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Comment by _heimdall | Hacker News Reader

You don't necessarily need to do an in depth study of the pool when every Olympic swimmer in it fails to meet their own personal records. A study may be useful to understand why depth still matters beyond the 2m point, but a study isn't needed to show that swimmer performance is impacted.

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> You don't necessarily need to do an in depth study of the pool when every Olympic swimmer in it fails to meet their own personal records.

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?

These athletes plan their whole training and fitness regime for years so that they are at their absolute best at this particular day.

Tbh I don't do much of that sort of thing for my grocery store trips at all.

> These athletes plan their whole training and fitness regime for years so that they are at their absolute best at this particular day.

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.

Or it could happen that the training, diet and injury-avoidance regime for long term success is different from that for short term optimisation. As it is for many, many sports.

All right. The 2020 Olympics were canceled and a replacement event was held in 2021. According to this theory, there should have been a shocking drop in personal records set at the 2021 event. Was there?

No, that's according to a theory to which you've added a strange caveat that a year is insufficient advance knowledge to know how to peak, despite annual world championships - and them often being the reason a competitor knows they're going to the Olympics at all.

Allow me to be equally facetious: according to your theory, Lamine Yamal is currently doing the same training he'd be doing deep into a season. Which is impressive, because his Instagram page currently suggests he's on holiday in another country.

> No, that's according to a theory to which you've added a strange caveat that a year is insufficient

I'm not the one who specified multiple years.

You're making my point. Scarblac claimed people set personal records at the Olympics because they plan to set that record years in advance, adopting a personal regimen with the goal that their performance before the Olympics won't be as good as their performance during the Olympics, because that would mean an embarrassing failure to set a personal record.

You're saying that (1) that can't happen, because people don't know they're going to be at the Olympics years in advance; and (2) the personal records result from short-term efforts, not long-term efforts.

And you're saying that, in particular, people don't know they'll be going to the Olympics at all until they see their own results from a recent high-stakes competition in the same event.

So... why aren't they devoting the same short-term efforts towards their performance in the Olympic qualifiers, or towards other annual competitions for their sport?

People who are capable of setting world records are capable of beating the competition, to allow them to qualify for a more prestigious competition, without 100% effort.

Those are people who do know that they're winning the qualifier before it happens.

Sure, there could be multiple peaks. That doesnt really subtract from my argument that this isn't a day like any other for these athletes, form and fitness wise.

The motivation of a commute is not comparable to the motivation of a swimmer in 4th place of a medal event, etc.

So what? Is the motivation of a swimmer in 2nd place in a non-Olympic event comparable? Is the motivation of a swimmer who wants to work toward the Olympics comparable? Is the motivation of a swimmer trying out for the Olympics comparable?

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?

Well, for one thing, world records don't get ratified in a local pool.

And athletes are competent enough to achieve the time needed for qualification without going all-out. Look at the finish times of the heats. Pan Zhanle was over a second slower.

Or maybe there’s something else going on? There are a lot of other variables in a pool except depth, no? Maybe water tension, density, viscosity? Someone else mentioned the walls of the pool also influencing the wave properties in the pool. Just noticing the pool being more shallow and people swimming slower doesn’t mean that’s the reason.

Explain to us how water "tension", density, and viscosity are variables that would change? It's just water, and temperature is set at ~25 C. The shape of the pool and gutter setup are the only major factors at play, assuming the filtration system isn't causing major currents.

It’s not demineralized water though, have you ever added a tiny bit of soap to water and it immediately reduced the surface tension? I’m not saying there’s soap in the water in France obviously, but there’s a lot of other additives that could theoretically affect water properties even with a fixed temperature.

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?

Yeah but it's not just "water", as in plain H2O. All water has different things dissolved or mixed into it. In pools there's commonly several chemicals added to that water: to correct the pH for humans, to sanitize, control corrosion of metal, avoid calcium deposits on other surfaces, etc. It's entirely possible that the additives in the water could be way off of normal and somehow affect things like viscosity or surface tension.

No, it isn't.

Rereading your last comment and I think I just misunderstood it, sorry! I first read it as saying a study would be needed to know if something about the pool was anything them down, but you were still specifically talking about whether the depth is the issue.

Yes, I think a lot of people misunderstood the point, I’m ESL so maybe i didn’t write it up properly. I was just talking about the effect of pool depth, not doubting that something is different this time.

For what it's worth, my misunderstanding wasn't actually due to your message at all. I simply focused on the first sentance and lost the next sentance that tied it back to pool depth.

Your English is actually very, very good! I wouldn't have guessed that it is a second language for you.

So to be clear, you have no idea, you just insist on discounting the experiences of the swimmers because you can?

I misread the earlier posts here when I started dow this comment path, but I actually agree with them. There seems great evidence, including the swimmers', experience to say that something about the pool slows them down. It seems less clear that the depth is the issue, it could be something else or a combination of factors related to the pool that cause it.

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