The 150-Metre Split and the Gap Vietnamese Swimming Hides Behind Its Medal Table

On the night of the SEA Games 31 swimming finals, I sat in a coffee shop on Nguyen Thi Minh Khai Street in Saigon with a blank spreadsheet open on my laptop. Every time the scoreboard flashed, I typed in the split. Then came the women's 200-metre butterfly, and I stopped. Not because of the medal, but because of the split at 150 metres: it was nearly two seconds slower than the 100-metre mark, while in the morning heats that gap had been just over one second.

A split does not decide a medal. But it is the first trace of something larger: the ability to hold speed through the final 50 metres. Behind it sits an entire system of conditioning, nutrition and competition scheduling. I re-checked that split four times. All four times, the result was the same. Numbers do not lie, but they know how to hide something.

That Saigon summer, I learned that data also needs watering. From a hastily built spreadsheet named "Chance Counting Data" in 2026, I gradually moved into recording swimming splits. I needed something that would hold up against praise, and the record sheet was the only thing I had.

Vietnamese swimming over the past decade has been tied to two names. Nguyen Thi Anh Vien, born in 2026, won 25 SEA Games gold medals in her career and retired after the SEA Games held in Hanoi in 2026. Nguyen Huy Hoang, born in 2026, won silver at the 2026 Asian Games in Jakarta in the 1500-metre freestyle and qualified for the Tokyo 2026 Olympics in the 800-metre and 1500-metre freestyle.

Those two names are enough to fill a medal table. They are not enough to fill a 50-metre pool.

For years, Vietnamese swimming lived on two pillars. When both were absent from certain events, the gap appeared very quickly. That is when I began recording the splits not only of Vietnamese athletes but of regional rivals: Thailand, Singapore, Indonesia, the Philippines.

People often ask me where Vietnamese swimming is weak. I do not answer with a feeling. I answer with splits, because a split is the only record that cannot be edited after the race ends.

Swimming is a sport with a rare advantage: everything is measured. Every 50 metres has a split. Every turn has a hundredth of a second. There is no room for arguments about biased officiating.

Precisely because of that, the analyst has to be more careful, not more relaxed.

When I record the splits of a 200-metre swimmer, I record three things: the speed of the first 50 metres, the difference between the two halves of the race, and the gap between heats and final on the same day. Those three things tell a story the medal table does not tell.

A swimmer can win a final with a slower time than the heats. That happens often. Looking at the medal table, people see dominance. Looking at the splits, people see an easy race and an opponent weaker than reality suggests.

I want to state this clearly: a SEA Games result does not measure the distance to the world, it only measures the distance to neighbouring countries. Those are two very different measurements, and confusing them is the most common error in regional sports media.

Across the last four SEA Games, most of Vietnam's swimming golds came in women's events, especially butterfly and medley. Men's freestyle events longer than 400 metres have essentially had one name capable of competing at continental level. A system with a single spearhead is not a system; it is one individual placed in the right spot.

I once spent eight months during the 2026 sporting shutdown archiving data from 2,400 Serie A matches to identify the bookmaker pricing bias against away teams. The same principle works for swimming, on one condition: the sample must be large enough.

One SEA Games has roughly 40 swimming events. Four editions is 160 events. That is a sample large enough to see the trend of a swimming nation, but not large enough to conclude anything about an individual. This is where many analyses go wrong: taking a whole nation's trend and applying it to one athlete, or doing the reverse.

In swimming, I always record two extra metrics: stroke rate and distance per stroke. These two are usually inversely related. A swimmer can raise stroke rate to go faster in the short term, but a falling distance per stroke means falling efficiency. That swimmer is burning more energy to cover the same distance.

When both metrics fall together over the final 50 metres, it is a sign of exhaustion, not tactics. And when that pattern repeats across multiple testing points in one season, it is no longer a problem of a single competition.

The pattern I record most often in Vietnamese swimming: good opening split, steady middle split, poor closing split. In other words, we teach fast swimming first and durable swimming second. That order is reversed compared with how leading swimming nations build athletes, where the endurance base comes first and speed is polished afterwards.

In 2026, I tried applying a simple model to swimming data: using the halfway split from the heats to predict the halfway split of the final. The average error came out at around 1.5 seconds for a 200-metre race. That error is not large, but it is enough to separate a swimmer holding rhythm from a swimmer merely trying to hold on.

I do not say these things from a single viewing. I say them from file after file that thickens with every edition of the Games.

There is a trap here. When Vietnamese swimming wins many golds, opinion says the sport is progressing. When it wins few, opinion says the sport is declining. Both conclusions rest on the same false assumption: that the SEA Games gold count reflects standard.

It reflects the balance of power within Southeast Asia. That balance shifts each edition, depending on which country sends its strongest team and which country treats the SEA Games as its main stage.

I once tracked one athlete across an entire season. In the morning heats, she swam a better time than in the evening final. That is normal. That afternoon, I noted the rest interval between her two swims: under seven hours. For an athlete in a heavy training block, seven hours is not enough to recover.

I later learned that at some regional meets, organisers are forced to schedule finals close to heats because of broadcast schedules and the sheer number of events. The athlete with the better recovery system keeps the split. The rest lose it.

Sometimes a bad split is not the athlete's fault. It is the fault of a schedule drawn up by people who do not swim.

I am a data person, but there is one word I do not believe in: maintenance. People talk about youth development the way they talk about a machine that needs regular oil changes. Every few years, open a new talent class, take in a few dozen children, then wait. There is no mechanism for a ten-year-old in a coastal district of central Vietnam to have his splits measured twice a week. There is no mechanism for his data to follow him from coach to coach.

That word sounds pleasant because it turns people into equipment. But an athlete is not equipment, and a spreadsheet does not run itself.

In a dossier I once reviewed for a sports organisation, I blocked a recruitment proposal built on a goal tally that the media had inflated, because the player's chances-created metric per match was far lower than the image. The same principle applies to swimming: a gold medal in an event with only three rivals says nothing about potential at continental level.

What I want to leave behind is not a conclusion. Vietnamese swimming does not lack talent. It lacks a recording system thick enough to know where the talent is, and transparent enough that the talent is not replaced by a slot that has been arranged.

The next cycle will begin at youth meets, where there are no cameras and no scoreboards. Whoever is willing to sit there and write down the splits will know the rest about two years early.