Altium i10 offers altitude adaptation in a can

New rebreather simulates altitude, trial shows performance gains

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Altitude training has long been a go-to performance enhancer for pro cyclists. Many of the world’s top riders seek heady heights of between 1,800 and 3,000m in search of a red-blood cell boost. Not everyone has the luxury of training in Tenerife, though, which is where the Altium i10 comes in.

Altium’s device is named after the Kenyan village of Iten, which sits at over 2,400m and is a home away from home for many world-class runners. The i10 aims to replicate the benefits of breathing the same high-altitude air as its namesake no matter where you are.

The i10, which costs £500, is essentially a rebreather. When you inhale, ambient air enters at 21 percent oxygen. When you exhale, a consumable soda lime cartridge – as used during general anaesthetics – absorbs and removes all exhaled CO2. The more you breathe through the i10, the lower the blood’s oxygen saturation gets – the proportion of oxygen dissolved in the blood – and the higher the altitude that’s emulated.

It’s worth mentioning that the i10 isn’t actually a substitute for training at altitude. Rather, it works like an altitude tent, giving access to breathing at such elevations and the apparent gains that can be made from this alone.


The i10 was designed using computational fluid dynamics, the same computer-aided technology used in the production of aero bikes. This allowed the parameters of the device to go through the trial and error process before production.

The i10 is quite large. Its PC central chamber has an aluminium skin and the whole device is wrapped in soft-touch plastic. The soda lime cartridges are screwed into the top and there’s a plastic lid into which a breathing spout is inserted for use. The i10 takes a bit of calibration to optimise for each athlete. This is achieved through the addition or removal of foam discs within the chamber and rubber studs on its base. 

Using the i10

Designed for use at rest, Altium recommends using the i10 for hour-long sessions. These are made up of repeated blocks of six minutes breathing through the i10, four minutes off. During time breathing through the i10, oxygen saturation (SpO2) should be brought down to, but not below, 80 percent. 

To accommodate this, the i10 comes with an oximeter. This simple device slips over your finger and measures your SpO2. This gives you an indication of when to take a breath outside of the i10 to avoid levels dropping too far.

The oximeter also communicates with Altium’s app, which takes auto readings and gives a live indication of your current ‘elevation’. Altium is also planning Strava compatibility based on breathing ‘altitude’. The app will link its data with performance uplifts on exercise-tracking sites, too.

The soda lime cartridges change colour when their efficacy diminishes, letting you know it’s time for a new one. Altium says each cartridge should last two to three one-hour sessions. The company is also looking into an alternative for soda lime that might offer a better user experience. Replacements will cost around £8 and Altium is planning a subscription service for ordering more.

Soda lime canisters avoid build-up of harmful co2:

The soda lime cartridges stop harmful CO2 building up

In the spirit of devil’s advocacy, we queried whether an oximeter and a paper bag could achieve similar results. The response was simple – without the scrubbing canisters, CO2 would rise exponentially in the blood stream. This might eventually lead to suffocation. Further, when breathing in and out of a bag, chemoreceptors (sensory receptors that turn chemical input into physical action) will eventually override the conscious control of breathing and force you to breathe due to the build up of CO2.

In another example, the i10 team pointed out that when holding your breath, your SpO2 would only drop to 94 per cent before the need to breathe becomes too strong. The i10 allows sustained breathing at lower oxygen saturations with safe amounts of CO2.

The i10 was demonstrated to us and certainly appears to do exactly as stated, bringing the tester’s SpO2 down quickly. Holding it there was a matter of the odd breath of fresh air to avoid it dipping too far.

That’s all well and good, but where the Altium i10 will rise or fall is on its performance-enhancing potential.

Lab trials

To investigate that potential, Altium undertook a trial undertaken by physiologist Dr Chris Easton and his team at the University of West Scotland. To keep things above board, the company’s involvement was limited solely to supplying the devices. The brand had no input on test methods or procedures. The proof-of-concept study isn’t due to be published, though Altium says it’s planning on publishing further studies following the launch of the i10 .

The canister is pc wrapped in aluminium – there’s a plastic lid and strap mounts too:

Could the Altium offer you a training-free power boost?

The study recruited 13 competitive male athletes, who all used the Altium for an hour, every other day for 28 days (14 sessions in total). During this period, the athletes were asked to complete the same training each week and undertook regular cycling tests in the lab with markers such as VO2 max and lactate threshold measured and venous blood samples taken to check red blood cell counts.

Dr Easton said that improvements differed throughout the group, but headline average figures include the following:

VO2max up 4%

  • This measure of aerobic capacity is the maximum heart rate at which the body can utilise oxygen while exercising. That’s a rise possible with dedicated structured and progressive training over a month, but not one easily achieved.

Maximum work rate up 3%

  • The power participants ended their tests on – the point at which oxygen consumption plateaued – was three per cent higher following use of the Altium i10. While not insignificant, this is less relevant for cyclists who aren’t regularly pushing up to their VO2max.

Lactate threshold up 11%

  • Participants showed an increase in the the sustained power achievable before lactate accumulates in the blood faster than it can metabolised into the muscle. Such a boost could be a boon for endurance cyclists working relatively hard for long periods.

Lactate turnpoint increase of 4%

  • This is the sustained power achievable before a sudden upswing in blood lactate (a higher intensity than lactate threshold) and could also benefit those looking to push their power at higher intensities.

One other key outcome of the trial was that there were no changes in blood parameters. Rather than the increased red blood cell count that training at altitude creates, following i10 usage, the participants’ red blood cell, white blood cell and plasma volume remained the same. The outcome of altitude tent usage would likely be the same.

Easton said these results show that all changes are therefore occurring at a muscular level and that the i10 is essentially training and adapting the muscles.

It does make one wonder whether there aren’t other factors at play, however. Were improvements perhaps down to the participants’ consistency of training over the period; their getting more used to suffering in a lab; different recovery strategies; the maximal tests themselves; or psychological, placebo-induced performance gains? Nevertheless, the improvements seen across the group make compelling reading for those wishing to increase performance.


At £500 (international pricing TBC), the i10 comes in a little cheaper than most entry-level power meters, though there is of course the added ongoing cost of cartridges.

Each i10 unit will ship with eight CO2-scrubbing canisters, a Bluetooth oximeter, nose clip and a neoprene bag to protect the i10 in transit.

We’ll be working with our sister publication 220 Triathlon to bring you a full test as soon as possible.

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Find out more about the Altium i10 at