Vietnamese Swimming and the Data Gap Behind Every Touch of the Wall

I opened my tracking sheet again after a major meet. The column for final times was full. The column for splits was empty. The column for stroke rate per lap was empty. Turn times at each wall, reaction time off the blocks, the number of metres swum underwater after the start — all blank.

That is the state of Vietnamese swimming data at the specialist level. We have results, but we lack process. We know how many seconds a swimmer took to touch the wall, but not where they lost time along the way. For someone whose job is reading numbers, that silence is more troubling than any defeat in the pool.

A familiar paradox

At the SEA Games, Vietnamese swimming is a genuine force. Names like Nguyen Thi Anh Vien and Nguyen Huy Hoang have delivered gold medals and left a mark at the Olympics. Nguyen Huy Hoang swam the men's 800m and 1,500m freestyle at the Tokyo 2026 Olympics — no small milestone for a country with a young swimming tradition.

But out on the continental and world stage, the gap opens quickly. The paradox sits here: we have results, but most of those results are recorded only as final outcomes, never as an analysable process.

I once worked as a swimming reporter for Thanh Nien newspaper before moving into data work for football clubs. That experience taught me one thing: a result without a process behind it is just a number to cheer, not a number to learn from.

The four phases of a swim and the cost of an empty cell

A competitive lane breaks into four clear parts: the start and reaction, the underwater phase after leaving the blocks, the turns, and swimming efficiency between them. Each part needs a different kind of data.

Reaction time needs a sensor on the block. The underwater phase needs a sub-surface camera to record metres covered and kick count. Each turn needs the time in and out of the wall, plus the depth of the glide. Efficiency needs stroke rate, distance per stroke, and the ratio between them.

In the leading swimming nations, those four data sets flow into one system. Japan is a useful example: its schools and swim clubs keep detailed year-by-year records, making it routine to track a talent from childhood to senior level. In Vietnam, most of that data does not exist in standardised form, especially at youth level. The same athlete may be logged in three places in three formats, and nobody ever links them together.

We still pick our swimmers with final times plus a coach's eye. That means talent is judged on raw outcomes. A swimmer with a slow start but an exceptional engine can be undervalued, because the raw view cannot separate slow-by-technique from slow-by-fitness. Conversely, a swimmer who peaks early on age-defying physique can be over-invested in, then left behind when peers catch up physically.

I once miscalculated a striker's sprint distance: 1.2 km instead of 0.8 km. A small drift, but it forced me to re-audit 14,000 data samples over three months and uncover three further system faults. A small GPS drift is enough to teach you: verification is everything.

With swimming the problem is far larger. In football, data still flows even when flawed. In Vietnamese swimming, many cells have never been filled at all. The system fault is not a wrong number — it is a number that does not exist.

Four years of data work for a club in Nha Trang taught me that what decides the value of a sport is not the machinery, but the habit of record-keeping. I believe in numbers, but only after a number has cleared three rounds of checking. That is the problem for Vietnamese swimming — most numbers are never harvested, so they can never be checked.

From the media side, the consequence is clear. A swimming article without process data can only circle around results: medals, records, rankings. The sport's best stories — a swimmer who fixes a turn and saves half a second per lap, a young talent whose stroke rate climbs after a year of training — stay out of reach, because nobody wrote them down.

When the recovery index is forgotten

During the pandemic I built a recovery-index model for players based on GPS data and injury history. The idea was simple: measure load, measure recovery, then forecast risk before it becomes a real injury. The result showed the three highest-intensity pressing teams carried a 23% higher injury risk.

The same principle applies to swimming. A young swimmer racing four events at one meet should have their load tracked, not only their times. But to track load you first need session-by-session data. To have session data you first need disciplined record-keepers, a standard measure, and data-entry discipline.

Before talking about the pool, Vietnamese swimming needs to talk about the data room — usually the emptiest room in the whole training centre. That shortfall affects results and the way we tell the sport's story. Without data, the media can only lean on medals. A culture of support is not built on the volume of cheering, but on the frequency of patience — and that patience only exists when spectators can see a process, not just a result.

A contrarian view

More data is not automatically better. A dense spreadsheet cannot rescue a bad decision, and it can hide one. Correlation is not causation: a swimmer with a high stroke rate does not automatically swim faster, and a fast swimmer does not automatically have a high stroke rate.

The greater danger is an old model elevated into dogma while new data that contradicts it gets dismissed. I learned this from a rejected transfer: a striker scored 18 goals on just 11.2 xG, and I advised against signing him. He scored 4 goals in 20 games. But if I used that story to claim data is always right, I would be fooling myself — it was one sample, in one league, at one moment.

For Vietnamese swimming, false certainty from a single source is more frightening than missing data. When data is absent, we at least know it is absent. When we are confidently wrong, we no longer know we are wrong.

What the next cycle is waiting for

Vietnamese swimming sits in a transition cycle. Anh Vien's golden generation has passed, Huy Hoang's generation is at its peak, and a younger cohort is coming up. The long-term fate of this sport will not be decided by the next few medals, but by whether we build a serious habit of record-keeping.

Three signals I will be watching: whether a unified national swimming database emerges; whether youth training centres begin logging session data; and whether coaches are trained to read numbers, not just medal tables.

Data does not tell stories. It only records everything so that a writer like me can tell them. And when a sheet still holds too many empty cells, the truest story is sometimes the one about everything we never wrote down.