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?