How to Acclimatize Before Running in the Andes

If you're planning to run in Cusco or anywhere in the Peruvian Andes, acclimatization isn't optional — it's the difference between a great experience and a miserable one. At 3,400 metres above sea level, Cusco is already higher than most people have ever been. Add running to that equation, and your body has a lot to adjust to.

The good news? With a bit of planning, most people acclimatize well and go on to have some of the best runs of their lives. Here's what you need to know.

Why altitude affects runners so much

When you arrive at high altitude, there's less oxygen available in the air. Your body responds by working harder — your heart rate rises, your breathing speeds up, and your muscles fatigue faster than they would at sea level. For runners, this is especially pronounced. A pace that feels easy at home can feel like a hard tempo effort in Cusco.

Altitude sickness — known locally as soroche — is also a real possibility in the first few days. Symptoms include headaches, nausea, dizziness, and fatigue. They're unpleasant, but in most cases temporary and manageable.

The key is not to fight your body. Give it time to adapt.

How long does acclimatization take?

Most people need 3 to 4 days before they feel genuinely comfortable at Cusco's altitude. For serious running — especially anything involving elevation gain above the city — a full week is ideal. Ultrarunners preparing for long efforts or multi-day routes should budget even longer.

Everyone adjusts at a different rate. Age, fitness level, and previous altitude experience all play a role, but none of them guarantee a smooth arrival. Even elite athletes can struggle on day one.

Step-by-step: how to acclimatize properly

Arrive early

This is the single most important thing you can do. If your race or run starts on a specific date, don't arrive two days before — arrive a week before. Give yourself time to adapt before you ask anything demanding of your body.

Rest on arrival day

Resist the urge to explore immediately. When you land in Cusco, take it easy. Settle in, drink water, eat lightly, and sleep. Your body is already working hard just by being at altitude. Let it do its job.

Drink plenty of water

Dehydration accelerates altitude sickness and slows adaptation. Aim to drink more than you normally would — the dry Andean air means you lose fluid faster, even when you're not exercising. Avoid alcohol in the first few days, as it dehydrates you and disrupts sleep.

Try coca tea

Coca leaf tea is the traditional Andean remedy for soroche, and it genuinely helps. You'll find it in virtually every café and hotel in Cusco. It's mild, legal, and worth drinking regularly in your first few days.

Walk before you run

Spend your first couple of days on foot — gentle walks around the city, maybe a visit to Sacsayhuamán or the San Blas neighbourhood. This gets your cardiovascular system moving without stressing it. Pay attention to how your body feels on hills.

Start running easy

When you do lace up, go shorter and slower than you think you need to. A 30-minute easy jog on day three tells you a lot — how your breathing responds, how quickly your heart rate climbs, how your legs feel on the uphills. Don't chase pace. The Andes will humble anyone who does.

Be proactive with your recovery Acclimatization isn't just about what you do between runs — it's about actively supporting your body throughout the process. If you want to speed things up, ReEnergize Cusco offers two options worth knowing about. A session in their hyperbaric oxygen chamber floods your system with concentrated oxygen, directly counteracting the effects of altitude and helping your body recover faster. Or, if you've already started running and your legs are feeling it, their altitude recovery combo — a massage followed by the hyperbaric chamber — is one of the most effective ways to reset between efforts. Both are available near San Blas, a short walk from the city centre.

Build gradually

Add distance and elevation across successive days. If day three is a short flat jog, day five might be a 45-minute run with some gentle climbing. By day seven, most people are ready for something more adventurous — longer trails, bigger elevation gain, the kind of running you came here for.

What to watch out for

Headaches are very common in the first couple of days and don't necessarily mean anything is wrong. Stay hydrated, rest when needed, and they usually pass.

A racing heart rate is normal. Don't be alarmed if your resting heart rate is 10 to 20 beats higher than usual — this is your body compensating for lower oxygen levels.

Shortness of breath on uphills is universal, even for fit runners. The city's steep cobbled streets will leave you breathing hard. That's normal. It eases over time.

Severe symptoms — persistent vomiting, confusion, difficulty walking, or chest tightness — are a different matter. If you experience any of these, descend and seek medical attention. Altitude sickness can escalate in rare cases, and it's not worth pushing through.

A note on altitude medication

Some runners use acetazolamide (Diamox) to speed up acclimatization. It can be effective, but it comes with side effects and isn't right for everyone. If you're considering it, talk to a doctor before you travel — ideally one familiar with altitude medicine. Don't rely on medication as a substitute for proper acclimatization time.

Running above Cusco

Once you've adapted, what awaits you is genuinely extraordinary. The air is clear, the views are vast, and the running is unlike anywhere else on earth.

Getting there just takes a little patience first.

If you're planning to run in the Cusco region and want local guidance on routes, pacing, and making the most of your time at altitude, Run the Andes offers guided runs and running holidays designed for all levels — from first-time visitors to seasoned trail runners.