14-flat
Cold-air effect on Oxygen 1/19/2008 2:45PM Reply | Return to Index | Report Post
So yesterday I was training with someone and he comments that a 32:00 10k this Saturday is worth about 31:30 in summer. It was about 16 degrees outside then so I just figured he meant that the conditions would be so bad today (9 degrees and 20 mph winds) that obviously you would run faster when it is 60 deg. and calm.

But he goes on to say to someone else who asked about it that it is slower in the winter because the cold air is rarified and less dense and therefore less oxygen in each breath. "Just like running at altitude," he says. I figured that he meant mild altitude because I have never found it slower in winter to run the hard 10-milers or 7-milers that I do in summer and winter. When it is cold but dry out I run about the same pace for these longer runs at 5:20-5:30 pace that I do in the summer and if the effect was greater than say about 2500-3000 feet of elev. the effect would be noticeable. The guy is kind of a nut anyway, so I didn't think about it too much.

He went on to say that running a lot of base mileage in cold weather (it is usually 20-30 degrees here) is "just like altitude training."

But today when I was training I thought about it a little and shouldn't the air pressure (and therefore the O2 concentration) be GREATER in winter (i.e. it is 9 degrees Fahrenheit today)?

I don't think the difference would be that significant but it seems fundamental that the colder the temp. gets the denser the air gets and therefore the O2 concentration in each breath is greater at say 20 degrees than 80 degrees?

Am I right?
masters fattie
RE: Cold-air effect on Oxygen 1/19/2008 3:35PM - in reply to 14-flat Reply | Return to Index | Report Post
there is some daniels type calculator that gives you equivalents at different altitudes and temps..it is what it is..whatever I run at altitude, sea level, cold, hot is what I run on that day..

the concentration of o2 is always ~20% its just the pressure that changes but I'm no "geologist' like some others up here..
Irishguy
RE: Cold-air effect on Oxygen 1/19/2008 3:40PM - in reply to 14-flat Reply | Return to Index | Report Post
Well, running in cold weather is not like running at altitude. In fact, if you run in weather that is cold enough, it can cause serious scar tissue in your lungs. Now, it is true that it is more difficult to breathe when the temperature is very low, but that is not related to low oxygen levels, rather the body's increased blood pressure and the heart working harder to maintain a reasonable core temp.

In essence, it is probably a better idea to run indoors on a treadmill when the temp is around 0-10 degrees. You aren't going to get a good aerobic stimulus running outdoors anyways.
Space Ghost
RE: Cold-air effect on Oxygen 1/19/2008 3:49PM - in reply to Irishguy Reply | Return to Index | Report Post
This stuff about scarring lungs must be an old wives tale. I've run with lots of people in Wisconsin in below zero weather and none of us have ever had (or even heard of) any lung problems. Sources please?
Sub 13:50
RE: Cold-air effect on Oxygen 1/19/2008 5:20PM - in reply to Space Ghost Reply | Return to Index | Report Post
yeah, think about how far into your body air has to travel to get to your lungs. I imagine that it would be warm enough not to do any damage by then. Wouldn't you get scar tissue in your mouth and throat way before the air has much of an effect on your lungs?

When I was training in Michigan people would tell me that, but I just can't imagine that it's true.
Dr.S
RE: Cold-air effect on Oxygen 1/19/2008 5:44PM - in reply to 14-flat Reply | Return to Index | Report Post
There are some tables somewhere I have about temperatures where it is dangerous to exercise heavily, but for the most part this whole scar tissue idea isn't a reasonable explanation.

Oxygen in the air is going to be the same percentage, hot or cold, and actually even at altitude! At altitude, it is the change in the partial pressure of oxygen which changes, not even the percentage itself. One major difference is the air generally is less humid with cold temperatures.

Individuals with asthma are especially responsive to this. If you seriously struggle with cold air compared to most others in the same conditions, you may need to get evaluated. However, from experience working with a top-notch asthma researcher, there are many doctors who misdiagnose asthma, and a dry air challenge test must be performed or else the diagnose may be missed.

Also, the fact about blood pressure being higher and heart working harder doesn't quite work either. Most people going out in extreme cold are going to be dressed warm. Any there are plenty of us that have gone for a run in the cold and come back quite sweaty, just because we dressed warm-enough. Therefore, maintaining a core temperature is not an issue of the heart in this case, but rather the clothes we wear. In fact, the heart is actually working harder in the heat, and heart rate is higher then.

During exercise, heat is produced as a by-product, through friction of muscle contraction and through chemical reactions within the cell - which is why we get warm with exercise. The body has numerous mechanisms of getting rid of this heat, and one is dilating the blood vessels of the skin. This allows more of the warm blood to come closer to the surface of the skin and be cooled by the air surrounding the body (assuming it is cooler). Hence, our veins stick out more when we exercise in the heat. Since more blood is being diverted to the skin, cardiac output has to increase for the same absolute amount of blood to get to the muscles. This is compounded by sweat, which basically is water that will in the end be lost from our blood stream, giving us less blood to pump through our system. So, all of this results in increased heart rate during exercise in the heat for a given intensity. It is a bit more complex than that, but you get the point.
sc42
RE: Cold-air effect on Oxygen 1/19/2008 9:17PM - in reply to 14-flat Reply | Return to Index | Report Post
The proportion oxygen is not affected by temperature. The density of the air IS affected by temperature. (The effect is appreciable: pilots of small planes have to be aware of temperature/density because you need more runway to take off on a hot day.)

So yes, cold are holds more oxygen per unit of volume (which is what matters) even though it holds no more oxygen per unit of mass.
Sir Octane
RE: Cold-air effect on Oxygen 1/20/2008 12:03AM - in reply to sc42 Reply | Return to Index | Report Post
Right you are on density--however, the difference is actually appreciable--why do you think that cars that are designed for high performance have intakes that take in air temperature air rather than engine compartment temperature air?

Figure that I ran in -4F degree temps today and you ran in 86 degree air--a difference in density of around 10%. If I could handle running fast at this temp--I would have 10% more O2 per breath than you. Add into that the fact that I am breathing dry air and you are breathing humid air (comprised of water + air) and the affect would be even greater.

http://www.engineeringtoolbox.com/dry-air-properties-d_973.html as the temperatures at different temps. For those who don't know, -273 C is = -462 F.
dr no
RE: Cold-air effect on Oxygen 1/20/2008 1:28PM - in reply to sc42 Reply | Return to Index | Report Post
I agree with sc42. Aviation has a term, density altitude, which refers to the lower density of air at higher temperatures. So I think there would be less 02 per liter when it is hotter. This would seem to result in slower times at summer temperatures even if you ignore the added stress of keeping the body cool. But i don't really know
Troy Hamon
RE: Cold-air effect on Oxygen 1/20/2008 4:58PM - in reply to dr no Reply | Return to Index | Report Post
There is more O2 per liter of cold air, as mentioned above. But if your muscles get cold enough, the hemoglobin in your muscles will hold on tighter to the O2 that it has carried from the lungs, effectively delivering less to the muscles. Not sure how much of an effect this has, but I doubt it is much of anything in ambient temps above 15 degrees. I notice a huge effect on my running when it is -20 or colder, but I'm slow to start with. And no, my lungs have no problem, though I wear a balaclava when the weather is below 0 because otherwise my throat gets sore.
quotable quotes
RE: Cold-air effect on Oxygen 1/20/2008 5:05PM - in reply to 14-flat Reply | Return to Index | Report Post
you are right - it is not "just like altitude training" - obviously your friend is not a scientist nor has he ever been to altitude.
luv2run
RE: Cold-air effect on Oxygen 1/20/2008 5:09PM - in reply to Troy Hamon Reply | Return to Index | Report Post
Another factor in the cold is that blood will tend to be focused on the core and the brain to warm it, thus some is not made available.

Hemoglobin gives up oxygen better in a warmer environment (Bohr effect). There are graphs in just about every ex phys book showing the curve so there is some decrease in performance.

A warm muscle also works better so muscle function is going to be a bit impaired.

I cannot believe people who exercise really still believe the myth about lung damage. Now it can certainly feel harder and when I was running last week in single digit (F) temperatures sucking in the cold air did not feel great, but there has been no damage from my 4 years in WI/IL and 10 years in Colorado.
SMJO
RE: Cold-air effect on Oxygen 1/20/2008 5:26PM - in reply to luv2run Reply | Return to Index | Report Post
"Not going to get a good aerobic stimulus running outdoors". Classic. What actually happens then?
The lung scarring is NOT an old wives tale. However, you need to be regularly performing at a hard race effort in order for cold air to scar your lungs. Just doing base work and even fairly hard running is not sufficient to damage so there is no need to take to the treadmill.
The proof is in the obvious scarring that is seen in the lungs of cold weather racers. Sled dogs and Nordic skiers show this damage. You don't necessarily feel this damage.