Wednesday, August 17, 2011

Sleeping in the Tent

So for nearly two weeks now, I've been sleeping in an altitude tent. I've got to say, it's a little strange. It feels very much like being the subject of a scientific experiment inside one of these:

I keep expecting to wake up and be surrounded by men in white suits with flashlights attached to their heads peering in from the outside saying things like "the subject seems to be making excellent progress." The altitude tent and the scientific glove box are quite similar: clear vinyl walls, PVC frame, air tight seals, and strange ports you can stick your arms through. It also feels a lot like being an an aquarium, especially when I fly my Air Swimmer around inside it.

Just kidding -- I don't have an Air Swimmer. However, here are a few of the essentials required to survive (and even enjoy) your time in an aquarium/altitude tent.

First up, you need an O2 sensor:

This little device tells you what percentage of the air is oxygen. An altitude tent works by condensing oxygen, and then removing it from the air. Normal air has 20.9 percent oxygen (that's regardless of elevation). At higher elevations, the air becomes less concentrated, and thus, you become less able to breathe. By removing some of the oxygen, the altitude tent simulates the amount of oxygen present at high altitudes. Alongside my O2 sensor, I keep an elevation chart:

This chart tells me what elevation my tent is simulating. At 16.7% oxygen, my tent is simulating just under 9000 feet above sea level. The air enters the tent through a 1-inch clear plastic tube (I forgot to take a close-up of the tube, but it totally adds to the science-experiment quality of the setup).

The tent is designed to be air tight, so aside from the gentle puffs of oxygen depleted air entering through the tube, there's not a lot of air-flow. It can get stuffy and hot. This leads me to another crucial piece of equipment: a fan!

The fan pushes air around the tent, and since the tent tends to heat up, provides me a way to stay cool when I'm trying to sleep. Once the tent is full of low-O2 air, I can open up a vent or two to maximize the air flow. There are lots of vents like this one:

Getting the tent tuned so that it stays at a steady elevation throughout the night took some practice. On more than one occasion, I went to sleep at a nice and practical elevation of ~7000 feet, only to wake up several hours later feeling like I was breathing through a straw, the elevation having risen to upwards of 10,000 feet.

The last important thing I take into the tent with me is a good book to read (right now Meriwether Lewis and William Clark are about to steak out their winter camp near the Mandan Indian tribe in the winter of 1804 in Undaunted Courage), and a water bottle. My mouth tends to dry up, and it's nice to get a drink without having to leave the tent and let all that richly oxygenated air inside.
I'm hopeful the altitude tent helps me when I get up to the high Rocky Mountain passes of the US Pro Cycling Challenge, but I can't say I'll miss sleeping it when the race is over.


Martin Criminale said...

Very cool to learn about these tents as I knew practically nothing. It also sounds almost dangerous! Keep that O2 sensor handy...!

Perhaps a Parrot said...

So I was scared at first too -- I mean what would happen if the percent of O2 went down to, say, zero? While I was in there? One of the first things I did was batten down the hatches as tight as I could, and let it run all day. I found out that with zero vents open, the max altitude I could get it to was about 11,000 feet -- a solid 1,000 feet lower than the race in Colorado.

Martin Criminale said...

12,000 feet...?! My lungs burn just thinking about that. I was watching some footage from the last few Leadville 100 races the other day thinking I might like to give that a go sometime and then did the research only to find out that the while race takes place between 10,000 and 12,000 feet. Maybe not.

I think I have only ridden my bike at 10,000 feet three times in my life and they were all VERY short lived.