How similar is altitude training and hot humid days?

no benefit to the heat, don't run it if you can avoid it.

You can search for the thread, but this was recently covered. A layman's synopsis: training at altitude increases the number of red blood cells thus allowing more oxygen to be transported in your blood; training in heat increases blood plasma (but not number of red blood cells). Not a ton of research showing benefits of increase in blood plasma alone, but there may be a benefit. Discussed to an extent here:

http://www.runnersworld.com/sweat-science/heat-stress-plasma-volume-and-the-benefits-of-dehydration

I once talked about this with Peter Snell who told me the two things are not alike at all, that you've got two different systems coming into play. That's as far as we got. On the other hand, Jack Bacheler was the only US 5,000 meter runner to qualify for the Olympic final in Mexico City. He later said he thought he adapted to altitude better than others because he'd trained in the heat and humidity of Gainesville. Personally, I've wondered why heavy humidity doesn't simulate the effects of altitude somewhat given that the increased water vapor in the air seems like it would reduce the amount of oxygen in a given amount. Anyone know?

The absolute difference between humid and not humid air makes nearly zero difference in the amount of O2 in the air. I think heat provides an additional stress or stimulus that may provide more fitness.

A PhD physiologist in Colorado Springs told me that people born and raised in hot weather like that of Arizona have an easier acclimatization to high altitude. Why? He said there a several hypothesis. Take it for what it's worth.

HRE wrote:

I once talked about this with Peter Snell who told me the two things are not alike at all, that you've got two different systems coming into play. That's as far as we got. On the other hand, Jack Bacheler was the only US 5,000 meter runner to qualify for the Olympic final in Mexico City. He later said he thought he adapted to altitude better than others because he'd trained in the heat and humidity of Gainesville. Personally, I've wondered why heavy humidity doesn't simulate the effects of altitude somewhat given that the increased water vapor in the air seems like it would reduce the amount of oxygen in a given amount. Anyone know?

It's certainly a grave concern for pilots. For runners there would be some effect. Not sure how much.

Here is an air density/altitude calculator. Try plugging in some numbers.

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)

Replacing dry air (28.97) with water vapor (18) lowers the density of air and thus resistance making it faster for running.

Correct. This is why a couple of the athletes attempting to break the world hour record in track cycling have done so in Cali, Colombia. High altitude plus warm, humid weather = the least amount of air resistance. However, altitude and heat will decrease pace at any given VO2 so you have to find the ideal sweet spot for your unique physiology. I realize this is cycling related but maybe a small amount would translate to running.

10minsapart wrote:

The absolute difference between humid and not humid air makes nearly zero difference in the amount of O2 in the air. I think heat provides an additional stress or stimulus that may provide more fitness.

It's not nearly zero. I've read that 100% humidity at 77 F (298 K) displaces enough O2 to be roughly equivalent to 1000 ft elevation. To me that's significant.

I'm too lazy to do the calculations, but I'm curious how 90 F air temp and 80 F dew point would stack up. That's upper level summer conditions where I live.

They are the same primarily because they both are an added stress that your body must adapt to. But physiologically the adaptation is only similar for certain aspects.

Likely most similar in that your mind also has to adapt to the added stress, so each make you "tougher" and you can accept and withstand added discomfort.

Some runners have had great success training in heat because they could not go to altitude. Benji Durden (top marathoner from 1980 ish) used to train in Atlanta wearing double sweat suits even in the summer. He felt it made up for lack of altitude training.

I can say from experience that the adaptations are different. I have been very well adjusted to heat but a race at altitude killed me. I have been very well adjusted to altitude but a race in heat killed me.

As long as you do not overdo it so that you become chronically dehydrated or electrolyte depleted, training in heat is ok.

Beware of becoming so well adjusted to heat that you can not tolerate of function well in a cool or cold weather race.

You and I live in similar conditions.

As to worrying about being unable to race in cooler conditions after training in swamps all summer, I wouldn't worry about it. I just don't think that the adaptations undertaken in response to heat and humidity have a detrimental impact on performance in cool weather.

I trained all summer in a Florida for fall marathons and got a cool day once and a moderate day another. The temps on the cool day had no impact (although the 20+ mph winds with 25+ gusts did).

I believe there is some evidence that training in heat and humidity can be beneficial to performance. Pretty sure I've read some stuff about improvements in economy after prolonged training in humid conditions.

They've already been a fair few threads on this topic. Search. You might find some useful information.

math is here wrote:

A PhD physiologist in Colorado Springs told me that people born and raised in hot weather like that of Arizona have an easier acclimatization to high altitude. Why? He said there a several hypothesis. Take it for what it's worth.

Could be the reason why Gammoudi ran so well in the 1968 5000m.

I love seeing the Liberal Snowflakes melt in 70 degrees at the Boston Marathon!!!! Hahahaha.....

math is here wrote:

A PhD physiologist in Colorado Springs told me that people born and raised in hot weather like that of Arizona have an easier acclimatization to high altitude. Why? He said there a several hypothesis. Take it for what it's worth.

That's great. I'm using that. Why? There a several hypotheses.