The Blank Lane: Why Vietnamese Swimming Data Cannot Be Reconstructed

The Blank Lane: Why Vietnamese Swimming Data Cannot Be Reconstructed

In late August 2026, at the national swimming championships, I sat in the third row, directly above lane 4, notebook open. The men's 200m individual medley final. The swimmer touched the wall, the scoreboard blinked, the crowd applauded and then went quiet.

A coach leaned down and asked me: "Did he lose it on the breaststroke leg or the backstroke leg?"

I looked at him, then at the screen. It showed exactly one line: the final time. Four wall touches — end of the 50m butterfly, the 100m backstroke, the 150m breaststroke, the 200m freestyle — not one of them was listed. The organisers did not record them. No machine output them. Nobody in the stands had managed to stop a watch in time.

The coach was asking a question that four numbers could answer. He asked the right person, but that person had nothing in his hands.

That night I went home, opened the phone video I had shot from the stands, slowed it down, and hand-timed four checkpoints. The error of that method lands around half a second. Over a 200m medley, half a second wipes out every conclusion. When I finished, I knew I had reconstructed something close to the truth — and I did not dare say it out loud.

The blank lane makes no sound. It just sits there, and each season it thickens by one layer.

Swimming is measured in the smallest unit in the sporting system

Swimming is a sport measured in hundredths of a second. A swimmer can win or lose by 0.01 seconds — the equivalent of an interrupted blink. On paper, this should be the sport with the densest data record of all.

At major meets, that holds. Through Omega's automatic timing system, every swim at an Olympics or a world championship is published not only as a final time but with 50m splits, reaction time off the blocks, and, in backstroke, the 15m underwater marker. Read the official record of a final and you can see how much faster the first 50m was than the last, and exactly which leg killed the swimmer.

At Southeast Asian level, the record thins out. At our national level, it is close to nothing.

I say this not to sneer. I say it because I have seen both ends. I have sat in the stands at a SEA Games where the scoreboard still displayed 50m splits. I have also stood at the pool deck of a domestic junior meet where three hand-held stopwatches, pressed by three different people for the same lane, disagreed by four tenths of a second.

That is where every analytical problem begins. Not a shortage of talent. Not a shortage of medals. A shortage of records.

Look at Vietnam's swimming roll of honour and you will find names capable of real damage. According to the official SEA Games 2026 medal table in Singapore, Nguyen Thi Anh Vien won eight gold medals, a haul that forced the whole region to look again. Three years later, at the 2026 Asian Games in Jakarta-Palembang, Nguyen Huy Hoang took silver in the men's 1,500m freestyle, the first time a Vietnamese swimmer stood on a continental podium.

Those are real peaks, recorded in medals. But beneath them lies a sediment nobody photographed: thousands of heat swims, hundreds of internal time trials, tens of thousands of wall touches that were never written down. We have the medals, but we do not have the process that produced them. And without the process, we cannot reproduce it in the next swimmer.

Three layers of data, and we only have the bottom one

In my daily work I divide swimming data into three layers.

Layer zero — the touch time. A single number per swim. This is the layer every meet in Vietnam has, down to district level. It answers fast or slow.

Layer one — 50m splits. Four numbers for a 200m event, thirty for a 1,500m event. This layer answers where he was fast and where he was slow. Most of our national meets do not publish it.

Layer two — stroke kinematics. Stroke rate, distance per stroke, turn time at each wall, underwater distance after the start and after each turn. This layer answers why he was slow. It barely exists in Vietnamese swimming records.

The difference between the three layers is not academic. It determines whether you can intervene in a result at all.

Take the 200m freestyle. A swimmer finishes 1.5 seconds off his personal best. Layer zero says: you were slow today. Only layer one says something worth saying: your third 50m was 0.9 seconds slower, while the other three were essentially unchanged. That is the story of a swimmer who faded mid-race, not of a swimmer who lost form. Those two diagnoses lead to two completely different training programmes.

Take the 100m backstroke. The rules allow up to 15m underwater after the start and after each turn. A swimmer who stays under for 12m before surfacing holds speed better than one who surfaces at 8m — but the price is the oxygen cost in the legs. Without layer two, a coach cannot tell whether he is teaching his athlete to save energy or to burn it. He only sees the time get worse and guesses.

Take the 200m breaststroke. After the start and after each turn, a swimmer is permitted exactly one dolphin kick before the first breaststroke kick. The timing of that kick, measured in tenths of a second, is one of the most decisive variables in the whole race. At a national meet without layer two, that variable is not measured, not coached, and not debated.

Then the 200m butterfly. This event is cruel in its own way: it allows no rest. The death of a 200m butterfly usually shows up as a falling stroke rate over the final 50m while distance per stroke stays roughly constant. With only layer zero, you see a swimmer finish slowly. With layer two, you see a swimmer trying to keep a long stroke by sacrificing rhythm — and you know what to fix.

There is one rule I always keep when writing reports: every number must translate into a familiar pool image. Being 0.3 seconds faster, for a swimmer, is equivalent to a missed breath in the closing stretch. Being 0.8 seconds slower over the third 50m of a 200m is equivalent to releasing the stroke one pull early. When a metric cannot be translated into an image, it is not yet data; it is only a symbol.

The problem is measurement error, not money

There is an argument I hear constantly: to have data you need money, you need automatic timing, you need equipment from the big brands. That argument is half right, and its wrong half is the part worth discussing.

Automatic timing via touch pads in the wall carries an error of roughly one hundredth of a second. Three hand-held stopwatches can carry an error of three or four tenths, depending on the reflexes of the timekeeper. In a 50m event, the gap between gold and fourth at a national meet is usually under three tenths. In other words, the measurement error is larger than the gap between the placings. Any split analysis built on hand-timing is an analysis of noise.

But here is the part worth discussing. A camera on a tripod at the pool deck costs less than a racing suit. Frame-by-frame video software, enough to count stroke rate and measure distance per stroke, is already available and runs on a laptop. A phone placed at the corner of the pool, shooting at 60 frames per second, can reconstruct wall-touch checkpoints with an error under a tenth of a second. That error is large for an Olympic final, but it is entirely sufficient to answer the coach's question at the top of this article.

What we lack is not equipment. What we lack is a person whose job is to stand there, press the button, and write it down.

What I have to say against myself

Here I have to turn the wheel.

The "Vietnamese swimming lacks data" narrative is easy on the ear, and because it is easy on the ear it is often right in the place that does not matter. Look closer and our swimming data is not exactly scarce. It is abundant in raw form and scarce in questioned form.

On the phone of every young coach at a provincial centre there are hundreds of clumsily shot clips from the pool deck. In the notebook of everyone doing coaching work there are handwritten times in ballpoint pen that go nowhere. The data is still there, scattered, sitting in devices that will break and notebooks that will be lost. The problem is not collection. The problem is asking.

And once you ask, ask correctly. My profession has a temptation: pick the easiest metric to count and call it the most important one. Stroke rate is the clearest example. It is easy to count, easy to present, easy to impress viewers because it looks powerful. But a high stroke rate does not automatically mean a fast swim. Over short distances a high stroke rate tends to accompany good times, but that is correlation, not causation. Swimmers raise stroke rate because they have become stronger, not the other way round. A swimmer told to raise stroke rate without gaining the underlying fitness will only shorten his distance per stroke and touch the wall later.

There is a second trap data people fall into: reading short-course 25m results and applying them directly to the 50m long course. A short course has double the turns. A swimmer who turns well and swims underwater well will shine in a 25m pool, then return to more modest numbers in a 50m pool. Over one season I watched a fair number of predictions collapse simply because the predictor forgot to count the turns.

And the final trap, the one I set for myself every time I sit down at the desk: treating probability as truth. I always have to add the phrase "with current confidence". A model that is right seventy per cent of the time is still a model that is wrong thirty per cent of the time. In a swimming pool, that thirty per cent can be a medal.

What the blank space is telling us

Back to that afternoon in late August. The coach did not have four numbers. He will go home, coach his athlete for another cycle, guided by feel. He may be right. He may also be fixing the wrong leg of the race, and every wrong session will compound until the next SEA Games.

A data void does not erupt into a crisis. It does not appear on the news. It simply slows an entire generation, a little each year, until people grow used to not knowing.

If I could choose one thing to do for Vietnamese swimming over the next three years, I would not build another training centre. I would introduce a rule: every swim at every national meet must have 50m splits recorded and published openly. The cost is close to zero. The value compounds every season.

Every race is a confession; I am only the one who decodes the whispers from the scoreboard. But to decode, someone must first write down the confession.

I do not pray with bells, but with scattered strings of numbers each night. And an empty pool is that strange marriage between data and loneliness.

So who will record the third breath of a fourteen-year-old swimmer in Quang Binh, on a morning with no spectators, when no one on the meet committee thinks that metric is worth keeping?