- Low Temperature: Regardless of the season, the temperature at high altitudes are much lower than the temperature at lowlands. You all know that temperature goes down by 6°C for every 1000m elevation in altitude. So even if you are traveling in summer, temperatures at high altitudes can be quite cool.
- Low Oxygen: Decreased pressure at high altitudes means that less oxygen – for example, 61% of oxygen available at altitudes of 4000m compared to sea level. This reduced oxygen means that your body needs to go into an oxygen conservative mode – saving the precious oxygen for the body systems that are vital to life.
Before you plan and get your body prepared, I recommend you to write down a list of your frequent health challenges, be it digestive issues, frequent colds, and flu, and / or any chronic health challenges. That will give you an idea of where you need to focus your preparation most. They are frequently the first symptoms that you will experience at high altitudes. A few examples:
- Cardiovascular health challenges such as high blood pressure will often bring on headaches
- Indigestion (leaky gut, abdominal bloating, constipation) can often bring on nauseating and / or aggravated digestive challenges
- Circulation challenges including inefficient lymphatic circulation will often bring on edema
- Respiratory health challenges such as asthma, COPD will often experience shortness of breath upon altitudes beyond 2000m
It is important to understand how the body acclimatizes for planning your journey:
- The general acclimatization process started when you ascend beyond 2500m, and the first sign can be hyperventilation (breathing at a faster rate) and possibly followed by an increased heart rate. By increasing respiratory rate and heart rate, the body is working to compensate for the reduced oxygen due to reduced partial pressure as well as reduced oxygen delivery to the cells of your body.
- The hyperventilation and increased heart rate will increase further with continual ascend (remember that less oxygen is available as you ascend). This is also when the early symptoms of the AMS (like a headache) will start to show.
- When the ascend continue for hours, the body will presume that this “hypoxia” (reduced oxygen) trend will continue and will trigger a mechanism to increase production of red blood cells (RBC). Red blood cells are responsible for delivering oxygen to the cells of your body, and red blood cells take roughly two days to produce. This is analogous to calling on more deliverers to help to deliver the parcels during peak festive seasons, and the deliverers have to be recruited beforehand.
- The 2 days’ lead time for recruitment (or “production”) of red blood cells are important considerations of planning your journey. You probably heard of the “Climb high, Sleep low”. The reason for this strategy is to enable your body to recover at night and enable the body to focus on the RBC production rather than having to deal with the AMS symptoms which tend to increase as you ascend beyond 3000m. There is a common practice for travelers to spend a few days in Shangrila in Yun Nan (altitude 31xxm) before going to Tibet for the precise reasons – expose have your body to high altitudes and trigger the RBC recruitment process without stressing it. By the time you get to Tibet, the body can adapt better as now it has more RBC deliverers.
I will share on strategies for increasing oxygen carrying and delivering capacity in the body, which is the crown jewel in adaptation to high altitudes in the next blog.