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

People who live up in the mountains tend to be rich.

People who live in hot muggy humid weather tend to be poor.

Humid air is thinner than dry air, hence "poor man's altitude." But not very much.

Nothing to do with physiology. Just something people who run in trash conditions are told to help with the constant need to make pace adjustments. Gotta convince yourself you'll come out fitter on the other side of summer, even as you suffer through workout after workout.

There has been speculation that it provides a bump to your training, so that when you race in normal conditions you feel great.

Elites travel to train at altitude. The rest of us are stuck dealing with humidity.

Higher humidity reduces air viscosity and density which slightly reduces resistance (good) but also slightly reduces oxygen content (bad) and also slows perspiration evaporation (bad), right? So there is thinner, and there is thinner.

I’ve lived and trained in both.

humidity is twice is difficult. There really never is getting use to it.and u can’t run intervals in it bc after the warm up and first rep or two u are drenched in sweat and u never fully recover

because only rich people live at altitude

Check my name. It just is

There is nothing "good" or "bad" about air. Its simple math.

Really? I dont think so.

That's incorrect. Arguably, there's stronger evidentiary support for performance benefits from training in hot/humid weather than training at altitude. There is no question that hot weather training significantly improves cold weather performance.

With altitude, there are likely long-term benefits that exceed those of heat training, but we don't have any good research on it. Anecdotally, it seems to be true.

For short term altitude training, we know what works and what doesn't. It's been studied exhaustively. Few athletes do what works. You need to be living at 7k and getting at least as low as 4k (ideally lower) for your workouts, or you aren't going to get a bump. You also need at least 3-4 weeks. 2 weeks is worthless.

Altitude = Dry

If someone were training for the Tokyo or Paris Olympics, if would be pretty darn useful to do some training in warm, humid conditions.

No physiology involved. It's just "hard" like altitude is so it's something people tell themselves to help them get it done and feel better about it. Much like snow, heat, rain, etc. You have to play some mental tricks to get it done sometimes.

Before the 1984 Olympic marathon, which was going to run in hot weather, Salazar, who was always in search of an edge, trained in Houston, but it didn’t make any difference. The belief at the time was getting hammered by the heat, resulted in Salazar having crappy workouts.

I disagree with the posters saying it really doesn't do anything. I lived in Florida for a summer and would get destroyed by the heat. Normally my training pace was around 6:30-45, when I trained in Florida I would do my runs at almost 8-minute pace. Ripping for me in Florida during the summer and hot times a day was 6:59 pace. When I came back up North that Fall I felt really strong. My workouts and runs were trash all summer but I just ran by effort. I ended up running in the 15:20s for the 5k that fall which was a pr at the time, when all my runs and workouts did not remotely reflect that type of fitness while in Florida for the summer.

Professional endurance athletes can afford to train at altitude where the temperature and humidity is ideal. Non professional endurance athletes can't.

The rich / sponsored can afford to go to training camps to work at altitude. The rest of us get with what we're dealt.

Suffering in the humidity (with heat) is such a strain that you will undoubtedly speed up naturally in the fall. I say with heat because anything under 60 won't really affect you that much , but 65, 70, 75 when the humidity is 85-95% is crazy tough.

Physiologically, you can't properly sweat so you're overheated, you still are sweating like a pig so big dehydration loss (yes both are true and opposite!). The dehydration also causes muscle cramps so you can't perform.

I'm often 10" slower per mile early July, pick up speed a bit through Aug then come September and 'wham bam thank you ma'am' you're at race pace.

Many moons ago I asked Peter Snell about this. He told me there are completely different mechanisms that happen when running at altitude than there are when running in humidity. But at the '68 Olympics the only American to make the finals in the 5,000 was Jack Bacheler (who got Montezuma's Revenge on the day before the race and didn't run.) Jack didn't spend as much time at altitude as many of our other distance guys in the weeks before the Games. He was in Gainesville working on his Ph.D and later said he thought that maybe he did okay at altitude because he'd mostly trained in a lot of heat and humidity there. I read an interview with John Tuttle in which he said a similar thing about the time he ran 2:10 at the New York Marathon, i.e., he'd been in Florida in the months before the race and thought running in the heat and humidity made him very fit. I remember training through the heat and humidity of Washington, DC summers and it was a bit of a struggle. Then there was always a time in September or October when the weather would break, become fall like, and it felt wonderful and energizing. So there may not be all that much physiology going on here but there is a good bit of experiential stuff.

I think the "poor man's" thing came along when it became common for runners to relocate to locations at altitude. Doing so required at least a bit of money to pay for the move and support yourself. Not everyone was in a financial position to do that.