Interval Hypoxic Training
(also known as Intermittent Hypoxic Training)
In Interval Hypoxic Training (IHT), also known as Intermittent Hypoxic Training, you do short intervals alternating between low oxygen air and normal air, using a mask. Although substantially different than sleeping at altitude, the goal of IHT is the same: improving athletic performance and/or acclimatization to high altitude. See also: Sleeping at high altitude (live high-train low).
The main effects of IHT are increasing the body's ability to tolerate low oxygen saturation levels in the blood, and increasing the efficiency of oxygen utilization in muscle cells. The increased oxygen economy caused by IHT is different than the effects of sleeping at altitude, which mainly boosts red blood cells counts. By performing IHT at several times per week, and optionally combining it with sleeping at altitude, you will increase the efficiency of oxygen utilization in muscle cells. Many users find IHT an effective, time saving method of altitude training and altitude acclimatization.
To perform IHT, you use a breathing mask supplied by a hypoxic generator such as the MAG-30. You alternate periods of breathing through the mask with periods of breathing normal air, and repeat this mask-on/mask-off pattern for a set amount of time or a set number of intervals. IHT is usually performed at high altitudes (low oxygen concentrations), anywhere from 10,000 to 20,000 feet (3000 to 6500 meters), or between 9.5% and 14% oxygen.
There are several different ways to approach IHT. They divide into three different categories: (1) short intervals of hypoxic exposures at rest, (2) short intervals of hypoxic exposure during high-intensity exercise, and (3) steady hypoxic exposure during aerobic exercise. Unfortunately, the naming of the different protocols has not been consistent, and the same or similar acronyms have been by different authors used to mean different things. We'll try and sort things out.
The main effects of IHT are increasing the body's ability to tolerate low oxygen saturation levels in the blood, and increasing the efficiency of oxygen utilization in muscle cells. The increased oxygen economy caused by IHT is different than the effects of sleeping at altitude, which mainly boosts red blood cells counts. By performing IHT at several times per week, and optionally combining it with sleeping at altitude, you will increase the efficiency of oxygen utilization in muscle cells. Many users find IHT an effective, time saving method of altitude training and altitude acclimatization.
To perform IHT, you use a breathing mask supplied by a hypoxic generator such as the MAG-30. You alternate periods of breathing through the mask with periods of breathing normal air, and repeat this mask-on/mask-off pattern for a set amount of time or a set number of intervals. IHT is usually performed at high altitudes (low oxygen concentrations), anywhere from 10,000 to 20,000 feet (3000 to 6500 meters), or between 9.5% and 14% oxygen.
There are several different ways to approach IHT. They divide into three different categories: (1) short intervals of hypoxic exposures at rest, (2) short intervals of hypoxic exposure during high-intensity exercise, and (3) steady hypoxic exposure during aerobic exercise. Unfortunately, the naming of the different protocols has not been consistent, and the same or similar acronyms have been by different authors used to mean different things. We'll try and sort things out.
(1) Short-Interval Hypoxic Exposure at Rest
aka Intermittent Hypoxic Training (IHT) or Intermittent Hypoxic Exposure (IHE)
Short-interval hypoxic exposure at rest involves 3-5 minute periodic exposures to low-oxygen air, alternated with normal air, while remaining sedentary (for example, reading or watching TV). A typical pattern is 5 minutes on, and 5 minutes off, repeated for 1 hour. The process is usually monitored using a fingertip pulse oximeter, which measures the oxygen saturation of the bloodstream. The goal is to get the blood oxygen saturation level down to 80 to 85% during the low-oxygen (mask on) interval, and recover to 95% or higher during the recovery (mask-off) interval. Research shows that short-interval hypoxic exposure at improves high-altitude tolerance, promotes ventilatory response (lung capacity), and is useful for altitude acclimatization.
(2) Hypoxic Exposure During High-Intensity Intervals
aka Intermittent Hypoxic Exercise (IHE) or Intermittent Hypoxic Exposure during Interval Training (IHIT)
A growing body of evidence shows that short bouts of high-intensity exercise are more likely to improve athletic performance more than sustained moderate exercise. Doing short intense intervals under low-oxygen conditions multiplies the effectiveness of interval training. Intervals are done with the altitude mask, and recovery between intervals is done at room conditions (mask off). Intervals typically last 1-3 minutes, with similar periods for recovery. Research shows clear evidence that short-interval hypoxic exposure during high-intensity exercise promotes adaptations at the molecular level in skeletal muscle tissue, as well as promoting better ventilatory response (lung capacity), leading to athletic performance gains at sea level and at altitude.
(3) Steady Hypoxic Workouts (Aerobic)
Although not strictly IHT, we include steady-state aerobic hypoxic workouts for completeness. Hypoxic workouts involve light to moderate exercise in low-oxygen air, delivered through a mask, typically on a cycle trainer or treadmill. The duration of an aerobic hypoxic workout is significantly longer that the short interval exposures, for example, 15 minutes to 1 hour or longer. HW improves high-altitude tolerance, and is excellent preparation for high-altitude events, including mountaineering. Hypoxic workouts can simulate the same conditions that may be encountered at high altitude. For example, you might prepare for a high-altitude trek on an inclined treadmill, wearing a weighted backpack.
Which IHT protocol is right for you?
Finding the best protocol for your training depends on your goals. At the risk of oversimplifying, we offer the following rules of thumb:
- To help acclimatize to altitude and increase your tolerance for oxygen debt, do interval hypoxic exposure at rest (#1 above)
- To achieve the most rapid gains in peak athletic performance, do hypoxic interval training (#2 above)
- To rehearse conditions and prepare for high altitude events, do steady hypoxic workouts (#3 above)