The Data Pool: Splits, Records and the Road Ahead for Vietnamese Swimming

In Paris, on the evening of August 4, 2026, Pan Zhanle touched the wall in the men's 100-metre freestyle final in 46.40 seconds. A world record. But what made me rewind the tape three times was not the final number. It was the splits. At the 50-metre mark, the Chinese swimmer was around 22.28 seconds, not leading. Over the next two lengths he swam as though someone had pulled the plug on the rest of the pool. Numbers do not lie, but they know how to hide something — that a sprinter's true strength is not peak speed, but the ability to hold speed while the arms fill with lactic acid.

I sat in Saigon at three in the morning, in front of an open spreadsheet. Reading numbers like these is my job. Sixteen years of watching sport, most of it devoted to the blue lane, taught me one thing: swimming is the most honest sport with data, and also the sport most deceived by data.

Swimming is a sport of distances. A 50-metre pool, eight lanes, ten swimmers, and a timing system accurate to one-hundredth of a second. No linesmen, no offside disputes, no room for interpretation. Only water, bodies, and the clock.

That purity makes swimming a paradise for the analyst. But it is also a trap. When everything is a number, people forget that behind every number is a body enduring pain, a mind fluctuating, and a historical context the clock cannot measure.

Vietnamese swimming enters this era with a paradox. We have a golden generation that has passed — Nguyen Thi Anh Vien, who once held a string of national and regional records and competed at three Olympics. We have a current generation still searching — Nguyen Huy Hoang, who once won an Asian Games medal in the distance events, and a group of young swimmers who have yet to make the leap. And we have a data system still in its infancy, where a complete split sheet is sometimes a luxury.

This article does not set out to recount a match. It sets out to read a pool. From Pan Zhanle's splits, to the records still hanging from the swimsuit era, to a larger question: is data helping Vietnamese swimming, or blinding it?

To answer that, I have to start with the smallest thing — one-hundredth of a second.

Splits: the confession of a swim

In football, I once wrote that PPDA is not a number; it is a confession. A low pressing metric does not say a team is lazy; it confesses that the team chooses to sit deep, cede territory, and wait for mistakes. Splits in swimming work the same way. They do not only show who swims fast. They confess what that swimmer believes in.

A swimmer who divides energy evenly across the first two and last two lengths believes in stability. A swimmer who bursts in the first 50 metres and collapses in the last 50 believes in early shock. A swimmer like Pan Zhanle, slow in the first half and explosive in the second, believes in the capacity to endure pain. Three beliefs, three ways of swimming, one 100-metre distance.

Based on my experience watching matches and major championships, I always open the split sheet before rewatching the tape. The human eye is easily fooled by the sight of a swimmer leading at 50 metres. Numbers are not. They tell me who is accelerating, who is holding, and who is dying quietly.

Take a simple example. In the men's 200-metre freestyle, a swimmer who clocks 1 minute 44 seconds can split it in countless ways. If he swims 50.5 in the first half and 53.5 in the second, he has lost three seconds in the final 100 metres alone. Three seconds, in a race where medals are decided by hundredths, is an eternity. But if he swims 51.8 then 52.2, he has distributed his energy almost perfectly.

The same total time. Two completely different stories.

That is why I never judge a swimmer by final time alone. I need to know where he paid the price. The first length is the length of technique and explosion. The second is the length of psychology. The third is the length of tactics. The fourth is the length of the heart.

Records and the swimsuit era: when a number carries a historical trace

There is a bigger trap than splits: comparing records across eras.

In 2026, at the world championships in Rome, a wave of world records fell amid polyurethane swimsuits — suits that helped swimmers float higher, reduced drag, and nearly turned the body into a fish. In 2026, the world swimming federation banned those suits. The textile era began.

Since then, every record set after 2026 carries a different value. They are not just times. They are times produced under fairer conditions.

When someone tells me a modern swimmer is slower than a 2026 record, I ask back: in which event, and in which month was that record set? If it is a pre-textile record, direct comparison is meaningless. You are comparing a runner on asphalt with a runner pushed by wind on a sliding track.

Katie Ledecky is the textbook example of textile-era value. She holds world records in the women's 400, 800 and 1500-metre freestyle — all set after 2026. Her nine Olympic gold medals, as of after Paris 2026, did not come from a suit. They came from a dominance so monotonous it becomes boring: swim the first length faster than everyone else, then hold that speed until the wall.

That monotony is the most frightening thing in data. A swimmer who explodes can be modelled. A swimmer who is steady cannot.

Olympic qualification: a race that begins before the race

In swimming, you do not only race the swimmer in the next lane. You race a time standard.

The Olympic selection system uses two levels: the A-cut and the B-cut. Hitting the A-cut means near-certain selection, provided the nation still has a quota. Hitting the B-cut means you wait — wait to see how many others hit the A-cut, wait to see how the national federation allocates places.

This creates a psychological paradox. A swimmer can be faster than someone who competes at the Olympics, yet stay home, simply because timing and conditions did not allow it.

For Vietnamese swimming, the equation is harsher. We do not have the depth to have several swimmers hit the A-cut in one event. Each Olympic place is usually a lone individual, carrying a nation's expectations.

Nguyen Huy Hoang once hit the Olympic standard in the distance events, and that is a technical achievement worth noting. But hitting the standard is only the doorway. In the pool, he faces swimmers raised in systems with hundreds of rivals at the same level at home.

That is a gap no split sheet can erase. But it can be measured. And measuring is the first step to closing it.

The map of world swimming: rulers who do not flinch

If you draw the map of world swimming on paper, you see a clear dominant tier: the United States, Australia, China, and recently France.

The United States has depth. It does not just have stars; it has a system. An American swimmer can finish fourth at the Olympic Trials — meaning no Olympics — and still be faster than the gold medallist of many other nations. That is a frightening surplus.

Australia has a tradition in freestyle and backstroke. Ariarne Titmus, Mollie O'Callaghan, Kaylee McKeown — names that appear steadily in major finals. Australians swim as though water were their natural environment.

China is producing a new generation. Pan Zhanle broke the men's 100-metre freestyle world record in Paris 2026 with 46.40. That is a technical statement, not a stroke of luck.

France has Leon Marchand, who made all of Paris 2026 hold its breath by winning four gold medals, including a world record in the 400-metre individual medley. Marchand is the product of a cross-border training system — he trained in the United States under a leading coach, then returned to compete for France.

Marchand's story opens a theme I want to reserve for the contrarian section at the end: the flow of talent. But before that, let us talk about something less discussed yet decisive — rules and anti-doping.

Rules and anti-doping: where trust is tested by a urine sample

Swimming is among the most scrutinised sports. Every record carries a silent question: is it clean?

That is not baseless suspicion. Swimming's history has dark stains that fans would rather forget. Doping cases have cast doubt over an entire period of the sport.

So when I read a new record, I check three things. First, whether the record is ratified by the international federation. Second, whether that swimmer is in a regular testing programme. Third, whether there is any abnormality in their competitive history.

This is where my ISTJ principle kicks in. I do not speculate. I verify.

One important point must be stressed: questioning the transparency of a record does not mean accusing an individual. Those are two entirely different things. An analyst has a duty to distinguish between grounded scepticism and unfounded defamation. When there is no evidence, I do not write. When there is evidence, I write with sources.

Vietnamese swimming, fortunately, has never been caught in a major international doping scandal. That is an asset. In a sport where trust is currency, cleanliness is capital.

Athlete careers: a barrier the clock cannot measure

There is a number that the split sheet never shows: age.

In women's swimming, there is a phenomenon called the puberty barrier. A young swimmer can break age-group records at 14 or 15, then suddenly stall as the body changes. The performance curves analysts draw — rising steadily, faster each year — suddenly break.

That is why I am extremely cautious when someone hails a teenage swimmer as a "future star". Youth data is highly deceptive. A fast 15-year-old may simply be exploiting a temporary physical advantage. The truly durable swimmer is the one who still improves after 18, when the body has stabilised.

In men's swimming, the story differs. Peaks usually come later, and performance curves stretch longer. A male swimmer can peak at 24, 25, even 27.

Nguyen Thi Anh Vien is a case worth studying. She appeared early, shone on the regional stage, and sustained her career across several major games. That is a psychological achievement, not only a technical one.

Because behind every performance curve is a question no spreadsheet can answer: does that swimmer still want to swim?

Vietnamese swimming: data and the gap

This is the part I want to spend the most time on, because it is my homeland.

Vietnamese swimming has three data problems. First, a lack of public splits. Second, a lack of longitudinal comparison. Third, a lack of an objective evaluation system to replace media sentiment.

When a Vietnamese swimmer competes at the SEA Games, the media usually reports only the final time and the placing. Splits are rarely given. That means fans cannot know what that swimmer won with, or lost with.

That summer in Saigon, I learned that data also needs watering. A dry spreadsheet, if uncared for, will die. It becomes a heap of numbers no one reads, no one understands, no one uses.

For Vietnamese swimming, "watering" the data begins with small things: recording splits, comparing across meets, and building an open database for young swimmers.

The SEA Games is an interesting arena to start. It is where Vietnamese swimming can genuinely compete with regional nations. A split-comparison table among Southeast Asia's leading swimmers would tell us what we lack — first-length power, the ability to hold speed, or turn technique.

But I must be honest. Vietnamese swimming also has limits that data cannot solve. Training conditions, the number of standard pools, nutrition, sports-medicine staffing. Those lie outside my spreadsheet.

A good analyst is one who knows their own limits. I can tell you a swimmer lost two seconds in the final length. I cannot tell you it was because of a vitamin D deficiency.

The contrarian angle: when the data tells a different story

Here, I want to argue against myself.

There is a popular belief in analyst circles: if you have enough data, you can predict everything. I do not believe it. Here is why.

Swimming has a feature many other sports lack: it takes place in an almost fully controlled environment. The same pool, the same water temperature, the same distance. That makes the data look very clean. But that very cleanliness deceives us.

It makes us forget that behind every number is a body we cannot control. A sleepless night. An unhealed shoulder injury. Family pressure. Those variables do not appear in the split sheet, yet they decide the split sheet.

So when I read an abnormal result, I do not rush to a conclusion about the swimmer. I ask: what other data is there?

Emotion is the most expensive thing in the transfer market — I once wrote that about football. It holds in swimming too. The public's belief in a swimmer is usually more expensive than that swimmer's actual value. And when that belief breaks, the collapse is not in the number but in the expectation.

An example of the difference between correlation and causation: a swimmer changes coach and then swims faster. The media writes: the new coach is the factor of change. But the data may show that the swimmer had increased training volume six months earlier, or changed their start technique, or simply recovered from an injury phase. The new coach may be a co-occurring variable, not a causal one.

That is the biggest blind spot in sports analysis. We love neat causal stories. We hate complexity.

But the pool does not care what we like.

Final reflection: a signal for the next lap

If I had to pick one signal to watch over the next two years, I would pick the final-length splits of young Vietnamese swimmers in the 200 and 400-metre events.

That is where the truth shows. The first length can be trained. The final length cannot. The final length is where body and mind talk to each other with no coach standing between them.

Vietnamese swimming does not lack talent. It lacks a system that records that talent carefully enough to know where it stands. When we start measuring the final length, we will start knowing what to fix.

And when football stops moving, when everything in the market grows noisy, I still return to the pool. Because there, there are no rumours. Only water, and a clock that does not lie — but always knows how to hide something, until you sit down and read every split.

Maintaining a data system is like maintaining a pool. You cannot let it stand still. The water must be filtered, the numbers updated, and the trust re-tested every day. A record today is tomorrow's data. And tomorrow, the one who reads again will be the one who asks the right question.

My question, hanging over the water: if Vietnam had a complete split sheet for every young swimmer, would we dare to look at it without turning away?