Do lower temperatures result in greater O2 intake (and faster running)?

Oxygen ain't 15°F when it hits your alveoli. Its all about dew point anyway.

Thinking about my run this past Sunday morning at -10 degrees F, I wasn't getting more oxygen because I was breathing through a wet rag that was covering my face to avoid getting frostbite. In fact, I was getting so little oxygen that I had to slow down at times so that I wouldn't hyperventilate.

The OP of this thread wrote:

nnalnno wrote:

Oxygen ain't 15°F when it hits your alveoli. Its all about dew point anyway.

Yeah but the point isn't what the temp is when it's in your body; I'm considering the density of the air outside. Based on simple chemistry, for an ideal gas d = PM/(RT) where P, M, R, and T are the pressure, molecular mass, gas constant, and temp, respectively. If the pressure stays at 1 atm (sea level), then as the temp goes down the density goes up. I'm not sure how the actual atmospheric pressure varies with seasons/temperatures; maybe that's compensating and keeping the density and thus the amount of air you take in about the same.

I don't think that's where the "bottleneck" is in the uptake of oxygen in to your blood and ultimately in to your muscles. I'm sure we exhale plenty of oxygen meaning that regardless of temp we are sucking in enough to allow absorption - the bottleneck is further downstream. Hopefully someone more knowledgeable than me can clear that up?

I assumed the amount of O2 taken in is important because altitude makes such a difference.

You are correct. Lowering temperatures do provide denser oxygen contents in the air, however oxygen uptake is almost never a performance limiter. Instead, the colder, denser air provides greater resistance which is more noticeable at higher running speeds, and it keeps the body cool, allowing all of the blood in your body to be used in the working muscles and not used for cooling.

Your analogy is countered by the freezing point of Water and how Oxygen is taken away from the atmosphere through frozen moisture. This is why once you get to about 40F, there is a small amount of it drawn away and a significant drop happens once you get to 32F (and only gets sharper as you cool down further).

The OP of this thread wrote:

crete wrote:

I don't think that's where the "bottleneck" is in the uptake of oxygen in to your blood and ultimately in to your muscles. I'm sure we exhale plenty of oxygen meaning that regardless of temp we are sucking in enough to allow absorption - the bottleneck is further downstream. Hopefully someone more knowledgeable than me can clear that up?

I assumed the amount of O2 taken in is important because altitude makes such a difference.

Why do you think altitude isn't detrimental to performance until about 4500 feet? Oxygen intake usually isn't the limiting factor

lower temperatures will shut your muscles down so you can't run fast no matter how much oxygen you get.

density = constant * Pressure / Temperature

where temp is in Kelvin

20F = 266K

70F = 276K

So a 50F difference would result in a 3.75% increase in density (all else constant). That's on the scale of moving down from 1000 feet above sea level to sea level.

I would say that higher temperature has a much larger effect on body temperature regulation.

runfarfast wrote:

density = constant * Pressure / Temperature

where temp is in Kelvin

20F = 266K

70F = 276K

So a 50F difference would result in a 3.75% increase in density (all else constant). That's on the scale of moving down from 1000 feet above sea level to sea level.

I would say that higher temperature has a much larger effect on body temperature regulation.

70 F is 294 K so it's about 9.5% different density.

Ya you're right my bad. So it's more like going from 2750 feet to sea level.

I wonder if breath volume changes with temperature

These are my thoughts as well

You dimwits make me crazy.

You can already breathe in more oxygen than your body has the ability to transport. It wouldn't make a measurable difference in your performance if you were breathing air with 25% more oxygen. The biggest limiting factor is transport of O2 by blood. What does EPO do? More red blood cells, to transport more O2.

angry willy wrote:

You dimwits make me crazy.

You can already breathe in more oxygen than your body has the ability to transport. It wouldn't make a measurable difference in your performance if you were breathing air with 25% more oxygen. The biggest limiting factor is transport of O2 by blood. What does EPO do? More red blood cells, to transport more O2.

This is true. You need to consider the Bohr effect. At lower blood temperature, you're going to have lesser dissociation of oxygen from hemoglobin at a specific partial pressure of O2 - which means it stays bound to Hb, and not taken up by the cells. A "leftward" shift (opposite of the rightward shift, which happens when temps increase), for those of you who are familiar with Bohr.

If the OP was talking about lower air temperature, that wouldn't have much of an impact on the blood temperature. Unless it's so cold the person is hypothermic. Then the person has more to worry about than running fast.

Yes I'm talking about how the air temperature affects the density of the air, and thus how much oxygen you breathe in.

So you say we are getting ample oxygen and 10% more intake won't make a difference. Fine. But what if you're at altitude? Then I'm assuming you aren't getting enough oxygen. In that case maybe a 10% difference in density would be meaningful.

angry willy wrote:

You dimwits make me crazy.

You can already breathe in more oxygen than your body has the ability to transport. It wouldn't make a measurable difference in your performance if you were breathing air with 25% more oxygen. The biggest limiting factor is transport of O2 by blood. What does EPO do? More red blood cells, to transport more O2.

Really? Even at altitude you are breathing more o2 than your body has the ability to transport too. The difference is the o2 density. The more available o2 molecules that diffuse into the bloodstream, the more likely they will bind with hemoglobin.

Just fyi to everyone, O2 content makes a big difference. That's why altitude affects performance. Also, Roger Bannister experimented with breathing various levels of O2 and found he could "run forever" while breathing ~60% O2 if I remember correctly. This is a bit surprising given O2 carrying capacity of the blood is mainly a function of hemoglobin content, but I some O2 can be dissolved in plasma also. Furthermore, when exercising at or very near VO2max, oxygen loading could be a problem.

Oxygen absorption from the lungs is (almost) never a limiting factor in distance running. Your blood leaves your lungs almost fully saturated with oxygen as it is. The main limiting factors are 1) having enough blood cells to saturate with oxygen and 2) processing oxygen in the muscles.

That being said, colder temperatures are desirable, to a point, for fast running in long distance races. One study pegged the optimal temperature for elite men's marathoning at 38 or 40 degrees F. But that's thermoregulation and heat production stuff, not oxygen-related.

physiology gu wrote:

Just fyi to everyone, O2 content makes a big difference. That's why altitude affects performance. Also, Roger Bannister experimented with breathing various levels of O2 and found he could "run forever" while breathing ~60% O2 if I remember correctly. This is a bit surprising given O2 carrying capacity of the blood is mainly a function of hemoglobin content, but I some O2 can be dissolved in plasma also. Furthermore, when exercising at or very near VO2max, oxygen loading could be a problem.

Blood saturation is indeed a problem at high altitude but that is because of the lowered partial pressure of oxygen. Density-wise it doesn't matter, it's a diffusion-mediated process. Same with asthma attacks: you can't get enough oxygen into your blood. But the same is not true with "extra" oxygen, e.g. in a hyperbaric chamber or at negative altitudes. You can't just get "extra" oxygen without having anywhere to put it.