1. The depth - which is only 7ft in Paris, unusually shallow for a competition pool.
2. The sides. Does the water spill over the sides into the gutters, or smash into a wall and bounce back, creating more chop.
A trained eye can see all the swimmers in Paris struggling in their last 10-20 meters (heck, an untrained eye can spot some of these). Bummer that it makes the meet feel slow but at least it generally affects all the swimmers equally
The setup was simple - a constant head vessel to provide a constant but adjustable flow of water in from one end, and a little plastic boat sat in the middle of the channel, attached to a force gauge at one end of the channel. The outflow of the channel had a gate with an adjustable height in order to vary the depth. Also, a couple of dye injectors at different heights in the channel in order to see turbulent vs laminar flow.
The key finding was that at shallower depths, turbulent flow began much more rapidly and resulted in erratic but overall higher resistive forces on the boat. Deep water remained laminar for much longer, and could flow much faster before turning turbulent near the surface. This was the expected result, but it was nice to experimentally prove it.
So in short, the pool depth almost certainly impacts the point at which turbulence kicks in, and therefore athletic performance. It’s probably the dive/entry that is being most impeded, as that’s when the swimmer will largely be experiencing laminar flow.
the difference of the resulting turbulence from the wave bounced back from the bottom surface at 2m here and from the more traditional 3m is a big deal. The water is pushed by the swimmer's hands with the speed of something on the scale of 2 meters per second, so, as the swimmer moves forward, that turbulent movement of the water reflected by the pool bottom may as well come behind the legs in the 3m depth case while in the 2m depth case it would catch the legs decreasing the efficiency of their movement.
The Olympics used to be held at Olympia. It's not difficult to make the conditions the same every four years.
Putting the faster qualifiers in the middle lanes is also a better view for the spectators on both sides of the pool.
I would be very surprised if they re-use it at all - an "above ground" pool of that size seems like it would be more trouble than it's worth to maintain over the long run.
A timelapse of the pool being put together: https://www.youtube.com/watch?v=jTuFidqy0yI
There's a lot in the book Soccernomics about how the economic value promised by politicians lobbying for hosting things like this rarely pan out.
If so, I guess this would be a serious competition only thing because you wouldn’t want them off for hours.
<https://resources.fina.org/fina/document/2022/02/08/77c3058d...> (PDF)
Most competitive swimming pools have a large number of inlets with diffusers on them, laid out every 2m or so across the pool floor.
Those are circular disks about 10cm in diameter, looking vaguely like this:
__________
\________/
| |
^^^^^^
Because the gutters are continuously removing water from the pool, circulation needs to be on to maintain a consistent fill level.
Maybe it's just the swimmers and not the pool as such
Plus, they are the worldwide foremost experts on competitive swimming. Definitely I would be more interested in their evaluation of a swimming pool rather than trust "research results" from the company that built the pool in question.
On some swimming forums competitors were complaining about the bidding process for the pool construction and giving a different opinion, noting that the depth is less than what was recommended by international standards bodies. There's also something about video equipment at the bottom of the pool?
I'm not sure what to think, as there are things to consider both ways, but there's a bit more out there than swimmers versus pool officials.
And if you don’t like inferring causation, one could just directly perform an experiment to test this pool vs another pool using swimmers who didn’t quite make the Olympics.
How the pool gutters neutralizes or doesn’t neutralize waves; water temperature; the design of the lane lines; design of the starting block; the electronic touch sensors(how hard are they - do you get a good solid feel for push off?); etc
Depth is probably only part of the reason the pool is slow. It would be very unlikely everyone happens to be slow at the Olympics this year.
Shouldn't the middle swimmer be worse off with "fast" pools? There would be less waves on the side lanes, compared to a "slow" pool where there are reflections.
> 2. The sides. Does the water spill over the sides into the gutters, or smash into a wall and bounce back, creating more chop.
My only experience with competitive swimming is playing some water polo some 25 years ago, but wouldn't that effect disproportionately affect the swimmers on the outermost lanes?
Edit: the article addresses this, so if anyone else is curious like I was, I suggest clicking.
Slightly deeper and there's drag from the floor as their arms barely miss it. That effect persists until it doesn't .. now it's deep enough.
It needs to be deep enough that vortex's created by swimmers have disapated by the time they reach bottom and reflect back to the surface so as to not interfere with following swimmers or swimmers returning.
This paper does a decent job of modelling how swimmers move through water: https://royalsocietypublishing.org/doi/epdf/10.1098/rsif.201...
>But the “slow pool” theory does not hold up as well when one looks beyond the winning times. In fact, it appears a bit, ahem, shallow.
>When you consider the times it has taken to earn a spot in the finals in Paris — which is to say, the eighth-place times from either preliminary heats (in events 400 meters or longer) or semifinals — those times have been faster than in Fukuoka in 10 of the 12 events and faster than in Tokyo in five of 12. In the women’s 400 free, for example, it took a time of 4 minutes 3.83 seconds to make it into the final, faster than in Fukuoka (4:04.98) or Tokyo (4:04.07).
https://www.washingtonpost.com/sports/olympics/2024/07/30/pa...
Are France competition pools across the country just always that shallow? What are dimensions of the pools from the past 10-15 Olympics? Should this have been an established standard? (gonna say yes to that one)
Although the recommendation has been 3 meters for a while.
Worth noting that the WR was from a Chinese swimmer and there's a current controversy around whether or not a large contingent of swimmers from the Chinese team violated anti-doping rules after a banned substance was found in their test results several months prior.
Reports are self-policed because it would spread the IoC or other international bodies too thin (ahem... convenient), and the Chinese reporting body "Chinada" dismissed it after saying "trace amounts were found in the kitchen where the athletes were staying at a meet".
I attempted to track down the report to see if the 100m world record breaker was amongst those who tested positive, but wasn't able to find it posted online anywhere. So he may have NOT been incriminated there, or may have been, can't say either way.
I want to celebrate the increased emphasis on swimming internationally as a former college swimmer, but it's also hard to ignore some of the clouds of controversy that have formed surrounding Chinese athletes. I understand the Olympics are a focus point for the country, and again as a former D1 swimmer I can empathize with wanting to do well, but at the same time I hope they're not crossing any lines in effort to win, as that defeats the spirit of competition.
Also worth noting that Phelps and Alison Schmitt testified before Congress and spoke about the intrusive frequency and nature of how often they were drug tested.
The NYT/The Daily did some great reporting and follow-up podcast on the situation.
https://open.spotify.com/episode/4Rcc852dmPSPytDdRCKInU?si=2...
Marchand beat the rest by more than 5 seconds in the end but basically "gave up" after 300 meters. Shoulda coulda woulda but he didn't need to push himself at all for the gold (his last split was the 2nd worst against everyone else).
More generally, and talking about being good, it’s noticeable how the US, the biggest force in swimming, is going through a change of generations, as their only remaining star is Ledecky, who’s on her fourth Olympics. The Russians are also missing, they always used to have one or two super-stars ready to push the Americans to the limit (think Popov and Pankratov). The Aussies are doing a very fine job, and fair-play to them for that, but they’re also kind of not up to the highest levels in the men’s competition.
If I recall correctly: - Javeline would go further (less air resistance) - High cardio events would go slower (less oxygen for athletes)
That would have been a "slow pool" factor all things being equal!
We traveled to Colorado for an invitational.
I was so slow and so tired. 18 year old me didn't realize that air changes. Idiot.
I also realized that if those guys ever came to the Midwest, they would absolutely dominate.
I live at 5000 ft now, but in my 30s I lived and slept at 9000 but did all my rides near 5000. That was an amazing time for my fitness. I could go hard at “low” altitude but recover at high which is what my body adapted for.
See this bit on the Velodrome in London: https://www.cyclingweekly.com/news/making-tracks-building-th...
You can see in the timelapse video here[1] the pool being built above the surface. They built it to a depth of 2.15m, the minimum required is 2m, but the recommended depth is 3m.
I can only assume that making it deeper would have cost more, and perhaps reduced the sightlines from the stands as the pool would have been higher in the arena?
[1] https://www.thesun.co.uk/sport/29555045/paris-2024-olympics-...
Which got me wondering if there’s any detectable correlation on record setting and what lane you’re in (closer to the side of the pool might be slower?)
But unable to locate it. Fairly certain it was Barcelona.
Now, I could make up reasons for this, like not every athlete is strictly "from" the place they compete for, but a just-so story isn't needed here, prepositions are what they are, often arbitrary but always specific.
Citation:
https://apnews.com/article/paris-olympics-china-swimming-pan...
This is a line of thought that leads to the consideration that sports as are whole are rationally meaningless. That leads to hobbies being meaningless. That leads to emotions and ethics being meaningless.
You can't apply rationality to explain why people care about things. But people do care about it, so it matters.
I completely understand why you might not want a slow pool in a competition like this, but the emphasis on it being "not ideal for record setting" is weird to me. I guess I just don't understand the constant quest to set better and better records. Do we really always need to be hitting new world records? What's the point of that, why does that need to be a thing? If records like that are expected to be broken at every Olympics, what's the point of striving to break them if they're just going to be broken again?
Meh, I'll go back to yelling at clouds, I guess.
It ain't special if it happens a lot, I guess is my thinking.
With that in mind though, what is the point of a world event like this if, given the time and resources, we're not going to try and optimize for peak performance for the participants given that for many of them it's the career peak?
I'd argue plenty of blame to go around though: for one, why is there not a standard pool design and dimension?
/shrug
Money. All else being equal, setting a new world record will lead to you earning more money, compared to 'just' winning gold. Both because there many cases are cash bonuses tied to world records, and from a sponsorship point of view it is easier to 'sell' a world record holder. Most people know that Usain Bolt holds the 100m world record and Olympic record, you have to be pretty into sprinting to know who won gold at the 100m last Olympics.
Good thing there's credible explanations about the differences in pools and how that effects swimming speed. Otherwise, I'd assume that no one wanted to "'fess up" to prior doping.
But you're right, they don't affect medals.
This type of focus leads to unhealthy expectations and doping in my opinion.
Something causing these elite athletes to be a bit off their game? Whatever could it possibly be…
- https://www.usatoday.com/story/sports/olympics/2024/07/31/us...
- https://www.walesonline.co.uk/news/uk-news/team-gb-swimmer-m...
- https://www.theguardian.com/sport/article/2024/jul/30/paris-...
- https://svenska.yle.fi/a/7-10061397
Yup, no idea. ¯\_(ツ)_/¯
Given lack of testing and that many countries (including European countries) are seeing Covid surges right now, I think it's highly likely that most competitors are competing with either current or recent Covid infections affecting their peak performance capacity.
Edit: I wouldn't suggest it's the sole cause of performance issues. But for an entire article on the topic of swim performance to completely ignore multiple reports of viral infection from top performers seems a glaring omission.
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1: "The 29-year-old does not have to isolate from other athletes and does not have to test negative before competing again": https://www.espn.com/olympics/story/_/id/40672610/olympics-2...
2: "For now, nothing has been put into place by the organizing committee … but hand sanitizer is available in its clinics and restaurants.": https://www.cbsnews.com/news/2024-paris-olympics-covid-cases...
[1]: https://swimswam.com/swimmers-pieroni-and-gatt-join-the-covi...
https://www.ted.com/talks/david_epstein_are_athletes_really_...
As with any tech talk, think critically. Athletes train more vigorously, and have much better nutrition. Earlier athletes in the Olympics and Tour de France drank alcohol and smoked during performance.
It's still helpful to pay attention to the venues, like the swimming pools, tracks , wrestling mats etc. My verdict is that venue plays a big part, and records are not comparable from different venues.
https://slate.com/technology/2024/07/paris-olympics-2024-bre...
But maybe they wanted not to be too many world records be broken, to damage control the apparent doping problem.
You can easily see on TV now, who is doped and who's not. All the dopers do have dark purple faces after the swim, usually the middle swimmers from the US, GB, AUS, Ireland, F, China, whilst the non-dopers keep their usual skin color. Italy, Hungary, Germany, ... Some hormone effect probably with these rushes.
Right.