A lot of Eastern and Midwestern hunters travel to the West and internationally to hunt mountains. And most of them don’t understand altitude’s effect on the body. This is a very no bueno kind of problem. Not only does the lack of understanding kill their performance, but it can also walk them into some seriously dangerous circumstances, compounded by the pride of wanting to be tough and push themselves. At the least, it could make a hunter miss opportunities or cause them to back out of a hunt because they cooked themselves. At the worst, it could cause a life-threatening bout of altitude sickness.

If you live at sea level, or close to it, and plan to hunt above 8,000 feet of elevation, you need to understand how altitude affects your body. And you need a plan that preps you for altitude before you even get to the mountains.

That’s what this guide provides.

What Happens to Your Body at High Altitude

The myth is that there’s less oxygen at higher elevations. That’s not true. The air is still made up of 21% oxygen. However, there is a decrease in barometric pressure, which disperses the oxygen molecules. They spread out, so you take in fewer of them with each breath. The oxygen is there. It’s just harder to access.

The pressure change starts around 5,000 above sea level feet but starts to change significantly at 8,000 feet. At 5,000 feet, oxygen availability compared to sea level drops to 83%. At 8,000 feet it drops to 75%. At 10,000 feet it drops to 68%. And it keeps dropping as you keep climbing. If you’re doing an early season, high-country mule deer hunt in Colorado, you might find yourself near 14,000 feet. If you’re heading to an Asian country to mountain hunt, you’ll more than likely go that high—or higher. 

How does your body respond to decreased barometric pressure and oxygen availability?

The Bodily Timeline of Altitude Effects 

Your respiration rate increases immediately, accompanied by an increase in heart rate. Your brain senses the decrease in oxygen availability and makes you breathe faster in an attempt to pull in more oxygen. Your heart works harder to distribute oxygen throughout the body.

Within a day or two, your blood volume drops. This happens because you’re dehydrating. The increased breathing rate causes you to lose more water. Your thirst is also suppressed. And you take a lot more leaks. (The technical term is increased urination.) This happens in part because your body is trying to concentrate your blood so it can efficiently transfer oxygen via hemoglobin. More on that.

During days two to four days, your kidneys try to offload more bicarbonate. Your blood becomes more alkaline because you’re offloading more carbon dioxide with your increased breathing rate. The kidneys work to correct this balance by making you pee more and increasing the concentration of hydrogen ions in your blood to balance the pH. You’re also offloading more water and electrolytes. This is called altitude diuresis, and it’s part of the process used to concentrate your hemoglobin for more efficient oxygen delivery. This process chills out around day five.

Then, after about a month, your red blood cell count increases. This happens because your body increases production of the hormone erythropoietin (EPO). I want you to read the first sentence of this paragraph again, and focus on the words between the parentheses. Full altitude acclimatization takes about a month. Heading to the mountains a few days before your hunt will not cause you to fully adapt to altitude. It’s crucial that you remember this. Otherwise, there’s a higher chance you’ll push much harder than you should, especially during the early stages of your hunt. 

How Will All of This Feel?

Well, you’ll immediately notice that you’re breathing more and are at least a little short of breath. This might lead to a panicky feeling. It also happens while you’re sleeping due to something called periodic breathing. Your brain senses the lack of oxygen while you sleep, and causes you to take deep, rapid breaths followed by a lot of shallow breathing. This often wakes you up, and can scare the hell out of you.

Everything will also feel more difficult. This is called an increase in your Rating of Perceived Exertion (RPE). For example, you’ll feel yourself working harder on grades you can normally fly up at lower elevations. And I sure hope you’ll notice the increased urination. Otherwise, you might have some other problems on your hands.

Then there’s the headache. The hypoxia (lack of oxygen), causes the blood vessels in your brand to expand in an attempt to deliver more oxygen to your brain. This hurts. It can also be a warning sign of HACE—High-Altitude Cerebral Edema. It’s nothing to fuck around with. Let’s talk about it and the other high-elevation dangers.

AMS, HAPE, and HACE: Lots of Letters, Very Serious Consequences 

Think of AMS as a warning sign that keeps you from experiencing HAPE and HACE.

AMS stands for Acute Mountain Sickness. It feels a lot like you drank 14 tequilas and fought a guy with very heavy fists. You’ll feel it if your headache gets worse, you start to feel nauseous, and fatigue settles in that you can’t shake. It’s a sign that you’re at an elevation that your body can’t yet handle, and/or you’re ascending too quickly. You need to think of it as a red light and not a yellow light. Here’s an example.

Let’s say you have yourself an altitude headache. That’s normal. You eat and drink something, then take some ibuprofen. If the headache goes away, you’re likely fine. However, if the food, fluids, and medicine don’t help, your condition is likely to worsen and you need to descend before you end up with HACE.

Cerebral edema means severe brain swelling. It can kill you. If you or your hunting partner starts to feel confused, stumbles around like they're drunk, or starts slurring their words, you need to take action. A simple field test is to have the person try to walk a straight line heel-to-toe. If they stumble, there’s a solid chance their brain is swelling. You need to immediately descend at least 2,000 feet—even better if you descend further.

HAPE stands for High-Altitude Pulmonary Edema—fluid in the lungs. It can kill you. The symptoms are extreme fatigue, extreme breathlessness even at rest, persistent cough (sometimes with frothy pink spit), cracking or gurgling sounds in the chest (it sounds like Rice Krispies popping if you put your ear up to their chest), and blue lips and finger tips. A person experiencing HAPE essentially feels like they are suffocating. If you start to see any of these symptoms in one of your hunting partners, you need to immediately descend at least 2,000 feet. As with HACE, it’s even better if you can descend further.

And, in both cases, you need to get your hunting partner immediate medical help.

You might think these conditions are only a big deal if you’re climbing above 10,000 feet. But the lowest elevation with a reported case of HACE is around 6,900 feet. You can’t fool around with this shit.

Now that we’ve covered how your body attempts to adapt to decreased barometric pressure, and all of the nasty stuff that can happen if you’re not careful, let’s cover all of the ins and outs of prepping for higher elevations.

We’ll cover training, nutrition and hydration, travel, making an ascent plan, and accessory actions that might help.

Training for High-Altitude Hunts

Aerobic Training, Muscular Endurance, and Tapering

I’ll start the training section with a very serious disclaimer.

No amount of training in the world is a replacement for altitude acclimatization. Even superior conditioning does not overcome physics and physiology. I’m telling you this to set a healthy expectation. You can be an absolute physical specimen, and you still have to play by the atmosphere’s rules. We’ll talk more about that during ascent planning, but it had to be said here. 

Your most important physical asset while hunting at high-altitude is a monstrously efficient aerobic system. Where there’s less access to oxygen, you must use the available oxygen as best as possible. You do that by accruing large amounts of aerobic capacity training, and some aerobic power training. 

Carb sparing is another important aerobic adaptation for high-altitude hunting. Metabolising carbs requires less oxygen than metabolizing fat. Carbs, then, are your body’s preferred fuel at altitude, even if you’re well-adapted to using fat as fuel. You need to be as efficient at metabolizing carbs as possible to spare oxygen and so you don’t burn through the carb stores in your muscles and liver.

If you plan to hunt above 8,000 feet, and want to be as prepared as possible, you need to work up to doing at least four hours per week of aerobic training in the months leading up to your hunt. And the bulk of that aerobic work should be done on inclines under your pack. Practice smaller steps for mechanical and metabolic efficiency. 

Muscular endurance is nearly as important, and is in part a byproduct of solid aerobic development. However, it’s not just aerobic development. And it requires specificity. You have to train your muscles to contract over and over to do the jobs they’ll do in the mountains. This, again, creates efficiency via movement economy. You need to save as many resources as possible.

Then there’s the aspect of high-altitude training that doesn’t get enough attention—tapering. A taper is a cut in training volume and/or intensity to allow your body to recover and adapt to training. It also allows it to rest. Starting your hunt well-rested is not only the best way to ensure your performance, but it’s also the best way to insure yourself against the altitude-related illnesses we discussed. 

Two weeks out from your hunt, cut your training volume back by 30% while maintaining the same intensity. One week out from your hunt, cut your training volume back by another 10% to 20%, totalling a 50% cut from your regular training volume. This gives your body the rest it needs while maintaining your training adaptations.

Training for Panic

Altitude masks, and similar training tools, don’t actually train you to acclimatize to lower oxygen density. However, restricted breathing can help psychologically prepare you for the panic caused by accelerated breathing at high-altitude. But you don’t need to buy a mask, or anything else, to restrict your breathing.

The simplest way to do it is by breathing only through your nose for some of your aerobic workouts. It will feel difficult if you’re working at the edge of your aerobic capacity. You don’t have to do it during every aerobic session. But doing nasal breathing workouts throughout the week can be a big help.

You can also use a workout structure I learned from my former coach, and good buddy, Doug Kechijian. This can be part of your aerobic power training. Do a series of hard sprints on an airbike, immediately followed by either a farmer’s carry or a goblet carry. For example, a 30-second sprint on the airbike done at an 8 or 9 out of 10 intensity, immediately followed by a relatively heavy goblet carry. Rest for 30 to 60 seconds, and repeat. The hard sprint creates an oxygen debt, and the carry restricts your breathing. It can help you build psychological resilience against the panic induced by thin air breathing.

Nutrition and Hydration During Your High-Altitude Hunt

Remember in Austin Powers Goldmember when Fat Bastard said he was on The Zone Diet because carbs are the enemy? He was full of shit. That’s especially true when it comes to high-altitude nutrition.

You need carbs.

First, digesting carbs isn’t as metabolically costly as digesting protein and fat. Protein and fat suck way more blood to your stomach and use way more resources to process. We have to eat them in the right balance and at the right times when we’re above the treeline.

Second, like we chatted about earlier, carbs are your preferred fuel source at altitude because they require less oxygen to burn. Your high-elevation nutrition plan must be carb heavy.

Let’s talk about where this all fits into a general strategy.

General Strategy

You will burn far more calories than you eat. You might burn up to 5,000 calories a day, or more, depending on the terrain, the elevation, and the weather, while only managing to eat 1,500 or 2,000. For example, if you’re packing in with around 45% of your body weight on your back, you could burn up to around 8 calories per minute. But calorie demands increase beyond physical exertion. Your body has to work harder to regulate temperature and maintain homeostasis. That gets real dang expensive. You’ll get cold. You’ll shiver. 

Here’s the problem you face when considering all of this—you won’t feel hunger. Hormones that signal hunger, like leptin, are suppressed at altitude. Digestion is costly, so your body slams on the governor a little too hard to try to stop you from eating. You won’t be able to lift the governor, so you have to consciously fight it. You do that by eating on a schedule.

One of the easiest ways to do that is by eating something every 20 to 30 minutes, especially while moving. Have some fast-digesting carbs like gummy candy or gels. Aim for at least 30g to 60g of carbs per hour, depending on what your stomach will tolerate.

The second part of the strategy is timing your macronutrient intake. Only eat protein and fat when you’ll be sitting or resting for a long time. Have a light portion of each while you’re sitting and glassing in the middle of the day. Have your main portions when you’re back at camp and settled in for the night. Start that meal with some broth to replace electrolytes and stimulate digestion. It’s important to note that even though you’ll rely heavily on carbs in the mountains, consuming protein and fat is still important. Each will help you recover, and fat helps maintain your overall caloric intake.

Here’s a simple maxim that helps you remember intake timing: Fast carbs while moving. Protein, fat, and slow carbs while resting. 

Let’s talk more about the most beneficial types of foods to eat at elevation.

Foods List

We’ll break the list into two categories—moving foods and resting foods.

Moving Foods

Dried fruit

Gummy candy

Gels

Honey

Sports drinks

Resting Foods

Before I get into the specific lists, rest is the best time to eat your freeze-dried, if you’re bringing it along. Make sure it’s calorically dense, and eat it when you’re settling into camp for the night.

Carbs

Oatmeal

Instant mashed potatoes

Noodles

Protein

Powder

Jerky

Salami

Whatever’s in your freeze-dried

Fat

Peanut butter/nut butter pouches

Salami

Mixed nuts

How Much to Eat/Sample Eating Day

Common practice is to shoot for about 2,500 to 3,000 calories per day on a backpack hunt. This keeps pack weight manageable without getting too deep into a calorie deficit. (However, it isn’t sufficient if you’re hiking and hunting hard. If you have room in your pack for an extra 500 calories per day, that’s a very good thing.) The following breakdown and sample eating day uses a 180-pound hunter as an example. The goals are to keep carb intake adequate for fueling and recovery without causing gastrointestinal distress, eat enough protein for recovery and weight management without displacing carbs, and round it all out with fat intake to ensure you’re getting enough calories to avoid accelerating your calorie deficit. You might have to try adjusting the carb intake up if you’ll be on especially gnarly and steep terrain. 

This is an example. It doesn’t provide for individual preferences or circumstances. Use it as a template, not as an absolute.

Daily Macronutrient Breakdown

Carbs: ~400g (4-6g/kg of body weight)

Protein: ~100g (1.2g/kg of body weight)

Fat: ~45g (fills in the balance left by the other macronutrients)

Sample Meals

Breakfast (In camp)

Oatmeal (2 packets)

Honey (1-2 tablespoons)

Protein powder (1 scoop)

Peanut butter pouch (1)

Instant coffee

Movement While Hunting

~60g of carbs per hour

-Mix between servings of dried fruit, gummy candy, gels, and sports drinks (powdered)

While Glassing

If you’ll be sitting for a while, snack on some small servings of jerky, dried fruit, and maybe a small serving of mixed nuts

Dinner (In camp)

Broth packet in warm water at beginning of the meal to stimulate digestion

Instant mashed potatoes (1.5 - 2 servings)

Freeze dried meal that includes protein

Jerky (1oz or so)

Mixed nuts (1 oz or so)

Hydration at High-Altitude

You’ll have to monitor your hydration levels while you hike and hunt. This requires nothing more than paying attention to your urine color. If it’s pale yellow, you’re in a good spot. If it’s darker than that, you’re not drinking enough. If you’re persistently pissing clear in high volumes, you’re likely drinking too much and putting yourself at risk for hyponatremia (electrolyte depletion). You want to aim for pale yellow urine at consistent intervals throughout the day. 

The problem is, there’s a solid chance you’ll have suppressed thirst. So, you may have to drink on a schedule the same way you eat on a schedule. It’s also important to remember that you’ll have a hard time regulating your body temperature if you’re dehydrated and your electrolyte balance is off. You will shiver more, burn more calories, and leave yourself further depleted. 

General guidelines say you should drink between 15oz and 30oz of water per hour while moving at high elevations. And you want .5g - 1g of sodium per 30oz of water. You will get some of that sodium from food, and from the broth packet you drink at dinner. But it would be helpful to have an electrolyte packet mixed in during one of your water bottle fills. Again, these are general guidelines that don’t account for individual variation. You have to pay attention. And it would be helpful to get a sweat analysis done while you train for your hunt so you know your baseline needs.

A Note on Pre-Hunt Nutrition

The last thing you want is to start your mountain hunt in a depleted state. So, as you cut your training back during your taper, keep your caloric intake the same or slightly higher. This ensures that you have some reserves before you ship out.

Traveling to Your High-Altitude Hunt

How you travel to your hunt can either set you up for success, or kill your performance and put you in danger. It’s important to mind a few things when traveling to hunt high in the mountains.

Your two biggest allies are sleep and hydration. As someone who’s failed to sleep and hydrate on the way to a higher elevation hunt, I can tell you that you don’t want to mess this up.

There’s a common practice that creates the problem. Many Eastern and Midwestern hunters drive to go on their hunts, often straight through from home to their hunting location without stopping. These drives often go for 24 hours or more. In the rush to get where they’re going, they don’t stop to sleep. And they fail to drink enough water because they don’t want to stop to piss. So, they show up to the trailhead underslept and dehydrated. Then they start hiking.

Your cardiovascular system takes an absolute shellacking when you’re underslept. Your resting heart rate rises and it’s difficult for it to adapt to whatever stressor is thrown at it. Dehydration makes it even worse because your blood volume decreases, which increases how hard your heart must work to pump blood. Layer the effects of altitude on top of that and you’ve all but punched your ticket for Acute Mountain Sickness.

Give yourself enough travel time to stop for rest. Stop to sleep along the way, and if you can, budget enough time for a night in a hotel or Air BnB when you get to where you’re hunting. Spend the night there, then start your hike the next day. This is especially useful if the town you stay in is between 5,000 and 7,000 feet of elevation. It gives your body time to make a mild adjustment to the elevation gain. 

Maintain your drinking schedule. You might have to stop to take more leaks than you’d like, but that’s a whole lot better than having to bag your hunt. The mountain isn’t going anywhere. But you might not make your way up it if you don’t take care of yourself.

Better yet, fly if you can afford it. This cuts all the stress of driving and gives you time to rest. But make sure you continue to drink. Don’t cut back just because you don’t want to get up to piss on the plane.

You’re obviously flying if you’re going on an international hunt. Schedule enough time to rest for a day or two when you reach your destination. And keep drinking water on the gaht dang plane!

Ascent Planning

If you’re going on a guided hunt, the outfitter should have this lined out for you. If they don’t, make sure you advocate for yourself based on what’s outlined below. (And maybe put a little more consideration into who you book with.) 

If you’re DIYing it, pay close attention to the following info. It could keep you on the critters you’re hunting. More importantly, it could keep you out of the hospital.

Sleeping Elevation: The Most Important Factor

We’ll start with the most crucial factor. If you’re hunting high, especially above 10,000 feet, your ascent plan should be based on your sleeping elevation.

Once you pass 8,000 feet, never increase your sleeping elevation by more than 1,000 to 1,500 feet per day. You can hike higher, but make sure you come back down to sleep. 

Here’s an example of what a smart ascent plan looks like.

Sample Ascent Plan

Let’s say you’re hunting between 10,000 and 11,000 feet. Here’s how you can line it out.

Day 0: Arrive at a hotel or Air BnB and go for a short hike.

Day 1: Short, easy hike in to around 7,500 feet and set a temporary camp.

Day 2: Easy to moderate hike to 9,000 feet and set base camp.

Day 3: Easy scout/hunt at 10,000 to 10,500 feet and return to base camp. 

Day 4: Hunt at 10,000 to 11,000 and set a spike camp at 10,000 feet.

Day 5: Hunt high if the critters are high, but be sure to return to your spike camp at 10,000 feet.

Day 6 On: Keep hunting however you need, just keep following the hunt high, sleep low rule.

Drop Your Ego and Go Slow

You might feel great on days 0 and 1, but resist the urge to just rip off huge, hard hikes. You will pay for it, even if your fitness is solid. Having solid fitness is a partial liability in this situation. It can allow your ego to take over and talk you into doing things you shouldn’t do. Drop your ego and go slow. Let your body catch up to the change in altitude.

Accessory Actions That Might Help You Prep for Altitude

Up to this point in the article, you’ve eaten the meat and potatoes of prepping for a high-altitude hunt. This section layers on some seasoning that might be useful for making the meal taste a little better. These flavors could be useful, but they are not to be done in place of anything outlined above.

Passive Heat Training

Passive heat training is often used by endurance athletes to top off their training adaptations before a big race or event. It doesn’t replace altitude acclimatization, but it does do some things that could help counteract altitude’s effects.

First, it increases your blood plasma volume by 5% to 15%. This can help counteract altitude diuresis. 

Second, it improves cardiovascular efficiency by decreasing your resting heart rate, and by decreasing your heart rate during submaximal exercise. All of this reduces cardiac strain at a given workload. 

Third, it improves your sweat response and ability to regulate body temperature. You’re much closer to the sun at high altitudes, meaning there is more solar radiation. There are also huge temperature swings. And, as you know, risk of dehydration dramatically increases.

To benefit from passive heat training, you need to do it three to five times per week for the three weeks directly before your trip. You can do it in a bath tub, hot tub, or sauna, and each session must last between 20 to 30 minutes. If you do it in a bath tub or hot tub, the water temp must be between 104 and 108 degrees. The sauna must reach the north side of 140 degrees. It’s also best to do these sits immediately after aerobic training to maximize the benefits.

It’s crucial that you hydrate before and after the session. Have 16oz to 32oz of water and 500mg of sodium before, and about 24oz to 48oz of water and between 1,000mg and 1,500mg of sodium after. It’s important to stay on the high end of that range if you train before doing a passive heat protocol. It’s also helpful to weigh yourself before and after the sit so you can dial in your replenishment. Spread your replenishment out over the course of 90 minutes. Don’t chug it all at once or you’ll just end up dumping water via increased urination.

(I wrote a passive heat training protocols guide for our Packmule members. If you’d like a copy, email me at todd@humanpredatorpackmule.com.)

Altitude Sleeping Tents

If you’re serious, and you don’t mind spending a little cash, an altitude sleeping tent could be useful. They simulate the decreased barometric pressure of higher elevations, helping your body acclimatize before you get to the mountains. They’re hooked up to a generator that decreases oxygen levels in relation to given altitudes. They work, and they are useful if you have no choice but to rapidly ascend.

To get the benefit, you have to sleep in them for 6 to 10 hours per night during the 4 to 8 weeks leading up to your trip. They must be set to simulate elevations between 8,500 and 12,500 feet. 

It’s true that they work, but they also have drawbacks. They are noisy. They are hot and steamy. And they are expensive. The cheapest I’ve found is $260, and it just covers your head. 

They also reduce your sleep quality, which is a big deal in the weeks leading up to your trip. So, if you choose to use one, you will have to dial back your training to ensure recovery. 

Full disclosure: I’ve never used one, but the research is promising, so I’m throwing them out as an option.

Finishing The Climb

Altitude is not to be trifled with. You need to understand what it does to your body. You need to dial in your training and nutrition so you’re as prepared as possible. And you need to be smart about how you travel and ascend. If you nail these things and want some extra sauce, add in passive heat training and/or an altitude tent. Do all of this well, and you’ll give yourself a better shot to perform on your high-altitude hunt while decreasing your risk of altitude illness.