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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|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]]''
* '''CO2 Scrubber'''. As detailed in the [[DIY Hypoxicator]] instructions, the CO2 scrubber is a consumable, so buy enough to last you for a few weeks. I typically buy 3-5 bags at a time.
* '''Pulse Oximeter'''. To monitor and control your altitude training, and to keep you safe, you need to measure your [[SpO2|SpO<sub>2</sub>]] with a [[Pulse Oximeter]]. You can get a good one for about $35, or one with a PC interface for recording and analysis with the [[Hypoxic Timer]] software for $85. Using this system without a [[Pulse Oximeter]] is dangerous as you may drop your [[SpO2|SpO<sub>2</sub>]] too low.
* '''Timer'''. You will need to time your hypoxic and recovery periods, either with a simple countdown timer or with some software like the [[Hypoxic Timer]] .
* '''Viral/bacterial filters'''. These will keep your lungs clean and should be replaced periodically. I have 2-3 open that I cycle through to make sure they have plenty of time to dry out between uses. They cost around $3 each; [http://www.allegromedical.com/respiratory-therapy-c534/main-flow-bacterial-viral-filter-p547468.html?a_aid=98b31cc5 Main Flow Bacterial/Viral Filter at Allegro Medical] or [http://www.allegromedical.com/wound-care-c541/breathing-filter-p548489.html?a_aid=98b31cc5 Breathing Filter].
* '''Hose'''. The hose I use is cheap, though you have to buy it in 100 foot (30m) lengths for $15. [http://www.allegromedical.com/respiratory-therapy-c534/corr-a-flex-ii-roll-tubing-p174363.html?a_aid=98b31cc5 CORR-A-FLEX II Roll Tubing at Allegro Medical].
|[[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.
* Like any form of training, altitude training has some inherent risks associated with it. It's a good idea to talk to your physician before starting any new form of training. If you have any concerns or possible medical issues, you should discuss altitude training with your relevant medical professional.
* I have not found a clear, approved list of contraindications, but the following symptoms are listed as reasons why you should not perform altitude training without explicit medical approval.
** Acute infections.
** Severe Chronic Obstructive Pulmonary Disease (COPD).
** Epilepsy.
** High blood pressure, such as over 145 systolic or over 90 diastolic.
** Low blood pressure, such as under 80 systolic or under 50 diastolic.
** Heart disease, pacemakers or irregular heartbeat.
** Blood disorders, such as sickle cell anemia.
** Anemia.
* I have seen no research on the effect of altitude training on pregnancy, but it would seem prudent to avoid altitude training if you are pregnant or believe that you maybe.
* If you are using altitude training to treat a specific medical condition such as asthma, sleep apnea, heart disease, Parkinson's disease, Alzheimer's disease, etc., then consulting your medical specialist is especially vital.
* It's unclear what the optimum [[SpO2|SpO<sub>2</sub>]] level should be, but generally [[SpO2|SpO<sub>2</sub>]] levels below 75% are not recommended and should be avoided.
* '''Never''' use the altitude training system without monitoring your [[SpO2|SpO<sub>2</sub>]]. While there are symptoms of low [[SpO2|SpO<sub>2</sub>]], such as lightheadedness or tunnel vision, these are not reliable predictors of a particular [[SpO2|SpO<sub>2</sub>]].
* The soda lime used to absorb the carbon dioxide is corrosive, and inhaling any soda lime is extremely harmful and will cause lung damage. Therefore, '''never''' use the hypoxicator without the antiviral filter in place and check the filter is intact.
* '''Never''' attach the mouthpiece to your face. If you should lose consciousness, it's vital that you'll drop the mouthpiece and breathe normal room air.
* Having your blood tested to ensure you are not anemic is highly recommended. The standard anemia test is often considered inadequate and instead you should get your serum ferritin levels checked. The range of values considered 'normal' varies between different authorities, but a representative example is 12-300 ng/mL for men and 12-150 ng/mL for women. However, it is recommended that for altitude training serum ferritin levels are above 60 ng/mL. (Remember that iron is toxic, so you need just the right amount. Do not take supplementary iron without knowing for sure that you need it.)
* The antiviral filter should be replaced periodically, and you should make sure it dries out fully between uses. I typically have 2 to 3 filters that I rotate through to make sure they are completely dry.
* 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.
=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.
=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.