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Is a 'slow' swimming pool impeding world records?

174 points| phkx | 1 year ago |sports.yahoo.com

329 comments

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samldev|1 year ago

I was a college swimmer, qualified for Olympic Trials in 2012 and 2016. There are absolutely slow and fast pools. It basically comes down to two things:

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

madaxe_again|1 year ago

I actually did a fairly lengthy research project on pretty much exactly this as a physics undergraduate - I wasn’t looking at swimming specifically, but rather boundary separation and Reynolds number in an open channel of varying depth.

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.

conductr|1 year ago

My untrained eye has noticed. But I also think it's not really a big deal. There are so few events where the conditions are exactly the same every 4 years. Just kinda the luck of the draw if you happen to be competing in the most ideal conditions for WR setting in any event

tweetle_beetle|1 year ago

I'm no expert, buy there also seems to be loads more stuff lying on the bottom of the shallow floor than I remember from previous Olympics. Not even sure exactly what it is - large white panels and other equipment that the swimmers don't look that far off touching when underwater (not the robot cameras which are relatively unobtrusive).

mysterydip|1 year ago

Would the swimmers in the center lanes have any advantage by being furthest away from the wall-induced chop?

ldng|1 year ago

Supposedly, all the Paris 2024 new accommodation were designed with re-usability for the general public after the Olympics. Is it possible that had an impact the swimming pool on design choices ? Put differently, are performance design at odd with more general/accessible design in the case of a swimming pool ?

Scoundreller|1 year ago

Dumb question I never thought about: do the circulation/filtration pumps get turned off during races? And for what minimum time before hand to let things settle?

If so, I guess this would be a serious competition only thing because you wouldn’t want them off for hours.

croes|1 year ago

>A lot of this is perception vs. reality,” he said. “If you were to talk to many very accomplished coaches, they would say the pool has to be a minimum 3 meters deep. Most of our research shows that anything over 2 meters is frivolous. … Obviously, some depth is very important. But after a certain point, it's diminishing return.

Maybe it's just the swimmers and not the pool as such

dredmorbius|1 year ago

The one aspect which isn't equal at least amongst Olympic and other competitions is that a slower (or faster) pool will generate fewer (or more) records overall. One measure of the current games' bias would be the number of new Olympic and world records set as compared with other events --- prior or subsequent Olympics, and other world-level competitions within the current year, say. I expect the quants at sites such as 538 would be looking at this.

rightbyte|1 year ago

> Bummer that it makes the meet feel slow but at least it generally affects all the swimmers equally

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.

pdpi|1 year ago

> at least it generally affects all the swimmers equally

> 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?

davidmurdoch|1 year ago

To a lesser effect, there's also the surface tension of the water, which can be adjusted with salt and borates.

ClassyJacket|1 year ago

This is yet another reason on the huge list of reasons to keep the Olympics in Athens and just use the same facilities each time.

adolph|1 year ago

Why aren't swimming lanes stadium shaped like running tracks or speed skating? Floor mounted LED indicators could advise competitors of the relative distance ahead and behind of nearest adversaries.

sschueller|1 year ago

Shouldn't that be part of the standard "Olympic Pool" definition? Depth, water height on side and overflow etc. seem to be as important as the nittting of a football goal net.

manojlds|1 year ago

Why doesn't it affect more the people closer to the sides?

jmalicki|1 year ago

For point 2, wouldn't the reflections off the sidewalls create more issue with chop on the outer lanes than the middle?

myworkinisgood|1 year ago

All swimmers are affected equally so I don't see a problem.

Yawrehto|1 year ago

Off-topic but congratulations for qualifying for trials!

croes|1 year ago

So now that two swimming worlds records have fallen, we can't blame the pools anymore, can we?

umanwizard|1 year ago

Why does it matter how deep the pool is?

Edit: the article addresses this, so if anyone else is curious like I was, I suggest clicking.

candlemas|1 year ago

The pool in Beijing was said to be fast (25 world records broken). But they were also using a now banned swimsuit. https://www.npr.org/2008/08/10/93478073/chinas-olympic-swimm...

5555624|1 year ago

But you don't need to compare these results to 2008. It's not the suit. There wasn't a banned swimsuit used by everyone in Tokyo three years ago. (The 2020 Olympics were postponed a year.) As the first sentence of the article says, the eight men in the men’s 100-meter breaststroke final would have finished no better than eighth in Tokyo. Mactinenghi won in 59.03 seconds, more than two seconds slower than the current world record (and slower than the then-world record set at the 2008 Olympics).

djtango|1 year ago

The water cube was such an epic pool - extremely deep and the level perfectly flat rather than elliptical. I still have dreams of swimming in it

expression1sh|1 year ago

Slow pools absolutely exist, as wave drag is the major impediment to speed and contributes about 55% of total drag. A shallower pool has more reflected wave energy in all directions. 2m is very shallow for a competition pool.

This paper does a decent job of modelling how swimmers move through water: https://royalsocietypublishing.org/doi/epdf/10.1098/rsif.201...

notatoad|1 year ago

from the washington post version of this article, the winners are slower but everybody else is faster...

>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...

lacoolj|1 year ago

So it's more shallow, which is a problem. Like if you trained for track on pavement vs rubber vs sand, you're going to have different results, even if "everyone has the same environment" not everyone's body will have the same relative response. I don't like that assumption that just because it's the same for everyone means the difference will affect everyone the same.

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)

p0ckets|1 year ago

"minimum standard of 2 meters that was still in place when Paris 2024 plans were approved; but below the new World Aquatics minimum of 2.5 meters."

Although the recommendation has been 3 meters for a while.

morepork|1 year ago

It's nowhere near the difference of a rubber all weather track vs pavement or sand, it's a difference of maybe 1-2%. In any sport different venues can have favourable vs unfavourable conditions that would exceed this

brk|1 year ago

Considering that the Olympics are supposed to be a test of high caliber athletics, you could argue that the lack of a standard, and the resulting variation, means that the athletes who are most adaptable have an edge. Which doesn't seem bad to me.

hot_gril|1 year ago

Plenty of pro sports have variation in conditions. World Cup soccer is played outdoors with rain, heat, whatever. Rain matters even more in Le Mans, where time records are being set. It doesn't really matter as long as it's cool to watch.

mlsu|1 year ago

I wonder if there is some kind of mesh that you could put on the bottom of the pool to absorb the interior waves. Sort of like soundproofing in a recording studio.

expression1sh|1 year ago

A lining of triangular foam blocks would make for an interesting pool. It might work, but practicality (installation, cleaning etc.) would likely rule it out

meling|1 year ago

There was a pretty strong world record tonight in the men’s 100 m freestyle of 46.40. Actually more than a second faster than the second place and beating the previous wr by 0.4 seconds.

Strongbad536|1 year ago

https://www.nytimes.com/2024/04/20/world/asia/chinese-swimme...

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...

trashface|1 year ago

I haven't been watching but I presume its a 50m pool. So the 100M would just have one turn, and so the swimmers would only be going through the "wall of chop" they generate once. In other words I'd expect shorter distance events to be less affected by pool depth and whatever turbulence effect that has. Also free might be less affected vs something like breaststroke due to the angle of the body in the water. (Without good technique breaststroke is really draggy, even amateurs can notice)

haunter|1 year ago

>Could we have seen a sub-4 minute 400 IM by Marchand

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).

paganel|1 year ago

We’ve just got a huge WR in the 100 men sprint by Pan Zhanle (just 19 years of age, the future is all his), I have no sympathy for those crying after WRs, maybe they’re not that good to begin with.

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.

Paddywack|1 year ago

Years ago Johannesburg put in an Olympic bid. Because of the high altitude (1753m) they had issues affecting a number of disciplines when it came to records due to the thinner air...

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!

kolja005|1 year ago

You might find it interesting to know that for track cycling the penalty due to lower oxygen uptake is less than the advantage due to less air resistance. In other words track cyclists, at least in some of the longer disciplines, will go faster at higher altitudes despite there being less air to breathe.

Loughla|1 year ago

That's actually super cool. I ran cross country through high school and one year of college. I was fast. Very, very fast in Ohio.

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.

w_for_wumbo|1 year ago

As we're probably familiar, dealing with an under spec computer for doing your job is frustrating. Even marginal differences in speed can be perceivable and lead to a growing dissatisfaction over time. I imagine these competitors face the same sort of frustration when dealing with a 'slow' swimming pool like this.

BigParm|1 year ago

How is there not a standard regulation design

eddieroger|1 year ago

One can ask the same about baseball diamonds and how it's remotely fair to compare home run records when the distance needed for one is different (though with a minimum) 30 times over.

benob|1 year ago

Do they make anechoic swimming pools that would absorb waves like acoustic anechoic chambers?

MisterBastahrd|1 year ago

Well, if this is the case, then wouldn't a person who gets out to an early start have a tremendous advantage over the rest of the group since she'd be swimming largely without interference for the first length of the race while the trailers would have more turbulance? Also, I've never understood why there aren't more standards for Olympic tracks / pools / gear. For example, everyone should be required to train in and wear identical apparel when in a timed event like swimming so that nobody gets a technological advantage.

toast0|1 year ago

Identical apparel is a non-starter unless the athletes have identical body shapes, or we're abandoning (US) broadcasting rights to go Olympic Style.

Ylpertnodi|1 year ago

...would they all have to train the same, eat the same food, etc?

f_allwein|1 year ago

What I remember from the London Olympics is that records don’t fall from the sky, but venues can be planned/ optimised for them. Maybe this did not happen in Paris so much?

See this bit on the Velodrome in London: https://www.cyclingweekly.com/news/making-tracks-building-th...

morepork|1 year ago

In Paris they didn't want to build a white elephant swimming venue that will never get filled outside of the Olympics. So instead they converted an indoor stadium, the Paris La Défense Arena that is normally used for rugby and concerts.

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-...

Waterluvian|1 year ago

I hadn’t really considered the energy bouncing off and interfering swimmers. I was just imagining the plausibility given the limited science I know about water flow in a stream and cross sectionally how the furthest from edges (drag) will be fastest.

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?)

outside1234|1 year ago

Feel like we should probably be looking deeper into the lack of doping (be it Chinese or otherwise) as probably a bigger factor here.

matsemann|1 year ago

I'm fairly certain I read a thorough analysis linked on here a few years ago, about how there was a kind of draft/current in the pool used in the championship at the time. Some analysis determining that certain lanes were favorable or not.

But unable to locate it. Fairly certain it was Barcelona.

jeppebemad|1 year ago

As a counterpoint to the Parisian pool being slow, China beat the world record in 100m free 10 minutes ago.

elliottkember|1 year ago

That's not a counterpoint, it doesn't imply the pool is fast or even normal. In a faster pool his time could've been even lower.

rty32|1 year ago

Nitpick: for individual sports, probably better to refer to participants as "Pan Zhanle from China" than "China".

beloch|1 year ago

If this is a "slow" pool, then should we toss world records from "fast" pools? There are a lot of other events where factors affecting performance aren't completely controlled. Perhaps comparing records across different times and places is meaningless.

BobAliceInATree|1 year ago

No, in the same way that all Marathon records are set in only a few marathons which have very favorable conditions.

BoringTimesGang|1 year ago

>Perhaps comparing records across different times and places is meaningless.

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.

jjulius|1 year ago

This is entirely just my own opinion...

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.

glitcher|1 year ago

Setting a new world record is part of making history, and many are not broken at every Olympics. Consider this example - the men's 100m sprint world record was last broken by Usain Bolt 15 years ago! Now if you're not into that particular sport then maybe that doesn't mean much to you, fair enough. But wow, when someone comes along who is able to break that record it will really be something special.

jwrallie|1 year ago

I think it might be a motivation for competitors when they are already at the top, it is a way they can compare their performance with all past (and future) performances, and most importantly, with their own performance in other competitions.

XorNot|1 year ago

The Olympic committee mandates that new facilities get built for every Olympics, which is partly why the games are so damn expensive everytime.

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?

dagw|1 year ago

I guess I just don't understand the constant quest to set better and better records.

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.

renewiltord|1 year ago

It's amusing that the day after this was published a monstrous world record beat occurred in the 100 m freestyle.

drdebug|1 year ago

According to airparif.fr air quality is currently degraded in Paris, could air pollution be the culprit ?

philip1209|1 year ago

It’s also not ideal to try setting a high jump record right after the Olympics in Mexico City. So what.

gwbas1c|1 year ago

Honestly, my first reaction was "oh, they just stopped doping."

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.

EternalFury|1 year ago

World records don’t matter in the Olympics. Medals go to those who show up and prevail.

knodi123|1 year ago

World records matter on their own, as long as the measurement is trustworthy. The way we know this matters at the Olympics, is that world records are being tracked and discussed at the Olympics.

But you're right, they don't affect medals.

Flop7331|1 year ago

Indeed. I also don't find fractional seconds very exciting. I call a difference of .02 seconds a tie.

cl0ckt0wer|1 year ago

Could the percentage of deuterium in the water be affecting the speed too?

djtango|1 year ago

Why would we expect that to vary by any appreciable level?

MichaelBurjack|1 year ago

In addition to physical issues raised (7ft depth, configuration of sides), I wonder if there might be any other reasons that aren't mentioned at all in the article…

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)_/¯

khuey|1 year ago

That's not a very satisfying explanation because everyone seems to be slow and it's pretty unlikely that everyone has COVID.

outside1234|1 year ago

Let's also not forget doping. Chinese swimmers noticeably slower this year than last olympics in particular. Wonder why that is?

raspasov|1 year ago

Has anything in the drug testing changed that can affect swimmers?

callalex|1 year ago

Russian imports/exports are much more restricted now than 4 years ago.

suyash|1 year ago

Chinese swimmer just broke the record, this article is nonsense.

tonymet|1 year ago

a good tech talk about the venue & technology and it's impact on olympic scores. tl;dr the surfaces and shoes likely account for 95% of the record breaking

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.

tokai|1 year ago

[deleted]

jlarcombe|1 year ago

Finally an explanation for my hopelessness at childhood swimming lessons. It was a slow pool!

rurban|1 year ago

Of course it's slower. CFD simulations would also prove that.

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.

xanderlewis|1 year ago

So you’re claiming the American, British, Australian, Irish, French and Chinese swimmers are all on drugs? And that everyone apart from you is unaware of that fact?

Right.