In the never-ending quest to better myself as a cyclist, I’ve ticked off all the initial and obvious boxes – get a coach, ride more, sleep more, eat better - and have now moved on to the more mythical, and exclusive top rungs. I’m entering rarefied air up in the higher echelons of cycling. The step I’ll be talking about is living in the clouds. If the allusions to the point of this article aren’t clear enough, I’ll state it bluntly; I’ve been sleeping in an altitude tent.
I’ve always been interested in the concept of using altitude to better oneself. Maybe it was too many readings of Into Thin Air, by John Krakauer, as a teen, but I’m drawn and fascinated by the effects of being high in the sky. In theory, the general practice of using an altitude system is quite simple and effective. Flip the machine on, zip the tent up, sleep and you’re a tour winner. Other methods like low-oxygen workouts and intermittent hypoxic training have also proved to be successful, but are less widely known.
This led me to scrap a large portion of my prize winnings together and begin the search for an altitude system. I did my research, looked high and low at the different companies and made as many connections as possible. A friend of mine provided the contact information for Hypoxico Training Systems and after a few conversations we struck up a deal.
A short time later, two very large packages arrived at my door and upon opening I was greeted by the full gamut of altitude living and training accessories. My bounty included a generator, tent, high altitude adapter, facemask, oxygen monitor, pulse oximeter and all the necessary literature.
Set-up was relatively painless. Aside from trying to put a queen size mattress in a tent while on a high bed frame, everything else was simply plug and play. Running the system is about as simple as it can get, press the “on” button, select a setting ranging from .5 to 12 units and hop in. As simple as that sounds, I was still a bit intimidated. My parents were adamant about not putting a plastic bag over my head as a child; so zipping myself in a mostly sealed plastic tent that was purposely supplying me with less oxygen seemed iffy.
Before my first foray into oxygen deprived sleep, I had a scheduled phone call with Hypoxico’s training consultant, Krista Austin. We would be talking about many things ranging from sleeping with a partner in the tent to intermittent hypoxic training, IHT for short. Sleeping was my primary concern and the biggest takeaway was learning about the optimal saturation of peripheral oxygen (Sp02) in the body, measured by the pulse oximeter. The device is a simple finger mounted sensor that passes light of different wavelengths through the finger and measures the change in absorbance.
While the science behind it may be complicated, the need-to-know part is quite simple. In normal conditions you should be around 99% saturation. While in the tent, I was told to shoot for the 90-92% range. In that zone, you are sufficiently deoxygenating your body to produce a response but hopefully not so far as to make recovery impaired.
Interestingly, many other key aspects reminded me of general training advice. Three weeks in and one week out were recommended and that should coincide with general training method of three weeks on and then a recovery week. A carbohydrate increase may be necessary to guarantee optimal training. Come out of the tent a few days before key events. Iron supplementation was recommended to aid in adaptation. Overall, it was similar to most other types of training with a build and taper phase and factors corresponding to what phase you’re in.
I also learned about IHT training, which requires an article unto itself, but I’ll go over the basics. Essentially, it’s interval training with altitude. Sessions typically are in the hour range and go through a cyclic process of breathing hypoxic air and then ambient air. This is where the high-altitude adapter comes in handy as you shoot for SpO2 levels down to 70% saturation.
Armed with my new knowledge, I did a bit of further reading just to quell any other trepidation I had about my low O2 living. My main curiosity was how the generator simulated altitude. Without getting into the technical engineering, the generator pulls in the ambient air that contains about 20.9% oxygen, does some magic and pumps out air with a lower percentage of oxygen, the difference made up by nitrogen. That air is pumped through a tube into the mostly sealed environment of the tent where the oxygen rich air is displaced by the lower O2 air. The excess carbon dioxide, expelled by you, as well as the oxygen rich air, escapes through the semi-ventilated fabric at the top as well as zippers and other non-fully sealed areas in the tent.
It was time to jump in. The first night, I chose setting number 5, which corresponds to roughly 5,000’ if the generator was at sea level. My current location in Chapel Hill, North Carolina has an elevation of roughly 500’ and you can simply add that to the estimated altitude. With a quick zip, my girlfriend and I were locked in and ready to climb up to Denver. My habit has been to find a city of the approximate altitude we’ll be sleeping at and tell her where we’re vacationing each night. My hope is that this distracts her from the fact that we sleep in a fancy plastic bag each night. With the quiet hum of the generator in the other room and the rhythmic breaths admitted from the filter capped tube, off we went to sleep.
Probably from excitement, I woke up around 5am and checked all the stats. My blood was holding steady at 97% saturation, down from the 99% pre-bed level, and the air was at 16.4% oxygen, down from the 20.9% ambient level. After a quick trip to the bathroom, which is somewhat like unzipping your tent and descending 5,000’ to the campground bathroom, I bumped the generator up a notch and went back to bed. I woke up next with my blood saturation down to 95-96% and the air had dropped to 16.2% oxygen. Although the numbers said otherwise, I didn’t particularly notice anything out of the ordinary.
The first night I really felt the altitude came at a setting of 7.5 when I woke up with a 90% SpO2 level and an oxygen percentage of 14.8. It wasn’t exactly difficult to breath, but each lungful of air had more depth to it. Stepping in and out of a deoxygenated tent is when the difference is most noticeable, but like your eyes adjusting to a bright setting, your “normal” quickly adjusts. I’m currently sleeping at a setting of 8.5, which correlates to about 10,500’. I prefer to say Leadville, Colorado or the wealthy part of La Paz, Bolivia, depending on the night.
I’ve generally been very impressed with low-oxygen living. The most common complaint I’ve heard is the build up of heat inside the tent, but from my experience over the winter, it has been great. We turn the heat off a bit before bed and sleeping has been more than comfortable. The numerical benefits of my system are hard to measure; can I be sure that my power is increasing because of the tent or is it just a year-to-year gain? I can’t be positive, but the science seems to be on my side, my power numbers are up and my weight is down. It’s hard to be unhappy with those results.