Two mountaineers from the Basque Country contacted our institute when preparing for an expedition to the highest mountain of the Trans-Alai range in the Northern Pamir mountain region.  Peak Lenin (7134m) borders Kirgizstan in the north and Tadzhikistan in the south. In 1928, the top of Peak Lenin was reached for the first time. Nowadays, it is a popular 7000-meter peak.

The twin brothers Aitzol and Axier Jaka (35), two passionate mountaineers, are aiming for the top of Peak Lenin the beginning of July via the Razdelnaya Top Route. It is their first attempt to climb a 7000-meter peak. They started preparing by evaluating personal previous high-altitude experiences. During a previous climb to Mount Elbrus (5610m), they observed individual problems with hypoxia. Although they stuck to common acclimatization procedure by climbing a 4000m peak beforehand, hypoxia caused difficulties during the summit attack day. In their opinion, the last sleeping altitude at 3750m was too low and caused a descent at an altitude of 5300m on summit attack day. They were able to reach the summit not before the following day.

„…instead, the next day, with really bad weather, windy and stormy, we could arrive the summit, because of the additional day of acclimatization.“ (Aitzol Jaka)

They draw following conclusions from this experience:

„our acclimatization process is slower than other people: we need more time to acclimatize than common people“

„we need ascend and sleep as high as possible to acclimate“ (Aitzol Jaka)

The evaluation of personal high-altitude experiences is the first important step when preparing further summit attempts, because acclimatization is a difficult process depending on many individual factors. There are no distinct scientific statements regarding acclimatization processes, which can be applied for every mountaineer. Scientific insights are mainly based on the collection of individual experience (F. Berghold, 2015, in Alpin- und Höhenmedizin).

Just as the two mountaineers assumed correctly, sleeping altitude is substantial for a successful summit ascent. The distances between sleeping altitudes define an acclimatization plan. For every single mountaineer, an individual “critical altitude” exists. After reaching critical altitude, several nights should be spent at this height, before further ascending. In order to avoid symptoms of acute mountain sickness (AMS), the daily sleeping heights above critical altitude should not differ for more than 400 meters. Since this is not applicable for many summit ascents (also the one of Aitzol and Axier) due to several reasons (including logistics), the number of nights spent at following altitudes defines a good acclimatization.

Principally, sleeping altitude should be as low as possible in order to provide optimal physiological regeneration. In return, the highest reached altitude per day can reach more than 1000 meters. The opportunity to descent to lower regions should always be given, especially after asking yourself questions like: do I suffer from headache or nausea after spending the night at altitude?

Aitzol reports from a further previous altitude experience:

„When I was in Ecuador, sleeping in refuges at 4700m – 5000m, I constantly woke up during nights. I couldn’t breath, it was a similar feeling to anxiety attack, but I wasn’t nervous and the next morning I was „well“ and I could climb without heavy headache…is it normal?“

With increasing altitude, subjective and objective sleep quality decrease in a linear matter. Studies show, that above 4000 meters, the prevalence of nightly arousals significantly increases. The partially unconscious arousals caused by a lack of oxygen saturation can last between a couple of seconds up to several minutes. The brain receives a signal of low oxygen saturation levels in the cells, which leads to accelerated heart rate and increased breathing rhythm (Pramsohler et al., 2019).

However, there are additional factors which influence sleep at altitude, such as position of upper body during sleep, cold inspiration air, digestion problems or pain. Daily activity also contributes to sleep quality. If an ascent on the previous day leads to severe exhaustion, increased adrenalin and cortisol levels can cause sleep loss, because they degenerate very slowly.

Based on their experiences, Aitzol and Axier developed an acclimatization plan for Peak Lenin (picture). For them, the critical part of the expedition will supposedly start at Camp 2 (5300m), because of a quite big altitude difference between Camp 2 (5300m) and Camp 3 (6100m).

Aitzol and Axier prepared the expedition with utmost care, they are well-trained and in good physical shape. Therefore, I’m confident, that the expedition will be a success. With a bit of luck, they will reach Peak Lenin summit between July 15^th and 18^th.

We will report on the ascent!

As cooperation partner of the University of Innsbruck, our Institute offers the perfect setting to conduct scientific studies with variable altitudes up to 6000m. Currently, our 3 hypoxic chambers are used for a pre-acclimatization study in order to assess the prevention of acute mountain sickness (AMS) in normobaric hypoxia. Assoz. Prof. Mag. Dr. Martin Faulhaber leads the study group from the Institute of Sport Science, University of Innsbruck.

Pre-acclimatization serves the purpose of preventing the manifestation of AMS. Symptoms of AMS are among others headache, dizziness, nausea, loss of appetite and fatigue/weakness. Depending on the degree of AMS, cognitive and motoric performance are severely disturbed. Most commercially guided tours to greater altitudes offer continuous acclimatization on the mountain, in order to reduce the risk of AMS. A study lead by Beidlemann et al (2018) recently showed, that only 2 days of pre-acclimatization at 3000m and 3500m in terrestrial altitude are enough to reduce the risk of AMS significantly during a follow-up stay at 4300m. Pre-acclimatization in normobaric hypoxia, as we offer it at the Hermann-Buhl-Institute, is logistically more practicable and easier to realize compared to terrestrial altitude.

Therefore, the aim of the study is, to investigate the effect of 2 pre-acclimatization nights on the incidence and manifestation of AMS during a following 22-hours exposition period to 4300m normobaric hypoxia.

Participants aged 18 to 30 years were recruited for the study. The first group of participants completed two pre-acclimatization nights at 3000m and 3500m. Immediately afterwards, a 22-hours stay at 4300m altitude was performed.

During the 22-hours stay, participants completed submaximal endurance tests. Each participant underwent an ergometry on a bicycle with measurements of lactate. These tests were previously conducted in normoxia and repeated during the altitude stay.

The second group of participants will be tested in the following 2 weeks. This group does not absolve two pre-acclimatization nights, but will stay at 4300m for 22 hours right from the start. This group will also complete submaximal endurance tests in order to compare parameters of exercise capacity with and without pre-acclimatization nights.

In the first group, mild symptoms of AMS already appeared. We are looking forward to the results of AMS manifestation in the second group!