Why is humidity the “poor man’s” altitude?

I've not seen it mentioned yet but one benefit of both humidity and altitude is that you can hit target HR zones or efforts at a slower paces in those conditions.

That means the strain on things like tendons and the stress on bone tissue is lower. Meaning you can potentially extend your workouts and other runs without increasing your risk of stress reactions, achilles tendinopathy etc.

Uganda is high altitude Kalenjin, just like their brothers in Kenya.

It's hard

I think all of you are overthinking the "poor man's" idiom. It has nothing to with wealth. It mean's that something is similar, but not as good, as what it is being compared to. For example, "Gary Busey is the poor man's Nick Nolte."

No one is confused except maybe you.

I have heard that the theory is that the humidity increases the water content in the air, making it harder to get as much O2 with each breath as drier air. Then, when you add the heat component, you have a greater demand for blood flow to your extremities to try to keep you cool. This would then require an adaptation of higher red blood cell counts to be able to perform in the heat and humidity. But I suspect the benefit is not as good as altitude because you are only getting the stimulus when you are training whereas at altitude the stimulus is 24/7.

Says they guy who has never dug trenches all day in South Georgia while serving time. I was only provided one hour to run, but 18 to dig trenches in the blazing heat and humidity. And that was considered a "privilege." I came out looking like Michelangelo's David.

And your Websters definition has nothing to do with the running idiom. The running idiom refers to the relative amount of oxygen when comparing training in humid conditions vs high altitude.

In humid conditions you are displacing dry air with water vapor. The most you can ever displace is about 4% of of whole (dry air) with water vapor. This relative percentage gain will never come close the the advanges afforded by high altitude. NEVER. Hence "poor man's altitude".

Yes, well... You are correct. You answered the OP's question. I think I got caught up in what the idiom meant. No quarrels from me. Now, I will go do my lunch run in 92 degrees and full humidity like the beggar I am. Good day to you, sir.

I have heard that the theory is the scientific definition of humidity.

colorado training camp? nah we goin to the everglades

If you understood anything posted you couldn't possibly come to that conclusion. I think you are kidding.

Oxygen (O2) molecular mass = 32 = (16x2)
Nitrogen (N2) Molecular mass = 28 = (14x2)

Air is 78% N2 and 21% O2. So (0.78x28) + (0.21x32) = 21.9 + 6.7 = 28.6 (molecular mass of N2+O2)

Molecular weight of dry air is actually 28.97 because the 1% remaining gasses have a total molecular mass of 0.37.

Water vapor H2O has a molecular mass of 18 (2 x1, plus 16 = 18)

The same could be said of altitude. Heat/humidity are like altitude in that both are environmental stressors that can unquestionably produce adaptations beneficial to running fast in the absence of those stressors. The most obvious adaptation to heat and humidity is greatly increased plasma volume, which can lead to a massive short-term spike in VO2max. This has been well documented.

Like any other stressor, however, there are optimum doses. You'd be better off at sea level than at 11k feet. Being at 7k feet and unable to get down for workouts is also worse than sea level for many athletes. In the case of both altitude and heat/humidity, it's important that you figure out a way to still get in your quality work. If you're in heat and humidity you might have to run early in the morning (depending where you are, though humid environments tend to have high overnight lows), or you might use a treadmill in an air conditioned gym.

I don't think anyone would say that Djibouti is an ideal training environment, especially without access to a treadmill. Obviously there can be too much of any stressor.

jfc the answers here (other than 800 dude) 🤣

let me help you guys out with this one

there are multiple advantages to moving/training at altitude (for responders):
1. increase in rbcs
2. increase in blood volume
3. increase in lactate buffering capacity
4. increase in anaerobic capacity (not often talked about, don't get hung up on this plz)
5. there are others, but those are the big 4 if memory serves me right

advantage to training in humid conditions:
1. increase in blood volume
2. there are others, but that's the main one (lot of people about heat shock protein for instance, but i honestly forget it's impact rn)

an increase in blood volume, even without any increase in rbcs (thus hematocrit goes down even if global hemoglobin levels are effectively static) increases aerobic capacity

if you do all your training mid-day in a hot/humid environment of course your results are likely to be bad. that would be like living at 6500' but choosing to drive further up the mountain to do all speed workouts. hard workouts generally need to be early morning or later in the evening, while the more moderate/easy workouts can be performed with more sun exposure

I actually think we (and "Agreed With the Guy") are in agreement. It is an idiom and therefore has nothing to do with being a "poor man".

(I am no Real Estate expert, but my sense is that property values are generally higher in the humid Northeast/Mid-Atlantic than in high altitude areas.)

5000: 12:35
10000: 26:11

checks out