Daiya Seto Chasing Michael Phelps’s 400 IM WR: An Analysis

Earlier this month, Japanese swimmer Daiya Seto indicated his goal of breaking Michael Phelps world record in the 400 IM at this summer’s Tokyo Olympics. Phelps’s record of 4:03.84 was set at the 2008 Beijing Olympics. Approaching 13 years since that swim, it is the oldest men’s individual swimming record.

Seto, like Phelps, is a great all-around swimmer. His 1:52.53 in the 200 butterfly makes him the third fastest person of all time in the event. Two years ago he put a 59.79 in the 100 breaststroke. In 2016 he swam 1:59.50 in the 200 backstroke. And while he’s not known as a freestyle specialist, his best time of 1:47.71 was back in 2015. Seto definitely has the pedigree and strength in the individual strokes to make a run at the record. 

In light of his stated goals, I decided to take a look to see what it would actually take for Seto to break this record. We don’t want to just look at Phelps’s splits and say that Seto has to be faster than that. No, we want to take a look at how Seto swims his races and use that as a base for the splits he needs to target.

As a refresher, Phelps’s world record splits were the following:

Butterfly Backstroke Breaststroke Freestyle Total
54.92 1:01.57 1:10.56 56.79 4:03.84

Seto’s best time of 4:06.09 was swum in January 2020 and ranks him as the fifth fastest swimmer all-time in the event. His splits of that swim break-down as follows:

Butterfly Backstroke Breaststroke Freestyle Total
54.22 1:03.46 1:09.83 58.58 4:06.09

A quick comparison shows us that Seto’s splits on the fly and breaststroke were actually faster than Phelps’s WR splits. The breaststroke split isn’t surprising as that was Phelps’s slowest stroke relative to his other four. What is surprising is that Seto’s fly split is faster than Phelps considering at one point Phelps was the WR holder in both the 100 and 200 fly. 

Rather than just look at Phelps’s raw splits from his WR and say “that’s where Seto needs to be”, we can dig a bit more into the splits. We can take each stroke and look at it as a percentage of the overall time. For example, using Phelps’s fly split, 54.92 seconds/243.84 seconds = 22.52%. 

Butterfly Backstroke Breaststroke Freestyle
Split 54.92 1:01.57 1:10.56 56.79
Percentage 22.52 25.25 28.94 23.29

We can do the same thing with Seto’s 4:06 from last year:

Butterfly Backstroke Breaststroke Freestyle
Split 54.22 1:03.46 1:09.83 58.58
Percentage 22.03 25.79 28.38 23.80

We can also do the same for other swims from Seto, particularly those within the past two years:

Meet Time Butterfly Backstroke Breaststroke Freestyle
Sette Colli 2019 4:07.95 55.92

22.55%

1:03.15

25.47%

1:10.00

28.23%

58.88

23.75%

Worlds 2019 4:08.95 55.73

22.39%

1:03.09

25.34%

1:10.07

28.15%

1:00.06

24.13%

Japan Trials

2021

4:09.02 55.47

22.28%

1:04.08

25.73%

1:10.36

28.25%

59.89

24.05%

We can confirm the trend where Seto is regularly faster on fly and breast than Phelps but Phelps is faster on back and free. With Phelps’s freestyle split being significantly faster than Seto’s, he will need to be well ahead of WR pace after the breaststroke.

Using the races and splits percentages, we can calculate the splits Seto would need based on the four races above:

Time Basis Butterfly Backstroke Breaststroke Freestyle Total
4:06.09 53.72 1:02.88 1:09.19 58.04 4:03.83
4:07.95 54.99 1:02.10 1:08.84 57.90 4:03.83
4:08.95 54.58 1:01.79 1:08.63 58.82 4:03.82
4:09.02 54.31 1:02.74 1:08.89 57.88 4:03.82

The numbers above show how truly impressive Phelps’s record is. There is a reason that the record has lasted almost 13 years — a swimmer needs to have a great combination of speed and endurance in all four strokes. Will Seto break Phelps’s last standing individual record? It will take a lot of work but at the Olympics in his home country, we’re saying there’s a chance.

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2Fat4Speed
5 months ago

My analysis is much shorter: no way he is breaking that at the olympics. Am I supposed to wager eating a piece of swim gear at this point? Still learning how things work around here.

Khachaturian
Reply to  2Fat4Speed
5 months ago

Let’s pray to Dean Farris for answers to whether it is truly possible.

USA 4x100 Medley Gold Medel 2021
Reply to  Khachaturian
5 months ago

Dean Farris goes 3:59 in his sleep

BKP
Reply to  2Fat4Speed
5 months ago

You’re a natural! I will eat my Finis snorkel if he even gets within a second of Phelp’s time!

Penguin
Reply to  BKP
5 months ago

Copied. Bookmarked. Screenshotted. Burned into my memory.

The unoriginal Tim
5 months ago

Looks like Seto needs to improve his backstroke to really challenge the record?

Riccardo
Reply to  The unoriginal Tim
5 months ago

I feel like he’s not a good enough freestyler. The 58.58 was kind of a unicorn split for him. If you look at most of his 400 IMs on the international stage he closes in right around 1:00, a few over a few under.

There's no doubt that he's tightening up
Reply to  Riccardo
5 months ago

Ye Shiwen closed in 58.68 in 2012 lol

Anonymoose

good name you have sir

ACC
5 months ago

Interesting that he’s faster than Phelps was in the short-axis strokes but slower in the long-axis. Given their height differential of 7 inches I can’t say it’s entirely surprising.

Billy mays
5 months ago

Opening in 53.7 would be kinda nuts

Unknown Swimmer
Reply to  Billy mays
5 months ago

Phelps coming home in 56 also seems kinda nuts…all of these splits seem kinda nuts!

Human Ambition
Reply to  Unknown Swimmer
5 months ago

All of them!

Dudeman
Reply to  Unknown Swimmer
5 months ago

No way all the splits in a nuts world record are also nuts!

Swimmer2
5 months ago

In the new peacock phelps series, phelps says that looking back on the 400 im, sub 4 min was possible. Mind blowing

Khachaturian
Reply to  Swimmer2
5 months ago

W-what?

Svird
Reply to  Swimmer2
5 months ago

Woulda coulda shoulda

BKP
Reply to  Svird
5 months ago

If “ifs” and “buts” were candy and nuts…

Dudeman
Reply to  BKP
5 months ago

we’d all have a merry christmas

frug
Reply to  BKP
5 months ago

then everyday would be Erntedankfest!

Sqimgod
Reply to  Swimmer2
5 months ago

The breast for phelps was very weak in 2008. Improve that with slight improvements in other strokes and sub 4:00 is definitely possible

TINY HANDS
Reply to  Sqimgod
5 months ago

lol. phelps had the fastest breaststroke split in the field.

Kitajima Fan
Reply to  Swimmer2
5 months ago

Doubt

Swimmer2
Reply to  Swimmer2
5 months ago

Link to phelps og goal sheet: https://m.imgur.com/a/50ZOj
Spicy one in there: 3:39 400 free

Khachaturian
5 months ago

There are a handful of 2008-2009 world records that have a better chance of being broken instead of this event.

I hope Daiya Seto will break it
5 months ago

You should also mention, that it was set during the supersuit era.

Phelps was wearing the full leg skin, which helped him in the last 100 when he was tired.

That’s why Ryan Lochte’s 4.05.1 in London is very impressive, with a very long glide at the end of the race.

Grant Drukker
Reply to  I hope Daiya Seto will break it
5 months ago

Phelps swam a 4:06 flat in an FS2 jammer at the 2007 worlds where the 400im in the last event. I would think if he swam the 400im at the beginning of the meet he might’ve been right around 404. I don’t think the suit helped that much.

Mr Piano
Reply to  Grant Drukker
5 months ago

Good point. Lochte swam the 400 IM at 2011 worlds as his last event, he was 4:07.1, a second slower than Phelps was in 07

Lochte's 4.05 is mindblowing
Reply to  Grant Drukker
5 months ago

No, it’s just an assumption.

In 2008, it was the first event and it was supersuited and he went 4.03 high.

So the 4.06 is his best time in textile.

Mr Piano
Reply to  Lochte's 4.05 is mindblowing
5 months ago

Yes but he swam that as his 16th race of a very long meet, Phelps said he was dead tired during that race. And again, the suit he was wearing for that 4:06 was terrible by today’s standards.

Penguin
Reply to  Grant Drukker
5 months ago

Phelps 4:06 flat in FS2 = INCREDIBLE. COULD’VE BROKEN 4:00
Seto 4:06 flat in textile = ehhh he won’t get anywhere near 4:03 high

sven
Reply to  Grant Drukker
5 months ago

Those legskins were ridiculous. I felt like I could kick forever and not get tired. The legs absolutely helped a ton at the end of that race.

While we’re subjectively extrapolating results, though: I see your “he was tired so I think he would’ve been 404” and raise you “give Lochte LZR legs and I think he would’ve been sub-4:03.8.”

Last edited 5 months ago by sven
He said what?
5 months ago

Phelps had said that he needed to conserve from each race. If the 400 IM had been his only race, it would have been faster. How much faster? Don’t know. But he and Bowman both said it would have been raced more aggressively. Sub-4? Doubt it. Probably 4:02 or 4:01 but not sub-4

Swimmer2
Reply to  He said what?
5 months ago

I think had he trained for 400 im exclusively we would have had a crazy fast last 100 and probably a faster fly

Mr Piano
Reply to  He said what?
5 months ago

Makes sense, since that was only the 2nd of 17 swims. It’s kinda scary to think how good Phelps was in Beijing. He probably would have won the backstrokes too if he tried them.