Does cold air have more oxygen?

Oxygen uptake into the bloodstream in the alveolar capillaries is dependent on the partial pressure of oxygen, not the absolute mass of oxygen per volume of air. So, while cold air certainly can have an effect on endurance, it's not because of increased oxygen availability/uptake in the lungs.

good point.

Does a 40 degree day have more oxygen in the air than a 55 degree day?

Along w/ OP's theory, wouldn't the more dense air also increase wind resistance?

Interesting point on oxygen partial pressure and uptake.

I did some analysis of air density and drag back in 2009 when Bolt set the 100m WR in Berlin. I found that hot, humid air is least dense and most conducive to fast sprinting. As long as it's not actually raining high humidity air is less dense than dry air because light water molecules (H2O) displace heavier air molecules (mostly N2 and O2).

From my experience cold air is usually dry so it could have slightly higher O2 fraction.

I don't think density would strongly affect drag because it's a function of speed squared. Marathoners are relatively slow - sorry guys.

categorically wrote:

Basic thermodynamics, right? Cold air is more dense than warm air so oxygen should be more concentrated in cold air. Would the effect be strong enough to make a difference for an endurance event like the marathon?

Q: does cold air have more oxygen?

A: by volume, yes

Q: does it matter for long distance running?

A: no, not really b/c the incremental difference in volume of oxygen per unit volume of air moving from 80F to 40F (say) is not relevant to the uptake of oxygen in to the blood

More important factors are at play in terms of performance in different temperatures than oxygen uptake: body cooling, drag coefficients, etc.

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A: no, not really b/c the incremental difference in volume of oxygen per unit volume of air moving from 80F to 40F (say) is not relevant to the uptake of oxygen in to the blood

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This is accurate. The blood still needs to absorb the oxygen. Also, you are wasiting energy warming up the air when you breathe it in. so In very cold weather 20 degrees or so, it is draining energy from you.

First poster had it right. All that matters is PARTIAL PRESSURE.

adsfadsdfdsf wrote:

First poster had it right. All that matters is PARTIAL PRESSURE.

Nope. The temperature itself matters. Oxygen affinity of hemoglobin is higher at lower temperatures.

Assuming the cold air reduces the temperature in your alveoli, you will indeed absorb oxygen more quickly from it.

random relevant study:

granted, alveolar temperature doesn't vary by much.

adsfadsdfdsf wrote:

First poster had it right. All that matters is PARTIAL PRESSURE.

I don't think it's quite that simple. As Wiggo states, oxygen's affinity for hemoglobin changes with temperature.

I know cars make more horsepower with cold air rather than hot air. I reckon there is an optimum temperature and humidity for oxygen uptake at a given elevation.

It has been correctly pointed out that cold air is denser and thus contains more O2 than warmer air. However, the increased density translates to a greater mass per unit volume and the additional weight offsets the O2 gain.

Bad Wigins wrote:

Oxygen affinity of hemoglobin is higher at lower temperatures.

Which would decrease the O2 availability to blood, correct? Higher affinity means less release of the molecule.

jezebel wrote:

Bad Wigins wrote:

Oxygen affinity of hemoglobin is higher at lower temperatures.

Which would decrease the O2 availability to blood, correct? Higher affinity means less release of the molecule.

Alvelolar blood is there for O2 uptake, not release. But as I fortunately mentioned before someone else did, the temperature in alveoli doesn't vary much. That study I posted was on hypothermic rats.

cold air does have more oxygen, but it is really the humidity that matters. More water in the air means less oxygen pressure.

However, this change will not help anyone run any faster (well, it would help people with severe lung disease, but ignore that.) The limiter is never the amount of oxygen in the air or even the blood. The limiter is how well your body can use the oxygen or tolerate the consequences of anerobic metabolism. Even if you had a mask with 100% oxygen flowing, a healthy person would not run faster at any distance.

They both have the same amount of oxygen. Cold air will occupy a smaller volume of air for the same number of O2 molecules.

PV/RT=n (pressure, volume, gas constant R, temp in K, n=number of moles)

Bad Wigins wrote:

jezebel wrote:

Which would decrease the O2 availability to blood, correct? Higher affinity means less release of the molecule.

Alvelolar blood is there for O2 uptake, not release. But as I fortunately mentioned before someone else did, the temperature in alveoli doesn't vary much. That study I posted was on hypothermic rats.

Were they message board rats?

Yeah, I later realized that you probably just warm up the air as you breath it in. Lots of interesting points put forth. It's pretty well known that cold weather is better for endurance running. Just trying to understand all the reasons.

I gather that super humid warm air can hold about 6% of water. So if you remove that water in cold dry air it might have 6% more oxygen partial pressure. 6% seems like enough to make a difference.

I know that the differences between individuals is far more important but let's take just one individual. He or she is bound to run faster over the course of a marathon if there is 6% more O2, right?

No. No one uses 100% of the O2 they breath, so a 6% increase would have no effect.