When the Lane Goes Silent: Vietnamese Swimming's Data Problem

On the third night of a SEA Games, I sat in front of a screen with a spreadsheet already open. Column A held the athlete's name. Columns B and C were empty. I was waiting for lane data — the 50-metre split, the stroke rate per minute, the number of breaths per length — but the only thing that came back was an electronic scoreboard with seven dry numbers. Not a single split. Not a single efficiency metric. Not one line enough for me to begin telling the story of a human being. That spreadsheet was empty, and inside that emptiness I recognised something more frightening than a defeat: silence.

I spent eight years as a competitive swimmer before moving behind an analyst's desk. Those eight years taught me to count every stroke, to feel every breath, and to understand that behind a single time on a scoreboard lie thousands of small decisions no spectator ever sees. When I left the pool to work as a sports data analyst, I carried a naive belief: that everything can be measured, and that whatever can be measured can be improved. That belief holds true in football, where a single match generates hundreds of thousands of data points. But when I returned to swimming — the sport I understand best through my own body — I hit a blank wall.

Swimming is a sport of forgotten numbers. A 200-metre lane unfolds over roughly two minutes, yet inside those two minutes are four turns, eight underwater push-offs after each turn, and about three hundred strokes. Every stroke is a unit of data: the pull, the entry angle, the distance per stroke, the tempo. In the leading swimming nations, all of it is measured. In Vietnam, we usually keep only one final figure — the finishing time — and then infer everything from it. That is reading a novel by its closing word alone: “end”.

In 2026, I was a second-year student in Exercise Science, and I happened to be asked by a lecturer to compile statistics for the U23 Vietnam match against U23 Thailand at the 29th SEA Games in Kuala Lumpur. I built my own spreadsheet tracking 37 passes in the opposition's final third, recording a 0.68 xG for Vietnam even though the team lost 0-3. I realised the media spoke only of the scoreline, while the data showed our midfield had been squeezed out of the game. SEA Games 2026 taught me that even poor data can open up a vast universe. But it took several more years before I understood that this universe also has dark regions no number can illuminate.

In 2026, when the pandemic suspended every competition, I rewatched the entire 2026-20 Bundesliga season on tape and noted the gaps between the lines when stadiums stood empty. When football returned, I found home teams won only 23% of matches, compared with 45% before the pandemic. In 2026, football stopped breathing, and I realised that data, too, knows how to wait. But the lesson was larger than that: data does not generate itself. It must be designed, collected and cultivated. When nobody keeps records, the pool becomes a blank space.

And that is precisely the problem for Vietnamese swimming. We have athletes, we have medals, but we do not have a data system to match. A sport that cannot measure its own progress is swimming without knowing whether it is moving forward or backward.

Picture it concretely. When a 200-metre breaststroke swimmer clocks 2:30 at 16 and 2:28 at 18, the media calls that progress. But if we had split data, we would see the opposite: the first 50 metres 0.8 seconds faster, while the final 50 metres 1.5 seconds slower. That athlete has not improved their physical base — they merely swam more recklessly in the first half and collapsed in the second. This is the kind of information that decides whether a talent is nurtured or burned out.

At major swimming centres, every training session produces a file: heart rate, lactate concentration, strokes per length, average distance per stroke. Coaches do not need to watch with their eyes; they read the table. When a swimmer plateaus, they know instantly which link failed — conditioning, turn technique, or competitive psychology. In Vietnam, when a swimmer plateaus, the answer is usually “psychology” or “injury” — two convenient labels for things we lack the data to name.

What matters is that this shortfall does not stop at the training pool. It shapes how we judge an entire SEA Games. Every time the Games end, medal tables are erected, and people argue over whether the team “succeeded” or “failed”. But a gold medal in an event where only three athletes in the region competed is entirely different from a gold medal in an event with ten world-class rivals. Without data on competitive density, every medal comparison is a comparison of numbers produced under different conditions.

When Nguyễn Thị Ánh Viên won eight gold medals at the 2026 SEA Games in Singapore, the media called it a miracle. And a miracle it was. But what few analysed was the structure of that achievement: at the time, in most of her events, Ánh Viên had almost no rival of comparable standard in the region. That does not diminish her value — it merely reminds us that a gold medal can carry two very different meanings, depending on whether it is measured by density or by colour.

I once built a small model to quantify this. For each event, I assigned a density index — the number of athletes in the region whose personal best fell within 2% of the leader. In some events, that index was one or two. In others, it rose to seven or eight. When I multiplied the density index by the medal's value, the order of the medal table shifted significantly. Some gold medals became lighter, and some silver medals suddenly grew heavier. The true value of a medal lies not in its colour, but in the density of those who tried and failed before it.

From the perspective of a betting analyst, this data shortfall creates a paradox. The thinner the information, the more easily a market is mispriced. In a swimming event where analysts have only the finishing time, the crowd tends to bet on the most recent result, ignoring the entire structure behind it. Someone with split data will spot a swimmer fading before the scoreboard shows it. But this is a double-edged sword: poor data creates opportunity for the sharp, and at the same time creates a market where luck is mistaken for skill.

In strong swimming nations, data begins at the junior level. Records run continuously from club to national team, turning every athlete into a file that can be tracked for years. In Vietnam, each generation of athletes is often discovered late, trained under conditions of weak measurement, and when they shine, we know them only through their medal. That talent supply chain resembles a river with no hydrological gauge: the water still flows, but nobody knows when the flood season will arrive.

But here is where I must be careful with myself. The nature of a data analyst is to believe that every problem can be solved by measuring more. That is a trap. I once received a completely empty analysis — no athlete's name, no event, not a single data point. The lesson from that empty spreadsheet was not “collect more data”, but the opposite: when there is no data, the most honest thing is to say there is no data — rather than fill the gap with speculation.

That is what I want to say about the limits of faith in numbers. We fall easily into two extremes. The first is treating numbers as absolute truth, forgetting that 70% is 70% and not 100%. The second is discarding data when it stops being convenient, retreating to sentiment and phrases like “greater fighting spirit” or “superior class” — phrases that cannot quantify how much fighting spirit is worth. Both extremes are ways of avoiding the truth.

There is one counterintuitive thing I have learned from my own profession: poor data is sometimes more honest than rich data. When you have only one number, you know clearly that you know nothing. When you have a thousand numbers, you easily fool yourself into thinking you understand everything. The silence of an empty spreadsheet is therefore a warning — it forces me to remember that behind every metric is a human being the metric can never fully capture.

I think of Vietnam's young swimmers, training every day with no one recording their stroke rate. They swim, they sweat, they improve or stall, and most of what they experience will vanish with the water. No spreadsheet preserves the moment they first broke through their own limit. No model predicts the day they will quit. Numbers speak, but no one asks how many times they have wept.

An empty stadium is the strange marriage of data and loneliness. In swimming, that loneliness is more intact than in any other sport, because every athlete enters the lane alone, with no teammate to shield them, no crowd pressing close. Data can be their only companion in that moment — but only if someone is willing to sit down and take notes.

I do not intend to close with a call to invest in technology. That would be too easy. What I want to leave behind is a question. When a Vietnamese swimmer achieves the best result of their career on a morning when no one films, no one times each lap, no one records their breathing — whose achievement is it, and which number recorded that swimmer's loneliness?

Perhaps the answer lies not in how much we measure, but in whether we are willing to sit long enough to listen to the table of numbers. A sport that can count every stroke of its athletes is a sport that has learned to respect the human being behind the number.