Have you ever considered what is actually different, physiologically, about exercising at high altitude? Surely most people have been above 5,000 ft and noticed something about their breathing was different, or their heart rate is higher. This post will explore and explain how increased altitude affects us during exercise and physical exertion. Having grown up in Florida and Georgia, then living on one coast or another most of my adult life, I have little experience at higher elevations, but I did have the opportunity to climb Mount Whitney a few years ago and at 14,500 ft, I got a large dose of those effects.
In 2015, I joined a small group of students from the Naval Postgraduate School to hike Mt Whitney. Whitney is located in the Sierra Nevadas and is the highest mountain in the contiguous United States. Prior to the hike, we were required to attend a few classes given by a qualified medical professional to tell us about the four H’s: hypoxia, hypoglycemia, hypothermia, and hypohydration. We learned about these adverse conditions, how to recognize them in ourselves and our comrades, and what we should do if they occur. We also learned that as we go higher in elevation, the air is less dense, therefore there is less oxygen per volume of air. As we breathe, our bodies are not taking in the same amount of air molecules, and the mixture contains far less oxygen. This drives up our perceived exertion and causes the body to work much harder to meet physical demands.
The acclimatization period is crucial for allowing the body to adapt in preparation to function at increased altitude. I found it interesting that there are short-term and the long-term adaptations that occur. When I hiked Mount Whitney, we were coming from sea level, so we arrived two days prior to the small outpost city of Lone Pine, near our entry point to the trail. Lone Pine sits at about 4,000′ MSL. We did a preparatory hike the next day up to about 9,500 ft and spent a few hours there trying to let our bodies get used to it.
The third day we hiked 11 miles from Whitney Portal which is at 8,000′, to the summit which stand at about 14,500′. I found that my body had not acclimatized to much. It turns out it can take months for your body to truly adapt and improve its oxygen carrying capacity and make the real physiological adaptations necessary. Three days did not do much, perhaps the value of arriving early was psychological, which does count for something. The hike occurred at a particularly quick pace so we could make it up and down in one day. I was fine until about 12,000′, at that point I started feeling dizzy, fatigued, and slightly disoriented. A few of the Navy SEALs that were with us, and one motivated Army Ranger, continued at a good clip, while the stragglers slowed down to fight an invisible monster. We slowed down dramatically for the last thousand feet and I believe the last mile took about an hour! I would walk slowly, then realize that I am not staying on the trail very well so I would sit down, this was repeated many times in that final stretch. It was well worth it once we reached the summit, but it was humbling to feel the effects of physical exertion at altitude. I ended up not wanting to stay on the summit for very long, I still felt horrible and I knew the only way to feel normal again was to go back down the mountain. As we descended, I progressively felt better. My morale improved with each step and each hiker we passed, looking like me a short time before, as they zombie-walk to the summit.
I should back up and mention my dinner the night before the hike. My German friend, Andreas, noticed an old saloon in Lone Pine, the type he had seen in the old American western films. He just had to go in, he wanted to experience how it felt to bust open the “batwing” saloon doors. I obliged and we ended up staying there for an hour or so. He convinced me, that in Germany, it is perfectly acceptable, nutritionally, to substitute a pint of beer for part of your dinner. In fact, he said that one beer was equivalent to two slices of bread. The little voice in my head: “Bread is chocked full of carbs, we will need carbs for energy tomorrow on the hike, this beer does taste good, so it makes perfect sense to have a few more.” We ended up having beer for dinner, perhaps the opposite of a good pre-Mount Whitney hike dinner. Andreas laughed it up the next day when I told him how much I hated German logic. “You actually believed me” he said. LOL. Lesson learned, never trust a German. Kidding of course, the real lesson is, leave the beer for after the hike, and only after you drink tons of water to rehydrate after a strenuous hike up the highest mountain in the contiguous United States.