# WR Line while swimming

Watching the Olympics I have found the swimming very interesting. I've noticed that while the swimmers are swimming the TV Channel (BBC) projects a line across the width of the pool saying WR (World Record) at the end.

I'm a bit unsure about this line, I know it's to show where the swimmers would need to be at to get the World Record but is the line showing where the swimmer who holds that world record was at that point or is it showing the required place through out? e.g. say the 100m WR was 50 seconds, then the line would progress 10m every 5 seconds.

I'm pretty sure it shows the world record pace, rather than the position of the holder at that point in the race - i.e. it advances at a constant speed. Unless the TV company had exact positional data on every world record swim, it would be impossible to plot the position of the swimmer.

The only reference I can find is at http://forums.usms.org/archive/index.php/t-11588.html which doesn't seem authoritative, while the page at http://ethw.org/Technological_Innovations_and_the_Summer_Olympic_Games, in the final section, talks about the line but doesn't mention the specific question asked.

EDIT: See the second bullet point from http://sports.yahoo.com/blogs/olympics-fourth-place-medal/world-record-line-most-distracting-technology-olympics-021256537--oly.html

• Do you happen to know if it corresponds to the position of the swimmer's hands or head? If someone is swimming with their head at that line, are they ahead of the WR pace? Commented Aug 9, 2016 at 17:21
• I have no source for this, but my intuition tells me that it's the hand position, as that's what stops the timing. So if the swimmer's hands are ahead of the line, they're ahead of the pace. Commented Aug 10, 2016 at 8:26
• Actually it's not out of the question to compile exact positional data on every WR swim at intervals of a fraction of a second, since most of them have been set in the digital age at major world meets where there's at least one camera on every swimmer all the time. But, all you really need are the lap times for that swim, and an interpolation model that can vary the speed of the line to account for naturally faster segments of each lap (launch, final touch in backstroke). Commented Aug 10, 2016 at 16:01
• Since they have splits at every wall, I'm 100% sure that the pace of the line is broken down and adjusted, instead of being a steady WR pace over the course of the entire race. I think they just do it by 50, instead of instant to instant. Commented Sep 30, 2016 at 14:49
• Can you provide an independent reference saying that? Commented Sep 30, 2016 at 15:43

It's definitely based on the particular race that set the world record to some extent.

Ye Shiwen's Women's 400 IM record in 2012 had an incredibly fast last 100m (the freestyle section). If you look at the line showing for the record in this year's races, it was generally a long way behind at the 300m point before surging up in the last 100m so it definitely matches the split times every 50m.

I'd guess that it goes at constant speed along each length but there may be more precise data included.

• Welcome to SE.Sport. To write good answers it is bettere to add one or more sources to confirm what you have written
– Ale
Commented Aug 12, 2016 at 14:51

The line is based on the world record's holder's lap split. The line goes at the average speed the world record swimmer would have had if swimming at a constant speed. It does not take in account the accelerations or decelerations of the swimmer (you would never see the yellow line go suddenly fast but always at the same pace).

• This is believable, but do you have a source to back this up? Commented Sep 29, 2016 at 12:16
• @PhilipKendall "the WR line will only be the average time of the swimmer's lap split as you cannot define the furthest point of the swimmer: his arms keep moving back and forth." - my swim coach who has been twice an Olympic swimmer Commented Sep 29, 2016 at 12:22
• @PhilipKendall +1. But the way I see this is I don't see any difference between this answer and other two answers.
– user10632
Commented Sep 29, 2016 at 15:46