Altitude: The Legal Advantage
Altitude Training FAQ
Welcome to the world of altitude tents, considered by many to be the next frontier of
training technology. For nearly 40 years, athletes have been experimenting with high
altitude training; the notion of simply sleeping at a high altitude has been around for about
15. To achieve this, athletes can install tents in their bedrooms, thereby seamlessly
integrating altitude training into their everyday lives. A long list of pros has been testing out
the concept. By some accounts, 16 of the top 20 finishers of the 2005 Tour de France, all of
the Americans tipped as hopes for the general classification at the 2006 Tour, and five of the
top six finishers of the 2006 Tour use the tents as part of their training program.
Training, as you know by now, isn’t just what you do on the bike. It’s also what you do off
the bike: how you eat, how you live. Proper hydration, nutrition, and rest can be just as
important as the number and kind of intervals you ride and how you manage life stress.
Good riders do this, and now they’ve added a new component to their training: they’re
sleeping at altitude.
Not living at altitude. Not dropping everything to hide out in some alpine redoubt. Not
going to inconvenient faraway places that are difficult to get to and come from and hell on
the rest of life. They’re sleeping high. In their own beds, in their own homes, amid their
Ever since the 1968 Mexico City Olympics, people have been catching on to the idea that
high altitude does wondrous things for athletic performance. Mexico City is approximately
7400' (2240m) above sea level. Most people remember Bob Beamon’s record-setting long
jump, but only running aficionados will remember 1968 as the Olympics when athletes from
high-altitude Kenya began dominating the distance running events in Mexico City; that
dominance that has only grown over time. It’s this nugget that caught physiologists’
attention. Danish bike racer Olé Ritter took note and set his hour record in Mexico City that
same year, though he chose Mexico City because of reduced air resistance—what helped Bob
Beamon soar and sprinters set world records—thanks to the less-dense air. Eddy Merckx
smashed the hour record there in 1972, and Francesco Moser broke Merckx’s record on the
same track in 1984.
More important to the hour record story is that Merckx was concerned about the altitude.
He had a device that simulated the air of Mexico City—probably just tanks of air mixed
with an oxygen concentration that mimicked Mexico City’s air—installed in his home.
Merckx hooked himself up to it through a mask and rode a stationary bike for an hour a day
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as preparation for his hour. This method allowed him the benefit of getting used to the thin
air while avoiding the polluted Mexico City air.
Merckx’s altitude preparation was dubbed “Live Low Train High” (LLTH). He was trying
to acclimate himself to the altitude while not interrupting the familiar rhythms of everyday
life. With the device, he could live at home, sleep in his bed, eat the foods he knew and
loved, and continue to train outdoors on familiar roads. The difference was that for the hour
or so a day he breathed air with less oxygen, his body had to work harder to do what it
accomplished with relative ease.
Merckx was onto something. There is considerable evidence, some of which had likely been
documented at that time, that living and training at a high altitude (greater than 5000', or
1600m) is more taxing than living and training at lower altitudes. But in Merckx’s era, the
evidence was generally more empirical.
Nowadays, we know much more about how and why high altitude can be beneficial to
athletic performance. Some athletes have experimented with moving to high altitude
locations for training, known as “Live High Train High” (LHTH), They’ve also tried “Live
High Train Low” (LHTL), where they live and sleep at an ultra-high altitude, and then train
at a lower elevation. Control groups in these experiments are usually doing “Live Low Train
Low” (LLTL), what most of us do most of the time.
Those who have been to Colorado or other high altitude locales know that adapting to the
“thin” air—it’s literally less dense—takes some time. A typical body’s response is usually fine
the first day, but, over time, the high living takes a toll. An athlete’s ability to perform, as
well as rest, suffers while the body adapts. Then, after a period of suffering, things start to
come around, and even improve past the starting point, provided the athlete hasn’t
overtrained in the intervening time.
There are many things happening to your body at altitude. Each breath brings in less
oxygen, which causes your muscles to function less efficiently. This lack of oxygen forces
your body to work harder to bring in more oxygen. The harder effort results in a higher
pulse, making rest and sleep more difficult as well. In addition, dehydration occurs more
rapidly at altitude, thanks to both the lack of humidity and the body’s response to the
altitude. Your appetite also tends to be suppressed, further contributing to fatigue. Your
body has a greater need for iron, so iron stores are taxed more heavily, and anemia could
become an issue. And if you go too way high too soon, you’ll get headaches or worse.
Hence, people are rightly concerned about living at a high altitude. If you can’t maintain
training intensities while building up greater fatigue, then it’s hard to see the benefit. Feeling
terrible at training camp or on a vacation and coming home wasted is not always a good
thing. Going too far into fatigue makes coming back all the harder.
Anyone who has trained successfully at high altitudes, or has been dropped by someone who
has been to altitude, can tell you what the benefit is. Altitude training can make you faster.
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The speed comes from increased efficiency, thanks to the body’s ability to deliver more
oxygen to your muscles. And that is largely thanks to thicker blood.
Thicker blood. Sound familiar? Exposure to high altitude results in the increased
production of the hormone erythropoietin (EPO). EPO comes in both natural and synthetic
forms; the synthetic one is illegal in competition. An increased level of natural EPO
increases the red blood cell mass. Altitude also boosts total blood volume, which helps move
oxygen in the blood. V02 max increases. There is elevated blood capillary volume, moving
more blood to the muscle cells faster. The total volume of mitochondria in the blood goes
up, which makes it easy for the body to convert oxygen into energy. And finally, living at
altitude increases the capacity of the lungs to exchange gases efficiently; every breath brings
in more oxygen.
The funny thing about this adaptation is that the only advantage is when those from high
altitude come down to sea level to compete. Doing the opposite means the sea level athlete
is usually at a disadvantage when first going to altitude. And all those already living at
altitude don’t have an edge on fellow high-living competitors.
Athletes looking for a competitive edge have long been trying to figure out how to get the
best of living at altitude without having to deal with the worst. Physiologists have been
trying to find out the same. The former group has historically used trial-and-error testing on
themselves, while the latter uses tightly controlled studies.
The two converged on “Live High Train Low” (LHTL). At one time, that meant live at the
top of the mountain, train at the bottom. Unfortunately, there are few places in the world
where one can effectively sleep that high and train that low. One would want to sleep as
high as possible, though at a minimum of 6,000' (approx. 2,000m), and then go much lower
A pioneer in LHTL was Shaun Wallace. In the early 90s, the British track racer and silver
medalist at the 1992 individual pursuit World Championships drove high into the
mountains above Colorado Springs, CO to sleep and came down to the Springs to train. By
1996, the US national track team was doing the same.
Wallace is important because he eventually started working on ways to bring the high
altitude down to sea level. Wallace developed his first altitude tent in 1997. He’s now Vice
President of Colorado Altitude Training (CAT), whose tents are available through
Competitive Cyclist. Since then, much more research has been done—studies implemented,
surveyed, and concluded. Commerce has gotten involved as well, with a few companies
designing and producing systems that allow one to sleep in a high altitude-like environment
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What’s Going On
For the scientific nitty-gritty on how altitude affects the body, we recommend reading
Altitude Training and Athletic Performance, by Randall L. Wilber, published by Human
Kinetics Press. Wilber is a senior sports physiologist at the US Olympic Training Center.
But we will try to explain it succinctly. The body’s adaptation is a classic stimulus-response
scenario. On page nine of his book, Wilber has a great illustration that goes into better
detail, which itself was taken from the book Human Anatomy and Physiology, 2nd edition.
The stimulus is “decreased RBC count, decreased availability of 02 to blood, or increased
tissue demands for 02.” That leads to “declining oxygen levels in the blood that causes the
kidneys to release EPO." That EPO then builds more red bone marrow, enhanced
erythropoiesis, more red blood cells, and increased oxygen-carrying ability overall in the
blood. Once equilibrium is reached, that becomes the new normal state of the blood.
Wilber’s book was published in 2004 and was meant to consolidate all the knowledge on the
subject of how altitude affects athletic performance in one place. The bibliography is
excellent, too. While the book doesn’t dwell on how to best use an altitude tent—only five
pages out of 231 are dedicated to the subject—it does have a wealth of information on how
altitude affects the body and its performance, reportage on major studies dealing with
training at altitude, successful altitude training programs, and current practices. While
academic in tone, it’s an incredibly informative resource for anyone interested in the subject
of altitude training, certainly good to have on hand when considering not only whether or
not to use the tent, but how to best integrate altitude into your training regimen.
It’s impossible to summarize Wilber’s book. The information contained has probably had
an influence on all those who have looked into using altitude to enhance performance; in a
sense, just about everything contained in this document has been influenced by the works
cited by Wilber, either directly or indirectly. One set of names that come up repeatedly in
the book, and among experts on this topic are doctors Benjamin Levine and Jim Stray-
Gunderson. The duo has authored some of the most influential research on the topic.
CAT, on their website, also has a relevant piece by physiologist Edmund Burke. Burke was
with the United States National Team in the 1980s and went on to publish a number of
books on training. Burke cites the following as the results of successful adaptation to high
“• Increased natural hormone erythropoietin (EPO) production, which in
turn increases red blood cell mass for delivering oxygen to muscle cells and
converting it into energy.
• A boost in total blood volume to move oxygen more efficiently through
• An increase in VO2 max-the maximum amount of oxygen the body can
convert to work, giving you more stamina for the long haul.
• Cranked-up hematocrit levels to provide greater percentage of cells carrying
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• Elevated capillary volume, creating more blood pathways to muscle cells for
improve muscle oxygenation.
• A higher volume of mitochondria-the powerhouses in cells that help your
body turn oxygen into energy.
• An increase in the lungs’ ability to exchange gasses efficiently-so that every
breath you take more oxygen gets into the bloodstream.”
The article that contains the above bulleted list can be found on CAT’s website. The URL is
An Easier Read
Cycling coach, racer, and MD Arnie Baker has published a detailed paper on altitude
training; it can be downloaded for free from his website, www.arniebakercycling.com. The
paper, which was co-authored by Will Hopkins, is titled “Altitude Training for Sea-Level
Competition.” The piece first appeared in 1998 in the peer-reviewed journal Sportscience
Training and Technology.
Baker’s report is a distillation of distillations, and for those who hate reading, he kindly puts
the summary on the first page. Essentially, he believes that training properly at LHTL for a
month can improve athletic performance in endurance athletes by 2-3%, with a few caveats.
Some are high-responders, while others are non-responders. People who engage in this
training need to devote a three- to four- week block of time to sleeping in the tent to realize a
benefit, but then can go without for somewhere between three weeks and three months (as of
the time of publication, tests had only lasted for up to a maximum three weeks) and still
experience a performance advantage. The report specifies an altitude of 2500 meters
(8,000’) as being a good altitude for realizing benefits without being too low or too high.
Simply put, by living high and training low, your body can both train harder and recover
more quickly and efficiently than if one lives and trains at altitude. Of course, it’s rarely as
easy as “buy tent, dial up high altitude, sleep in tent, get faster...” Life rarely is. There’s a
training price to pay for the adaptation to altitude and that needs to be heeded if one is to
use the tent well.
Zipping in to the Tented Life
Rule number one about using an altitude tent is: take it slowly. There is no way to know
how your body will respond to the stimulus. Some people might be extremely sensitive to
variations in altitude, and the worst result is Acute Mountain Sickness (AMS). While it’s
pretty rare, it is something you don’t want. Too much altitude too soon will not only wreck
your sleep, but can also push your body into an overtrained state. If you’re overheating,
can’t sleep, or experience headaches, either dial back the altitude or get out of the tent. Or do
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both. If your performance deteriorates—by this, we mean something concrete, like the loss
of ability to maintain power levels, not something relative like elevated pulse—spend less
time in the tent or dial the tent back to a lower altitude.
Rule number two is from Allen Lim, who advised Floyd Landis, and currently serves as the
full-time coach of the TIAA-CREF professional cycling team, and is a Ph.D. physiologist.
He states, “Experience is more important than advice.” If you get a protocol from a coach
and it’s not working for you, don’t continue basing your altitude training principles on that
advice. Accept that it’s not working and adjust your training plan. You own the tent and
you can use it forever. One week more of slow adaptation or a few days out of the tent might
not seem like it’s helping your training, but consider the big picture.
Any time at altitude taxes a body’s iron stores. It’s good to have your iron levels tested before
starting with the tent. One’s iron shouldn’t be too high or too low; it should fall within the
range of normal. Based on your doctor’s recommendation, you may want to take a
multivitamin with iron as a daily supplement. Women are particularly sensitive to iron
depletion and should take more care than men to prevent anemia.
When getting iron levels, checked, the thing doctors are referring to is serum ferretin.
According to Dr. Levine, “the ferretin measures iron throughout the body, including bone
marrow and liver, and provides the best picture of overall iron stores.” “Normal” values are
28-365 ng/ml in men and 9-148 ng/ml in women. He believes the numbers for women,
“reflect the fact that women are often iron deficient. This can happen even without anemia
(low red blood cell count), and makes it clear that many women are ill prepared to handle a
change in iron requirements, such as altitude.”
The flip side of low iron levels is high iron levels. A crazy thing about iron levels is they may
go up because of a cold, an infection, or inflammation somewhere in the body. So false
highs can be recorded. However, there is a common genetic disease called hemachromatosis,
which is very common, and results in the body handling iron very poorly. People with this
disease commonly record iron levels of over 500, and sometimes over 1,000. Those with this
disease should never use iron supplements.
Dr. Levine also recommends getting hemoglobin and hematocrit checked. There’s a pretty
wide range for what normal is. Cyclists often show lower than “normal” levels of hematocrit
because they have greater blood volume and tend to be more vigilant about hydration. In a
sense, the number itself doesn’t matter; it’s just being recorded for a benchmark. The
number might not even be “normal” for you. If you’re run down, your hematocrit could
well be lower than when you’re rested.
Arnie Baker tests his altitude-tenting athletes on a regular basis, just to see what’s going on;
there’s a chance the person is a “non-responder” (someone who’s body doesn’t increase
hematocrit as a result of the stimulus), but even a non-responder can see performance
benefits. As Baker points out, “you wouldn’t want to see sludge.” Sludge is a term for
overly-thick blood, the kind that probably killed a number of cyclists in the 1980s, most
likely from EPO abuse; they died in their sleep. At some point, with several blood tests
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done, a pattern might emerge that could be tied to training load, time in the tent, general
After a month, it’s a good idea to test again to get another set of numbers, for iron,
hemoglobin, and hematocrit. Those numbers matter most to elite athletes, who face blood
tests, and don’t want to record a hematocrit over 50 (a benchmark set as the high limit of
“safe” hematocrit levels), but it’s good for everyone to know how tent use is affecting the
Not everyone believes hematocrit is an obvious indicator of altitude tent success. Allen Lim
says total red blood cell mass is more important, as hematocrit can be effected by a number
of things, including hydration level.
Weighing oneself regularly before, during, and after implementing regular use of an altitude
tent is similarly wise. As we’ve mentioned already, altitude works as an appetite suppressant
for some. While just about everyone believes they can afford to lose “a few” pounds and that
losing body weight is a key to greater on-bike performance, it’s not always the case. It’s wise
to establish your weight before starting with the tent, weigh yourself daily in the first few
weeks, and then cut back the weighings a bit when your appetite and weight seems stable.
The extra data might seem a bit obsessive, but it’s purpose is to ensure that weight loss isn’t
adversely affecting performance and recovery.
The First Night
The first night inside an altitude tent may be the toughest. Everything will feel different.
For good reason, the tent is a room within a room. Since going slowly is the most important
thing, athletes should set the altitude pretty low, around 5,000' (of absolute altitude) or
lower. Remember that the virtual altitude created in the tent is not an absolute figure, it’s
relative to the actual altitude of where the tent is located. Those at 5,000' or above already,
can probably move the altitude up about 1,000'.
An alternate plan is to open all the zippers in the tent and have the air being pushed in be the
equivalent of 10,000’ above. This is for those who are concerned about claustrophobia,
overheating, or those who want to start extra slowly.
In terms of preparing the bed and the area around it, keep in mind that the adding tent
effectively reduces the size of your bedroom to somewhere between small and tiny. Whether
you sleep solo or with a partner, the body heat generated will warm the small space a good
deal more than it does the room. You may want to trade the down comforter for a lighter
blanket. Also keep in mind that household appliances like lights and televisions produce
heat, and the effect will be more noticeable in a smaller space. You probably want the room
to be cooler than usual as well—a cooler room should help cool the inside of the tent one
way or another.
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When setting the altitude in the tent, know that the CO2 expelled by the bodies inside the
tent may have a noticeable effect on the virtual altitude. That’s because as bodies process
oxygen, the result is a release of CO2. The CO2 further reduces the oxygen concentration
inside the tent. Two bodies will produce more CO2 than one body. The effect is less
noticeable the larger the tent. The net increase in altitude could be a few hundred feet of
virtual altitude, something most may not notice, but it could be as high as 1,000', which
most will notice, at least initially. If you experience breathing problems early in the
morning, this could be a culprit. A way to minimize the effect is to set the virtual altitude a
bit lower than the altitude you’re trying to simulate and expect it to go higher during the
night. You can measure the altitude both before going to bed and after waking up to
confirm how great the effect was, and then adjust the settings accordingly. An oxygen
monitor is included with all tents, for both precision in setting the altitude and measuring
how altitude changes over time.
You also may well react to the reduced oxygen by increasing heart rate, which will generate
still more body heat. Pets who sleep inside the tent should react the same way and can add
more heat and further increase CO2.
If two of you are sleeping in the tent, it is a good idea to share all your knowledge with your
sleeping partner, specifically what sensations they might feel, both good and ill, when
adjusting to life in the tent. Neither of you will be happy if only one of you has a good
night’s sleep. And if both of you experience a fitness gain, all the better.
There is some evidence that trained athletes might have a tougher time adapting to altitude
than civilians. If your partner sleeps fine and you’re having problems, this might just be due
to a greater sensitivity to changes or a greater awareness of your body. Change something
that night or the next: Switch to a lighter blanket or a lower altitude, or try to cool the room
more. Of course, if your partner is having trouble and you’re doing fine, you might want to
make the same adjustments for the sake of the relationship.
Remember that hard on-bike training can make adaptation to sleeping at altitude more
difficult. Try to save your introduction to tenting for either an easy stretch of training or the
off-season. If you want to start with it right away, you should consider reducing training
loads for that initial week or two or start at a very low altitude. Do not use the tent when
you’re coming off a hard block of training or seem to be suffering from fatigue, or are
fighting off a virus or respiratory infection, or if there’s an important event within a few
weeks of starting in the tent.
If you’re responsive to your body’s needs and can adjust accordingly, you should be used to
sleeping in the tent within a week.
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The Second Night Through The Rest of Your Life
Since LHTL, or some might prefer Sleep High Train Low (SHTL), is still new, it’s hard to
find friends, acquaintances, and coaches who have experience with tent living. Just as with
doctors, it’s good to get a second opinion. We contacted several coaches and athletes who
have experience using altitude tents and altitude rooms to see what we could learn. Not
surprisingly, everyone had his or her own take on the matter. As with any training tool,
some people recommend an aggressive adaptation while others more conservative.
The Guru’s Protocol
Shaun Wallace isn’t just a vice president at CAT, he’s also a long-time altitude trainer. He
has been playing with altitude and performance since the 1980s—and it was the fact that he
had trouble adapting to altitude that got him interested in its benefits. Even though he lives
at sea level in California, his bedroom and office are at altitude. He’d love to give a stock
protocol for adjusting to the tents, but believes that there’s too much variation from person
to person. He says, “The biggest variation is seeing how long it takes to get to 9,000'. (For)
Some it takes several weeks... The best way is on feel. Start at 5,000'; if it was ok, then crank
it up a bit. If you had a hard day of training, maybe not push it up. Don’t rush it. If it’s
new to you, you might be getting all the stimulus you need at lower altitude and you don’t
need it. Maybe the person stuck at 7,000', there is reason to believe that the person is
getting the max benefit at that altitude. There is a pulse oximeter that can measure, and
maybe this will be the evaluation measurement in the future.” (The oximeter measures
oxygen saturation in the blood, and is explained in greater detail later in this piece.)
Wallace says overheating, poor sleep, and poor recovery are all indicators that the altitude is
too high. If people are looking for an extra boost before an event, Wallace believes the key
isn’t more altitude, but extra time in the tent. Conversely, if people are worried they’ve
done too much at altitude, the solution is to bring down the altitude a bit. Wallace himself
drops the altitude down to 7,000’ for the three nights leading to a major event.
In terms of recovery, Wallace sees no problem sleeping at altitude even during and after hard
training. “I’ve never found that cutting out altitude to be more restful. The Australian
Institute of Sport did an amazing thing last year. They had riders do hard efforts on the
bike, and half slept at altitude and half at sea level. At the end, they found no difference in
recovery. If anything, there’s a slight improvement at altitude.”
A Pro Protocol
Jonathan Vaughters, Director of the TIAA-CREF cycling team and lifelong resident of high-
altitude Colorado, has CAT as a sponsor and provided tents for all his riders. He thinks it’s
best to start using the tent as long as possible before the season. He got his riders into tents
in October; racing that matters began in March. Since high altitude conditions slow
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recovery, he feels it is important to have his riders adapt when their body stresses are the
The TIAA-CREF riders were instructed to start off at about 7,000' (total altitude, not
virtual) for four to five nights per week, and to ultimately work their way up to 9,000' for six
nights a week. This was all for the off-season. Once their training got harder intensified and
the racing began, the riders stopped sleeping in the tents and used them for three hours a day
at 10,000'. They used the time to take mid-day naps, read, watch TV, etc, all activities that
require them to be still.
Vaughters thinks that as long as they’ve been using the tents all winter, his riders can go for
six weeks without the tents and still reap the benefits of having been at altitude. With the
off-season in the bank, they can probably get back in the tent for three hours and 10,000' at
a time and keep some of the benefits of altitude.
Vaughters tells his riders never to use the tents if they are sick. He also recommends airing
them out as much as possible and replacing the generator’s filters as specified in the
Insights from A USOC Physiologist
After reading Wilber’s book, we were interested to see if he had any further advice on the
ideal use of altitude tents. He recommends setting your tent at 7,000’ for the first week,
then increasing altitude by 1,000’ a week until reaching 9,000’, but the speed should be
adjusted to keep the air in the tent within an individual’s comfort level. Then, once at
9,000’, use the tent eight to ten hours a day, for five to six days a week, for five to ten weeks.
According to Wilber, you should limit tent use during periods of high-intensity training
because the emphasis should be on optimal recovery. The use is best reserved for base
periods of training and select periods during the training year, ostensibly when your training
loads are lower.
Reflections After Working with Pro-Level Athletes
Dean Golich is a name you might not know, but you’ve almost certainly heard of the
athletes he has coached. A former coach and physiologist with the national team at the
Olympic Training Center in Colorado Springs, CO, Golich now works at the coaching
concern Carmichael Training Systems (CTS). He suggests you begin by going to a high-
altitude location to see if the body responds to altitude. Once you’ve there for a while, have
your blood tested to see if a response has manifested. If there is a sign of a response, then the
tent will likely work for you.
Once your body has proven itself responsive, it’s time to chart out a year plan for using the
tent. It’s best to use the tent for three distinct one-month periods per year, though those
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with tent experience can potentially do more. Those periods are when the on-bike training
efforts that are not more intense than base volume and lactate threshold training. The first
month-long block should be in the winter.
Golich recommends beginning altitude training a bit higher than others. “First week, 6500’.
And then progress it to the third and fourth week at 8,500’ in first exposure. All along, you
have to monitor the training...If they’re doing intensity, they’re too fatigued, so they’re
getting neither a training effect nor an altitude effect. Training will give you a 10% gain if
everything is perfect. Altitude is 1-2%, so if you mess up training, then you have
For sea-level athletes, living in the tent full-time is not a good idea, according to Golich, is
not a good idea. He thinks that will be too much off-bike effort for getting the best out of
one’s on-bike training. As a caveat, he says, “The general public might not notice because
their training load isn’t enough.” He also doesn’t recommend sleeping at altitude after hard
Protocol from a Cycling Coach and User
Andy Applegate is a Masters National Champion in the time trial as well as a coach. He
tested out the tent making himself the guinea pig. The results of the experiment were
published in Velo News in 2004. Applegate keeps the article on his website at
We asked him if he had further insight on his experience and if he could make any
recommendations for new users. He had many. Applegate recommends sea-level athletes
start the altitude at 3,000’ to 4,000’, and then gradually increasing the altitude every few
nights until reaching the desired altitude. Applegate told us, “Four weeks MINIMUM
seems to be needed to get a decent adaptation...I would recommend 12 weeks or more to get
the full benefits of the system though.”
In terms of training, he believes training load should be reduced to balance out the effort of
sleeping in the tent. “During adaptation (about two weeks) training needs to be modified to
take the extra stress into consideration.” This should be regarded as a personal measure,
though. It’s only when the stresses of sleeping at altitude seem to subside that training loads
be increased again. If it takes three weeks, so be it. Applegate found preparing for racing
events at altitude to be effective, especially in terms of recovery between races. If you are
traveling regularly, he recommends not using it for a few days and then off for many days
and back in when home.
Applegate’s partner is also a competitive athlete, so both were interested in altitude training.
Both of them experienced problems with tent living. “Quality-of-life issues are probably the
only reason I don't use the system more often...let's face it...it is a pain in the neck to
use...but worth it is many instances.” One of the frustrations with using the tent is having to
lock his cats out of the bedroom.
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Protocol from a Triathlon Coach and User
Rick Kattouf is a multi-time All-American and Team USA Duathlete. He’s also a coach
who does online coaching and runs triathlon camps through his team, Team Kattouf. He’s
been sleeping at altitude since the start of 2001, first in a tent, and then in a room. He
thinks the biggest problem people have with using tents is not adapting to them properly.
The main users make is pushing the altitude too aggressively. Kattouf considers time at
altitude to be just another aspect of training, one that needs to be carefully built up.
“Nobody is going to start going to the track and doing intervals without already having some
decent volume. Don’t start at 10,000’. Someone is in the midst of their training. If you are
going to push altitude, you have to back off training. I wouldn’t start off higher than
1,500’.” He started at that altitude himself and took six months to work himself up to
10,000’. He did this so he wouldn’t have to reduce training load.
Likewise, Kattouf is a believer in reducing use after heavy blocks of training and/or racing.
Just like easy training days, easy sleeping nights can aid in recovery. He told us, “That
Sunday night or the following Monday, I might drop the altitude to 3,000’ for a few nights
and then bump it back up. Another thing that worked well, I found…that 10-12 days after
altitude you can still reap the benefits…from the fourth or fifth day to the tenth day, that is
out of the tent, I found a big performance benefit. I would stop sleeping at altitude five days
before the big event, and five before that I’d start tapering.” After getting home, he’d get
back in at a lower altitude, but found he could get back up to his preferred sleeping altitude
A Warning from Arnie Baker
Asked about limitations to tent use, Baker gave the following reply: “Athletes often get into
trouble because if a little is good, more is better. These tents haven’t been around for long.
It’s barely 10 years old. We’re pretty confident that living at 6,000-10,000’, going up and
down every day, seems to work pretty good. At 12-14,000’ we’re going into uncharted
territory. Because it’s new, we don’t know if it will cause problems later. One of the things
that happens is you grow new blood vessels. Long term, there are changes that occur in the
lungs. We don’t know if the blood vessels might be fragile and that a fragile blood vessel
might burst and cause a stroke. It’s attractive to say if 8,000’ is good, then 14,000’ is better.
I don’t want to be a guinea pig and find out.”
A High-Tech Alternative to Protocols
For all the ink spent describing how to increase altitude safely and with minimal disruption
in one’s life and training, there could be an alternative to “X nights at Y altitude,” etc. That
alternative could be found in using a device known as a digital pulse oximeter. The oximeter
measures oxygen saturation in the blood and pulse via an infrared light flashed on a fingertip.
The idea is fairly simple. First, establish a personal baseline outside the tent. Fire up the
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tent to a higher altitude. Then, get in the tent, stay for a few minutes, and check the oxygen
saturation again. More than a certain reduction in oxygen saturation will be sufficiently hard
to tolerate that it won’t be worthwhile to be at that altitude. The hope is to keep it within a
range that causes a change in saturation, but not one that’s too extreme. Kind of like finding
the right heart rate ranges.
It appears that 98% saturation is considered “normal.” The number means that 98% of
your red blood cells have oxygen in them. Some speculate that getting oxygen saturation
below 90-93% results in too much stress on the body. So, if you go in and the saturation is
below that range, reduce the altitude. If it’s above, you can probably pretty safely increase
The concern here is that the digital pulse oximeter, like so much else in altitude tents, still
needs further testing. It is something to try and could be the future of ideal adaptation, but
at this point, this method still experimental. Don’t let the oximeter override the sensations
you’re feeling as you work on adapting to sleeping high.
Protocols and warnings are fine, but they might not always work in the field. Athletes are
the ones who have to sleep in the tents.
Craig Lewis, Espoir national criterium and road champion in 2006, and a member of the
TIAA-CREF cycling team, has been using a tent for two years. He found the transition
pretty easy. In fact, he believes he sleeps better in the tent, though he only uses it for some of
the year. Travel is part of the reason, as is a concern that he won’t be able to recover. He
won’t start sleeping in it if he’s got just a week at home, since he doesn’t think there will be
any benefit occurring in such a short time. He uses it most in the winter, when his training
loads are lower. He doesn’t hang out in it during the day because the tent is over a bed in a
storage room and isn’t the most pleasant place to spend time.
Alison Dunlap, now retired from competition, set up her bedroom as an altitude chamber in
2000 and 2001. 2000 was in preparation for the Sydney, Australia Olympics, where she
finished seventh in the cross-country. 2001 was for the world MTB championships in Vail,
Colorado, which she won. She found the experience very different than that of Lewis.
Dunlap found sealing off her room to be claustrophobic, and the room itself was hot. She
got used to the first and quickly decided on using an air conditioner to keep the room cool—
she found that between herself, her husband, and the CAT generator, the temperature in the
room went up to 90° Fahrenheit without an air conditioner. Her spouse found it hard
sleeping at altitude as well. “You have to tell them how much better it is going to make you
as an athlete,” she explained. “You have to do lots of nice things for them.” She skipped
using the tent in the off-season, and when she was sick, and when she had a “super hard” day
of training. In terms of the overall experience, She reported, “Sleeping at altitude makes
you feel tired all the time. You also don't feel like you recover so you don't feel very good
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during training. It is a hard trade off…you feel tired and run down all the time. Mentally
that is hard for training.” But it worked.
Heather Haviland, a pro triathlete on the Timex Multisport team started sleeping at altitude
in 2005. Initially, the tent wasn’t very effective because her blood iron count was low. She
thus began taking an iron supplement on a daily basis, and, a one-time vegetarian, starting to
eat meat again, specifically buffalo burgers, on occasion.
Former world time trial champion Mari Holden, a member of the T-Mobile professional
cycling team has been using altitude training for a long time. So long, she’s not certain when
she began, though at least by 1999. She didn’t use the tent full-time nor in the off-season,
just in preparation for big events. Her coach, Dean Golich, set up her program for altitude
training, and she largely stuck with what he recommended; lots of steady-state riding, with
endurance and lactate threshold efforts being the kind she was focusing on while riding.
After a VO2 max interval session, she wouldn’t sleep in it.
Holden’s altitude ceiling was 9,500’, but she was starting from 6,000’ in her home base of
Colorado Springs. She says, “I’d get out of it before the big events. I’d need time to recover,
basically.” The white noise of the generator helped her sleep, though she learned the hard
way that she couldn’t sleep in it all the time. “When you first get it, you think you can do it
all the time. I couldn’t because I couldn’t recover. I’d get circles under my eyes, and that
was a sign I’d have to get out. The changes weren’t huge or drastic, but I did get better.”
Tara Norton, who finished fourth at Ironman Lanzarote in 2006, is so convinced that
altitude sleeping helps her training that she’s getting a second tent. The CAT 430 will stay
at home, while the CAT 150 will go on the road with her. Most of her experience is with
the 430. The room where she put the tent is was warm to begin with, and inside the tent, it
was even hotter, so she purchased a portable air conditioner that is placed right outside the
tent. Inside, she has a fan to increase the air flow; she finds it effective for increasing the
comfort level inside the tent. Norton started her acclimatization at 4,000’ and very gradually
increased the altitude so that 10,000’ is fine; the transition was so gentle that she was
comfortable even while maintaining her pre-tent training load.
Norton employed a few strategies to help with long-term use of the tent. She takes an iron
supplement. She’s been having regular blood tests to monitor her iron. After super-hard
efforts, she reduces the altitude. After Ironman Coeur d’Alene 2006, she reduced the
altitude to 5,500’ for a few days to help with recovery.
Competitive Cyclist currently carries the following CAT products: The 150, 315 and 430
tents, the CAT 9 and CAT 12 generators, the exercise mask, the digital pulse oximeter, and
the air conditioning unit.
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The heart of the system is CAT’s generator. They call it a “high-flow hypoxic air delivery
unit…The air unit draws in ambient room air and separates the oxygen molecules from the
nitrogen molecules, creating hypoxic or oxygen-reduced air. The separation is done in a
special filter called a molecular sieve bed.” The generator sucks in the air near the machine,
draws it through a filter that reduces the oxygen and pumps out oxygen-reduced air, much in
the way an air conditioner removes moisture.
Air everywhere is 20.9% oxygen. Air inside the tent can vary from that to about 16%, which
is the equivalent of 12,000’ above the room the tent is located in.
While the air can be pumped anywhere, the best place for it is into a sealed enclosure. A
tent. Air gets forced in and it is constantly forcing in fresh oxygen-reduced air as long as the
generator is running. The old air gets pushed out through the seams and zippers, even when
the tent is all sealed up.
CAT has two altitude generators. The CAT 9 can create air that’s 9,000’ above the room
where it is located. The CAT 12 can go up to 12,000’ above. All generators come with 25
feet of hose, allowing the generator to be placed in another room if people choose to do so.
There’s also a high-altitude conversion that can be made for those interested in going
higher—though doing so has not been discussed in this article and was not broached as a
training suggestion in any literature read or discussion had.
The CAT-150 tent is a portable unit. It was designed for Lance Armstrong to take on the
road. The easy-to-assemble tent fits in a small duffel bag, while the generator is still full-size.
The tent itself can be assembled in a small space and slid around a queen-size, or smaller,
bed. The flip side of the small size is that the tent heats up faster than others and might feel
claustrophobic to some. This is the model the TIAA-CREF team members received. It’s
also the one we tested out (discussion below). It should take under a half-hour to set up, and
can be partially disassembled if people want to move it out of the way. From the moment
the generator is turned on, it should take less than a half-hour to reach any desired altitude.
The CAT-315 is a walk-in tent. Its dimensions are 7’x7.5’x6’. It’s big enough for a queen-
size bed, and a night table and a little more. It is six feet tall, so most will be able to walk in
and easily move around inside. The 315 should take 45 minutes to assemble, though people
who have to re-arrange their bedrooms might need longer. This model will probably
necessitate disassembling one’s bed and moving the furniture around it, and then re-
assembling after the tent is set up. The 315 will take 60-75 minutes to get to any desired
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The CAT-430 is King Tent! 7’6”x9’6”x6’. Big enough for a king-size bed and various
bedroom accoutrement, and still some space to pace. As with the 315, this tent will
probably necessitate temporary bedroom furniture re-arrangement or disassembly. Not
including those efforts, the 430 should take an hour to assemble. As with the 315, the 430
will take 60-75 minutes to get to any desired altitude.
The exercise mask is for those who want to simulate the sensations of exercising at altitude.
It is designed to be affixed to the generator and thus gives people the experience of breathing
high-altitude air at home. This is training high, much like Merckx did, though the scientific
term is Intermittent Hypoxic Training (IHT). IHT is separate from short term, passive
high-altitude exposure, which is known as Intermittent Hypoxic Exposure (IHE). There
have been studies, and though some successes have been noted, it is unclear whether or not
this is a guaranteed way to boost fitness. Wilber has a discussion in his book for those who
want greater detail. Some have tried using the mask for light to moderate exercise for up to
an hour a few times a week as preparation for high altitude exercise.
Digital Pulse Oximeter
The digital pulse oximeter seems essential. This non-invasive device uses infrared light
flashed on a fingertip to measure saturated blood oxygen content and pulse. It can help you
quantify how your body is adapting to the high altitude—and was so described earlier.
Air Conditioning Unit
The air conditioning unit can’t be used in all tents. The size—about the size as the CAT
generator, is too big for the 150, but can fit inside the 315 and the 430. The device has two
parts, one that sits inside the tent to cool air and suck out humidity and a second component
that can be situated up to 10’ away for exhaust. The device in the tent runs on electricity, so
an electrical cord needs to go into the tent and an exhaust hose needs to go out.
The CAT-150 in Practice
We tested out the CAT-150 with the CAT 12 generator. Each component is shipped in its
own box, with one light, small box for the tent, instructions, and oxygen-content meter and
another big, heavy box for the generator. The generator weighs about 70 lbs and is on
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We read the instructions. They were decent enough, but didn’t give good advice on where
to start the assembly, mainly, which tent poles should be assembled first. The tent poles
come broken into segments held together by shock cords. Yes, very much like a camping
tent. Based on the instructions, it was impossible to tell the three short poles from the three
long poles. After assembling a few, we realized that the short poles have a stubby end
We found it best to assemble the long poles first. These fit into the short tent lengths. Their
purpose is to give the tent shape, specifically to create the upside-down “U”s that are on the
From there, we moved the bed forward a bit, and placed the entire tent behind the bed, with
the bottom of the tent below the mattress but above the box spring. From there, we pulled it
forward until the entire mattress was inside the tent. Finally, we set up the short tent poles,
which hold the tent up.
Then we fired up the generator. Maybe it was bare wood flooring, maybe sensitive ears, but
we found the generator a bit noisy for use in the same room. That’s the beauty of having a
25-foot long hose, which comes standard. We were told not to put the generator in a closet
or poorly-ventilated bathroom. That’s for good reason. The generator does produce some
heat as it filters and the generator draws in air from the area where the generator is giving off
heat. Vaughters mentioned putting the generator, or even the tent, in a basement for this
reason. The ideal spot for the generator seems to be under an air conditioner or in the
coolest room in a house. For the noise, having the generator on carpeting and/or padding is
a good idea. CAT doesn’t recommend using extension cords, so positioning the generator
within a few feet of a wall-mounted outlet is necessary.
Being inside the tent initially gives the odd sensation of camping in your bedroom. Because
the tent flaps are only at one end, you have to climb over the foot of the bed to get in and
out. And, like any good camper, you have to zip up the tent pretty much immediately upon
entering and exiting, not so much to keep out the bugs, but keep in the oxygen-depleted air.
The hose, which is made of thick, transparent, rubber is small enough to run under many
doors. It can enter the tent wherever there is a zipper opening. CAT’s Jonathan Modine
says the entry point doesn’t matter. We used a side zipper. The air coming in makes a
gentle sound, almost like ocean waves rolling up a shore.
It was definitely helpful to have cooler air enter the tent as well as having the room cooled
with air conditioning. For reference, we started testing out the tent in late June. The
temperature in the tent was warmer than the temperature in the room outside it, such that
lighter covering was chosen for the second night in the tent. In terms of finding a good place
for the generator, it was first placed in a hallway, but the air was a bit too warm. Next, we
put a fan by the generator. Still too warm. It was then placed by an open window, which
brought in cooler air.
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Included in the tent package is a digital gauge to measure oxygen content. First, the gauge is
tested and calibrated in a room or space well away from the tent. Oxygen concentration is
20.9% of air. While that percentage remains constant regardless of altitude, the percentage
needs to be lower if you’re at altitude within the tent. It’s a good idea to calibrate the meter
outside the tent every day for the initial week and then keep the meter inside when inside to
make certain that the virtual altitude inside the tent corresponds with the altitude you want
and what the dial on the generator reads. For this purpose, CAT provides a chart that takes
altitude and corresponds it with percentage of oxygen in the room. The dial is roughly
accurate, but the meter is much more precise and any altitude you use should be based on
It would be great to write about an impressive performance response. Sadly, this was not the
case; the result was more of a cautionary tale. Our test was very much the one that coaches
warned us about. We started at over 5,000’ thinking the altitude was conservative. Sleep
was hard and hot. Fitness went down, fatigue went up. This push the wrong way was
helped by the fact that the tent use started in the thick of the racing season. We also tried
Vaughters' recommendation of hanging out in the tent. Even this effort, in the middle of
the race season, was too much too soon. We came across Applegate’s article, which read like
a parallel experience after having problems with adaptation.
The Ethics of Altitude Tents
It is worthwhile to ask if using an altitude tent qualifies as cheating. The question has come
up in many places, including international sports federations. And the subject will be
debated for some time.
The World Anti-Doping Agency (WADA) made a study and released a six-page position
paper to their stakeholders on the subject on May 24, 2006 (it is, as of this writing, not
publicly available). The point of the paper was to further discussion. WADA asks, and
answers three questions.
“1. Do artificially induced hypoxic conditions have the potential to enhance
2. Do artificially induced hypoxic conditions represent an actual or potential
health risk to the athlete?
3. Do artificially induced hypoxic conditions violate the ‘spirit of sport’?”
For question #1, they answer, “artificially induced hypoxic conditions are considered to have
the potential of enhancing aerobic performance.” For question #2, they answer, “a potential
risk for health is not considered to be fulfilled under controlled conditions, but it remains
difficult with current knowledge to rule out any definitive risk. Consequently, this criterion
The biggie is really question #3. WADA acknowledges that people use synthetic EPO to get
the same benefits of high altitude. To answer the question, they start with the 2003 World
Anti-Doping Code, which says, in part, the spirit of the sport, “it is the essence of
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Olympism; it is how we play true. The spirit of sport is the celebration of the human spirit,
body and mind.” The paper then moves on to discuss technology and its impact on sport,
and the WADA authors make a distinction between “passive” and active technology; hypoxic
tents and rooms are seen as passive. And that they see the conditions as passive is the
sticking point. They find it is problem.
They conclude with the following statement:
“The WADA Ethical Issues Review Panel regards the use of
artificially induced hypoxic conditions to modify performance as an
invasion of technology that does not require athlete’s insight, effort or
significant active participation of any kind. As such, artificially
induced hypoxic conditions to modify performance are a violation of
the spirit of Olympic sport, which celebrates natural talents and their
WADA’s report was bound to stir up a response. And the first response was a big one: some
78 physicians, bioethicists, and sports scientists, including the top hypoxic training
researchers, signed a letter rebutting the assertions of the WADA paper. On the first
question, they point out that while hypoxic training is not entirely certain, the results of
EPO definitely are. More importantly, they point out that there is no difference between
getting in a tent and driving up a mountain to sleep at the top. In terms of the body, they
are all equally natural. On the second question, they agree; there’s no proof of it being
unhealthy, and that any stimulus can be used improperly; there’s even proof that more
“athletes have been serious injured drinking water than using simulated hypoxic devices.”
The doctors’ letter focuses on the third question, whether or not hypoxic training violates the
spirit of sport. They point out that recovery, regardless of the form it takes, is not passive,
and is as complex as training. They cite several examples of techniques that could easily be
defined as passive, including air conditioning, icing, and massage. And they suggest that
since there are no “fundamental biological or physiological differences between real terrestrial
altitude and simulated hypoxic environments and there is no effort to ban altitude training.”
There has been no effort to regulate where people live, and rightly so.
When we approached the USOC’s Wilber for comment, he didn’t offer his opinion on
whether or not he agreed with WADA or the 80 specialists. “You could argue it back and
forth for weeks…As I've said many times, if you want to provoke a barroom brawl, there are
a couple of polar topics that are sure to do it: capital punishment, abortion and altitude
This debate has caught the attention of the mainstream media. On July 24, 2006, The New
York Times ran a story on the front page of their Science Section, entitled “Live at Altitude?
Sure. Sleep there? Hmm.”
482 ($4.95 to purchase) The article was even teased on the front page with a picture of the
CAT 150. In the article, reporter Gina Kolata introduces the topic, and then gives the
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various pro and con arguments. A proponent of banning the tents is quoted as saying,
“There are some people who are in a sense geographically fortunate.” An opponent says,
“Any athlete who wants to be competitive in the world scene would have to move to altitude
or cheat by using an altitude room (assuming tents are banned) or taking illegal drugs.”
One thing that isn’t addressed in the WADA letter, and is arguably beyond their purview, is
the impact of cost on “the spirit of sport.” The Times piece touches on it briefly. The
Union Cycliste International (UCI) has addressed the matter of cost in the past. Altitude
tents aren’t cheap. Many athletes can’t afford them. And the cost divide has the potential to
separate the moneyed athletes from the non-moneyed. We don’t want to see people turn
away from cycling because of cost.
Living at altitude also costs. People living at altitude get the benefit seemingly for free, while
others would have to invest in traveling to altitude. It would be hard, not to mention a bit
unsporting, to ask people to refrain from living above 5,000’. Sea-level athletes will probably
grumble at the thought of competing against those who have altitude tents. We understand
this grumble. But after looking at the complete picture it’s hard to see a fair way to ban
The dark side to the ethical discussion is that people are touting the benefits of altitude tents
to discourage people from doping. As mentioned earlier, time spent at altitude can increase
natural EPO production. Synthetic EPO is a scourge haunting all endurance sports, as
some competitors take it to gain an edge on their competition. Some altitude training
proponents claim that living and/or training high is a way to give those who want to live and
compete clean a way to neutralize that edge. There is a concern that some EPO users will
blame a hypoxic environment for their high hematocrit, but since there are tests for synthetic
EPO as well as blood transfusions, this argument seems a bit thin.
Since we don’t believe this is cheating, we are comfortable selling them. People might not
consider us a disinterested party; we understand this criticism. We want to encourage clean,
safe cycling, giving our customers the means to help further their cycling, and if this is a
stake to use against dopers, even better. We expect that altitude tents will be a topic of
debate for some time. If we have added light to the topic, we’re happy. Altitude training
isn’t easy, but it has the potential to deliver to those who are willing to take the time and
effort to master it, another way to improve. Most importantly, it’s a legal and safe way to
improve cycling performance.
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