Myrtha Says The Mystery Of Fast-Lane/Slow-Lane Splits ‘Not Down To Circulation’

Was one lane favourable to another at the Palau San Jordi? [Photo: Patrick Kraemer]

Myrtha Pools has denied that the circulation in the temporary facility installed at the Palau San Jordi for the 15th FINA World Championships could have mad one side of the pool “faster” than the other; evidence of a clear pattern in splits spills well beyond the sprint events

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Myrtha Pools has denied that the circulation in the temporary facility installed at the Palau San Jordi for the 15th FINA World Championships could have mad one side of the pool “faster” than the other; evidence of a clear pattern in splits spills well beyond the sprint events



It seems Myrtha Pools has fulfilled its duty of care. They have recognized the possibility of currents and made tests as precautionary measures to make sure their circulation system doesn’t cause a current in a pool. If they are capable of evidencing that the pool in Barcelona was precisely similar to the ones in Shanghai and Montreal, it is weird that there are no similar anomaly in results?

Cate Campbell was also asked via twitter about the issue and her savvy view on this is worth mentioning: “@mick_cowley @swimvortex interesting, but not relevant. What’s done is done and I am happy with silver :)”

Anyway, an academic conversation is highly welcomed and further investigations would be worthwhile.


I am far from being an expert in issues like these but I think one question concerning the evidence gathered from long-distance events needs to be addressed.

Why actual swimming itself appears to have no effect on the supposed current? Is the current so strong? The fact that swimmers go both directions nullify any effect on the ongoing currents in the upper layer of the water? Swimming just can’t have an effect on the currents in a pool? Or what?


CL, I think you made a mistake:

in the third paragraph, shouldn’t lane 5-8 be more consistently the fastest lanes?

Craig Lord

Yes, other way round in 50 free etc… now reads correctly… (as in original article I link too)… thanks for the spot and paying attention 🙂


Academia is weighing in

“Nevertheless, given that the outcomes of this competition include World record performances and there may be important monetary consequences to the athletes, coaches and teams, further consideration of this problem
is warranted. “


How do we know that the video from myrtha was filmed under exactly the same conditions as when racing took place?


Are comments on here censored Craig? i just left one and it’s been taken off. Or does Myrtha advertise on this site?


Ok, so we have this Myrtha pool demostration video…
But I don’t think that the circulation system is turned on there. If it is turned on, than how effective is that system? because as you can see there are no current at all(only which was caused by the ink injector).


Plus it’s not the same pool!


Is there anyway you can publish the video with the bottle tests of the actual competition pool from day 3 and 6? And does the video prove that the circulation actually was in competition mode?


I haven’t looked at all of the studies in much detail yet, but I hope that some analysis on variability is being done, as just looking at former World Championships’ split distributions (like in that IU paper) is not a large enough statistical sample to understand the limits of potential trends of split variability.

I will also say in my experience some pools I have spent significant amount of time in can appear to have zero current while no one is in them, yet end up creating a current once swimmers are in. I suspect this is because of the circle-swimming effect. I guess that some pool’s construction lends to easier current creation from such activity. It would be interesting to see results of an analysis as to how much circle swimming was done during events. I have a recollection of the women’s 1500 having some of the swimmers circle swimming within their lanes, but that is certainly no scientific analysis.

A current derived from swimmers circle swimming counter-clockwise, as is the norm for most, would cause lanes 1&2 to be faster during the odd splits of the 1500 and lanes 7&8 to be faster on the even splits, as was the case.

One final note: I once swam a meet, and it was even a fairly high level meet, where it was so obvious that lanes 7 & 8 were dealing with a massive current that we are talking seconds different between odd and even 50s splits. But, interesting to note, that the opposite effect was not happening in lanes 1 & 2. My guess is that the effect was dampened as would be expected if there was a localized effect (like by a pool circulation malfunction), so my guess is that whatever was going on at WCs was not due to one or two faulty valves in the circulation system as then we wouldn’t see such a symmetrical pattern.

Craig Lord

Interesting observations … though at major meets, very little ‘circle’ swimming goes on in races, of course… most are swimming fairly straight up and down.

Craig Lord

1. I can ask… and 2, No… it is taken on their word/trust.

Craig Lord

No Matthew… no comment of yours was taken off/Myrtha does not advertise with us (and neither do you)… comments must be approved… and I’ve been in a forest climbing trees with our boys all day… I just approved all your comments… like I said, no-one has taken any of your comments off. I reserve the right to remove libel, lies and obvious personal abuse.

Craig Lord

We don’t… we take their word… it is up to federations to pose the same questions as I have raised if they feel the answers given raise more questions. Nothing will happen on this unless swimmers/coaches/federations ask, in the spirit of knowing as much as it takes to avoid anything like this happening again, if indeed there is external influence, as the figures point too.


There is no motivation for FINA to find anything wrong with the Myrtha Pool. Myrtha pays a very large sum of money to FINA annually and in return, FINA is contractually obligated to only promote their pool system. USA Swimming has a similar contractual relationship. If you want to see the true effect of the Myrtha circulation system, check out their video exclaiming the benefits of the referenced strahlenturbulenz inlet fitting.

Craig Lord

Those kind of relationships exist throughout the sport (and many other sports and businesses)… and to a large extent that is transparent and unproblematic … if and where there are issues, however, effective change remains in the hands of some key protagonists who might have something to say about issues (doping, suits, pool circulation etc etc): it is up to swimmers, coaches, teams etc, to speak out if they unhappy…or at the very least make representations to federations domestic and international… and if they feel unable to do that, then they must live with the environment that they are prepared to tolerate.

Kevin McNally


As an ex swimmer and pro statistican you’ve got my interest.

If the trends in events like the 800m are as clear cut as you describe then a comparison of splits from these worlds and the previous few will be interesting. By using trends from previous worlds even data from the 200s where the patterns are not as obvious might be revealing. The data from seeded heats might be useful too.

It looks like xml files of all results are available from omega timing. Could take a while to dowload, parse and analyse it properly but I’ll have a look.

Craig Lord

Great – and thanks. if you can’y find anything, let me know.

Stephen Fritzdorf

Hello from Denmark,

(1) Is it the swimmer, or the stream?

We should be careful not to rule out the possibility that for the longer distances, the fast-slow (or slow-fast) pattern is due to something that the swimmers are doing, rather than something in the pool.

Take your comparison of Friis and Ledecky in the 1500m free final, for example. We would expect zero (or close to zero) current in these lanes – lanes 4 and 5. Yet, as you say, Friis shows the pattern. Lotte breathes to the left, and Katie breathes to the right, which means on the outgoing lap, when Lotte swims her faster laps, the two swimmers are looking at each other. Conversely, Lotte is slower when looking away from Katie. This could provide a good explanation for why Lotte shows this pattern – and therefore we could conclude that Lotte’s pattern is due to the swimmer, and not the streaming.

This could also explain the pattern we see for Pal Joensen in the men’s 1500m – he swam in lanes 8 and 2, and for the laps where he looked into the pool – that is, towards his competitors – he swims a slow lap. Maybe his competitors distract him. You could also hypothesise that he swims a slow lap when the current is against him. It is difficult to know which of these hypotheses is correct.

We could look to Shanghai. Here, in 3 of his 4 races over 800 and 1500, Pal also showed a pattern consistent with either streaming or “distraction”. But there is no talk of streaming in Shanghai, so we could conclude that Pal’s pattern in Barcelona, like Lotte’s, is not due to a stream. Instead, it is due to something that the swimmer is doing himself.

However – this is just a sample of 2 swimmers.

More importantly, this does not explain the extreme pattern seen in the 50m races, for which breathing side is not a valid hypothesis.

(2) Myrtha’s response

It is great that they have responded – but without making their video and measurements public, they will continue to remain under suspicion. I hope that these measurements were made immediately before or immediately after a competition session.

Their analysis of the 21 races is also flawed. Firstly, why only 21 events, and not all 40? Why not every single race of the championships? Their reputation is at stake, and if they think they are innocent, then it would pay them to take the extra time to do the full analysis.

And anyway, the argument against them is that there was an advantage/disadvantage *only in the 50m events* – so it makes no sense to analyse which lane won the longer distances.

If we look at the longer events, then if we can say anything about advantage and disadvantage, it would be that the outside lanes had a disadvantage compared to the middle lanes. This is because the energy lost swimming *against* the stream is not made up for by the energy gain swimming *with* the stream. Their analysis of the 21 races shows that no race was won from lane 1,7 or 8 – which in fact *supports* the notion that the outside lanes were at a disadvantage due to a stream.

Finally, Myrtha and FINA can’t get away with saying “we can see that there are data evidencing a problem, but it wasn’t a stream” without also investigating further where this anomaly comes from. Maybe it was lighting, positioning of the scoreboard, volume or positioning of the start signal (was it louder in lane 8?), or something else. If they can not suggest another explanation, then no matter how unlikely it might be that streaming was responsible, if it is the *only* possible explanation, that it *must be* the explanation.

They also need to tell us how they propose to avoid this problem in the future.

(Damn, this was a long comment. It would be OK with me if you published this instead as a “blog” post)

All the best, and see you Europeans in Herning!

Stephen Fritzdorf.


Thanks for the explanation Craig. My comment hadn’t appeared and I wondered why. It is now there. I am not a statistical expert, but what I remember from A-level stats it seems to me things were slightly odd in Barcelona, which as importantly as some people not winning medals that perhaps may have done, it also affected my betting performances on the 50s. I doubt I will get my stakes back however! On a serious note, is it not worth checking the last 4 or 5 Olympic 50m results also?

Craig Lord

Hi Stephen,
Thanks for the long and considered thoughts on this. It is not an easy subject and there have been oddities on splits on many occasions. You make good points on Myrtha but I should note that the 21 races at random is my selection: I didn’t look at all 40 because I didn’t have the time to do so before posting… it was just an example of how the picture can be made to look one way or the other when stats are being poured over…

Herning here we come 🙂

Craig Lord

Yes, I agree… certainly looks clearly like there was external influence… yes, too, on the historical checks… always revealing… I have no time to do that over next 2 weeks but will get to it if someone hasn’t done it in the meantime.

Stephen Fritzdorf

Hi Craig,

Sorry – because of the indenting, I thought it was Myrtha that did the 21 race analysis.

But indeed, it should be them, and/or FINA that do this kind of analysis, rather than leaving it to the swimming community.


Hi all, some fascinating analysis and comments above. I’m coming to this late, sorry, but here’s another possible angle…

I notice this year that the official WC website has published even more detailed splits than usual – 15m, 25m, 35m splits (and more!) to 1/100th for each swimmer on the 50m events, for instance – DDias posted it on an earlier thread, and it’s all there (see Series 1, here, for instance):

This may be worth examining in further depth. If there’s a circular current, I guess you’d expect the effect to be strongest in the middle third of the pool, and weakest towards the walls as the current ‘cuts the corners’ (I’m just considering the outside lanes here, i.e., 1&2 v 7&8, not the central lanes where the current would be more lateral). So, for instance, in the 50m events, if there are two swimmers on opposite sides of the pool clocking identical times, you’d expect the lead to switch ever so slightly as they enter and exit the middle 20m section of the pool (i.e., 15m-35m). I’m sure a curvilinear statistical technique would identify some such effect with a large sample size (if, indeed, there is a current). For instance, a quadratic regression analysis predicting speed from distance-from-start, controlling for the typical slight deceleration you’d expect over a 50m, with lane (1&2 v 7&8) as a potential moderator variable, may throw something up? This might eliminate most of the swimmer-level variables that others have mentioned (side breathing etc) and provide a more direct test of a potential circular current effect? Statisticians, would this make sense (I only dabble, sorry!)?

PS: It’s looking like another footnote may be needed in the record books, though, unfortunate timing for the sport…


Gosh to me FINA and Myrtha pools reaction clearly shows something is dodgy !! Why on Earth would you not try to solve the issue ??? there clearly is an issue ! They even acknowledge it saying the time patterns are odd.

And if not a current then what ??? the breathing explanation could potentially work for longer distances but it should also be seen in former championship then and it doesn’t work for the 50’s …

I really hope they come up with ideas and explanations, at least plausible ones instead of just trying to stop the issue from spreading by ignoring it !

And I’m a bit disapointed in the swimmers (like cate campbell whom I like but she had a bad reaction to this) !! they should be more concerned !! Nobody wants to rewrite the medals, what is done IS done but that doesn’t mean you can’t try to find an explanation to solve the problem so that it doesn’t arise at future championship …

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