AltoLab, A cheap Altitude Training system

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AltoLab is a cheap and effective way of Altitude Training. It uses a chemical (soda lime) to remove the CO2 from your exhaled breath, allowing you to rebreathe the air that now has lower O2. I have replaced my AltoLab with a DIY Altitude Training system that is cheaper and works better than the AltoLab system.

1 Introduction

The AltoLab consists of a Breathing tube and lid, a cylinder of CO2 absorbent (Hypoxic Silo) and a series of tubes filled with foam cylinders that hold your exhaled breath for you to re-breathe (mixers). Each mixer is supposed to be around 5,000 feet of altitude, though this obviously varies a lot.

AltoLab components

Below is a copy of the AltoLab manual page showing how the system works.

How AltoLab Works (click for a larger image)

2 Results

So far, I've used the AltoLab system for several bouts of training. The manual recommends using the system for 15 daily sessions, but I've found that I get better results from continued usage. I've found that training with AltoLab makes a difference to my performance both at altitude and at low levels. The training effect seems to build slowly, so it's not an obvious, dramatic change. However, I believe that the effect may compound over time, as the benefits of Altitude Training make me faster, which in turn allows for harder training as well as improved race performance.

3 Observations

  • The first training bout was the hardest to keep up. Each subsequent bout seems easier, but I'm not sure why. It may be that my body is remembering the adaptation, or it may be that I just know what to expect.
  • The manual suggests starting with 2 mixers, which should give a blood O2 saturation of 90%. Mine dropped to below 80%, which may be part of the reason I do so badly at altitude. By the fifth session I found my Breathing pattern changed, and my saturation did not drop as far.
  • For the first few sessions of my first training bout, I ignored the manual and let my blood O2 saturation drop to around 80%. This was enough to make me feel light headed and my vision to change. After 6-8 sessions, the saturation dropping to 80% did not cause the same problems.
  • After the first training bout, I ignored the manual even further and went directly to 4 mixers, and let my O2 saturation drop to around 75-70%.
  • One simple test I did to check the effectiveness of AltoLab was to check my O2 saturation when flying. After using the AltoLab, I found that my O2 saturation was noticeably higher than before. (I used a barometric altimeter to check the cabin pressure to make sure the circumstances were similar.)
  • After my first training bout I tended to ignore the slow, steady build up of intensity that the manual recommends and use four mixers (equiv 20,000ft) and aim to drop my O2 saturation to around 70-75%.
  • I use a different pattern of training than suggested by the manufacturer. I do 1 hour/day for 15 days, then change to half an hour each day thereafter, tapering for races. I find that 4x (6 min hypoxia + 2-3 min recovery) works quite well.
  • It's important to let everything dry between uses, especially the bacterial filter. If it gets damp, it is hard to breathe through.
  • Air you breathe through the AltoLab is quite warm, partly due to rebreathing exhaled air, partly due to the heat from the CO2 scrubber. I tend to drink something in the rest periods.
  • The downside to using the AltoLab is probably similar to other Altitude Training systems; being in a low O2 environment is unpleasant. I find myself struggling to perform the training sessions as the feeling of asphyxiation was off putting.
  • In theory you can watch TV while doing the AltoLab, and that’s how I used it, but the low O2 saturation can make it hard to concentrate at times.
  • If my O2 saturation drops below about 65% I tend to phase out, and it’s easy to drop into a strange dream like state for a few moments. This is almost a shamanistic experience, but I try to avoid this situation as it's probably quite unhealthy.
  • Reading a book while using the AltoLab is tricky because you need to hold the tube in your mouth.
  • You need to keep the mouth piece angled upwards to prevent saliva flowing into the system. If you don't the anti-bacteria filter will be hard to breathe through and the tube will fill up!
  • For the first couple of bouts of AltoLab training, the initial sessions seemed to leave me a little weakened and slower than normal. I also found that the Altitude Training tended to give me a headache that would come back periodically.
  • I found there is quite a bit of lag in using AltoLab. When you start Breathing through the AltoLab, it will take a couple of minutes before your O2 saturation drops, and when you have the rest period, it can also take a minute or more before your O2 saturation returns to near normal. However, I also found that the feeling of low O2 saturation seemed to lag even further behind the reading from the Pulse Oximeter. My assumption is that the O2 saturation of your blood can change, but the tissues your blood is supplying will take time to change to match the O2 saturation of your blood. The practical implication is that my blood O2 saturation could drop to 65% quickly and I would feel more or less okay for a short time. Once my blood O2 saturation had been low for a minute or so, the impact would kick in and I'd start to feel light headed. Likewise, when I had a rest period, my blood O2 saturation would rise to normal but my head would still be feeling the effects.
  • I do not use the nose clip, as I found it uncomfortable. I find I can breathe through my mouth quite easily and do not require a nose clip.
  • I wrote some software (Hypoxic Timer) that would interface with a USB enabled Pulse Oximeter. This gave me a graph of how my blood O2 saturation was changing over time. It also allowed me to calculate the 'Hypoxic Training Index' so I could compare different training sessions.

4 Conclusion

Overall, I think the AltoLab is a cost effective and useful way of training for high altitude conditions, and possibly for improvements at sea level. I suspect that the downsides of using other intermittent systems will be similar to AltoLab. From what I understand from other people who've slept in altitude tents, there are different, but equally significant downsides to that approach, including poor sleep quality.

5 Usage

Example of O2 saturation from an AltoLab training session. The green vertical line marks the end of the hypoxic time and the red vertical line marks the beginning of the hypoxic time. The red line is O2 saturation, with the green fill showing above 90%, blue fill showing 90-75% and the pink fill showing below 75%. The blue line is heart rate.

6 The parts ordered

I ordered the following components

  • The starter kit ($190) and which contains 3 mixers giving 5,000-15,000 ft of elevation, 2 CO2 scrubbers proving 4 hours of usage, and the tubes.
  • Three extra mixers for $36
  • Six extra CO2 scrubbers for $108 (I did not need these)
  • A Pulse Oximeter which are much cheaper than if you purchase them with the AltoLab.
  • Bulk CO2 scrubber. Each 3 pound bag is $7.80 + $10 shipping.
  • After some time, I ordered extra anti-bacterial filters, which cost less than $5 from a medical supplier. I got mine from Allegro Medical

Total cost was $306 (excluding the unused scrubbers). An alternative would be to buy

With the scrubber, that works out as $214.80

7 CO2 Scrubber

  • The CO2 scrubber lasted for two sessions of an hour, 6 minutes on, 3 minutes off. AltoLab claim 2-3 sessions.
  • The scrubber does not die quickly or obviously; I find my blood O2 saturation not dropping as far each time, but the biggest indicator is that I'm struggling to breathe. This is because the CO2 is building up in the blood and causing deeper Breathing. Swapping to a new scrubber returned to the original behavior.
  • The absorbent material (soda lime) has a color change that indicates when it is exhausted. However, the color change is only present immediately after use. If you leave the scrubber for a few hours, it will return to its original color, even though it is still expired.
  • I created a video of opening the silo for scrubber replacement at
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8 Running Costs

Each CO2 scrubber costs $22, or $18 when you by 6 at a time. This works out as a running cost of nearly $10 per hour, which can get a little pricey. I have found that the scrubbers open up quite easily, and can be refilled with a bulk CO2 scrubber. I used JorVet soda lime (see above) which is $10 for 3 pounds. Each CO2 scrubber holds about half a pound, and lasts for 3-4 sessions, rather than 2-3 for the original. This reduces the running cost less than $1 per hour.

9 What about just breathing through a tube?

Occasionally people ask if you can just breathe through a tube or snorkel rather than buying a system. Sadly, this does not work. All that happens is the CO2 in the tube builds up, so you breathe faster without lowering your O2 saturation.

10 Pure DIY

Looking at the parts for the AltoLab, it seems possible to construct one out of PVC piping, some foam, CPAP tube, etc., but this may require some effort to find the right parts. Given that the AltoLab system is only the cost of a couple of pairs of good running Shoes, it does not seem worth the effort.

11 Optional Oxygen Sensor

I added an oxygen sensor to my AltoLab set up to make it easier to control my SpO2 levels. I chose the OxyCheq Expedition-X Oxygen Analyzer because it has a separate replaceable sensor and a remote display, and the price was reasonable ($250 at Higher Peak, the cheapest place I've found it). I've found that knowing the oxygen level I'm Breathing gives me the finer control of how hypoxic I am as the Pulse Oximeter alone has a significant delay. If you start Breathing air with more or less oxygen it will sometimes take over a minute for this to affect the circulating blood in your fingertip that the Pulse Oximeter is monitoring. This delay makes it tricky to stay in the right SpO2 range. With the O2 sensor I can see how the depth of my Breathing is affecting the oxygen level, and combined with the Pulse Oximeter I'm able to get a much more effective hypoxic exposure. The diagram to the right shows my current configuration:

  • I generally use six of the black foam filled mixers.
  • Attached to the black mixer is the green CO2 scrubber, the end cap and the original hose.
  • Next the O2 sensor is attached to a blue "T" adapter. This is connected by a wire to the display unit. These sensors have an expected life of about two years, so it's handy for them to be easily replaceable.
  • Finally there is the viral filter, the optional expandable swivel tube and the mouthpiece.

The cost of the Oxygen Sensor more than doubles the cost of the overall system, but this was worthwhile to me as I use the system on a regular basis. I would not recommend getting an Oxygen Sensor until you know how you get on with basic setup, but I've found it much easier to control my SpO2 than using the Pulse Oximeter alone.

My AltoLab system with the OxyCheq O2 sensor attached.
The OxyCheq Expedition-X Oxygen Analyzer.

12 See Also