The Hypoxic Tent System creates an hypoxic environment within the tent via a  patented air separation unit that continually pumps low oxygen content air into the tent.  Inside the HTS the total pressure stays the same, and the oxygen content (%) reduces - so the partial pressure of oxygen is reduced.This allows the user to obtain the advantages of altitude training from any location.  It's like having your own portable mountain.

The process of the hypoxic method can briefly be described as follows: at altitude, or in it's hypoxic equivalent, the reduced partial pressure of oxygen means that the arterial oxygen saturation (a measure of the level of oxygenation in the blood) is reduced from it's normal level of about 98%.  After several hours this triggers the body to make it's normal adaptive response, the most significant being an increased rate of red blood cell production.

Red blood cells are responsible for delivering oxygen to the tissues (muscles) which combine with stored nutrients to produce energy.  Having more red blood cells allows one to deliver more oxygen to the working muscles.  This is the primary adaptation that translates into improved athletic performance. In the past, the only way to obtain this adaptation was to spend long periods of time in high altitude locations or in a reduced pressure (hypobaric) chamber.  The HTS allows you to not only create an hypoxic environment at any location, but it also provides a number of other advantages over typical high altitude/hypobaric training:
 

Unlike the constant hypoxia present in the mountains, the "intermittent" hypoxia of the HTS gradually adapts the body to perform normally in a low-oxygen environment, and substantially better in a normal oxygen, or "normoxic," environments (sea level). The body is thus adapted to both environments.

In addition to the physiological advantages that the HTS offers over traditional altitude training, there are also logistical advantages
 

     Using the HTS will:

• increase you red blood cell mass - This means more red blood cells are available to transport oxygen to the muscle cells. More oxygen to the muscles working muscle cells will result in improved performance.
• increase your total blood volume - this moves oxygen more efficiently through the blood stream. Greater blood volume means the heart's stroke volume (amount of blood pumped by the heart with each heartbeat) also increases  A greater stroke volume means more oxygen rich blood reaches the working muscles, again, resulting in improved athletic performance.
• increase your hematocrit (the ratio of red blood cells to total blood serum) - This means a greater percentage of the cells in your blood are carrying oxygen.
• increase your number of capillaries - More capillaries means there are more pathways for the blood to get to the muscle cells. With more blood to the muscle cells, there is more oxygen to convert to energy. With improved oxygenation of the muscles, there is better athletic performance.
• increase your muscle cell mitochondria.  The mitochondria are "the powerhouse of the cells" where oxygen is converted into energy. More mitochondria means the muscle cells can convert oxygen into energy more efficiently.
• improvement your oxygen association curve and increase your efficiency of gas exchange- This means that for every breath you take, more oxygen gets into the blood stream.
• increase your VO2 max - Your VO2 max is the maximum amount of oxygen your body can convert to work. More oxygen converted to energy equals more power, more endurance and greater speed and more power.
• Improve your aerobic capacity - This means increased endurance and faster speeds at a given level of exertion and more efficient metabolism.
• Improve your anaerobic capacity - This means increased endurance at high and max levels of exertion.  Using the HTS increases your  blood content levels of hemoglobin and myoglobin - both of which are excellent buffers of lactic acid. That is, they counter the build up of lactic acid which ultimately limits anaerobic capacity. In short, use of the HTS delays the onset of "the burn".

Using the HTS is actually better than being at altitude...

As you may have experienced, training at altitude, particularly for athletes who are coming from sea level, creates greater than normal stress on the body (due to the decreased content of oxygen in the air).  Consequently, training intensity levels must be reduced to tolerate the diminished oxygen content environment.  This can lead to a detraining effect that can often negate the positive physiological adaptations that occur as a result of being at altitude.

The "High-Low" Breakthrough

Recently the procedure of "living high" and "training low" has reduced this detraining effects while still providing the positive benefits. A study by Levine and Gundersen  looked at  39 competitive runners that were (following a 6-week control period) split into three groups:  Thirteen continued to live and train at sea-level, thirteen lived and trained at 2500m, and thirteen lived at 2500m but traveled down to 1250m to train.  

Despite the excellent gains, the High/Low groups program was still inherently a compromise: the training performed was still done away from home and at a
significant altitude (1250m) - certainly enough to have some detraining effect. Under ideal conditions, the High/Low group would have lived at 2500m, but trained at sea level. However, the physical limitations of finding a location where this is available without extreme daily travel (up and down the mountain) makes it impossible.   However, even with these compromises the improvement over the control group was quite significant, in the order of 40 seconds in 17 minutes.  The HTS would have allowed the High/Low group to train at sea level (ideal for training purposes) and sleep at altitude.