The Altitude Tent

Altitude tent

Altitude training has long been a fixture for endurance athletes. It has been common for riders to head for the mountains for some time. As well as familiarising themselves with the local passes and working on the pedal stroke riders are also subject to hypoxia or oxygen deprivation, triggering a set of responses in the body.

But riders need not go to the high mountains for this. It is possible to sit at home yet experience the conditions of altitude thanks to what is commonly known as an altitude tent.

The Physics
They say there is less oxygen at altitude but this is false, the mix of gases in the air is the same. Instead the higher up a you go the air pressure gets lower. Consequently the partial pressure of oxygen is reduced. An altitude tent does not copy this change in pressure. Instead it pumps refined air with a reduced oxygen content into a confined space.

The Physiology
Go to the mountains and the effects become measurable above 1,500m and noticeable above 2,000m. Even if you are seated and idle the breathing quickens and the heart rate increases, outward signs of hypoxia. If you spend time at altitude there are longer term responses. The blood chemistry changes and in time the idea is that the body responds to the hypoxia by producing more red blood cells which help carry oxygen. Typically at least two weeks is needed, if not three weeks before this happens to a significant degree. When the athlete returns to sea level the increased concentration of red blood cells will decline, but over weeks giving them a greater ability to transport oxygen than before.

That’s the basic theory but the science appears a lot more nuanced. First some respond better than others. Next the haematocrit, the concentration of red blood cells, can fall at first before rising. Some claim the thicker blood is harder to pump around the body but these studies probably have not seen pro cycling in the 1990s. It is also said the acidity of the blood changes for the worse for athletes and that muscle tissue can wither.

In summary there can be gains for some but if these are significant, they are not quite transformational. The achievable increase in red blood cells is substantially lower than illegal means like EPO use or blood doping.

The Mechanics
Oxygen concentrator
An altitude tent uses a home oxygen concentrator. These machines were developed for the sick needing extra oxygen at home. The concentrator sucks air in via an intake and then uses chemistry to remove nitrogen from the air, with two exhausts, one with the concentrated stream of oxygen for the patient and the other with the unwanted nitrogen.

The athlete uses a modified version. Whilst the sick patient gets concentrated oxygen via a pipe from the unit, the athlete reverses this and connects a pipe to the exhaust where the nitrogen is piped into a sealed space. Often a type of tent is used so that the oxygen reduced air can be pumped in. Sometimes the athlete will convert a room at home to make it almost airtight. This can be DIY-style with tape around the windows and doors but in some cases athletes have had built specially-designed rooms with specially sealed doors.

The air inside the tent or room is monitored to ensure the oxygen level is correct with a simple device used by scuba divers to check their air tanks. For example to simulate 3,000m above sea level the oxygen concentration is reduced from the normal 20.9% you get at sea level to around 15%.

How Is It Used?
This varies. Some will train outdoors and then return to rest and sleep in the hypoxic conditions. Others might exercise inside a chamber or use a mask to supply rarefied oxygen/nitrogen mix whilst they ride indoors. But it seems the tent is the most common use with it being placed around the mattress. The athlete climbs in, zips the flap just like they’re on a camping holiday and sits or lies there and waits.

The reduced oxygen levels don’t make it easy. In Paul Kimmage’s book “Rough Ride” the Irishman recounts how he struggled to sleep after a mountain stage when staying at altitude. But if some find sleeping in a ski resort hard, try to imagine being even higher and then inside what amounts to a large unbreathable plastic bag and add the noise of the pump rumbling nearby.

Who Uses It?
There’s hardly a central register but usage is very common. The old Slipstream-Chipotle jersey even used to feature the CAT logo, a provider of this gear.

I don’t think Wiggins was on a camping holiday. This isn’t to single him out, I recall it mentioned for Cadel Evans and many riders do the same. In recent days, I’ve seen a piece in Cyclesport Magazine where Thomas de Gendt is mentioned. And I got the idea for this subject after a tweet by Greg Henderson yesterday:

The Mile High Club?
Typically riders train at sea level and then climb into this at home to rest or even sleep overnight. But as Wiggins hints above when a kilo of beetroot soup meets intestinal bacteria the results in a near-airtight chamber must be horrific. A tent isn’t the most romantic place at the best of times, yet alone an airtight one with a noisy pump standing outside. Add this to the actual altitude where the reduced oxygen levels get uncomfortable and it’s no wonder riders tend to rig these in the spare room or basement as opposed to the marital bedroom.

But at least this allows the athlete to stay at home. Sleeping at altitude for real means staying in a remote ski resort out of season which can be peaceful but it means staying in a cold place where snow can be common and a long drive awaits to find flat roads.

The Ethics
In one word: legal. But if it’s legal in most countries it is not allowed in Italy where a rule forbids manipulation of blood values via artificial means.

This is a tricky subject because it uses artifice to trigger a response in the body instead of going to altitude for real. For me a crucial difference is that this uses an exogenous method to trigger the response as opposed to an endogenous means like swallowing a pill or injecting EPO. In addition whilst some have gone wild with EPO it is hard to make the body respond to hypoxia, the gains are far slower and more limited. Organisations have looked at banning this method but there are practical difficulties. Short of raiding someone’s house it is impossible to detect.

Sometimes called an altitude tent a “hypoxic chamber” would be the more appropriate term. These rely on pumps normally designed for the sick but modified to provide reduced oxygen to the athlete.

It’s legal but relies on artificial and technological means to make the body adapt. But some users don’t respond well to hypoxia and the performance gains can be limited for those that do. But in a competitive environment where the smallest legal gains are seized it is understandable that the use of these machines is a widespread but often unspoken part of the training regime.

64 thoughts on “The Altitude Tent”

  1. Spent 6 weeks in it (8 h per night) and conclusion is clear:
    It does have some effect but I would say not worth,
    recovery is much worse,
    life became much more complicated,
    its hard to manipulate exact altitude
    sometimes is hard to fell asleep
    and most notably I eat like a lion during day but lose muscle mass and from 7% of BF droped to 5%

    I would sugest real altitude camp or nothing, as all studies I read said you need 16 h per day (night) which is simply not possible

    Anyway great article but until somebody try it, cant get clear idea about it.

  2. I clearly remember seeing some stage winner in a grand tour sitting in the team car after the race with a mask clapped over his face and a small bottle of gases. I would suggest that he was not taking on extra oxygen but rather was “going back to altitude” to recover!

  3. I can’t help but suspect that many athletes are “using” altitude tents simply as a means to explain away the appearance of blood manipulation in their passport results.

      • Mick:

        Great point. Was not thinking about that, but this makes all the more sense. Even better, is that they do not even then need to use these for anything more than Twitpics to the public as evidence of use.

      • In a recent interview with Michael Phelps and his coach about his preparation for the London Olympics, they made sure to get in a segment about him sleeping in an altitude tent. When I saw this, I couldn’t help but think “wow, its not just cycling and skiing anymore.”

    • You’re not the first to say this, it is a handy excuse… but the gains from using a tent are small and slow. If it is used as cover it only covers small changes although under the biopassport all “gains” will be exploited by cheats too.

    • That must have changed – I once stayed in a XC Ski training centre in Trysil, Norway that had an entire wing sealable and able to go hypoxic. It was about 1996 and we were asked if we wanted to pay extra for using this. I turned them down but I know other teams were all for it.

  4. Dani E., for sure not. Altitude is NOT for recovery, but for stimulation of blood cells production.
    Recovery on altitude is much harder and slower!

    He (that cyclist you saw him) was taking oxygen for sure.

    In air you breathe, there are about 21% of oxygen, on altitude, depending of m’s its can go down to 15% (25% less oxygen than on sea level) which is significant difference… But if you have gas with, for example 50% of oxygen, recovery is faster for sure… Its hiperbaric effect…

    • @Ognjen: “They say there is less oxygen at altitude but this is false, the mix of gases in the air is the same. Instead the higher up a you go the air pressure gets lower. Consequently the partial pressure of oxygen is reduced. An altitude tent does not copy this change in pressure. Instead it pumps refined air with a reduced oxygen content into a confined space.”

      As INRNG points out in the quote above, there is not less oxygen at altitude than at sea level…the partial pressure of oxygen is reduced with air pressure being lower. The body is taxed when utilizing oxygen at altitude. Hence, everything slows down.

      The gain of RBCs (with an altitude tent) is much lower than with EPO-use or blood doping.

      And as INRNG also points out the body responds to oxygen deprivation by producing more oxygen-carrying red blood cells. And look at the time factor: “Typically at least two weeks is needed, if not three weeks before this happens to a significant degree.” To achieve maximum potential [of red blood cell gains], staying at altitude for most riders for 2 – 3 weeks isn’t usually possible.

      What you said above speaks volumes, that it’s hard to fall asleep in the tent and that recovery is much worse. I don’t think these tents’ benefits outweigh the costs to the body and lifestyle.

      I always laugh here in the states when teams play American football in Denver, CO; the stadium is called “Mile-High Stadium,” which is roughly 6000 ft in elevation (1829 meters). When the camera zooms over to the sidelines, players are often seen with oxygen masks on after having just run off the field. Physiologically, they think they’re being helped to a great degree, when the reality is that it’s really more of a placebo than anything else.

      Yes, there’s nothing like the “real thing.” Get high and stay high for best results!

      Fantastic, accurate article…really appreciate the time you put into these features @INRNG.

  5. Since the game is about recovery I would think training at altitude but then sleeping in a high oxygen environment to promote maximum recovery is best.

    • Exactly. This is why many of the Colombians often have such an advantage, many live and train high, but also race high AND low. Many riders on Continental teams have lived in Colombia at high altitudes their entire lives; then they fly abroad to a race which is often at a lower elevation. That being said, last year’s Tour of Utah and USA Pro Cycling Challenge (in CO) were both races which featured very high elevations and the Colombians excelled!

      In the ToU, Sergio Henao (now Team SKY) was riding for the Colombian team Gobernacion
      De Antioquia-Indeportes Antiquia. He won the opening, tough uphill Prologue at Olympic Park;
      his teammate, J Acevedo (Col) won the tough Stage 4 Criterium and Henao won Stage 5, a summit finish at Snowbird ski resort where elevations of above 11000 ft (3353 m) are not uncommon.

      Throughout this race and also in the USA PCC, the Colombians really shined. In Utah, Henao took 2nd on GC, Oscar Sevilla 4th. Overall, Gobernacion had four riders finish in the Top 20, six in the Top 30. Team Competition: 2nd to RadioShack and Gobernacion’s Montoya took Best Young Rider. Three of their riders finished 2nd, 4th and 9th in the Points Classification.

      My point: athletes like the Colombians who grow up and may still live at high elevations excel in races such as those highlighted above. Additionally, temperatures were very high in Utah…during the Criterium won by Acevedo (Col), temps hovered around 35.5 degrees Celsius. The Colombians are also well acclimated to high temps.

      …ain’t nothin’ like the real thing…

      • Michele Scarponi’s training on the Stelvio for LeTour. Years ago our group was riding up there and saw Museeuw and a lot of Mapei riders doing the same thing. Another year we saw Andre Tchmil doing hill repeats on the Mortirolo! I doubt pro cycling is a healthy activity when you consider the extremes some go to….especially when you see these guys with their shirts off at the end of a 3 week stage race!

  6. Wiggins has stayed at Altitude on Tenerife. I think other teams also use this as a base.

    Long distance runners also make use of high altitude training camps (and also altitude tents). e.g. Mo Farah and Paula Radcliffe in Kenya and also the Pyrennes I believe.

    Is using an altitude tent cheating? Firstly it is not banned by the sports governing body so it is a valid training technique. The UCI has banned some things such as calf length socks! and fancy clothing materials but not altitude tents.

    Wiggins is just training within the rules. I see no problem with that.

  7. This is not legal in Norway either. Our biggest cross country star ever, Bjørn Dæhli, was using this kind of stuff, and they even built a house in Norway where athletes could live, eat and sleep at big heights.

  8. Ring you continue to amaze me. You have covered business, legal, engineering, and nutrition. And now you give a great look into one of the most complicated issues of exercise physiology. You must be a cycling polymath or there is more than one person behind the moniker.

    There has been a number of exercise physiology studies into the various permutations of training and recovery at various altitudes. The one that showed the most promise and opened the door to live-high-train-low (LHTL) was by Levine and Stray-Gunderson in 1997. The benefits were significant and long lasting.

    Since then further studies have refined the model to suggest living and base training at high altitude, while descending to perform intervals gives and even greater training response (Stray-Gunderson et al. 2001). Get out your map and look for altitude camps with trips to a coastal setting.

    • “Get out your map and look for altitude camps with trips to a coastal setting.”

      No need , Tenerife is the place ( other Spanish Islands are available )

  9. “They say there is less oxygen at altitude but this is false, the mix of gases in the air is the same. Instead the higher up a you go the air pressure gets lower. Consequently the partial pressure of oxygen is reduced. ”

    Surely that does mean that in effect, there [i]is[/i] less oxygen? While the mix of gasses will be more or less consistent with lower altitudes, because there is simply less of anything (less pressure and lower air density) there will by definition be less oxygen per cubic metre at altitude than sea level. No?

    • Yes!! Thank you Science nerd for posting this as I was about to. The percentages of gasses may not change but the density of O2 (and all other gasses) will be lower.

  10. normal haematocrit is ~33%, that is around 33% of our blood is made up of red blood cells. If a cyclists goes above 50% they are banned, so its assumed and the blood passports presumably testify to the fact that most pro cyclists Hct is 45%+. thus, how much extra benefit can life at simulated high altitude be? i would suggest that the ‘whole body’ holistic responses to living and training at altitude (excluding the low altitude interval forays) are far better than an expensive tent. it sounds a little like a marketing gimmic designed to make money – however, it would likely help us sportivistos with Hct in the region of 30-35%

  11. How much do these cost? Not that I could afford them, but seems handy if you were to (say) register for a 1200k brevet in Colorado while living at sea level…

  12. If you read the Wiggins interview in The Guardian from a few weeks back, Tenerife was ideal for him because he was living/training at 2000m based in an expensive,quiet hotel with good food and no distractions but to go up and down a big mountain in the heat at various tempos. Apparently the same hotel is used by Liquigas and was used by The Shack on Armstrongs return

  13. As noted above, the method is not on the banned list so hence is not cheating… but I have qualms about it because it does enable one to ‘sleep high, train low.’

    When training at altitude it is not possible to train with the same intensity as can be achieved at sea level. This results in a lower level of fitness and muscle mass. Columbians are (generalised as) great climbers, not so much as TTers or classics strong men. When considering living at altitude, or spending time at an altitude camp, the athlete has to choose between boosted red blood cells but lower quality training or ‘normal’ blood values and better quality training. The use of a hyperbaric chamber avoids this choice – to some extent.

    • …but, the evidence seems to suggest that altitude as you say is good for conditioning the cardiovascular system but ‘live high, train low’ – train low being go to sea-level to put in the high intensity interval efforts. live high, train high may be a motto for someone like pantani, but thats not what we are talking about here

  14. Another great post; you always cover the stuff that I like to read. A future post on the peloton’s use of inspiratory muscle training techniques would be of much interest.

    Just to add a point to the normobaric hypoxia thread. Using tents is common for cyclists, whereas many football clubs (such as Tottenham in the UK) use permanent hypoxic booths in the gym and as you say, face masks are also an option. I know Dwain Chambers used a mask for his 2008/09 comeback.

  15. As others have pointed out, its just the pressure that changes and this effect is on all the gases.
    I wonder why its not possible to just pull a slight vacuum on the tent with a vacuum pump? Itd be the exact opposite of the tents they use for altitude sickness. All I can think of is liability issues if something goes wrong?

    • The tent would have to be structural, rather than just preventing mixing of inside and outside air. Probably more of a hassle than the way it’s done now.

  16. Lets take it to its base level, two teenage athletes, A and B are both relatively equal in terms ability.
    However athlete A has a sugar daddy to throw money at them and can afford this tent (or any-other “aid”), while athlete B has no sugar daddy and so cant afford the aid. Athlete A goes on to a glittering career claiming never to have doped or manipulated in anyway, while athlete B plods on through life having a teenage dream broken.
    QED, its an aid, it boosts performance, its only available to those with cash, ban it.

  17. Logically following that argument you’d be banning an awful lot of other things. Athlete B could struggle for a hundred reasons through having to make ends meet. Athlete A could have access to the best coaches, the best nutrition and ability to fly around the world to races and training camps without ever having to worry about putting food on the table.

  18. Reduced pO2 means less molecules per litre of air, so there is less O2, even if the % is the same.

    The point about ‘live high, train low’ is that the athelete gets a (limited) benefit of increased red blood cells, but can train harder when they come down to sea level .
    It is worth doing some high altitude work in training, so you know what is coming in the alps, but the great majority of the training should be low. Training to exhaustion is detrimental.

  19. Compared with EPO high altidude would give you more than just the elevated hematocrit/hemoglobin level. Hypoxia force the body to increase not just oxygen delivery (higher hemoglobin, increased cardiac output) but also increase oxygen uptake/extraction in muscle tissue (production of 2,3-DPG, capillary proliferation).

  20. Does hypoxia represent a health hazard? If no, end of the question. If yes, down from what level? That’s all we need to ask ourselves. Let’s not forget it’s the health hazard that is the bottom-line regarding doping definitions (and of course the not the unspecific and easy to manipulate “spirit of sport” concept).

  21. The more I think about it “Sleeping in my tent tonight after nearly a kilo of wife’s beetroot soup, you know what comes next” sounds more like typical British humour, along the lines of “hovering duvets” and the likes of the movie Thunderpants.

  22. Australia seems to have an obsession with altitude training and many of our pro sporting teams travel overseas for short camps just to gain the debatable benefits. The richest AFL team has a whole part of their gym turned over to altitude training but make frequent trips to Arizona. Our Olympic swimmers camp in the tents and our high school and university physical science (education) courses all mention it as a training method. Results point to the dangers of not being acclimatised to Altitude, this time rugby matches played at Johannesburg i South Africa. The CSIRO and AIS have both researched this matter and seemed to have returned the same evidence as Inner Ring. There are benefits, but just how great is a matter of interpretation. It would seem the greatest benefits from altitude training are in acclimatisation and recovery at sea level. The haemocrit count is not the only factor in this method, but also the efficiency and number of myoglobin as well many of the other training adaptions associated with aerobic training such as increased number of alveoli. However how much benefit this will give to elite endurance athletes such as Wiggins is a matter for interpretation.

  23. The main reason to train/live at altitude is to prepare for competition at altitude. Everyone responds differently to such training interventions, and so a blanket approach (to say a squad or team) would be foolish.

    Suggest reading Randall Wilber’s book, “Altitude Training and Athletic Performance”, which goes through much of the science.

    I might post up an item I wrote a couple of years back to summarise the topic.

  24. Why is banned in italy ? I think ethics came here… same athletes, same race.. why someone can use it and other are forbidden ? Ban it!

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