Literally, Intermittent Hypoxia should be understood as any exposure to hypoxia that is not continuous 24 hours a day.
Although it is possible to be exposed to a continuous environmental hypoxic state in an artificial environment (Hotel / Hypoxic Apartment), it is not usual due to the practical limitation for an athlete to be confined in a reduced environment for a long period (~ 12 days – 8 weeks) required to benefit from the adaptations of a simulated altitude stay.
Therefore, in practice, Simulated Altitude Training methods have to be understood as Intermittent methods in one way or another.
Said intermittence can vary in the duration of the hypoxic cycle (long, medium, short, very short), in the Mode of application (unicycle, multicycle), in the Activity carried out during the cycle (rest, sleep, exercise), in the Intensity of the hypoxia applied (medium altitude to extreme altitude) and the Type and Recovery Time between cycles (recovery in normoxia or hyperoxia) that will set the pattern for the Intermittent Hypoxia cycle.
The percentage of arterial oxygen saturation in the blood will be the most accurate and immediate indicator of the effect of applying the systemic hypoxia method used.
In the event that physical activity is carried out during the hypoxic cycle, the hypoxemia generated will be a mixture of that caused by the degree of environmental hypoxia as well as that produced by the body’s own oxygen consumption, as a result of said activity.
These factors can be individually modulated within a joint strategy, in pursuit of specific individual objectives. Science has not yet said everything in this field and research is still ongoing and novel results are found that may help the athlete in their preparation.
A key factor to monitor throughout the process is the individual response of the subject exposed to hypoxia, which can be highly variable, which is why individualized observance is recommended.
Within the models or types of Intermittent Hypoxia application techniques, we can mention the following:
Of these, the last 2 have different modalities.