This week's Altitude Academy article was inspired by one of our athletes. He took his KILIMA system to a training camp at 2000 meters because he wanted to increase his altitude exposure even further while he slept.

It made us realise something.

Most people would simply use the same generator settings they use at sea level.

That's a mistake.

It's one of the biggest misconceptions about simulated altitude training, and it's surprisingly easy to understand once you know one simple fact:

Your altitude generator adds altitude to where you already are. It doesn't replace it.

Let's explain why. 

The Air Doesn't Contain Less Oxygen

Wait... what?

One of the most common myths is that there's "less oxygen" on top of a mountain.

Not exactly. Whether you're standing on a beach in Portugal or hiking at 3000 meters in the Alps, the air still contains approximately 20.9% oxygen.

So why does breathing become harder? Because the atmospheric pressure is lower.

Lower pressure means the air is less dense. All gas molecules - not just oxygen - are spread farther apart. Every breath therefore contains fewer molecules overall, including fewer oxygen molecules.

In other words:

The percentage of oxygen stays the same, but the number of oxygen molecules you inhale with each breath decreases.

Partial Pressure Is What Really Matters

Your body doesn't care about oxygen percentage. It cares about oxygen partial pressure (PO₂) - the pressure exerted by oxygen molecules within the air you breathe.

At sea level:

• Atmospheric pressure: 760 mmHg

• Oxygen concentration: 20.9%

• Oxygen partial pressure: ≈159 mmHg

At 2,000 meters:

• Atmospheric pressure: 596 mmHg

• Oxygen concentration: 20.9%

• Oxygen partial pressure: ≈125 mmHg

Notice something?

The oxygen percentage never changed.

Only the pressure did.

That's why breathing becomes harder as you climb, even though oxygen still makes up 20.9% of the atmosphere.

What Your Generator Actually Does

Our altitude generators use Pressure Swing Adsorption (PSA) technology with a molecular sieve. The system selectively removes oxygen from the surrounding air, creating hypoxic air with a lower oxygen concentration.

At sea level, selecting 2000 meters produces air containing approximately 16.3% oxygen, giving your body roughly the same oxygen availability as sleeping at 2000 meters.

So far, so good.

Now let's take that exact same generator...

...and drive it into the mountains.

Does the Generator Work Differently at Altitude?

The short answer is yes - but only slightly. Our altitude generator is calibrated and designed for sea-level atmospheric conditions.

As altitude increases:

• Air density decreases.

• The compressor draws in less air mass with each cycle.

• The pressure swing characteristics change slightly.

• The molecular sieve operates under different ambient conditions.

Because of this, the generator may produce slightly different oxygen concentrations than it does at sea level, particularly at very high elevations. However, the PSA technology itself works exactly the same way.

It continues removing approximately the same fraction of oxygen from the incoming air.

The important difference is that the incoming air already contains fewer molecules because atmospheric pressure is lower.

So even if the generator still produces approximately 16.3% oxygen, each liter of that air contains fewer oxygen molecules than it would at sea level.

The Generator Doesn't Know You're Already at Altitude

Imagine you're sleeping at 2000 meters.

You set your generator to your usual 2000 meter setting.

The generator happily produces approximately 16.3% oxygen.

Your oxygen analyzer happily displays 16.3% oxygen.

Everything appears perfectly normal.

Except your body disagrees.

That same 16.3% oxygen now exists in air that's already under much lower atmospheric pressure.

Instead of experiencing around 2000 meters, your body is suddenly dealing with something much closer to 3800-3900 meters.

Without touching a single button.

Congratulations.

You accidentally doubled your altitude exposure.

Why Your Oxygen Analyzer Doesn't Tell the Whole Story

At this point, many people ask:

"But my oxygen analyzer still says 16.3%. Surely that's correct?"

It is.

The analyzer is doing exactly what it's designed to do. It measures oxygen concentration (FiO₂). It does not measure atmospheric pressure.

That means these two situations produce exactly the same reading:

Location	Oxygen analyzer	Physiological effect
Sea level	16.3%	≈2000 m
Already sleeping at 2000 m	16.3%	≈3900 m

Same oxygen percentage. Very different physiological stress.

Oxygen analyzers are excellent for confirming that your generator is working correctly.

They simply cannot calculate your total altitude exposure once you're already in the mountains.

So What Should You Do?

If you're already staying at altitude, your usual sea-level settings should almost never be used.

Instead:

• Spend the first night with the generator turned off.

• If additional hypoxia is desired, begin with the lowest generator setting.

• Increase gradually over several nights.

• Monitor your SpO₂, resting heart rate, HRV and sleep quality.

• Remember that real altitude and simulated altitude add together.

More altitude is not automatically better.

Most successful "Live High" protocols expose athletes to the equivalent of roughly 2000-3000 meters during sleep. Going significantly beyond this often increases sleep disturbance and physiological stress without providing additional performance benefits.

The Takeaway

Your altitude generator doesn't replace your current altitude.

It adds to it.

That's why using your normal sea-level settings while already sleeping in the mountains can create a much stronger hypoxic stimulus than you intended.

So if you're taking your KILIMA system on a training camp, holiday, or mountain adventure, remember one simple rule:

The higher you already are, the lower your generator setting should be.

Your body will thank you.

Probably by letting you sleep.