The performance and physics of the fish kick | Hacker News Reader

The performance and physics of the fish kick

nautil.us

92 pointsdnetesn56 comments

I'd be remiss if I didn't point out that this isn't even remotely new. Anyone who's watched the olympics knows they do the first 25-40m underwater for the butterfly or IM.

Hell, 20 years ago when I was on swim team I did the first 20m underwater. Not sure why this is "new."

Edit: yes I read the article. Doing it on your side is also not new. Has nobody ever watched the olympics?

If you read the article there is more to it than just staying under water. The stroke is basically like the dolphin kick on your side. They mention that it may be more efficient because you are able to pull in more water laterally than vertically due to not breaking the surface of the water, or having vortices hit the ground. It would be interesting to see if this could actually impact swimmers in other lanes.

Most racing pools are deep enough that you can do it vertically and not have to worry excessively about either the surface of the water or the pool bottom.

Plus, if you tried to do this in a race horizontally, you'd be fighting against the vortexes of your competitors, which would make the attempt even more rough and inefficient (for the leader as well).

So, you didn't read the article then? It's about the 'fish kick', which is like an underwater dolphin kick, but on your side.

The staying under water thing is according to the the article about 30-40 years old. That to me is extremely new. After all we've been swimming for thousands of years.

https://en.wikipedia.org/wiki/Pearl_hunting

Okay, you really want to misinterpret this, don't you.

Yes... until you take into account that this is only really useful for swim races, and is not really practical for 'survival' swimming.

Its a very difficult to learn swim technique that is really only useful when you are trying to maximize your speed very slightly over a very small distance to the extent you are willing to give up your ability to breath.

'Regular' swim strokes give you the ability to continue for large distances and to breath while you swim...

But people have been doing recreational running for thousands of years. Are you implying that competitive swimming is new?

As per the article there has been a 15m underwater limit off each wall in butterfly, freestyle, and backstroke since 1998. Though the article doesn't state it there was a 10m limit in backstroke 1988, that was relaxed to 15m in 1991. The rule change was spurred after David Berkoff and Daichi Suzuki[1] battled in the 100 backstroke in the 88 olympics going mostly underwater on the first length[2]. Though FINA said it was for safety concerns, it was more likely that they wanted the strokes to be preserved and not have swimming boil down to a breath holding contest.

[1] http://swimswam.com/david-berkoff-daichi-suzukis-underwater-... [2]https://www.youtube.com/watch?v=ztDlHwqD7pA

Did you ever see Denis Pankratov do his underwater? Back in the day he was truly unbelievable!! It's too bad there are limits on the underwater portion, the cameras they have on the pools now are really great at capturing the underwaters and I don't think much would be lost unless you're not able to watch it on screen. But on freestyle there are no limits on anything except pushing off the bottom, so if you wanted to chance it I wonder if someone could try and win the 50 fr with a fish kick?

In freestyle some part of the swimmer must still break the surface by the 15m mark. Otherwise, people would probably go farther for shorter distance events (50 and 100).

Yeah, that was my initial reaction as well. It looks like she flexes at her shoulders more than I'm used to seeing, but nothing groundbreaking.

We've known that a dolphin kick is faster than any of the strokes for a long while.

I haven't ever seen someone do it sideways, but I suppose that's probably because it's more difficult to keep going straight.

This was exactly my reaction after looking at the article. Mastering underwater dolphin kick has been critical to success at the national and international level since the late 1990s.

God I hate these titles. It's potentially faster than dolphin kicking within about a foot of the surface, or in very shallow water. That's all. If you're trying to swim fast, your underwater is going to be deeper and that last foot is about the transition anyways.

So why shouldn't this be faster than freestyle? We know that deeper than a foot, this should be the same as dolphin kicking. That's the current mode of underwater competition swimming, so we have a good comparison. If dolphin kicking is faster than swimming, we'd expect to see swimmers staying underwater until the rules say they have to surface. We see that in backstroke, so underwater swimming must be faster than backstroke. We see some butterfliers go to the limits too, but not all. For sprint freestyle, however, they surface pretty much immediately, so as you could have inferred from the clickbaity title I'm calling bullshit.

I know absolutely nothing about swimming, so forgive me if this sounds dumb, but I don't feel like current competitive trends is evidence against this new technique. It's very possible that top swimmers are at a local maxima.

New techniques being discovered and transforming the competitive scene has happened at least two times in other sports - high jump and long distance running.

https://en.wikipedia.org/wiki/Fosbury_Flop

https://en.wikipedia.org/wiki/Cliff_Young_(athlete)#The_Youn...

Good point, one more example from ski jumping: https://en.m.wikipedia.org/wiki/V-style

No need to leave swimming: Butterfly was invented as a way of going faster in Breaststroke:

https://en.wikipedia.org/wiki/Butterfly_stroke#History

The catch here is that in competitive swimming, as mentioned in the article, FINA said that you can not go past ~15m underwater from the start or turns. The reason was that it is faster. Since they block that from being too long then they effectively prevent changes to the strokes from taking advantage of that too much. So while it's faster, possibly, it's not really possible to be used.

Even so, nobody kicks to the full 15m in the 50 free (the shortest, fastest event in swimming).

Thanks for helping me understand. I wonder if the popularity of new techniques would put pressure to change the rules.

And the skate technique in cross-country skiing (https://www.skiinghistory.org/history/cross-country-skating-...)

> I don't feel like current competitive trends is evidence against this new technique.

Indeed it is not, because i've been Fish Kicking since the 1980s when i was a swimmer in college. It isn't anything new. If you watched swimming competitions earlier than the 1980s you'd see Fish Kicking swimmers in freestyle and backstroke competitions, too.

It isn't anything new.

And it isn't as effective as other strokes because humans need to breathe while they swim. Fish Kicking is done submerged.

This is not a new swimming stroke. It's Dolphin Kicking.

In swim team, after the dive, we were trained to dolphin kick until surfaced, then go into the stroke (freestyle or butterfly depending on the race).

Fosbury flop, mediocre example. High jump was a relatively new sport (~a century vs. humans swimming for 20,000 years) and his technique was only made possible by the then-recent addition of a very soft and raised landing pad. The Fosbury Flop wasn't really an option before that, when you tended to land on dirt 6 or 7 feet below the bar.[1]

Cliff Young, bad example. Young won because no one had ever done a race that long before (that was the first year) and the other competitors slept way too much. Once everyone else caught on the next year, Young never won the race again.[1] The "Young Shuffle" had little to do with it and is definitively not "transformative" or even used by any modern elite distance runners. In fact, the "Young Shuffle" is how anyone runs if forced to slow down to walking pace -- you can watch the "Young Shuffle" live anywhere you can find some elderly hobby joggers out for a cruise.[3]

[1] https://upload.wikimedia.org/wikipedia/commons/0/07/1912_Kon...

[2] http://www.theage.com.au/articles/2003/11/07/1068013394824.h...

[3] https://www.youtube.com/watch?v=2OD96zocXRU

Thanks for the feedback. I definitely didn't understand the context around why the Fosbury Flop became possible.

I don't mean that current trends are evidence against it. I mean the physics is against it being any different from dolphin kick anywhere but right at the surface. The rest of my argument was why dolphin kick isn't faster than freestyle.

Then the question is why don't they just stay within a foot of the surface? The problem is buoyancy. You have to be able to control your depth to keep from surfacing before you want to. It's hard to do that so close to the surface.

We changed the title to the subtitle (minus its own baity bit).

Thanks. You guys doing that is one of my favorite parts of HN :)

This isn't new. At all. And they even say so in the article - what a terrible title.

This has always been the fastest and best way to kick when underwater when appropriate for the stroke (In this case - anything but breaststroke, and ensuring you're not completely on your side if doing it during backstroke.) There's a reason why there are markers on the lanes for how far you can go underwater - otherwise swimmers would be underwater all the way until the next wall.

I was disappointed (particularly given the title) not to see a comparison against freestyle swim times. The other strokes are essentially handicapped events - they measure how fast you can go given certain specific restrictions on what you can do. In some cases, those restrictions didn't anticipate underwater swimming, so that loophole was exploited (particularly in back stroke and breast stroke, where the rules resulted in slower times than free and fly). But for freestyle, where there are (almost) no restrictions on the style of stroke, does this fish-style of underwater swimming provide any advantage? I am curious if anyone is aware of a comparison.

The advantage is that you aren't fighting against the surface tension of the water. The disadvantages are that you can't breathe, or use your arms.

In my (admittedly dated) experience, a good crawl stroke (what is usually used in freestyle events) will beat the underwater dolphin kick, because the arms create a remarkable amount of forward power.

I was disappointed too but then a comparison might not be fair. Most swimmers have had a lot of frontcrawl practice and it would take a lot of commitment to achieve the same level in this stroke

The woman in the photos is wearing swim fins, which makes an enormous difference.

Give a freestyle swimmer the same fins and (s)he'll blow the underwater swimmer away.

No, I wouldn't be convinced. There's a big difference between the two kicks and being underwater is a lot more efficient.

Here's a question: how do swim fins work?

I mean, it seems obvious, but when I start to think about the forces at play, and draw vectors, etc, things actually get less clear. Anyone have an intuitive but rigorous answer?

(My question reminds me of the "how do we suck in spaghetti" question, which once again seems kinda dumb but then is frustrating when you start to break it down. http://www.straightdope.com/columns/read/1260/how-does-one-s... )

In the first video, where she's winning the race against others doing butterfly, she's not wearing swim fins so far as I can tell.

As a swimmer, I was much faster underwater with fins than above water, up to a distance where I needed to breathe more than once a lap (~ 100 yards).

Looks as if somebody was watching too much tv in the 1970/80s.

https://en.wikipedia.org/wiki/Man_from_Atlantis

I wonder if the vortices from the fish kick would interfere with the swimming of the competitor the next lane over.

Yup, like birds (or planes) in formation fighting against the wingtip vortexes.

It's really hard to find and apples to apples comparison in practice. The fastest 50m swim on record is 20.91. The fastest underwater dolphin kick, different from the one in the article, is 23.10 [1]. These aren't super fair comparisons for many reasons but one major one is that the underwater has a slower start. Probably a better comparison is world record for 50m backstroke which is 24.04. I imagine if there were any olympic underwater race (be it fish or dolphin kick), it could probably get close to and possibly overtake the freestyle record, but it would probably take a few years.

[1]https://www.youtube.com/watch?v=4EFjQDgIfKM

Curious why actual dolphins didn't evolve to use it. I'd guess it's some combination of horizontal vs. vertical stroke only mattering in the top meter of depth, and issues besides raw swim efficiency.

One reason may be that cetaceans evolved from land mammals that had evolved spine-flexing in the vertical plane as part of a galloping gait.

I think this is it. They should change the blueprint of their body and rotate eyes and snorkel by 90°. A pretty major adjustment.

This also means we could teach something about swimming to dolphins :-)

> A pretty major adjustment.

True, although flounders manage a similar 90° rotation, including migrating one of their eyes to the opposite side of their head during their early life.

https://en.wikipedia.org/wiki/Flounder#Eye_migration

One other reason is that cetaceans need to come back to the surface for breathing and so their movements are more vertical axis based than horizontal vs. fishes. Horizontal tail propulsion allow a faster pitch control for swimming creatures than vertical + horizontal fins.

As far as I know, Dolphins cheerfully swim on their sides when they want to. The point is they don't break the surface except when they want/have to so it does them no good.

Here's a video of a dolphin swimming in shallow water:

http://m.youtube.com/watch?v=Wk0X9hbaTuU

Indeed. Maybe most of their hunting ability relies on their intelligence and not speed so they didn't need to develop past their current abilities. Or maybe it has to do with their need to breath. It certainly would be interesting to find out.

It's fascinating, and I've always wondered about the emergence of new strokes as we begin to understand bio- and fluid-mechanics better

That said, I can't see myself doing a 2.4km swim using this stroke :-/

I wonder to what extent certain strokes "sabotage" other racers, since the individual lanes are really just markings overlaid on the same body of water.

In summary swim like a tuna and not a dolphin by doing your underwater dolphin kick on the side.

I have to try this next time I'm in the pool. I already kick ass with butterfly, so I should be able to test this theory pretty well.

I upvoted you for being good a butterfly.

Edit: It's a hypothesis you muscle head.

I wish they had an underwater sprint in the olympics. It would be great to really test how fast people can go in water.

I've been using a similar dolphin kick when scuba diving just for playful fun in the water.

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