How to Train for an Ultramarathon at Altitude When You Live at Sea Level

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How to Train for an Ultramarathon at Altitude When You Live at Sea Level

Every year, thousands of runners who live at or near sea level sign up for ultramarathons at altitude. Then the fear sets in. How can you prepare for the increasingly hypoxic environment between 6,000 and 14,000 feet above sea level while spending most of your training time between zero and 4,000 feet? Do you need an altitude or tent? Should you move to Colorado for a month?

Thankfully, the most effective strategies are relatively simple. If you follow the following framework, you’ll be well prepared for a positive experience at your high-altitude event:

1. Focus on fitness first.
2. Plan your travel intelligently.
3. Understand what altitude will do to your performance.
4. Learn to manage effort at altitude.

Altitude is a legitimate challenge, but it doesn’t have to derail your race.

Fitness Is Your Best Advantage at Altitude

The single most important thing you can do to prepare for an ultramarathon at altitude is to arrive as fit as possible. Altitude takes a bite out of your ability to perform, so the more fitness you start with, the more you’ll have left to work with.

Here’s what’s happening at a physiological level. As elevation increases, barometric pressure decreases. The percentage of oxygen in the atmosphere remains about 21%, but the lower pressure means there are fewer oxygen molecules in each lungful of air. Less oxygen is available to bind to hemoglobin and get delivered to working muscles.

Your body compensates by breathing faster and deeper, and at a given pace your heart rate response will likely be higher than it would be at sea level. Your maximum aerobic capacity (VO2 max) decreases as elevation increases, too. It can be about 10% lower at 6,000 feet above sea level and then decline even more as you go up. This affects amateur as well as elite athletes. Everyone suffers some level of progressive performance decline as elevation increases, but there is also a lot of variability in how individual athletes adapt and perform at altitude.

Generally, athletes who arrive with the strongest aerobic systems, durable legs, and well-developed endurance have more capacity to absorb the physiological penalty of altitude.

Don’t let altitude anxiety derail your training.

Continue building fitness right up until it’s time to travel. A well-executed training block without altitude-specific interventions will generally be more valuable than a mediocre training block coupled with reliance on expensive altitude gadgets.

Planning Your Arrival At High Altitude

Once your fitness is dialed, one of your most important decisions is when to arrive at high altitude. There isn’t a single universally accepted acclimatization protocol. Research and governing bodies offer different recommendations, and individual responses to altitude vary considerably.

Generally accepted ascent guidelines suggest that once you’re sleeping above approximately 9,000 feet, you should avoid increasing your sleeping elevation by more than about 1,600 feet per day. An additional acclimatization day is recommended for every 1,000 meters—or approximately 3,300 feet—gained above that level.

Spending several days at an intermediate elevation of roughly 5,000–8,000 feet before moving higher can also provide a useful staging strategy.

Applying these principles to ultramarathons, there are two main scenarios to consider. The first is a race in a sustained high-altitude environment (e.g., Leadville 100). The second is a mountainous race that features intermittent exposures to elevations above 6,000 feet.

Two Arrival Strategies for Sustained High-Altitude Races

Consider a race such as the Leadville 100, where the start is already above 10,000 feet and the course climbs to approximately 12,500 feet.

For a sea-level athlete, two approaches make sense:

• Arrive very close to race day. Arriving to the start area within roughly 24–36 hours means you race before the worst impairments from the initial altitude exposure set in. Think of this as “start racing before the devil knows you’re there”.
• Arrive 10-14 days before race day (up to 21 days if possible). If you have time to arrive 10 days, two weeks, or ideally three weeks before race day, you’ll have more time to meaningfully acclimate to the altitude.

Avoid the middle ground, meaning try not to show up to Leadville or a similar high-altitude environment 4-7 days before your race. This will put you in an uncomfortable window where you’re experiencing the initial negative effects of altitude (i.e., poor sleep, elevated fatigue, dehydration, potentially headaches) but you don’t have enough time to meaningfully acclimate to the altitude.

Lower Starting Elevation Changes the Equation

Many races start and/or finish at lower elevations and feature intermittent exposures to high altitude environments. The Pikes Peak Marathon is a good example. The race starts at 6,000 feet (just high enough to have minor effects on performance) in Manitou Springs, Colorado, before climbing to 14,000 feet and returning to finish at 6,000 feet.

Other races that fit into this category include Ultra Trail du Mont Blanc, which has an altitude range of 3,400 – 8,300 feet above sea level, and even Western States, which has an altitude range from 8750 feet atop Emigrant Pass to just 550 feet at the finish in Auburn, California.

Traveling to a race with intermittent altitude exposure is generally not as tricky, especially if the start area is at or below about 6,000 feet.

The work and sacrifice to achieve altitude-related performance advantages may not be as important or worthwhile for races featuring intermittent altitude exposures. Maximizing fitness will be the highest priority, followed by learning how your body performs at elevation so you can adjust your effort and pacing accordingly.

Training Camp: Learn About Your Personal Response to Altitude

If your schedule allows it, spend 3 – 5 days training at altitude about 5 to 8 weeks out from your goal event. A short, dedicated altitude camp is not long enough to improve your physiological capacity to perform better at higher elevations. In other words, it’s too short to increase your blood’s oxygen-carrying capacity.

Rather, an altitude camp creates an experience that’s difficult or impossible to replicate at sea level.

You can learn:

• How much you need to slow your uphill effort
• How your normal pacing changes
• How altitude affects your perceived exertion
• How your appetite changes
• How hydration feels different
• How you sleep during the first few nights
• How your body responds to sustained climbing

That information is incredibly valuable.

You can have the most sophisticated training software and detailed race plan in the world, but it can’t tell you exactly how your body will respond to a particular altitude. This provides an important strategic and psychological benefit. You can go home and train, then return to altitude with the confidence of knowing what running at altitude feels like for you, specifically.

Heat Training: Potentially Similar Effects to Altitude Training

Heat acclimation and altitude acclimatization are not the same thing, but some of the adaptations from heat training can potentially improve performance at altitude. Heat acclimation can expand plasma volume, reduce resting heart rate, and improve the body’s ability to manage cardiovascular strain during exercise.

Altitude exposure creates adaptations associated with low oxygen availability, increased erythropoietin (EPO) signaling and, over time, an increase in red blood cell mass. Heat training does not reliably lead to an increase in red blood cell mass. However, prolonged exposure to either heat or altitude leads to an increase in blood plasma volume, which increases cardiac output and improves performance at altitude.

So heat training shouldn’t be viewed as a replacement for altitude exposure, but it can be thought of as a complementary strategy.

If you can’t spend substantial time at altitude before your race, at-home heat training protocols in the weeks and months before your goal event may be an inexpensive way to stimulate some cardiovascular adaptations that may help you tolerate altitude stress. For more information on these strategies, visit this article on heat training for ultrarunning.

Are Altitude Masks and Altitude Tents Worth It?

Altitude masks are among the most misunderstood pieces of equipment in endurance training. Despite the name, an altitude training mask doesn’t simulate altitude unless it changes the partial pressure of oxygen in the air you’re breathing. Most masks that claim to simulate altitude or create hypoxia just restrict airflow, which increases the work of breathing and alters carbon dioxide levels. That’s a fundamentally different physiological stress.

An airflow-restricting mask can certainly make an interval workout feel harder, but that’s not going to stimulate your body to create more red blood cells, increase plasma volume, or any of the other adaptations you achieve from an actual altitude (or heat) exposure.

What About an Altitude Tent?

Altitude tents offer a physiologically plausible benefit. Normobaric hypoxic systems can reduce the oxygen concentration in the air you breathe, which is the relevant mechanism for altitude adaptation.

For most athletes, the issue is time. Meaningful hematological benefits require substantial exposure to a hypoxic environment, like 12 or more hours per night for three to four consecutive weeks at an appropriately calibrated simulated elevation.

Cost, consistency, comfort, and compromises are all real-world challenges with altitude tents. The equipment is expensive, can be noisy, and sleeping in a sealed tent can be a difficult compromise for couples.

Most importantly, sleeping in a hypoxic environment can reduce sleep quality, particularly when athletes use higher simulated elevations. Sleep is one of your most valuable recovery tools. If an altitude tent makes you sleep poorly for weeks, you may be sacrificing recovery in pursuit of an adaptation that could be difficult to obtain in the first place.

For most ultrarunners, particularly amateurs and age groupers, the cost-benefit equation simply doesn’t favor an altitude tent. The money and effort are likely better invested in consistent training, recovery, and even a short trip to altitude.

Racing At Altitude: Forget Your Sea-Level Pace

This is where many otherwise well-prepared athletes get into trouble. Your sea-level paces don’t apply at altitude. A pace that feels comfortably aerobic at sea level may demand considerably more from your cardiovascular system at altitude. If you insist on maintaining the number on your watch, you’ll expend your limited physiological resources too early.

Rate of perceived exertion is the best, and sometimes only, way to gauge efforts at high altitude. Your heart rate can provide some context, but the questions should be: How hard does this effort feel? Does this effort level feel sustainable?

It’s also important to accept that if you live at sea level, you are at a physiological disadvantage compared to athletes who live and train at altitude. That doesn’t mean you can’t race successfully up high. It just changes the calculus a bit. Your goal isn’t to erase that gap entirely. It’s to show up as fit as possible, time your arrival to minimize the negative effects of time at altitude, and race with the best effort and strategy you’re capable of that day.

In Short: The Altitude Race Preparation Framework

If you’re preparing for an ultramarathon at altitude and live at sea level, keep the priorities simple:

1. Build fitness first. Don’t sacrifice your fundamental training to chase marginal altitude adaptations.
2. Study the elevation profile. Starting elevation matters. Maximum elevation matters. The amount and rate of climbing matter.
3. Plan your arrival strategically. For high starting elevations, consider arriving very close to race day or arriving sufficiently early to achieve meaningful acclimatization. Avoid the middle ground (4-7 days).
4. Schedule an altitude camp if possible. A 3- to four-day camp five to eight weeks before the race can provide invaluable race-specific experience.
5. Consider heat training. It isn’t a substitute for altitude acclimatization, but it can provide some overlapping cardiovascular adaptations.
6. Skip the altitude mask. Masks that restrict airflow do not create the conditions that stimulate the same adaptations as either altitude or heat exposures. They just make workouts harder.
7. Think carefully before buying an altitude tent. The required exposure is substantial, the equipment is expensive, and compromised sleep can undermine recovery.
8. Race by effort, not sea-level pace. Perceived exertion is your best intensity gauge on race day, no matter the elevation.