Training for High Altitudes: A Guide for Trail Runners, Backpackers, and Mountaineers
High-altitude environments present unique challenges for athletes, impacting their performance and requiring specific training adaptations. Understanding how to train for events and treks at high altitudes is crucial for backpackers, mountaineers, and trail runners alike. In this article, we will explore the physiological effects of altitude, acclimation strategies, training methodologies, and practical tips to enhance performance in high-altitude conditions.
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Table of Contents
The Challenge of High Altitude: Oxygen and Performance
One of the most significant challenges at high altitudes is the decrease in the partial pressure of oxygen. Contrary to popular belief, oxygen isn’t actually lower at higher altitudes. The composition of gasses in the air remains the same (20.93% oxygen, 0.03% carbon dioxide, and 79.04% nitrogen), but the lower pressure makes it harder to get oxygen into the lungs and from the lungs into the bloodstream. This reduction in oxygen availability can severely limit performance in endurance events, as the body relies heavily on oxygen for sustained efforts.
Aerobic vs. Anaerobic Cycles Explained
In the world of sports and physical performance, understanding the difference between aerobic and anaerobic cycles is crucial, especially when considering the effects of high-altitude training.
Aerobic Cycle
The aerobic cycle refers to the process by which the body produces energy using oxygen. This cycle is predominant in endurance activities such as long-distance running, cycling, hiking, and mountaineering. During aerobic exercise, the body uses oxygen to convert carbohydrates, fats, and proteins into energy, a process that takes place in the mitochondria of cells. This cycle supports prolonged, steady-state activities by providing a sustained energy supply.
Key Characteristics of the Aerobic Cycle:
Duration: Sustains longer periods of activity.
Energy Source: Primarily uses carbohydrates and fats.
Oxygen Dependence: High; requires a continuous supply of oxygen.
Byproducts: Produces carbon dioxide and water, which are easily expelled from the body.
Anaerobic Cycle
The anaerobic cycle, in contrast, occurs without the need for oxygen. It is the primary energy system for short, intense bursts of activity, such as sprinting, weightlifting, and high-intensity interval training (HIIT). During anaerobic exercise, the body relies on stored glycogen in the muscles for quick energy production. This process occurs in the cytoplasm of cells and results in the production of lactic acid.
Key Characteristics of the Anaerobic Cycle:
Duration: Supports short bursts of high-intensity activity (usually up to 2 minutes).
Energy Source: Relies on glycogen stored in muscles.
Oxygen Dependence: Low; does not require immediate oxygen.
Byproducts: Produces lactic acid, which can accumulate and cause muscle fatigue.
Impact of High Altitude on Aerobic and Anaerobic Performance
Studies have been conducted about how high altitude affects these two energy cycles differently:
Aerobic Performance: Endurance athletes, who depend heavily on the aerobic cycle, struggle due to the reduced partial pressure of oxygen at high altitudes. With less oxygen available to fuel their aerobic metabolism, their performance suffers significantly. This is because the efficiency of oxygen-dependent energy production drops, leading to quicker fatigue and decreased endurance.
Anaerobic Performance: Conversely, anaerobic athletes, such as sprinters, experience a performance boost. The reduced air density at high altitudes leads to lower air resistance, allowing sprinters to achieve faster times. Since their events rely less on oxygen and more on quick, intense energy bursts from the anaerobic cycle, the reduced oxygen availability has a minimal impact on their performance.
Understanding these differences is vital for athletes and trainers, especially when preparing for high-altitude events. Strategies for acclimation and training can be tailored to optimize performance based on whether the activity is primarily aerobic or anaerobic.
Physiology of Altitude Acclimation-Read This!
When ascending to high altitudes, your body undergoes a series of rapid adaptations to counter the decreased oxygen availability. These adaptations can begin within the first 24 hours and continue to develop over several weeks. Here’s a closer look at these physiological changes:
Initial 24-72 Hour Window
The initial 24-72 hours at high altitude are often the most challenging for many individuals. During this period, the body starts to respond to the sudden drop in oxygen availability, and these changes can make you feel particularly uncomfortable. Common symptoms include elevated heart rates, increased respiratory rates, and general feelings of fatigue and malaise. Understanding what happens in this critical window can help in planning your acclimation strategy effectively.
Haemoconcentration:
Rapid Response: One of the first responses your body has to high altitude is haemoconcentration. This process boosts the density of red blood cells to help transport oxygen more effectively. This temporary solution is crucial as it takes time for the body to produce new red blood cells.
Trade-off: The downside of haemoconcentration is that it reduces blood plasma volume by 10-25%, forcing the heart to pump faster to maintain cardiac output. This decrease in plasma volume lowers stroke volume, requiring a higher heart rate to ensure sufficient blood and oxygen circulation.
Hypoxic Ventilatory Response:
Increased Ventilation: The hypoxic ventilatory response kicks in as your body tries to cope with lower oxygen levels. This response involves an increase in both the rate and depth of breathing to maximize oxygen intake.
pH Balance: This increased ventilation causes a shift in blood pH levels (respiratory alkalosis), which can lead to a feeling of discomfort. The body responds by making you urinate more frequently, as the kidneys work to balance the pH levels by excreting bicarbonate.
Symptoms and Performance Impact:
Physical Effects: During these first few days, you might experience dizziness, shortness of breath, headaches, and a noticeable decline in physical performance. This period is often described as "the worst of it" because the body is working hard to initiate the acclimation process, but the adaptations are not yet complete.
Performance Considerations: Athletes and trekkers often feel their worst during this time because the body is still adjusting. It's a crucial time to monitor health closely and avoid pushing too hard, as the risk of altitude sickness and overexertion is higher.
Long-Term Adaptations
After surviving the initial tough period, your body continues to adapt over the following weeks:
Erythropoietin (EPO) Production:
EPO Release: The body’s hypoxia-induced pH shifts stimulate the kidneys to release erythropoietin (EPO). This hormone plays a key role in the production of new red blood cells, a process known as erythropoiesis.
Time Frame: Erythropoiesis takes about one to three weeks to mature new red blood cells fully. These new cells increase the blood’s oxygen-carrying capacity, significantly improving endurance and performance at altitude.
Expanded Blood Plasma Volume:
Restoring Balance: As new red blood cells are produced, the body also works to restore and expand blood plasma volume. This balance between red blood cells and plasma volume helps stabilize cardiac output and improves overall cardiovascular efficiency.
Hematocrit and Hemoglobin Levels: Increased hematocrit and hemoglobin levels enhance the body’s ability to transport oxygen to muscles and other tissues, allowing for better performance and reduced fatigue during prolonged physical activity at high altitudes.
Understanding these physiological changes and the critical 24-72 hour window of initial adaptation is important for athletes and adventurers planning to train or perform at high altitudes. By recognizing the symptoms and knowing what to expect, you can better prepare for the challenges and make informed decisions about your acclimation strategy. Whether you’re a backpacker, mountaineer, or trail runner, these insights can help you maximize your performance and ensure a safer, more enjoyable experience at high elevations.
How to Prepare for High Altitude Adventures
Preparing for high-altitude adventures can be particularly challenging for those who live at low altitudes due to their bodies not being naturally adapted to reduced oxygen levels. The key to success lies in proper planning, understanding acclimation strategies, and employing effective training techniques.
Preparing ahead of your race or trek will go a long way in helping your body adapt to and perform at higher altitudes. There are two main types of altitude acclimation strategies:
Hypobaric Hypoxia Exposure: This involves living and training at natural high altitudes. Spending two to four weeks at elevations between 5,905 feet (1,800 meters) and 9,842 feet (3,000 meters) is ideal for maximizing adaptation benefits, particularly in enhancing red blood cell production.
Normobaric Hypoxia Exposure: Utilizing altitude tents or rooms to simulate high-altitude conditions can also be effective. However, the adaptation process requires cumulative exposure of at least 8-10 hours daily over three to four weeks. Challenges include potential impacts on sleep quality and blood plasma volume. I’ll share more on this later.
Alternative Strategies for Those Who Live at Low Altitudes
Heat Training: Exercising in high temperatures induces physiological adaptations that partially mimic responses to altitude exposure. Benefits include increased blood plasma volume, improved cardiovascular function, and potentially reduced physiological strain during altitude activities. More research still needs to be conducted in this area, so take that into consideration, and always check with a doctor to ensure your unique health needs support this type of training.
Gradual Exposure
Gradual exposure to increasing altitudes is crucial for acclimation. If possible, schedule several trips to higher elevations in the weeks leading up to your event. This approach allows your body to initiate physiological adaptations slowly, reducing the risk of altitude sickness and enhancing performance.
Begin your altitude exposure well in advance of your event or trek. Ideally, start at lower elevations and progressively move to higher altitudes over several trips. For example, if your event or trek is at 10,000 feet, consider spending time at elevations between 5,000 to 7,000 feet initially, then gradually increase to 8,000 to 9,000 feet in subsequent trips.
The duration of each trip and the frequency of visits depend on individual adaptation rates and event timelines. Aim to spend at least a few days at each altitude level to allow your body to adjust before moving to higher elevations.
Engage in light to moderate physical activities during your altitude trips. This helps stimulate circulation, oxygen utilization, and adaptation processes in your body. Avoid strenuous activities initially to minimize the risk of overexertion and altitude-related symptoms.
When to Arrive for your High Altitude Event or Trek
Arriving at the right time before your high-altitude event or trek makes a big impact for optimizing acclimation and performance. Here’s a detailed look at the two primary arrival strategies and their considerations: arriving a week ahead of time, or less than 24 hours before the event.
Optimal Arrival Time
Arriving at least one week before your event provides several advantages:
Acclimation Phase: The initial 24-72 hours at high altitude are often the most challenging as your body adjusts to reduced oxygen levels. Arriving early allows you to pass through this phase when symptoms like headache, fatigue, and nausea may peak.
Positive Adaptations: Beyond the initial phase, your body begins to adapt positively to altitude conditions. Physiological changes such as increased red blood cell production, improved oxygen utilization efficiency, and enhanced buffering capacity can start to take effect.
Training Opportunities: Early arrival offers opportunities to familiarize yourself with the environment, test your performance at altitude, and adjust training intensity based on your acclimation progress.
Activities during early arrival include:
Light Exercise: Engage in light aerobic activities such as walking, easy jogging, or gentle hikes to stimulate blood flow and oxygen utilization without overtaxing your body.
Hydration and Nutrition: Focus on adequate hydration and balanced nutrition to support physiological adaptations and prevent dehydration, which is common at high altitudes.
Rest and Recovery: Prioritize rest and quality sleep to aid in adaptation and recovery. Altitude can disrupt sleep patterns initially, so establishing good sleep hygiene practices early is beneficial.
Considerations for Arriving Just Before the Event
If circumstances prevent early arrival, arriving within 24 hours of your event may be necessary. Here’s what to keep in mind:
Symptom Management: Arriving closer to your event minimizes exposure to the initial acute symptoms of altitude sickness. This strategy aims to compete while symptoms are minimal or after initial acclimation challenges have subsided.
Limited Acclimation: Late arrival limits the time available for physiological adaptation to altitude. While you may avoid peak symptoms, your performance may still be affected by reduced oxygen availability and physiological stress.
Rest and Relaxation: Focus on relaxation and mental preparation upon arrival. Minimize physical exertion and prioritize hydration to maintain optimal performance readiness.
Strategies for Last-Minute Arrival:
Brief Activity: Engage in light stretching or short walks to stimulate circulation and oxygen uptake without inducing fatigue.
Mental Preparation: Visualize your race strategy and familiarize yourself with the event details, course conditions, and environmental factors to enhance mental focus and confidence.
Gradual Exposure: Plan to spend time at increasing altitudes gradually. If possible, take trips to higher elevations in the weeks leading up to your event to help your body begin the acclimation process.
Hydration and Nutrition at High Altitudes
Increased Hydration Requirements
High altitudes pose challenges to hydration due to increased fluid loss through respiration and urination. The dry air and lower atmospheric pressure at altitude lead to enhanced evaporation of moisture from the body. Things to take into consideration to prioritize hydration:
Water Intake: Drink ample water throughout the day to maintain hydration levels. Aim for at least 3-4 liters of water daily, adjusting intake based on activity level, altitude, and individual sweat rate.
Electrolyte Balance: Besides water, replenish electrolytes lost through sweat with sports drinks or electrolyte supplements. Electrolytes such as sodium, potassium, magnesium, and calcium are vital for maintaining fluid balance and muscle function.
Nutritional Strategies
Proper nutrition plays a pivotal role in supporting acclimation and performance at high altitudes. Consider the following dietary adjustments:
Balanced Diet: Emphasize a well-rounded diet that includes carbohydrates, proteins, and healthy fats. Carbohydrates provide energy for physical activity through the Krebs Cycle, proteins support muscle repair and growth, and fats serve as a sustained energy source.
Carbohydrates: Prioritize complex carbohydrates such as whole grains, fruits, and vegetables, which provide sustained energy and replenish glycogen stores.
Proteins: Include lean proteins like poultry, fish, beans, and nuts to support muscle recovery and immune function.
Healthy Fats: Opt for sources of unsaturated fats like avocados, nuts, seeds, and olive oil, which contribute to cardiovascular health and energy production.
Practical Tips for Hydration and Nutrition
Preparation: Plan meals and hydration strategies before traveling to high altitudes. Consider packing electrolyte powders or tablets for convenient replenishment.
Monitor Hydration Status: Pay attention to urine color and frequency as indicators of hydration. Clear or light-colored urine suggests adequate hydration, while dark urine may indicate dehydration.
Gradual Adjustment: Allow time for your body to adapt to the altitude. Start hydrating well before arrival and continue adjusting fluid intake based on altitude, weather conditions, and physical exertion.
Impact of Alcohol at High Altitudes
Alcohol consumption can have significant adverse effects on your body, especially at high altitudes. Here's how alcohol impacts you at altitude and guidelines on avoiding it:
Increased Dehydration: Alcohol is a diuretic, which means it increases urine production and can lead to dehydration. At high altitudes, where fluid loss is already elevated due to respiration and urination, alcohol exacerbates this issue.
Impaired Acclimation: Alcohol can impair your body's ability to acclimate to high altitudes by interfering with sleep patterns and reducing the production of hormones that aid acclimation.
Exacerbation of Altitude Sickness: Alcohol consumption can worsen symptoms of altitude sickness, such as headaches, dizziness, and nausea. It can also impair judgment and coordination, increasing the risk of accidents and injuries.
Reduced Physical Performance: Alcohol negatively impacts physical performance by reducing coordination, balance, and reaction time, which are crucial for activities at high altitude.
Guidelines for Alcohol Avoidance
Pre-Altitude Preparation: It is advisable to avoid alcohol for at least 48-72 hours before ascending to high altitudes. This allows your body to start the acclimation process without the additional strain of dehydration and impaired physiological functions.
During High-Altitude Exposure: Refrain from consuming alcohol while at high altitudes to maintain optimal hydration levels and support your body's acclimation efforts.
By prioritizing hydration with adequate water intake and electrolyte replenishment, and maintaining a balanced diet rich in essential nutrients, athletes and individuals can optimize their performance and acclimatization at high altitudes. Avoiding alcohol supports hydration efforts and enhances the body's ability to adapt effectively to altitude challenges. Remember, individual needs may vary, so adjust hydration and nutritional strategies based on personal responses and environmental conditions at altitude.
Technology for Altitude Training
Altitude Tents
For athletes who cannot spend extended periods at high altitudes, altitude tents offer a practical alternative by simulating high-altitude conditions through normobaric hypoxia exposure. However, there are several considerations to keep in mind:
How They Work: Altitude tents create a low-oxygen environment by enclosing your sleeping area and using a generator to reduce the oxygen concentration in the air. This setup can mimic the hypoxic conditions found at high altitudes.
Usage and Adaptation Time: Effective use of altitude tents requires consistent use over several weeks. Typically, athletes spend 8-10 hours per day (usually overnight) in the tent for at least 3-4 weeks. This cumulative exposure can help stimulate physiological adaptations such as increased red blood cell production.
Challenges: There are practical challenges associated with the use of altitude tents:
Affordability: Altitude tents can be expensive, making them a significant investment.
Sleep Quality: The confined space and noise from the generator might disrupt sleep, potentially affecting the athlete's overall training quality.
Living Elevation: The benefits of altitude tents may be more pronounced for athletes who already live at elevations closer to the minimum effective altitude.
Time Before Event: Ideally, athletes should use the tent consistently and also try to arrive at their high-altitude event more than 72 hours before to maximize acclimation.
Overall, while altitude tents can be beneficial, the practicalities of their use must be carefully considered to ensure they fit well within an individual’s training regimen and lifestyle.
Airflow Restriction Devices (ARDs)
Airflow Restriction Devices (ARDs) aim to simulate the sensation of reduced oxygen availability by restricting air intake. However, they fall short in terms of inducing the necessary physiological responses for effective altitude acclimation:
How They Work: ARDs limit the volume of air an athlete can inhale, creating a feeling similar to breathing at high altitudes.
Limitations: Unlike altitude tents, ARDs do not reduce the oxygen content in the air. Therefore, they do not trigger the same beneficial adaptations such as increased red blood cell production and improved oxygen utilization.
Effectiveness: Research indicates that while ARDs can strengthen respiratory muscles, they do not provide the systemic adaptations needed for true altitude acclimation. Consequently, they are not recommended for athletes aiming to prepare for high-altitude events.
Altitude tents and Airflow Restriction Devices represent two different technological approaches to simulating high-altitude conditions for training purposes. Altitude tents can be effective for acclimation if used consistently over several weeks and an individual spends enough time in them, as they create a true hypoxic environment that stimulates beneficial physiological adaptations. On the other hand, ARDs, which only simulate the sensation of restricted breathing, do not induce the comprehensive physiological changes required for effective altitude acclimation and are not recommended for this purpose. Athletes considering the use of these technologies should carefully weigh their benefits and limitations and consult with professionals to ensure they are used effectively and safely.
Understanding Altitude Sickness
Altitude sickness, also known as acute mountain sickness (AMS), manifests with varying symptoms depending on the elevation change experienced. The greater the altitude difference, the more severe the symptoms can become. Typically, symptoms arise within 12 to 48 hours of exposure to higher altitudes.
Mild Symptoms:
Dizziness
Fatigue and loss of energy
Shortness of breath
Loss of appetite
Sleep disturbances
Moderate Symptoms:
Worsening fatigue, weakness, and shortness of breath
Difficulty with physical activity
Severe headache, nausea, and vomiting
Chest tightness
Severe Symptoms:
Shortness of breath even at rest
Inability to walk
Confusion
Fluid buildup in the lungs and/or brain
The primary cause of altitude sickness is the decrease in air pressure at higher altitudes, which impairs the exchange of oxygen between the lungs and blood. Interestingly, one's fitness level does not necessarily mitigate the risk of altitude sickness.
Recommendations for Athletes and Adventurers
When traveling to higher altitudes from lower elevations, it's advisable to avoid strenuous exercise or training for the first few days. This allows the body to acclimate gradually without additional stress, optimizing adaptation.
Intervention
Interventions for altitude sickness vary based on its severity:
Mild symptoms: Over-the-counter medications can alleviate symptoms, but time for natural adaptation is often the most effective remedy.
Moderate symptoms: Medications or descending to an elevation 1,000 to 2,000 feet lower than the onset of symptoms can provide relief.
Severe symptoms: Immediate descent below 4,000 feet is recommended, along with consultation from a healthcare provider.
Prevention
The best prevention for altitude sickness is gradual acclimatization through progressively increasing exposure to higher altitudes over time. For those based at sea level, using altitude tents at home can simulate hypoxic conditions, aiding in acclimatization, though this option is costly and requires careful consideration, as mentioned in the above section.
Considerations for Medication: Checking Anti-Doping Agency Databases
Before using any medication to alleviate symptoms of altitude sickness, athletes who are competing in events should seek guidance from healthcare providers experienced in sports medicine and anti-doping regulations and consult the anti-doping agency databases. These databases provide comprehensive lists of prohibited substances and methods, including specific guidelines on the use of medications. It is important to cross-reference any prescribed or over-the-counter medication against these lists to ensure it does not contain prohibited substances or fall under restricted categories. If you are not competing in a specific official event, consult with a doctor about your unique health needs.
Final Thoughts
Training for high-altitude environments is challenging but rewarding for backpackers, mountaineers, and trail runners–you get to explore the world literally from new heights! Effective acclimatization involves gradual exposure, proper hydration, and balanced nutrition. Understanding and managing altitude sickness symptoms are crucial for safety and performance. With careful planning and consistent exposure, you can enhance your endurance and safety, ensuring a successful and enjoyable high-altitude adventure.
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When you purchase gear through these links, you may contribute a small commission to us as an affiliate, which helps us continue providing valuable educational content for free! We appreciate your support, as it enables us to break down barriers and make outdoor education accessible to everyone. Happy trails!
About the Author
Shannon is a certified running coach accredited by UESCA with a passion for high-altitude adventures. With years of experience in backpacking and trail running, she shares her experiences to help outdoor enthusiasts maximize their performance and safety in challenging environments.