I thought I’d pull this up because I was looking at a discussion on another site about wind assistance and it was clear that there is a general misunderstanding of how wind actually assists.
Wind does NOT push you. A wind of 4mps moves the air you are cutting through forward, reducing the resistance but not eliminating it unless the wind is travelling at the same speed you are (in this case over 12 meter per second).
The amount the wind affects you is determined by your velocity, as resistance rises as a cube of the velocity, so it affects the top speed and speed end portion of the race and aids the fastest runners proportionally more than slower ones.
Wind readings are often misleading but splits tell you a lot about the true help if they are available.
In this case, the times to 50m are a pretty good indicator of what likely could be recorded with a legal wind. The difference between what these splits would normally yield in a legal race and the final times here indicates the true scope of the assistance over the second half, as you would expect.
Does everone get this?
Thank you very much, Charlie–that makes it a lot more clear. That was how I also understood wind assistance (from your other posts)–one question I have though is this: have you found wind to be of significant assistance during acceleration? Are wind aided times to 40-50m (depending on the level of sprinter) pretty much the same or very close to the same as non-wind aided conditions?
I would think there’s a limited effect because much more force is needed to accelerate from a standstill and not enough speed to develop the wind resistance you need help getting through but the higher the level of the athlete, the sooner he reaches that speed threshold.
makes sence
so re-head winds then.
would a slower runner suffer more, eg, 11.5 runner, as they hit max speed much earlier, say 30m, so they are overcoming acc resistance much earlier and so have 70m into a head wind resistance that can cause the slowing effect. v’s 40-50m for a much faster runner. And at a guess, a much stronger runner could overcome these winds better too with a higher strength reserve?
Charlie- I think I know which message board you were on. 
I wish I would have seen your post before I made mine. You explained it a hell of a lot better than I did.
Charlie, I hate to correct you on a minor point, because you did a good job explaining it, but resistance rises with the square of the net velocity (the difference between air speed and your speed).
You might have been thinking about power: the power needed to overcome the drag (official term for air resistance) rises with the cube of the net velocity.
The other site didn’t happen to be AB.com did it?
I’m not sure the answer to that, but I can tell you the following:
In a 0 wind situation, a 9.8 runner will be facing about 80% more air drag than an 11.5 runner at their top speeds.
Into a 2m/s headwind, the 9.8 runner is facing about 60% more air drag.
With a 2m/s tailwind, the 9.8 runner faces about 100% more, or twice as much air drag.
I’m VERY curious about how much of top speed is determined by air drag. Suppose you had a treadmill going 13m/s, and put Usain Bolt on it, could he move his legs quickly enough to stay on it? Obviously it will vary with different athletes, but I can’t put it into specific numbers.
well - if its indeed drag - then perhaps there is scope for some sort of costume design?
like how cyclists have time trail helmets, not for head protection, just for aero-dynamics- then you could have a suit with a light weight attachment to the rear to minimize drag…
NO because it is determined by how fast you are going into the wind. the faster you are, the more you will be pushed back towards the rest of the pack.
I think you had to correct me before but couldn’t remember the exact formula. You’re right to point out the different between drag and the power needed to overcome it, but it’s the power that counts at the end of the day.
No, I saw the discussion on Sprintzone, which has had some good discussions on it about form and racing recently. Just on this one point it got a bit off track, I thought.
In a way, the bodysuits they all favour now probably help a bit.
Another point to ponder is the effect of atmospheric heat on time.
That could be looked at by trying to see if the very high speeds reached in the mid/late race phases in Eugene can be explained by wind alone (tough because of the inaccuracies there- vector etc.). An example would be the legal 9.77 by Gay that has the splits pattern of the wind aided races. What was the temperature at that time versus other rounds?
Hot air rises because the air molecules are farther apart, reducing drag, regardless of wind. The secondary effect is on the looseness of the joints and the ability to generate higher core temperatures in the athlete (a warmer warm-up?), lowering electrical resistance in the MM Neurons.
There should be heat in spades in Beijing! Might make Eugene look like a spring day!
The heat in Beijing is much, but not as much as Osaka last year, it was really dangerous to stay outside the hotel during the day. The sky in Beijing is locked by a big fog which prevents the sun to come through.
The pre-Olympic meeting in the “Bird Nest” showed that the structure of the stadium prevents the wind to blow. The recordings were between -1.2 and +1.1, with most of the winds between -0.5 and +0.5, which is a very light breeze you can barely feel.
In Eugene, the three +1.6 in a row for the men’s quarter final are highly suspicious. Now way the wind reading can give three times consecutively the same number.
On side note, Gay went to the ceremony, but no Powell and Bolt. The Ethiopian runners weren’t there, i’m not even sure they arrived in Beijing. Very long event and the athlete’s can’t seat down.
A lot of things about track timing/measurement are highly suspicious. The world is lucky that the USA finals this year weren’t recorded as +1.6 or -4.1 or +0.0 or +Doha
Why track measurement? This is a measurement you can do as many time as you want during a day. Easy to verify. That’s not the case with the wind, and the way of measuring it has be proven to be unefficient since the first tests in 1932 Olympics, the 100m final had -ive winf at the beggining of the race, and +ive wind at the end.
What’s wrong with Doha?
By measurement I meant Athletics performance measurements in general (throws, jumps, etc). Problems in measurements occur more often than you’d like at the NCAA level. I can’t speak for the international level. Wind measurements can be a circus. Athletics performances are sadly not as absolute as people would like to think. Way too many variables.
What’s wrong with Doha? What’s wrong with 2008 USA trials?
NCAA is great. Set-up the photo finish 1m from the start line and everyone runs massive PRs… it’s happened more than once.