Edit: maybe I’m not making myself clear:
I don’t doubt they are slower in the current pool than they were before. But I doubt they can accurately tell you that it’s because of the pool depth. There are other factors that could also influence the performance, and I’m not sure the swimmers can accurately determine which factor is the primary difference.
Australia, as one example, took swimming (and a few other sports) next level with a plethora of studies on all things performance related.
Any theorectical results from, say, CFD, would be parallel tested in real conditions and|or modelled in a scale pool (like a wind tunnel for water).
Those who competed at that level in sport in the larger countries almost certainly heard first hand bleeding edge results from cutting edge sport science.
My niece was not fast enough to be invited to the trials this year (missed by .03 seconds in her favorite event), but her time would have put her into the second heat in Paris. She's the ~150th fastest person in the USA, but would have come in ~25th place in the Olympics. It's the same situation in China, Australia, Canada, UK, etc.
Most countries only have a small handful of elite swimmers. The power nations can each provide 20-50 swimmers fast enough to get to the semi-finals in every single event. They're analyzing and optimizing for everything. This is why most of the elite swimmers not from these countries go and train in the powerhouse countries. And why the powerhouse countries don't care that they do. I'd bet that 90% of all the medal winners this year do their training in 5 countries.
Venue shopping might feel ick, but I don't think it's too bad if you're in the competitive envelope, as opposed to what's perhaps a tradition of less then competitive entrants in some events.
This is a weird standard. Out of 200 people doing anything, how many do you expect to set a personal record? Say you drive to the grocery store. Are you setting a time record for the trip more than 0.5% of the time?
Tbh I don't do much of that sort of thing for my grocery store trips at all.
The only way this could actually happen is if they intentionally sandbag their performance starting several years in advance -- and continuing indefinitely -- which would prevent them from qualifying for the Olympics in the first place. It's not a possibility.
Every Olympic athlete, with the possible exception of the Jamaican bobsled team, has been equally motivated at dozens or hundreds of officially-measured points in the recent past. Why do we expect personal records at the Olympics?
Edit: for example, compare salt and fresh water properties here: https://ittc.info/media/4048/75-02-01-03.pdf#page2
At 25 degrees, fresh water has a Viscosity of 0.000890 Pa⋅s and sea water has 0.000959 Pa⋅s. That’s an 8% difference in viscosity by adding NaCl to water. Is it that strange that there could be a 1% difference in viscosity for example by having different additives in the pool water?
I have these data points:
1) The pool is shallower than normal in this Olympic
2) The pool seems to be slower this Olympic
3) swimmers seem to think it’s because the shallower depth
4) people responsible for building the pool say the effect of depth is negligible
5) there are other things that can be different about the pool except depth because the pools aren’t strictly standardized in their properties
My only claim was that point 3 doesn’t tell me a lot because I find it very plausible that you can’t really detect the reason for the slowness just from swimming. I don’t have positive proof of that though.
It will get you a fair amount of the way there, but at some point you have to go and actually do the thing to validate your model.
The how can be argued
Would a large, blind empirical study be more trustworthy?
I am aware the above may be proportionality bias, but at the same time there is some kind of "reverse proportionality bias" at play here: the assumption that since the effect of a shallow pool are too small, they can't significantly affect the athletes. Human behaviours are very nonlinear, and even very small sensory inputs may very well "throw off" an experienced swimmer.
Like this reminds me of Beckham/Ronaldo doing free kicks. They had a deep understanding of controlling the ball well beyond what scientists knew how to measure and explain what they're doing.
The gold standard would be an empirical randomized controlled trial to compare two pools, assuming you could hide “which pool” from the participants.
As a swimmer, I remember everyone lauding over how cool the Beijing Water Cube was because it was a uniform 3m deep which made it excellent for racing in - this was 16 years ago in 2008.
Since the Paris Olympics were accepted the regulation recommendation for pool depth has been revised from 2m to 2.5m
So clearly people vested in the sport and live and breathe it have seen enough evidence (including the sleepy regulatory board) to advise deeper pools.
If you wanted another possible explanation for how depth may affect the swim - a crucial part of the swim is the dive and also the underwater kicking. Both of those may have separate dynamics to swimming on the surface.
