There’s a reason elite runners flock to towns like Dullstoom, Mpumalanga (2100m above sea level), and Iten, Kenya (2 400 metres above sea level) — and it’s not just the gorgeous scenery or ample share of running trails (though these elements certainly don’t hurt). The big allure? Altitude training.

These towns offer runners the chance to utilise a research-backed practice for boosting overall fitness and race performance, whether you’re an Olympian or an everyday athlete.

But reaping the benefits of altitude training isn’t as simple as packing a bag and heading off to the mountains. There’s nuance to this type of running, as well as safety precautions to keep in mind. We tapped two experts to learn the dos and don’ts of altitude training, plus why it is beneficial in the first place. Here’s what you need to know.

What does altitude training really mean?
Put simply, altitude training involves living and/or running at elevation to gain physiological advantages. With altitude training, you can either live and train at elevation, or live at elevation and then train at a lower altitude, the latter known as a “live high, train low” approach.

What constitutes elevation? Well, it depends on your goals, but the “sweet spot” for many athletes is between 1 800 to 2 400  metres, Dr Trent Stellingwerff, chief performance officer at the Canadian Sport Institute, tells Runner’s World.

Research supports the existence of this sweet spot. For example, a 2013 study of 48 collegiate runners found that those who completed four weeks at a “live high, train low” altitude camp, where they lived at either 2 084 or 2 453  metres, significantly improved their sea-level race performance and VO2 max.

By contrast, athletes who completed a similar four-week “live high, train low” camp that involved living at a lower elevation (1 779 metres) or higher elevation (2 799 metres showed no changes in sea level performance. Researchers pointed to an elevation range of about 1 980 and 2500 metres as the ideal conditions.

What are the benefits of altitude training?
The biggest draw of running at altitude is its ability to boost your VO2 max, which is widely considered one of the best measures of cardio fitness, as it defines the amount of oxygen your body is able to use to fuel cardiovascular exercise.

Exposure to altitude causes your kidneys to release erythropoietin (EPO), a hormone that stimulates red blood cell growth, Tom Cuddy, an exercise physiologist and endurance sports coach, tells Runner’s World. Red blood cells help transport oxygen throughout your body, so the more of them you have, the better your oxygen uptake will be.

Of course, if you’ve travelled to the mountains and found yourself tired and nauseated, then you know this change doesn’t happen overnight. It can take three to four weeks to see a robust increase in your red blood cell count, Stellingwerff says.

Altitude training can also initiate muscle adaptations. Only a few studies have looked into this effect because it involves taking a small muscle biopsy, Stellingwerff says, but scientists know that exposure to altitude turns on dozens of positive processes. Your body creates more capillaries and blood vessels, and altitude also stimulates mitochondria, your power energy cells, which help endurance efforts.

Another perk of elevation training is that it can improve your body’s ability to buffer (absorb) lactate in the blood. Lactate is a byproduct of exercise that is typically soaked up in the muscles, but can also be buffered in the blood. Although also understudied, limited research suggests that in as little as 10 to 14 days at altitude, your body can improve its ability to clear lactate in the blood, Stellingwerff says.

This theme of “understudied” information is often due to studies not implementing a sea-level control group, Stellingwerff says. He believes this leaves room for the “training camp effect” to influence results. Basically, if you take an athlete out of their normal routine and away from the distractions of work and life — allowing them to focus solely on eating, sleeping, and running for three weeks — they’re going to come out with a performance or fitness boost. However, this boost can occur at altitude camps and at sea-level camps.

However, there is some reliable research that shows that altitude training offers an approximate 1- to 2-percent improvement in performance. “I know that doesn’t sound like a lot, but 1 percent is 2 seconds in the kilometre; 2 percent is 5 seconds in the kilometre,” Stellingwerff says. This is why elite runners often train high, because 5 seconds or more, in longer-distance runs, can add up to a significant performance improvement.

Can an altitude mask offer the same benefit of training at elevation?
Unfortunately, altitude masks, along with tents, do not have a lot of evidence to support their benefits. The main issue is “hypoxic dose,” says Stellingwerff. If you go to altitude, you get about 168 hours per week of altitude exposure, while in a tent you might get 70 to 80 hours. Similarly, the hypoxic dose in a mask is even smaller, about a handful of hours per week.

This may not be enough for you to see those big gains in VO2 max, lactate, or performance in general.

Are there risks with altitude training?
When first arriving at moderate altitudes, runners may experience things like disrupted sleep, hampered recovery, and a higher resting heart rate. But having true altitude sickness, where your body struggles to adjust to the lower level of oxygen is very unpleasant, and can lead to symptoms like a headache, nausea, vomiting, or dizziness. In extreme cases, it can lead to lung and brain problems, although this is “really rare,” says Stellingwerff.

That said, going to higher altitudes — think 3000 to 4200 metres — does increase your risk of altitude sickness and more severe problems.

Be aware that an intense headache and symptoms that feel like a hangover, according to the CDC, such as severe fatigue and nausea, can often be alleviated by going to a lower altitude and seeking medical attention. Often, just getting yourself closer to sea level will be enough to help you feel better, Stellingwerff says.

How can you maximise the benefits of altitude training?
If you’re keen on giving altitude training a shot, follow these tips from Stellingwerff and Cuddy:

1. Embrace carbs
Carbs are important for runners in general, but they are especially key at altitude. That’s because fats require more oxygen to metabolise, so with less available oxygen at elevation, your body relies more on carbs, Cuddy explains.

Also, being at a high altitude can suppress your appetite, so don’t rely on hunger cues alone. Plan on adding a little more starch to your dinner plate, plus including sports drinks or gels with your training, Stellingwerff says.

2. Take supplemental iron
Iron is fundamental for red blood cell growth, Cuddy says. In fact, iron is “the most important micronutrient associated with altitude training,” Stellingwerff says. He recommends asking your physician for a blood work panel on your iron stores several months before altitude training. From there, you can work with them to determine if iron supplementation is appropriate for you at elevation.

3. Adjust your training metrics
You likely won’t see performance gains during your initial altitude workouts. In fact, in the beginning, you may spike a higher heart rate than you would be doing the same exact run at sea level. Instead of using pace to guide your workouts, focus on heart rate and rate of perceived exertion, Cuddy suggests.

“Listen to your body — don’t try to do these heroic workout sessions,” Cuddy says. Simply living at elevation, and doing lo- to moderate-intensity training there, is enough to reap the benefits.

Stellingwerff co-authored a 2019 review of altitude training and suggests adjusting your training during the first three weeks at altitude: Increase recovery periods and dial back intensity.

“Once you’ve been there for a couple of weeks, within reason, you can almost train like you would at sea level,” he says, cautioning that you may still need to incorporate more rest into certain workouts.

4. Expect to feel symptoms
You might expect day one at altitude to be the toughest, but that’s actually not the case. Instead, day three or four is when you’ll likely feel your crummiest, Cuddy explains. That’s because when you arrive at altitude, your body does everything it can to circulate oxygen, which can trigger a host of compensatory mechanisms that peak in intensity after several days.

One such mechanism is an increased breathing rate, known as the “hypoxic ventilatory response.” This is critical for increasing the driving force of oxygen in your lungs, but it causes you to offload more carbon dioxide than usual. This makes your body slightly more alkaline than normal. “With this very short time period of being more alkaline, you’ll start to release and get rid of your bicarbonate stores,” Cuddy says, which helps with buffering metabolic acidosis that builds up in your muscles. As a result, your tolerance for high-intensity exercise will drop.

Your body will also prioritize sending oxygen to your brain, and because oxygen is in short supply at altitude, your body will also reduce its overall blood plasma volume. Then other areas of your body are hit with the negative consequences of reduced blood flow, which may mean headaches and tiredness.

Again, all this typically peaks around days three to four, so avoid planning tough workouts around that time period.

5. Strategise your timing
Remember, the physiological benefits of altitude training don’t happen overnight. For the time and money investment to be worthwhile, plan to stay at elevation for at least a couple weeks, with three weeks being ideal, Stellingwerff says. Then, plan to race about two weeks after you wrap your elevation training.

6. Stay on top of hydration
It tends to be drier at higher altitudes, which means you can more easily become dehydrated. Keep close tabs on your fluid intake. Stellingwerff suggests, monitoring your thirst levels, pee colour, and body weight.

7. Don’t skimp on caffeine
Given the hydration factor mentioned above, you may think of curbing your coffee habit at altitude because it’s a diuretic, but that’s actually a myth. You would have to drink tons of Joe in order for it to have that effect on you, Cuddy explains.

Instead, your best bet is to keep on sipping. “We actually recommend people use caffeine when they’re at altitude,” Cuddy says. That’s because it can stimulate your nervous system to support many of the physiological changes that occur at altitude, like increased breathing and elevated heart rate.

At altitude, “your body has to work a whole lot harder, and having a stimulant like coffee, or whatever form of caffeine you like,” can support all those efforts, Cuddy adds.

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