. The study shown a tiny improvement in blood parameters (hemoglobin/hematocrit) normally associated with altitude training.<ref name="alto"/>
* IHE ==Intermittent Hypoxic Exposure and Asthma==Studies have reported an improvement in asthma, with reduced attacks, reduced severity of attacks and reduced need for medication. ** IHE increased lung force in asthmatic and non-asthmatic athletes<ref name="asthmatic"/>. There was no deterioration in asthma status from the trial, and half of the asthmatics reported a reduction in the need for medication. The trial used 15 sessions over three weeks, with each session being 5 min hypoxia followed by 5 min normal air, repeated for 60 minutes. The hypoxia was equivalent to 22,500 ft. ** IHE has been shown to reduce the shortness of breath and congestion of childhood bronchial asthma, reducing or eliminating the attacks<ref name="Serebrovskaya-2012"/>. The protocol was 4 repeats of 5-7 minutes with 12% O<sub>2</sub> which resulted in a [[SpO2|SpO<sub>2</sub>]] of 89-92%. Other studies have reported a similar improvement * IHE reduced the bronchial resistivity by 31–37% in bronchial asthmapatients<ref name="Levashov-2012"/>. IHE also increased reserves of lung ventilation, restored the physiological level of alveolar ventilation in 78% of patients with reduced attacks, reduced severity of attacks and reduced need for medicationchronic obstructive pulmonary disease (COPD)<ref name="Levashov-2012"/>.  
==IHE and Live High, Train Low==
Some literature considers sleeping at altitude (or with low oxygen levels) to be 'IHT'. This Wiki uses IHT to be separate from LHTL and to mean shorter periods than overnight [[Zeo Sleep Monitor|sleep]] and generally at much lower oxygen concentrations.
<ref name="HTI">http://en.wikipedia.org/wiki/Hypoxic_Training_Index Hypoxic Training Index</ref>
<ref name="Serebrovskaya-2012">Serebrovskaya, Tatiana V., et al. "Intermittent Hypoxia in Treatment of Bronchial Asthma in Childhood." Intermittent Hypoxia and Human Diseases. Springer London, 2012. 135-143.</ref>
<ref name="Levashov-2012">Levashov, Mikhail I. "Beneficial Effects of Intermittent Normobaric Hypoxic Training on Respiratory Function in Patients with Chronic Pulmonary Diseases." Intermittent Hypoxia and Human Diseases. Springer London, 2012. 115-126.</ref>
</references>
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