Training for High Altitudes: A Guide for Trail Runners, Backpackers, and Mountaineers
High-altitude environments are like that one friend who’s fun at first but then makes you question all your life choices—they challenge your body, your mind, and your lungs. Whether you’re a trail runner, mountaineer, or backpacker, training for altitude isn’t optional if you want to survive—or, you know, actually enjoy yourself. This guide dives deep into the physiology, the training hacks, and the “how the heck do I even breathe up here?” moments, with a generous sprinkling of practical tips (and humor).
*Heads up: Clicking some of the links below may earn me a tiny commission as an affiliate. It doesn’t cost you a thing, but it helps keep my trail-loving, outdoor-education obsession alive and free. I only link to gear I’d personally wrestle a mountain goat for, promise!
Table of Contents
The Challenge of High Altitude: Oxygen and Performance
First, the biggie: oxygen. Contrary to what you might think, there’s not less oxygen at higher altitudes—it’s still 20.93% oxygen (plus some nitrogen and carbon dioxide for drama). The problem? Lower air pressure makes it a royal pain to get that oxygen into your lungs, then into your blood, then into your muscles. Translation: your endurance takes a nosedive, and that mountain looks way taller than it did in pictures.
Aerobic vs. Anaerobic Cycles Explained
If your body were a party, the aerobic cycle is the chill friend who quietly keeps the snacks coming for hours, while the anaerobic cycle is the one who bursts in, bangs a drum, and collapses five minutes later. Understanding these two energy systems is especially important when you’re climbing mountains, running trails, or gasping for oxygen at high altitude.
Aerobic Cycle
The aerobic cycle is your endurance superstar—it uses oxygen to slowly convert carbs, fats, and even proteins into sweet, sweet energy. It’s what keeps you moving during long runs, hikes, cycling escapades, or those “why did I think climbing a mountain sounded fun?” moments. Your mitochondria, those tiny powerhouses in your cells, basically run a 24/7 energy factory fueled by oxygen.
Key Characteristics:
Duration: Keeps you going longer than a Netflix binge.
Energy Source: Carbs and fats (yes, your body actually likes them).
Oxygen Dependence: High. You can’t fake this one; oxygen is non-negotiable.
Byproducts: Carbon dioxide and water—basically your lungs and sweat telling you, “You’re doing it right.”
Anaerobic Cycle
The anaerobic cycle is your high-intensity, “all-in-or-die” friend—the one who sprints into the room, burns through all the snacks, and leaves lactic acid chaos in their wake. This system doesn’t care about oxygen; it’s all about instant, explosive energy for short bursts of action. Think sprinting, HIIT workouts, or that last scramble to grab the snacks before your hiking buddy.
Key Characteristics:
Duration: Short and brutal—usually up to 2 minutes before your muscles start sending “help me” texts.
Energy Source: Stored glycogen in your muscles—basically the emergency candy stash of your body.
Oxygen Dependence: Low. Oxygen is like that boring friend you ignore when adrenaline hits.
Byproducts: Lactic acid. AKA the reason your legs feel like jelly after a killer hill sprint.
High-Altitude Twist: While your aerobic system is whining for oxygen, your anaerobic bursts might actually feel a little lighter thanks to lower air resistance. Just don’t celebrate too hard—you’ll still need oxygen eventually.
Impact of High Altitude on Aerobic and Anaerobic Performance
High altitude is basically a party crasher for your energy systems, and studies have shown is affects the energy cycles differently.
Aerobic Performance: Endurance athletes—your long-distance runners, hikers, and mountaineers—are the drama queens here. With less oxygen to feed your aerobic engine, your body suddenly feels like it’s running on decaf coffee. Energy production drops, fatigue shows up uninvited, and that steady-state endurance you love? Yeah, it just ghosted you. High-altitude air makes your aerobic system whine louder than a kid missing snack time. Expect quicker fatigue and decreased endurance.
Anaerobic Performance: Sprinters and other burst-mode athletes? You get the VIP treatment. Lower air density = less air resistance = faster times. Your body doesn’t care as much about oxygen for short, explosive bursts, so you might even feel like a superhero zooming through thin air—just try not to gloat too hard when your aerobic friends are wheezing nearby.
Pro Tip: Knowing how altitude messes with your energy systems is key. Tailor your training and acclimation strategies depending on whether you’re more about endurance or speed. Because nothing says “prepared” like laughing in the face of oxygen scarcity while your lungs quietly plot revenge.
Physiology of Altitude Acclimation-Read This!
Climbing to high altitudes is basically inviting your body to a party it didn’t RSVP for. Your body freaks out, scrambles to adapt, and slowly learns how to survive on thinner air. These adaptations start within the first 24 hours and keep evolving over weeks, so buckle up—it’s a bumpy ride.
Initial 24-72 Hour Window
The first 24-72 hours at altitude are notoriously brutal. Your body realizes the oxygen supply has been cut, and it responds like a sleep-deprived toddler: frantic, uncomfortable, and slightly irrational. Common symptoms include elevated heart rates, increased respiratory rates, and general feelings of ugh, what’s happening to my body?
Haemoconcentration:
Rapid Response: Your body thickens your blood to squeeze more oxygen into your system. Basically, your red blood cells are now bodybuilders crammed into a studio apartment. This gives your body time to produce new red blood cells.
Trade-Off: Plasma volume drops by 10–25%, forcing your heart to beat faster like it’s auditioning for a drumline. Stroke volume drops, and suddenly climbing that hill feels like running through molasses.
Hypoxic Ventilatory Response:
Increased Ventiliation: Your lungs go full drama queen, increasing rate and depth of breathing to grab every last molecule of oxygen.
pH Chaos: Your blood’s pH shifts (respiratory alkalosis), and the kidneys work to balance the pH levels by excreting bicarbonate, which makes your kidneys pee like they’re training for a marathon.
Symptoms & Performance:
Physical Effects: Dizziness, shortness of breath, headaches, fatigue—you name it, you’ll probably feel it for the first few days.
Performance Considerations: This phase is often called “the worst of it” because your body is hustling to adapt but hasn’t quite figured out how to adult yet.
Pro Tip: Don’t go full hero mode. Monitor your health, pace yourself, and accept that your oxygen-deprived brain may have questionable judgment, so you don’t get altitude sickness.
Long-Term Adaptations
Once you survive the initial drama, your body starts adulting properly over the next few weeks:
Erythropoietin (EPO) Production:
Hormonal Help: Your kidneys release erythropoietin (EPO), which kicks red blood cell production into overdrive. Think of it as the body hiring reinforcements for the oxygen army.
Time Frame: One to three weeks until your new red blood cells are fully trained and ready to boost your endurance.
Expanded Blood Plasma Volume:
Balance Restored: As new red blood cells appear, plasma volume slowly returns, stabilizing your cardiac output and making your heart stop panicking at every step.
Muscle Oxygenation: Hematocrit and hemoglobin levels rise, meaning oxygen delivery to muscles improves, fatigue drops, and you finally start feeling like a human again.
Knowing what’s happening in that torturous 24–72 hour window—and how your body gradually recovers—lets you plan smarter for high-altitude adventures. Whether you’re backpacking, climbing, or trail running, understanding these physiological changes can help you survive, thrive, and maybe even enjoy yourself while your lungs throw their little tantrums.
How to Prepare for High Altitude Adventures
So, you want to climb mountains, run trails, or backpack at altitudes where oxygen politely declines to show up? Congrats—you’re about to make your body work harder than it does when you accidentally eat three-day-old sushi. Preparing for high-altitude adventures is all about planning, strategy, and a tiny bit of masochism.
Hypobaric Hypoxia Exposure:
This is the “live the high life” method. Basically, move or spend serious time at real high altitudes—think 5,900 to 9,800 feet (1,800–3,000 meters). Two to four weeks of this will pump up your red blood cells and make your aerobic system feel like it’s had a motivational seminar.
Normobaric Hypoxia Exposure:
For the lazy but ambitious, there are altitude tents or hypoxia rooms. They simulate high-altitude air while you snooze like a royal in a tiny tent. You’ll need 8–10 hours a day for 3–4 weeks, which is great if you love sleeping in a glorified hamster cage. Warning: your sleep quality might nosedive and your blood plasma might throw a tantrum.
Alternative Strategies for Those Who Live at Low Altitudes
Heat Training:
Can’t get to the mountains? Sweat it out instead. Exercising in high temperatures tricks your body into partially mimicking altitude adaptations. You’ll boost plasma volume, improve cardiovascular function, and maybe feel like a desert warrior—but definitely check with your doctor before turning into a human rotisserie.
Gradual Exposure:
Altitude isn’t a “go big or go home” party. The smarter approach is slow and steady: make several trips to increasing elevations over weeks. Your body will start adapting gradually, lowering the chance of altitude sickness and helping your performance actually resemble human capability instead of desperate gasping.
Start low, then move up—if your target is 10,000 feet, begin with 5,000–7,000 feet, then climb to 8,000–9,000 feet. Spend a few days at each elevation to give your lungs and legs a chance to figure out the plan.
Keep Moving (But Not Too Much):
Engage in light to moderate activities—easy hikes, gentle jogs, or anything that won’t make your heart sue you. This stimulates circulation and oxygen use, helping your body adapt, while avoiding full-on collapse mode.
When to Arrive for your High Altitude Event or Trek
Timing your arrival at high altitude is basically like showing up fashionably late to a party—but one where the party favors are headaches, dizziness, and oxygen politely refusing to cooperate. Arrive at the right time, and your body thanks you. Arrive at the wrong time, and it files a formal complaint. Let’s break down your options: arriving early vs. showing up last-minute.
Optimal Arrival Time:
Arriving at least a week ahead of your event is like giving your body a spa retreat before making it run up a mountain. Here’s why:
Acclimation Phase: Those first 24–72 hours at altitude are basically your body’s version of “trial by oxygen deprivation.” Headaches, nausea, fatigue—they all make an appearance. Arrive early, and you get to survive this stage before the main event, instead of during it.
Positive Adaptations: Once you survive the initial chaos, your body starts leveling up. Red blood cell production cranks up, oxygen utilization improves, and your cardiovascular system slowly stops throwing tantrums.
Training Opportunities: Early arrival gives you a chance to test the terrain, figure out how your legs feel at altitude, and adjust your workouts without feeling like a wheezing disaster.
Early Arrival Activities Include:
Light Exercise: Think gentle hikes, easy jogging, or walking like a civilized human. Stimulate blood flow without turning your lungs into drama queens.
Hydration & Nutrition: Keep water and balanced meals on hand. Your body will thank you instead of staging a dehydration mutiny.
Rest & Recovery: Sleep is sacred. Altitude can wreck your patterns, so start practicing good sleep hygiene early.
Last-Minute Arrival: The “I Like to Live Dangerously” Approach
Sometimes life happens and you arrive less than 24 hours before your trek or race. Brace yourself—this is basically telling your body, “Surprise! Oxygen is gone, good luck!”
Symptom Management: The upside? You skip most of the dramatic initial symptoms. The downside? Your body is still adjusting while you’re out there pretending you’re a superhero.
Limited Acclimation: Your performance might not peak—think of it as running on a phone with 3% battery. It’ll get you there, but don’t expect miracles.
Rest & Relaxation: Prioritize chill time. Hydrate like it’s your new hobby, and mentally prepare. Visualize glory instead of wheezing.
Last-Minute Strategies:
Brief Activity: Light stretching or short walks only. Don’t try to impress the mountain yet.
Mental Prep: Visualize the course, plan strategy, and send motivational texts to yourself. You’ll need them.
Gradual Exposure: If possible, sneak in a few trips to higher altitudes beforehand. Any oxygen your body meets before the event is better than none at all.
Your New Best Friend: Water
High altitudes are basically like your body’s personal dehydrator. Between the dry air and the extra fluid you’re losing just by breathing and peeing, staying hydrated becomes a full-time job. Here’s what you need to do to keep your cells from staging a mutiny:
Water Intake: Chug like your life depends on it—because it kind of does. Aim for 3–4 liters a day, and adjust based on how hard you’re moving, how high up you are, and how much your sweat thinks it’s auditioning for a reality show.
Electrolyte Balance: Water alone isn’t enough. Your body also needs sodium, potassium, magnesium, and calcium. Grab sports drinks, electrolyte tablets, or whatever magical powder makes hydration feel like a cocktail (minus the regret).
Fuel Your High-Altitude Engine
Proper nutrition isn’t just nice—it’s survival. The right foods help your body acclimate, keep your energy up, and prevent dramatic meltdowns on the side of the mountain.
Balanced Diet: Load up on carbs, proteins, and healthy fats. Carbs = fast energy. Proteins = muscle repair (because your legs will hate you otherwise). Fats = endurance fuel for those long treks where you start questioning all your life choices.
Carbs: Stick to complex carbs like whole grains, fruits, and veggies. These provide steady energy so you’re not a wobbling, hangry mess halfway up the trail.
Proteins: Think lean proteins—poultry, fish, beans, nuts. Muscles and immune system will send you thank-you notes.
Healthy Fats: Avocados, nuts, seeds, olive oil…basically all the stuff that makes your diet Instagram-worthy and functional.
Pro Tips for Not Becoming a Dehydrated Disaster
Plan Ahead: Pack your electrolytes, plan meals, and don’t just wing it. Your future self, struggling at 12,000 feet, will send you a very stern thank-you.
Check Your Pee: Clear or pale yellow = good. Darker than apple juice = panic, hydrate, repeat.
Go Slow: Start hydrating before arrival. Let your body ease into the thin air instead of treating it like a surprise audition for “Who Wants to Pass Out First?”
Alcohol: The Mountaineer’s Frenemy
We need to talk about booze. Yes, that celebratory glass of wine, beer, or questionable mountain-top margarita. High altitude plus alcohol is basically setting your body on fire…gently, but insistently.
Why It’s Evil:
Extra Dehydration: Alcohol = diuretic. High altitude = dehydration. Together = very bad idea.
Messes With Acclimation: Alcohol messes with sleep and hormones, which are exactly the things you need to survive thin air.
Worsens Altitude Sickness: Headache, dizziness, nausea—why suffer more?
Reduced Performance: Coordination and balance go out the window, so suddenly hiking down a rocky trail feels like tightrope walking on a unicycle.
Guidelines for Survival:
Pre-Altitude: Skip alcohol for 48–72 hours before going high. Your kidneys and red blood cells will thank you.
During Altitude Exposure: Avoid it entirely. Yes, even that one “just one glass” thought.
By staying hydrated, keeping electrolytes in check, eating like a responsible human, and leaving alcohol for another adventure, you give yourself the best chance to not only survive but thrive at high altitudes. Everyone’s body is a little different, so tweak as needed—but remember: the mountain doesn’t care if you think tequila counts as hydration.
Technology for Altitude Training
So you live at sea level but dream of conquering mountains without spontaneously gasping like a goldfish? Enter technology: the altitude training gadgets that promise to trick your body into thinking it’s climbing Everest while you’re really just binge-watching from your bedroom.
Altitude Tents: Sleep Like a High-Altitude Hero
How They Work: Altitude tents create a mini-mountain inside your bedroom by lowering oxygen levels while you sleep. Yes, you get to nap while your body freaks out in all the right ways. Think of it as oxygen deprivation cosplay.
Usage & Adaptation: Pop in 8–10 hours a night for 3–4 weeks, and your body starts cranking out more red blood cells. Warning: you might feel like you’re sleeping in a spaceship capsule that’s slightly haunted.
Challenges:
Pricey: Altitude tents cost roughly the same as a small used car.
Sleep Quality: That generator humming all night? Not exactly soothing lullabies.
Living Elevation: If you already live somewhere slightly elevated, bonus points—but if not, your tent might feel like a cruel joke.
Pro Tip: Pair your tent nights with early arrival at your actual high-altitude destination. Your body will be like, “Ah yes, I know this song,” when the real mountains hit.
Airflow Restriction Devices (ARDs): Breathing Like a Dragon
ARDs are those weird little mouthpieces that promise to simulate altitude by restricting your air intake. Think “I want to feel like a mountaineer but also look ridiculous at the gym.”
How They Work: They limit the amount of air you can inhale, making you huff and puff like you just sprinted a marathon…while standing still.
Limitations: Reality check: ARDs don’t actually lower oxygen in your blood. You may feel like a heroic, wheezing mountain goat, but your red blood cells are not magically multiplying.
Effectiveness: Good for strengthening respiratory muscles, bad for actual altitude adaptation. Basically, they’re for bragging rights and Instagram content, not serious training.
Verdict: Tent vs. ARD
Altitude Tents: Expensive, slightly annoying, but actually works. You’ll produce more red blood cells and feel more prepared when the real mountain hits.
ARDs: Fun to look tough, maybe strengthen your lungs a bit, but don’t expect any miraculous high-altitude endurance boost.
Bottom Line: If you want to cheat the mountain (ethically), tents are your friend. If you want to look like a hardcore adventurer while getting zero physiological benefit…ARDs are your playground.
Understanding Altitude Sickness
Ah, altitude sickness. That charming little gremlin that shows up uninvited to your mountain adventure, making your head pound, your stomach revolt, and your dreams of summiting feel like a cruel prank. Technically called acute mountain sickness (AMS), it’s your body’s way of saying, “Whoa there, we weren’t built for this oxygen shortage, Karen.”
Symptoms: Mild, Moderate, and “Why Did I Think This Was Fun?”
Mild Symptoms:
Dizziness – suddenly spinning isn’t just for dance floors anymore.
Fatigue – the stairs now feel like the finale of a triathlon.
Shortness of breath – even just blinking counts as cardio.
Loss of appetite – your granola bar suddenly looks like a rock.
Sleep disturbances – good luck dreaming of anything but oxygen.
Moderate Symptoms:
Worsening fatigue and weakness – your legs are basically on strike.
Trouble with physical activity – even small hills now qualify as Everest.
Severe headache, nausea, and vomiting – your stomach is officially staging a protest.
Chest tightness – like someone glued a tiny brick to your ribcage.
Severe Symptoms:
Shortness of breath at rest – apparently just existing is now a sport.
Inability to walk – goodbye dignity, hello horizontal life.
Confusion – suddenly your map-reading skills are replaced with interpretive guessing.
Fluid buildup in lungs or brain – the party crasher you really do not want.
Why It Happens
The culprit: lower air pressure. Your lungs try valiantly to suck up oxygen, but the atmosphere is like, “lol nope.” Fitness level does not protect you; even Olympic-level athletes can suddenly be reduced to wheezing amateurs.
Recommendations for Adventurers
Step 1: Chill Out – Avoid intense activity for the first few days. Your body needs to catch up on oxygen and avoid throwing a tantrum.
Step 2: Intervene Wisely
Mild: OTC meds can help, but sometimes the best medicine is literally just waiting it out.
Moderate: Consider medication or a gentle descent of 1,000–2,000 feet. No shame in a tactical retreat.
Severe: Drop below 4,000 feet immediately. Altitude is not worth risking your life for Instagram points.
Step 3: Prevention
Gradual acclimatization is your BFF. Incrementally increase altitude exposure over time—think of it as sneakily training your body without it realizing it’s working. If you’re a sea-level dweller, a home altitude tent can help, but yes, your wallet might cry.
Step 4: Check Medications
If you’re competing in an official event, double-check with sports medicine pros and anti-doping agency databases before popping anything. You don’t want altitude sickness AND a DQ to ruin your adventure.
TLDR
Altitude sickness is basically your body’s dramatic audition for “most inconvenient co-pilot ever.” Take it seriously, ascend gradually, hydrate like it’s your new religion, and respect your body’s complaints. With the right planning, you can survive (and maybe even thrive) at high altitudes without your brain turning into scrambled eggs.
Final Thoughts
Training for high-altitude adventures is basically signing up for a rollercoaster your lungs didn’t RSVP for—but the views are chef’s kiss worth it. Backpackers, mountaineers, trail runners: with the right prep, your body can learn to love the thin air instead of staging a protest every 5 minutes.
Key takeaways:
Gradual exposure is your friend. Think of it like convincing your body to go to a party it didn’t want to attend.
Hydrate like you’re single-handedly keeping the desert alive.
Eat well, sleep well, and avoid making poor life choices (looking at you, alcohol) until your oxygen-starved brain forgives you.
Listen to your body. If it screams, “Nope!”, honor that. Altitude doesn’t care about your ego.
Follow these strategies, and you’ll be summiting, trail-running, and breathing just enough to feel like a functional human—not a wheezing zombie—at high elevations.
Gear Up Like a Pro (or at Least Like You Tried)
Whether you’re summiting peaks or just hiking like a boss, having the right gear is non-negotiable. Lucky for you, we’ve rounded up some of our top picks that we actually use (because nothing ruins adventure vibes like regrettable purchases).
REI – big brand, big reliability, slightly fewer weird novelty items.
Alpine Sisters Amazon Storefront – everything we personally love, curated for your high-altitude shenanigans.
Backcountry.com – snag past-season colors for deals so good you’ll almost forget it’s still a workout.
Garage Grown Gear – support small businesses while pretending you’re a mountain influencer.
Buying gear through these links may give us a tiny commission at no extra cost to you. Basically, it helps keep this educational chaos online for free while ensuring your next adventure is well-equipped. Consider it a win-win: you get gear, we get to keep yelling at people about hydration, and the mountains remain slightly less terrifying.
Keep climbing, keep gasping, keep smiling!
About the Author
Shannon is a UESCA-certified running coach and high-altitude junkie. With years of trail running and backpacking experience, she helps outdoor enthusiasts survive—and enjoy—the thin-air chaos of lofty adventures.