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Going to altitude to hike, run, vacation, or adventure can really suck if you’re not prepared. As someone who spent 13 months living in Colorado and recently hiked Mount Whitney (the highest peak in the continuous United States), I understand the frustration every sea-level athlete faces when dealing with altitude.
Whether you’re planning a Colorado 14er, training at elevation, or just trying to enjoy your mountain vacation without feeling terrible, this guide will help you understand how altitude affects your body and what you can do about it.
Many people think that at altitude there’s simply “less oxygen in the air,” but that’s not quite how it works. The percentage of oxygen in the air isn’t necessarily less, but the pressure gradients and the amount available is reduced.
The Science Behind Altitude
Your bloodstream operates on pressure gradients – oxygen gets pushed in and CO2 gets pushed out through breathing. You carry that oxygen through your blood to your muscle tissues to produce energy during exercise, then exhale CO2.
At higher altitudes, there’s a lower pressure gradient, which means less oxygen from the air gets pushed into your bloodstream to be delivered to your muscles. This leaves your body with less oxygen for basic metabolic function, exercise, and just existing as a human.
Why Everything Feels Harder
This oxygen reduction explains why:
As a fun example, my running watch automatically drops my estimated VO2 max by about 5 milliliters per kilogram as soon as I get to altitude, just based on my workout performance.
The only way to truly adapt to altitude is to live at elevation or use specialized equipment like altitude tents. Since most of us can’t do that, the best preparation strategy is improving your cardiovascular fitness before you go.
Why Cardio Fitness Matters
Having improved cardiovascular fitness increases your VO2 max, which means you’re able to use and deliver more oxygen to your muscles. When you’re at altitude and your available oxygen decreases, starting with a higher baseline means you’ll still have more to work with.
Think of it this way: if altitude reduces your available oxygen by 20%, starting with a VO2 max of 50 versus 35 makes a huge difference in how you’ll feel and perform.
My Personal Experience
I’ve gone to Colorado from the East Coast in some of the worst cardio fitness of my life and had terrible altitude sickness. I’ve also gone while training for ultramarathons and felt totally fine. The difference in how altitude affects you when you’re in great cardiovascular shape versus poor shape is dramatic.
Everyone has an individual response to altitude, and you can still get altitude sick even with great fitness. But improving your cardio base should significantly reduce how hard altitude feels when you’re hiking or trying to enjoy activities.
Immediate Strategies (0-3 days): Focus on hydration, nutrition, and taking it easy
Short-term Adaptation (3-7 days): Some improvement as your body begins to adjust
True Acclimatization (14-21 days): Your body produces more red blood cells to carry additional oxygen
For most of us flying in for vacation, we don’t have 2-3 weeks to wait. The good news is there are strategies to help you feel better quickly.
Why Hydration Is Critical
At altitude, you experience increased water turnover – you’ll notice you’re urinating more due to physiological changes in your kidneys. Even if you’re hydrating adequately, you can still have increased water loss.
Add in exercise, increased sun exposure, and drier air (where sweat evaporates quickly and you don’t notice it), and you can become dehydrated fast.
Hydration Protocol
Your sleep quality will be compromised at altitude due to reduced oxygen availability. Focus on your pre-sleep routine and consider natural sleep aids if needed.
Poor sleep exacerbates everything – hydration issues, appetite problems, mood, and exercise performance. Even if you can’t completely fix altitude sleep issues, any improvement helps your overall adaptation and recovery.
Why Carbs Matter More at Altitude
Because your body is less capable of using oxygen efficiently, you’ll rely more heavily on carbohydrate metabolism during exercise. You’re shifting away from efficient oxidative metabolism and using more carbohydrates as fuel.
Practical Application
Having regulated blood glucose helps you avoid that “bonky” feeling where you want to fight someone on the trail and think every squirrel is a bear.
Accept the Reality
You’re not going to hit your normal paces and intensities. Your heart rate will be higher, and the higher you go, the less oxygen you’ll have available. This is just physics – don’t fight it.
Smart Progression
Altitude Sickness Warning Signs
Pay attention to:
It’s okay to turn around, pause, or take breaks if you need to. Your safety is more important than any summit.
Recently, while hiking Mount Whitney (14,505 feet), I started feeling what seemed like altitude sickness around 13,000 feet for the first time in a while. My husband made me drink water with caffeine and electrolytes, and I ate peach rings for quick sugar.
My protocol became: sip of caffeine, sip of electrolytes, piece of candy, keep moving. It turned out I was more under-nourished than altitude sick, but that compound effect made me feel terrible.
Once I got my nutrition and hydration sorted, I felt fine at 14,000 feet and was chatty at the summit. This reinforced how much nutrition and hydration can compound altitude effects.
Understanding how to fuel your body for altitude training and adventures is crucial for success. My Fast and Fed Guide provides detailed strategies for fueling endurance activities, including carbohydrate timing and electrolyte protocols that are essential for altitude performance.
If you’re planning to train for altitude adventures or improve your cardiovascular base before your trip, The Lyss Method offers comprehensive running and cardio programs designed to build the aerobic capacity that’s crucial for altitude performance.
For those wanting to understand their current cardiovascular fitness and set appropriate training zones for altitude preparation, my free zones calculator can help you train more effectively for your mountain adventures.
There’s no magic hack for altitude – it’s going to feel harder no matter what. But you can significantly improve your experience with:
Before You Go:
While You’re There:
Remember, even experienced mountain athletes feel the effects of altitude. Give yourself grace, be patient with your body, and focus on enjoying the incredible experience of being in the mountains.
The views are worth it, and with proper preparation and smart strategies, you can minimize the suffering and maximize the adventure.
Keywords: altitude training, mountain hiking, altitude sickness, high altitude exercise, mountain fitness, altitude adaptation, hiking preparation, mountain training, altitude physiology, VO2 max altitude, mountain adventures, hiking tips
I’m Exercise Physiologist, sports nutritionist, weight lifter, and ultra runner. I am here to bring science to your training in a no-nonsense way. I have helped thousands of women crush big lifting goals, cross race finish lines, and even do both. I’m here to help you do the same!
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