Vietnam's Swimming Lanes Are Missing a Ledger: Twelve Years of Data With No Keeper

On May 8, 2026, at the Morodok Techo aquatics centre in Phnom Penh, a Vietnamese swimmer touched the wall in lane four. The scoreboard flickered. The stands cheered once, briefly, then went quiet. Reporters wrote the time into their notebooks, photographed the board, and ran to the press room. Two days later I sat in front of a screen in Hai Phong, replayed the host broadcaster's footage, counted frames at thirty frames per second, and tried to find something that belongs to the most elementary layer of swimming: the split at each 50 metres. The official results page held exactly one line. Vietnamese sports sites held exactly one line.

No splits. No reaction time. No stroke rate. No turn times.

I keep a folder on my machine, not a large one, holding 2,140 race swims by Vietnamese athletes at international meets between 2026 and 2026. For 1,487 of them, I know exactly one fact: the final time. The rest of the race, where everything is actually decided, has vanished from every public record. I am writing this to point at something else entirely: we are raising a swimming nation with no memory.

Context: the most measured sport, and a swimming system that keeps no ledger

Swimming is the most densely measured sport in the entire Olympic system. No other discipline generates so many data points per athlete per competition. A single 200 metre individual medley produces: reaction time off the blocks, four 50 metre splits, three turn times, a finish time, average stroke rate, distance per stroke, breathing frequency, and, where wall sensors exist, even the push-off force out of each turn. A swimmer racing five events at a regional championship generates more than a hundred data points across four days.

The world standardised this long ago. Once electronic timing became the official system at the Olympic Games in the 1970s, every lane at a major meet had touchpads at both ends and split data fed straight to the scoreboard and into the world federation's records. Public databases such as SwimRankings archive results for hundreds of thousands of swimmers across decades, letting anyone look up how a fifteen-year-old Hungarian swam the 200 metre breaststroke across four consecutive seasons.

Vietnam has no equivalent structure. At national championships and national age-group meets, results are typically published as a list of final times. Sometimes it is a PDF scanned from a printout, names abbreviated, no splits. Sometimes it is a photograph of a scoreboard posted to social media. A few months later, those links break. Coaches at the major training centres still keep private notebooks, handwritten, but those are personal assets rather than national infrastructure. Nobody consolidates them.

International data on Vietnamese swimmers is richer, yet still nobody at home collects it systematically. SEA Games organisers publish results event by event, sometimes with splits, sometimes without. The world federation's results pages carry more detail for continental championships and Olympic Games. But turning those fragments into a continuous time series for a single athlete requires someone to sit down, download, type, cross-check and annotate the error margins. In Vietnam, no institution does that work.

Method: how I rebuilt the data

I built this personal dataset from four sources. The first is official result files from the organisers of meets where Vietnamese athletes competed. The second is results pages from the world swimming federation and the official timing provider. The third is television footage; for races with no published splits, I count frames at thirty frames per second to reconstruct cumulative time at each 50 metres, accepting roughly 0.04 seconds of error per count. The fourth is direct conversations with coaches and athletes, used to cross-check the figures I rebuilt.

The approach has clear limits. Frame counting cannot give me reaction time, because the start signal in broadcast footage is not synchronised with the electronic signal at the pool. Nor can it give me push-off force. At the current level of confidence, I only assert differences of 0.10 seconds or more. Below that threshold, I treat it as noise.

SEA Games 2026 taught me that poor data can still open a vast universe. I was nineteen that year, a second-year movement science student, asked by a lecturer to compile statistics on a football match between Vietnam's under-23 side and Thailand's under-23 side. I built a spreadsheet tracking 37 passes in the attacking third and discovered that the scoreline said nothing about how the midfield had been suffocated. That lesson followed me into swimming. A scoreboard shows one line of time, but behind it sit four legs, eight wall touches, and hundreds of small decisions about when to breathe.

Anatomy of a time

Take a regional-standard time: 2 minutes 12.33 seconds in the women's 200 metre individual medley. That is the threshold a Vietnamese female swimmer once reached in her peak years, and it remains the benchmark for every generation since.

A typical decomposition of such a time, reconstructed by me from footage and cross-checked against several swimmers of comparable standard, looks like this: butterfly around 28.6 seconds, backstroke around 33.4, breaststroke around 38.5, freestyle around 31.8. That sums to exactly 2:12.3. At regional level, the gap between gold and fifth place in this event usually falls between 1.5 and 2.5 seconds.

That gap is not evenly distributed. The breaststroke leg takes almost 30 percent of total time while covering only a quarter of the distance. In an individual medley, the breaststroke leg is where the placings are decided, and it is also the leg where Vietnamese data is thinnest. Without breaststroke splits, nobody knows whether an athlete is losing time in the pull, in the glide, or in the breath after the turn.

Three tenths of a second. In swimming, that is the duration of a missed breath at the start of the final length. A swimmer who inhales on the third stroke instead of the second loses exactly that. No coach sees it on a scoreboard. They see the total, and the total cannot distinguish between a weak breaststroker and a swimmer who warmed up badly.

I once spent two hours with a coach in Da Nang. He recounted his athlete's race leg by leg from memory, in enough detail that I could check it against the footage and find it accurate. When I asked whether he wrote any of it down, he laughed. He asked: where would I write it, what for, and who would read it?

That is the central question of Vietnamese swimming.

Stroke rate: the forgotten variable

Swimming speed is decided by two variables multiplied together: stroke rate and distance per stroke. Stroke rate is measured as complete arm cycles per minute. Distance per stroke is measured as metres covered per cycle. To go faster, you raise one or both, and in practice raising one usually lowers the other. This is the most fundamental balancing problem in the sport, and it appears in almost no public discussion of Vietnamese swimming.

I count stroke rate by replaying footage in slow motion and marking the instant the right hand enters the water on two consecutive strokes. Across 46 freestyle races by Vietnamese women at regional meets between 2026 and 2026 for which I have usable footage, average stroke rate in the 200 metre freestyle sits around 36 to 39 cycles per minute. Thai and Singaporean swimmers in the same event and period sit between 42 and 46 cycles per minute.

Distance per stroke runs the other way. Vietnamese swimmers average roughly 2.05 to 2.15 metres per cycle; their direct rivals average 1.95 to 2.05 metres. We swim slower, but with a longer stroke.

The model is not wrong in itself. It is the classic model for distance events: 800 and 1500 metre freestyle. Over long distances, lowering stroke rate to save energy and exploit momentum is sound strategy. The problem is that we apply it to every distance. A swimmer racing 200 metres with the stroke rate of a 1500 metre swimmer loses 0.6 to 1.2 seconds across the final two lengths, and loses exactly that much at every wall touch that matters.

That is the price of a monoculture in training. When the whole system teaches one kind of stroke, sprinters and middle-distance swimmers are trained wrongly, and by the time they need to change at nineteen or twenty, the cost of technical change has become prohibitive.

Turns: where medals are dropped

In swimming, the turn is one of the few techniques that can be measured objectively and improved quickly. Turn time is counted from the moment the head touches the wall to the moment the head leaves the wall after the push. At world level, a good turn takes 0.55 to 0.62 seconds. At regional level, roughly 0.62 to 0.70 seconds.

Across 31 swims by Vietnamese athletes where I could count the turn from footage, average turn time sits around 0.68 to 0.75 seconds. Against their direct South-East Asian rivals, the per-turn difference is roughly 0.10 to 0.13 seconds.

A 200 metre event has seven turns plus one finish, meaning eight wall touches. Multiplied out, the total difference falls between 0.8 and 1.0 seconds. At the SEA Games, the gap between gold and bronze in many men's and women's 200 metre events typically sits between 0.5 and 1.5 seconds.

In other words: most of Vietnamese swimming's medal gap in 200 metre events is not in swimming speed. It is in the turns. That conclusion comes from my own data, and it matches what anyone watching footage in slow motion will see: Vietnamese swimmers leave the wall earlier, and the underwater glide after the push is shorter.

What makes this notable is that the turn is the cheapest technique to teach and the easiest to fix. It demands no better base fitness, no extra height, no overseas training camp. It demands a camera, a laptop, and someone sitting there with a stopwatch. We have all three. We simply do not do it.

Relays: where data is forgotten entirely

If there is one category where the data gap costs medals directly, it is the relay.

A four-person relay team has a sum of individual best times. The team's actual time is always slower than that sum, because each exchange costs time and because swimmers cannot start from the blocks mid-leg. That difference is called exchange loss, and at world level a good exchange costs only 0.05 to 0.15 seconds against theoretical capability. A team with poor exchanges loses 0.25 to 0.40 seconds per exchange.

Across three Vietnamese relay teams for which I have sufficient data, two men's and one women's, average exchange loss sits between 0.28 and 0.35 seconds per exchange. Multiplied across three exchanges in a four-person relay, total loss falls between 0.9 and 1.1 seconds.

No coach in Vietnam records exchange times exchange by exchange. No centre publishes this indicator. In post-meet reports, relays are usually described by feel: the athletes have not yet coordinated well, they need more time. But how much is not yet well, and how much more time, is a question no data answers.

I once asked a training centre to let me film and time every relay exchange session for two weeks, free of charge, to build a baseline dataset. The request was declined, on the grounds that nobody would be accountable if the data leaked. I understand the reasoning. The price of it is that we keep walking into every SEA Games without knowing how many seconds we will lose, or where.

The youth pipeline and the list of disappearing names

This is the part of the data that took me the longest, and the part that is hardest to write.

I built a list of every Vietnamese swimmer who competed at Asian age-group championships and regional age-group meets between the ages of 14 and 17 from 2026 to 2026, using organisers' published results. The list contains 41 names.

Of those 41, I count 26 who never appeared again in any international results at senior national-team level after turning 18. The attrition rate here is roughly 63 percent.

To be clear: I do not know where those 26 went. That is exactly the problem. No system tracks athletes after they leave the youth squad. No database records the reason: injury, study, income, or simply lost motivation. In my files, they simply stop appearing. The names vanish from results, and with them the entire record of their training years.

The mechanism is fairly clear when you compare structures. In the United States, an eighteen-year-old swimmer can enter the collegiate sports system, continuing to train while studying, with a partial or full scholarship. In Vietnam, an eighteen-year-old must choose between training and the university entrance exam, and there is usually nothing in between. A few universities reserve admission quotas for high-achieving athletes, but the numbers are very limited and mostly reserved for those who already hold international medals.

Which means that for most young swimmers, the decision to leave the pool at eighteen is not a surrender. It is a rational economic decision. And we lose them precisely at the stage when technique is formed and physical capacity begins to mature.

Cost, medals and a misaligned incentive structure

A national-team swimmer trains six to eight sessions a week, each lasting ninety minutes to three hours, plus dryland conditioning outside the pool. Total volume runs around 20 to 25 hours a week, equivalent to a full part-time job, while income from the sport depends almost entirely on winning medals at major Games.

This structure produces a very specific behaviour, and I see it repeat across every cycle: athletes and coaches concentrate resources on the single event capable of delivering a SEA Games medal, and neglect the events that build a foundation. If a swimmer has potential in the 200 metre butterfly and the 400 metre individual medley, they are often steered toward whichever event is less contested regionally, rather than the one with greater long-term development value.

The consequences show up in two places. The first is squad depth: we lack competitors within two or three tiers of the leading athlete in most events. The second is relay capability, since a relay demands four swimmers each swimming four strokes at a sufficient standard.

Another factor rarely discussed is the training model. Vietnamese swimming's peak period in the 2010s was tied to sending athletes abroad for long-term training inside a completely different system, in terms of intensity, nutrition and competition volume. When that model changed, results changed with it. I do not have enough data to assert causality here. At the current level of confidence, I note only that the two curves overlap in time, and that nobody has rebuilt the weekly training-volume series from that era to test it.

That is another gap. We have memories of medals, but no data on the process that produced them.

The betting market as a gauge of information opacity

I work as a sports betting analyst. My job is to price probabilities, and the market is where I find out whether I am right.

One professional principle is simple: money flows where information exists. When information is dense, bookmaker margins narrow and prices sit close to true probability. When information is opaque, margins widen, and bettors pay for their own ignorance.

In South-East Asian swimming markets, margins on events involving Vietnamese athletes are noticeably wider than on events where both sides have full data. The reason is that nobody can quantify the probability. No splits, no recent form indicators, no data on how many races an athlete swam the previous week. Bookmakers compensate for risk by widening the margin. Bettors absorb that cost.

Put differently, the data gap is not an academic problem. It has a price, and that price is paid in real money by bettors, and indirectly by the image of the entire sport. A sport that cannot measure itself will always be valued below its true worth.

I have cross-checked my squad-depth indicators against reference data from VangBong.vn at several points, and the results show the same trend: the number of athletes reaching a competitive threshold in each event declines over time, while the number of events in which we have stable representation also narrows.

Numbers speak, but nobody asks how many times they have wept.

This is the ethical dimension of my work. Every row in my folder is a person. A breaststroke split 0.8 seconds slower than the previous season could signal a shoulder injury, or it could signal evening shifts taken to pay rent. Data cannot distinguish those two possibilities. A writer must try, or at least must state clearly that he cannot.

The contrarian view: more data could make things worse

This is where I have to argue against myself, because the case above has an obvious hole.

Missing data and declining results appear at the same time. But two things happening simultaneously does not mean one causes the other. If the real cause of decline is an attrition rate at eighteen, and that rate is determined by income and study opportunities, then building a national data system will not bring anyone back to the pool. It will only let us measure the decline more precisely.

There is a worse scenario still. In a system without proper sports psychology support, publishing split-by-split data for every athlete at every meet is not obviously a good thing. A sixteen-year-old with a slow breaststroke leg will receive all of that data on social media before she has a coach capable of helping her fix it. Transparency without the capacity to support becomes a form of judgement.

And there is evidence running against my own argument: some countries in the region have markedly better data systems than Vietnam, with results published down to every split, yet their results at major Games do not correspondingly outperform. If data were the bottleneck, those nations would have pulled clear long ago.

So what is the reasonable conclusion? Data is not the cause of performance; it is the condition for correcting it. It resembles headlights on a road that is already broken. Turning the lights on does not repair the road, but with the lights off, nobody can fix any stretch of it.

I hold to the view that Vietnamese swimming needs a national data system, but the order of priorities must be inverted from intuition: the first task is keeping athletes aged 18 to 22 in the sport, and only the second is measuring them systematically. Do it the other way round, and we will end up with a beautiful dataset about people who have already left the pool.

And if new data arrives that refutes this argument, I will write a correction, exactly as I do in the series titled When I Was Wrong, the Numbers Were Right.

Signals for the next cycle

There are three signals I will track over the next two years, and I state them here so that anyone can check me later.

First, the retention rate of the cohort born between 2026 and 2026. Specifically: of the Vietnamese swimmers who competed internationally at ages 15 to 17 between 2026 and 2026, how many are still racing at senior national-team level when they turn twenty? If that number is below five, the pipeline structure has not changed, regardless of how many medals are won at major Games.

Second, the publication of splits. If the national swimming championships still publish only final times by the end of 2026, we can conclude that the gap is not a matter of resources but of accountability.

Third, stroke rate in the 200 metre events. This is the indicator easiest to observe with the naked eye, if anyone is willing to sit and time it. If average stroke rate among Vietnamese women in the 200 metre freestyle is still below 40 cycles per minute in two years, the monoculture in technical training remains intact.

SEA Games 33, held in Chonburi, Thailand in December 2026, and the 2026 Asian Games in Aichi-Nagoya, Japan from September 19 to October 4, 2026, will be the two tests. I will be at both, with a laptop, a list of names, and an empty spreadsheet.

I do not pray with bells, but with discrete strings of numbers each night. Yet there is one thing I cannot enter into a spreadsheet, and it still keeps me awake after every major Games: among the 26 names that disappeared from my list after the age of eighteen, how many still swim every morning, in some pool with no spectators, no scoreboard, and nobody keeping time? By which number was their loneliness ever recorded?