It’s kind of tricky trying to record myself while I’m running. It’s a good thing I have a strong chin for everyone to stare at. Seriously though, I’m really plunging into preparing for this exciting journey to Nepal. I’m so grateful to the Mars Academy USA for inviting me to join their team, and several other participants have already reached out to welcome me to the crew. They sound like an amazing group of intrepid adventurers!
I wanted to share this video to kind of demonstrate the physical challenge that we’ll be up against when we go to Mt. Everest Base Camp in a few months. I had just started running at 8,000 feet above sea level when I began recording, and I was already out of breath. Granted, trying to talk while I’m running is always a bit taxing, but high altitude will humble you quickly! I run fairly regularly and I spent several weeks this summer backpacking at 10,000 feet, so I’m in reasonable physical condition. I won’t lie though— I’m a little intimidated by this challenge. My run today was at 8,000 feet, and we’re going to be trekking up to more than twice that elevation! To really drive that home, allow me to give a quick and dirty lesson on some of the vagaries of the atmosphere we tend to take for granted.
You may already be quite well aware that Earth’s atmosphere consists of about 78% nitrogen, 21% oxygen, and 1% other trace gases and water vapor. This distribution is fairly consistent throughout most of our atmosphere, so when someone says that there’s not as much oxygen up at higher altitudes it’s not entirely accurate. What’s really happening is that the atmosphere is at a lower pressure. The standard atmospheric pressure at sea level is roughly 1000 millibars (approximately equivalent to 14.5 psi or 30 inches of mercury). Because oxygen is 21% of the atmosphere, the partial pressure of oxygen at sea level is about 210 millibars. In order for that oxygen to be absorbed into the blood stream in the lungs, the partial pressure of oxygen has to be higher than the partial pressure of oxygen in the blood. That’s not usually a problem down at sea level, but at 18,000 feet the atmospheric pressure is about half (500 millibars) of what it is at sea level. That means that the partial pressure of oxygen is only about 110 millibars.
This reminds me of the experiment that we did when I was in high school where we took an egg and soaked it in vinegar for a week. After several days the vinegar permeates through the egg’s membrane by osmosis until the pressure equalizes between the inside and outside. If you take the egg out of the vinegar the process will reverse itself because the pressure is higher inside the egg. This is similar to what happens in the alveoli of the lungs, where oxygen osmoses across the lung membrane and binds to the hemoglobin of the red blood cells. If you happened to be in an airplane that experienced a loss of cabin pressure at high altitude the partial pressure of oxygen in your blood stream would be higher than the partial pressure of oxygen in the atmosphere, and breathing would pump the oxygen out of your body.
Hypoxia is a medical condition associated with a lack of oxygen in the body’s tissues. Although we most commonly think of this with regard to high altitudes where there’s a reduced amount of oxygen being pushed into the blood (hypoxic hypoxia), several other factors can impact respiration with similar effects. Low iron in the blood cells inhibits the hemoglobin’s ability to bond with oxygen and reduces the blood’s ability to transport oxygen to other parts of the body. Similarly, carbon monoxide bonds more readily to hemoglobin than molecular oxygen does, leaving the oxygen without a ride to the body’s tissues. One particular danger of carbon monoxide poisoning is that a person can asphyxiate even after moving away from the source of carbon monoxide to an oxygen rich environment because the blood won’t carry the oxygen while the carbon monoxide is still bonded to it. An ample supply of oxygen in the blood does not necessarily ensure that the oxygen will transfer to other body tissues. Certain chemicals can inhibit tissue from absorbing oxygen from the blood stream.
All of these variations of hypoxia have pretty similar symptoms, but they can be hard to recognize if you’re not familiar with them or alert to the possibility of hypoxia. Fatigue, lightheadedness, euphoria, headache, cyanosis (bluing of the fingertips), and reduced visual acuity are a few of the common manifestations of hypoxia. When I’ve experienced it a few times over the course of my career I’ve noticed that I just feel kind of slow. Here’s an interesting video of an Air Force pilot undergoing hypoxia training in an altitude chamber. You’ll notice his symptoms pretty quickly, even though he never really picks up on them.
Apart from avoiding high altitude environments (not exactly an option for pilots, astronauts, or Himalayan explorers), there are several things that you can do to reduce your susceptibility to hypoxia. Good physical conditioning and a balanced diet help to increase red blood cell count and stave off anemia. Smoking and alcohol use also have a detrimental effect on the body’s capacity to utilize oxygen. Taking time to acclimate to high altitudes is also important for mitigating the effects of prolonged exposure to high altitudes. In theory we could probably make our trek to Mt. Everest Base Camp in three or four days, but we’re going to stretch the journey out over a week to give our bodies a chance to adjust to the unfamiliar conditions.
All of this is kind of a poor excuse for sucking wind during my run this afternoon. I’m not interested in excuses, though— just motivations. I was hunting with my teenage daughter a couple years ago and we had a particular challenging night packing out of the forest in the middle of the night. When it was all over I asked her if she would do it again if she knew that it was going to be as difficult as it was. “No!!!”, she replied without hesitation. Two weeks later, though, she was asking to join me on my next hunt. I pointed out to her that we can choose to do hard things so that when we’re compelled to do hard things we already know that we can. Bring it on!
By the way, if you haven’t already been to my fundraising page please check it out here and consider donating. I truly appreciate anything you can spare, and I’m so grateful for all the support that I’ve been receiving.