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[[Altitude Training]] is an effective way of improving performance or preparing for a visit to high elevation. However, many of the solutions are expensive, often running to the thousands of dollars. I've used the [[AltoLab]] system for some time, and while it works well, there are some obvious improvements that can be made, plus it's remarkably expensive for what it is. I've created a simple DIY altitude training system that is cheap, effective and does not require any significant fabrication tools or experience.
=How does it work?=
At high altitude there is the same percentage of oxygen in the air, but the air is under lower pressure, so each lungful contains less oxygen. This causes a drop in the level of oxygen in your blood (called [[SpO2|SpO<sub>2</sub>]]). Nearly all altitude training systems work by reducing the amount of oxygen in the air you breathe (hypoxia), rather than reducing the pressure (hypobaric). There are various ways of achieving this reduction in oxygen, but the simplest is to rebreathe your exhaled air. This works because you absorb oxygen from the air you breathe. Each time you rebreathe the same air the oxygen level drops. However, there is a problem with simply rebreathing the same air as the carbon dioxide levels rise as the oxygen level drops. Because your [[Breathing]] rate is driven by the CO2 level in your blood, this will cause you to increase your breathing, which in turn will prevent any drop in your blood oxygen level. The solution is to breathe in and out via a chemical that will remove the CO2, called a CO2 scrubber. This is the function of the [[DIY Hypoxicator]], which is at the heart of this DIY system.
=Types of Altitude Training=
''Main article: [[Altitude Training Approaches]]''
This altitude training system uses [[Intermittent Hypoxic Exposure]] (IHE), which uses repeated short periods of low oxygen (hypoxia) rather than a single overnight period that you would get with an 'altitude tent'. With IHE the hypoxia exposure is at rest rather than while exercising. Intermittent Hypoxia while exercising is called [[Intermittent Hypoxic Training]] (IHT), though the terminology is used inconsistently. This system could be used for IHT, but I've not tried that.
=What you will need=
You will need to get the following components.
|[[File:DIYH MouthpieceChoice.JPG|none|thumb|500px|A couple of other mouthpieces you can get. One is from the [http://www.allegromedical.com/respiratory-therapy-c534/micro-mist-nebulizers-with-6-corrugated-tube-p174367.html?a_aid=98b31cc5 MICRO MIST Nebulizer] ($2) and the other is from the [http://www.allegromedical.com/respiratory-therapy-c534/respirgard-ii-nebulizer-p176122.html?a_aid=98b31cc5 Respirgard II Nebulizer] ($12).]]
|}
=Three Configurations=
{| class="wikitable"
|[[File:With O2 sensor.JPG|none|thumb|500px|This is my configuration, with the optional O2 meter.]]
|}
=Cautions=
Please read this section carefully, as it is not simply a liability disclaimer.
* The mouthpiece should plug directly into the antiviral filter so that there is very little unfiltered air in the system.
* All tubing and equipment should be cleaned periodically. You really don't want to breathe in any mold or bacteria.
* The CO<sub>2</sub> scrubber can produce Carbon Monoxide, but this appears to only occur if the CO<sub>2</sub> scrubber becomes desiccated (dried out) and comes into contact with anesthetic gasses<ref name="AhmedMannion2011"/>. As altitude training does not involve anesthesia (the primary use of CO<sub>2</sub> scrubber), this should not apply. However, if you're concerned, you can use a latest generation scrubber such as Amsorb Plus which does not produce carbon monoxide.
=Using the System=
* Connect all the parts as shown in the pictures above.
* Once your [[SpO2|SpO<sub>2</sub>]] drops, but before it reaches your target you will need to start mixing some room air into the system. You can either do this by cracking open the ball valve slightly or by taking a partial breath from the room. You will need to find the right balance of room air to rebreathed air that will keep your [[SpO2|SpO<sub>2</sub>]] near your target based on trial and error. This is takes some practice to get right, but it a lot easier with the ball valve.
* Once your time is up, remove the mouthpiece and breathe room air. After the recovery period, restart the hypoxia and repeat the appropriate number of intervals.
=IHE Plans=
Guidance on the plans for the pattern of hypoxic exposure and recovery can be found at [[Intermittent Hypoxic Exposure]].
=Hypoxic Timer =
I've created a simple utility that interfaces to a [[Pulse Oximeter]] and displays the real-time [[SpO2|SpO<sub>2</sub>]], as well is calculating the hypoxic dose (Hypoxic Training index, or HTi). You can find more details at [[Hypoxic Timer]].
|[[File:HypoxicTimer.jpg|none|thumb|500px| A screenshot of the [[Hypoxic Timer]].]]
|}
=After Use=
After you've finished using the system, disconnect the parts to let them dry out. However, the hypoxicator should not be dried out as moisture is part of the CO2 scrubber. Put the hypoxicator into a plastic bag and seal it so that it is airtight. You will see quite a bit of condensation in the hypoxicator, which is quite normal.
=CO2 Scrubber Replacement=
Because the CO2 scrubber uses a chemical reaction to remove the CO2, it will become exhausted over time. I've found that the scrubber seems to last much longer in my DIY system than the [[AltoLab]] system I used before. The best indication that the scrubber is exhausted is that you will feel a change in your lungs. This feeling is due to the buildup of CO2, which creates a strong desire to breathe, and you will feel like you can't get enough air. If you have that feeling, it's time to replace the CO2 scrubber. The scrubber has a color change indicator that will go purple, which you can see if you use a clear sided container. The color will change even on the first use, but it will fade after a few hours. I've found that once the color change is still present next time I come to use the system it's probably close to exhaustion.
|[[File:ExhaustedScrubberImmediate.JPG|none|thumb|500px|Immediately after use the CO2 scrubber had a much darker color.]]
|}
=Troubleshooting=
There are a few common problems you may encounter with this DIY system.
* If your CO2 scrubber seems to get exhausted quickly, check that you are filling it fully. See the image below for details.
[[File:PartialFillScrubber.JPG|none|thumb|500px|Here you can see the result of a slight air gap at the top of the scrubber. The air is choosing the path of least resistance, and flowing up and over the CO2 scrubber, resulting in poor CO2 removal and rapid depletion of the scrubber. The color of this picture has been enhanced so you can see the purple of the exhausted scrubber, and I've outlined the area. Note that there is only a slight air gap, but it's enough to make a difference.]]
=Iron Deficiency and Anemia=
If you are deficient in iron then it will be difficult for your body to adapt to altitude training. The best thing is to get your iron levels checked with a serum ferritin blood test. I have mine tested periodically at a local [http://www.walkinlab.com/ferritinserumtest.html Walk In Lab]. The cost is about $40, though they sometimes run offers.
=Other People's Systems=
If you build one of these systems, I'd be grateful if you let me know how you get on. I'm also interested if you find any improved parts or other suggestions for improvements. Below are photos of systems that other people have built.
|[[File:Ted DIY 2.jpg|none|thumb|500px|Bag close-up]]
|}
=References=
<references>
<ref name="AhmedMannion2011">Osman Ahmed, Stephen Mannion, The Cost Implications of Replacing Soda Lime with Amsorb Plus in Clinical Practice, ISRN Anesthesiology, volume 2011, 2011, pages 1–4, ISSN [http://www.worldcat.org/issn/2090-5548 2090-5548], doi [http://dx.doi.org/10.5402/2011/730483 10.5402/2011/730483]</ref>
</references>