Training Before Expedition – The Role of Aerobic Base and Hypoxia

If you’re planning a high-mountain expedition, aiming to conquer ambitious peaks in the Alps or the Himalayas, you’re likely wondering what type of training is crucial. What makes some individuals seem like indestructible “mountain machines”? How can you achieve a similar level of fitness? These are questions worth answering, especially if you’re a sports enthusiast with diverse interests and aren’t sure which one is the most effective. So, what truly determines your strength in the mountains, enabling you to maintain a steady pace for hours on end, regardless of the conditions?

Certainly, mental fortitude plays a significant role, but an equally important factor is endurance, the ability to sustain a consistent, efficient pace of effort for an extended period. This phenomenon is most evident during long-distance running, one of the disciplines that best develops this ability. If you’ve ever attempted long-distance running, you’ve likely encountered the sensation of hitting the infamous “wall.” The same can happen in the mountains, which can be perilous, especially in critical situations or in the so-called “death zone,” where prolonged exposure brings us closer to death with each passing minute. Therefore, I will attempt to answer an essential question: how should you train to delay the arrival of the renowned “wall,” the limit of our physical capabilities?

I want you to better grasp the content of this article, so let’s discuss several key processes occurring in our muscles during physical exertion. This brief medical introduction will help you understand how our bodies function during physical activity.

The Key to Endurance – Energy Production Process

To understand how to improve your endurance, we need to examine the energy production process in our bodies. Three letters play a crucial role here – ATP, or adenosine triphosphate. ATP is the primary source of energy for the cells in our bodies. It powers all life processes and enables us to function normally. ATP production in our bodies occurs through two unique metabolic pathways: anaerobic glycolysis and aerobic metabolism.

Anaerobic Glycolysis

Anaerobic glycolysis is a process that occurs rapidly, especially during intense efforts like sprinting or crossfit. This process yields 2 ATP molecules and pyruvate. Depending on the availability of oxygen, pyruvate can be processed in two different ways. Under conditions of low oxygen supply, it converts into lactate, which can remain in muscle cells and lead to acidification, resulting in a dramatic drop in running or skiing speed.

Aerobic Metabolism

This more complex metabolic process takes place in the mitochondria, often referred to as the powerhouses of our bodies. Although it’s slower and requires more oxygen, it generates a whopping 36 ATP molecules. Moreover, in well-trained athletes with a strong aerobic base and a significant number of mitochondria in their muscles, this process can use not only glucose but also the byproduct of anaerobic glycolysis, which is pyruvate. This helps us avoid the accumulation of lactate, which can lead us to a metabolic dead-end. Staying on the aerobic pathway, meaning the absorption of pyruvate by the mitochondria, generates vast amounts of valuable energy, enabling further physical exertion. In anaerobic conditions, ATP production eventually slows down, limiting the athlete’s ability to maintain their previous level of endurance.

Muscle Fibers

Aerobic processes occur in what are called slow-twitch muscle fibers, which dominate in long-distance runners. Anaerobic processes prevail in fast-twitch muscle fibers, typical of sprinters. While all these processes are important, for mountain enthusiasts, aerobic metabolism is crucial. It allows for the continuous production of a substantial amount of energy needed for extended trekking or summit attempts. Anaerobic processes become more relevant in short, high-intensity efforts, such as technically challenging sections or crisis situations, where rapid movement is a priority.

Aerobic Deficiency Syndrome – relatively common phenomenon

When we exceed the capacity of aerobic metabolism to meet our energy demands, our bodies are forced to resort to anaerobic processes to compensate for the increasing deficit. As you may know, this inevitably leads to reduced performance, which sooner or later results in slowing down. Athletes who frequently engage in high-intensity training often have a low aerobic threshold (the level of physical exertion at which the body can no longer supply sufficient oxygen to produce energy) because they have diminished their aerobic metabolism efficiency, reinforcing the dominance of anaerobic metabolism. This condition is known as the Aerobic Deficiency Syndrome, characterized by an exceptionally low (often shockingly low) pace at the aerobic threshold. This often leads to frustration and anger in individuals affected by this problem. Despite their strenuous training, they are unable to increase their running speed or even their walking pace without immediately exceeding the aerobic threshold. When advised to reduce the intensity of their workouts, they react with disbelief, questioning the benefits of such slow-paced exercise – and I speak from personal experience. The only way to overcome this low aerobic capacity is through training with high volume and low to moderate intensity.

Building an Aerobic Base: High Volume, Low Intensity

Your training plan before a mountain expedition should be diverse. It’s valuable to invest in strength training, which develops leg strength and shoulder girdle fitness, and occasionally engage in high-intensity training to acclimatize your body to strenuous efforts in oxygen-deficient conditions. However, the key to success lies in a solid (sometimes built over years) aerobic base. Long-distance runs, day-long ski tours, cycling, and other low- to moderate-intensity activities help your muscles more efficiently utilize oxygen and increase the number of mitochondria, which will be ready to convert every metabolic byproduct into new energy reserves instead of waste causing progressive muscle acidification. This is a process that takes time and patience but allows you to build endurance you could only dream of!

If you would like to delve more deeply into these topics, I recommend the book ‘Training for the Uphill Athlete’. The book was written by three outstanding specialists: coaches Steve House and Scott Johnston, who have been training Himalayan climbers, mountain runners, and ski mountaineers for many years, and Kilian Jornet, who put their advice into practice and became one of the most renowned mountain runners. In the book, you will find a detailed discussion of the processes that occur in our bodies during exertion, and you will learn how to program your training to be as effective as possible. You will also find stories of athletes who shared the challenges they faced, including aerobic deficit syndrome, and how they overcame it.

Training in Hypoxia

Many people planning to conquer the giants of the Himalayas wonder about the significant impact of hypoxia, training, or sleeping at high altitudes. Can these methods improve our endurance? This question has been addressed by numerous scientists interested in high-altitude matters for years, as they observe the successes of Kenyan and Ethiopian long-distance runners and their incredible endurance. These countries are situated at high altitudes, with the East African Rift Mountains stretching through the region, and many people live at altitudes exceeding 2000-2500 meters above sea level. Adaptation to high-altitude living is a long-term process occurring in the bodies of people who have lived at high altitudes (such as the Sherpas) for millennia. Unfortunately, we lowland inhabitants can only achieve acclimatization, not the adaptations that develop over centuries and affect our genotype. Acclimatization is a relatively short-lived process, but during it, various changes occur in our bodies that enable us to better tolerate effort in low-oxygen conditions – increased muscle blood supply, heightened hemoglobin production, and more frequent breaths.

Scientists have long pondered whether training or sleeping at high altitudes in hypoxic conditions can make us better athletes. Various training schemes have been tested – LHTH (“live high, train high”), LHTL (“live high, train low”), short, intermittent hypoxia exposure strategies at rest, or cyclical single hypoxic workouts. Questions arise about how long such exposure should last and to what altitude an individual should be exposed. Currently, scientific research has not provided clear, evidence-based answers to these questions. It seems that more than 14 hours a day, at altitudes of 2000-2500 meters above sea level, for 2-4 weeks or more, may have a beneficial impact on performance. This is logistically challenging but suggests that pre-expedition acclimatization in a hypoxic tent where you sleep at night might be somewhat cumbersome yet advantageous. Individual workouts also make sense – they won’t significantly affect overall fitness, but they allow you to test how your body responds to physical effort in extreme conditions. Scientific research hasn’t provided unequivocal evidence for the benefits of training in hypoxic conditions, but it appears that living and sleeping at high altitudes for extended periods may have a positive impact on endurance. I will dedicate a separate, more detailed article to the topic of acclimatization in oxygen tents and training in hypoxia.

In Summary

To summarize, all forms of physical activity wield influence over our endurance levels in mountainous terrain—whether it be long-distance running, trekking, strength training, or high-intensity sprints. For novices embarking on this journey, commencing with low- to moderate-intensity training, such as long-distance running, mountain hiking, ski touring, and cycling, is a prudent approach. It is through patience and unwavering consistency that you will cultivate a formidable aerobic foundation, enabling you to, quite literally, ‘move mountains’.

References:

1. “Training for the Uphill Athlete” Author(s): Kilian Jornet, Scott Johnston, and Steve House
2. “High Altitude Medicine and Physiology” Author(s): Ward, Milledge & West