The Empty Splits Column: Vietnamese Swimming Is Missing an Entire Verification Layer

On the evening of 19 May 2026, the Mỹ Đình aquatics hall was so packed that row eleven had to double up. I held a stopwatch in my left hand and a phone in my right, eyes fixed on lane four. When the Vietnamese swimmer touched the wall, I pressed the button, wrote a number into an empty cell of my spreadsheet, then opened the World Aquatics results database to cross-check.

The page returned four fields: name, nationality, event, final time. The splits column was empty. Not one 50-metre line. No reaction time. No turn times across three wall contacts. I sat still for about thirty seconds, then did what I had done nineteen years earlier at the Thanh Niên Báo newsroom: I hand-timed the race myself and logged the margin of error beside it.

Hand-timing error over 200 metres sits around ±0.2 seconds if the timer is alert, and stretches to ±0.5 seconds if the crowd roars at the exact moment the swimmer surfaces for air. I wrote that number plainly in the notes column. A splits table produced by a journalist in the stands is worth far less than one produced by the Omega touchpad system built into the wall. But it still beats an empty cell.

Data never lies, but it knows how to hide. And in Vietnamese swimming, it is hiding very well.

Context: a swimming nation read through medals

I entered the profession in 2026 as a swimming reporter at Thanh Niên Báo. Results arrived printed on paper, handed to reporters in the press room, and the only things we had were final times and placings. Splits never appeared in a single dispatch. Twenty years later my phone can reach the World Aquatics database, yet for most domestic and regional meets the splits column is still as empty as it was in 2026.

That gap shapes the entire way Vietnamese swimming is narrated. A swimmer wins gold, walks into the press conference, and the first question is about emotion. The second is about targets. Nobody asks what the first 50 metres cost, what the last 50 metres cost, what the reaction time was, or which of the three turns was the slowest. Because nobody has the numbers to ask with.

The result is an information ecosystem in which the medal is the only unit of measurement. A SEA Games gold becomes the yardstick for form, for sponsorship, for a province's investment decision. But a medal is a binary variable: yes or no. It cannot distinguish a 2:14.0 swim that wins by 0.3 seconds from a 2:11.0 swim that wins by 0.01. At the level of analysis, those two results belong to different worlds.

I have lived inside a similar ecosystem in another sport. COVID closed the stadiums, so I reopened the V-League directory. No league is meaningless. In 2026, with football stopped, I rebuilt five seasons of V-League history, tracking 240 players, and found fitness curves no outlet had ever published. Vietnamese swimming sits in exactly that position: enough competitions to build a dataset, and nobody building it.

Twenty-five metres and fifty metres: two championships running in parallel

The most common error in any conversation about swimming, including among people who have covered the sport for years, is comparing a 25-metre pool time directly with a 50-metre pool time. It is the most serious technical mistake in the trade, and it is so widespread that it is barely treated as a mistake.

Over 200 metres, a 50-metre pool offers only three turns. A 25-metre pool offers seven. A well-executed turn produces a stronger push-off than an ordinary stroke cycle, plus an underwater glide phase that is faster than swimming on the surface. Seven push-offs instead of three creates a gap of one to three seconds over 200 metres, depending on the stroke and on the swimmer's turning quality. Over 400 and 800 metres, the gap widens further.

World Aquatics records short-course and long-course records in two separate ledgers and never merges them. A national record set in a 25-metre pool cannot be placed against an Olympic performance in a 50-metre pool. Anyone who does otherwise is producing a meaningless comparison — and worse, a comparison that looks correct.

In Vietnam, most pools used for training and age-group competition are short course or non-standard in length. National championships are held in both types of pool. That means a young swimmer can post an excellent time in a short-course domestic meet, be celebrated by the press, then arrive at a long-course international meet and lose an advantage she never created. Nobody notes the pool length in the report. Nobody questions the conversion.

Splits: the only thing that makes a lane readable

If I had to choose one data type to rebuild the entire Vietnamese swimming analysis system, I would choose splits — the per-50-metre times. Without hesitation.

A final time tells you who touched first. A splits table tells you why. It shows whether a swimmer went out fast and faded, or held back and unleashed. In technical terms, a negative split versus a fly-and-die. Those two structures can produce an identical final time while carrying completely different meanings about capability and about growth potential.

A swimmer who goes out 1.5 seconds faster than she closes over 200 metres is spending energy in a way that does not sustain. A swimmer whose last 50 is 0.4 seconds faster than her first owns the thing every national head coach wants: controlled energy distribution. Same final time, two different prospects.

Here I have to state my own limits. Sitting in the stands with a stopwatch, I can only catch the moment a swimmer surfaces at each end, not the moment of the underwater touch. In breaststroke and butterfly, where swimmers touch while still submerged, my error grows substantially. That is why I always publish the margin rather than presenting a splits table that looks precise.

Reaction time is the second piece. At world level it sits around 0.6 to 0.7 seconds. A swimmer at 0.75 has already lost 0.1 seconds before the body leaves the block, and over 50 metres 0.1 seconds is the distance between a medal and a heat exit. In a sport decided by hundredths, reaction time is life-or-death data. But it only exists if the organiser publishes it.

The underwater phase — the glide and dolphin kick after the start and after each turn — is where modern records are made and where data is thinnest. Without sensors and without a 15-metre split, every technical claim about the underwater phase is an inference from television footage, and television footage does not carry enough frames to count kicks.

The WR line and the polyurethane shadow of 2026–2026

Every swimming performance analysis needs a reference frame. The standard frame has three tiers: the world record, the all-time list, and the current-season ranking. Without those three, a time is just a string of digits.

But there is a historical trap anyone working with swimming data must clear before comparing anything. In 2026–2026, when World Aquatics was still called FINA, the sport saw a wave of full-body polyurethane suits. So many world records fell in those two years that the entire all-time list was distorted. From 1 January 2026, those suits were banned outright.

The consequence is that every record set in 2026–2026 must pass through an era filter before being compared with today's performances. A swimmer today who is 1.2 seconds off the world record may in reality be closer to the historic ceiling than a 2026 swimmer who was 0.8 seconds off it. Without the filter, every comparison errs in the same direction.

It is worth noting that FINA renamed itself World Aquatics in December 2026. A small detail, but a critical one for data work: every legacy database says FINA, every new one says World Aquatics, and reconciling the two is an engineering problem rather than a search operation.

OQT/OST: the name changed, the reading did not

In Vietnamese media, people still call the Olympic standards A-cut and B-cut. That terminology has been obsolete since the Tokyo 2026 cycle. The current system uses two concepts: the Olympic Qualifying Time, OQT, corresponding to the old A-cut, and the Olympic Selection Time, OST, corresponding to the old B-cut.

The difference is not in the name. An OQT grants direct entry to the Olympics. An OST only places a swimmer in the selection pool, dependent on the remaining quota for each country and each event. A swimmer with an OST may go to the Olympics, or may not. A swimmer with an OQT is essentially certain.

In a commentary piece, that distinction sounds academic. In an investment decision, it is everything. A province funding a swimmer on the basis of "met the B standard" is betting on an unsecured slot. A sponsor signing an athlete billed as "sure for the Olympics" under the old terminology is mispricing its risk.

And here the selection mechanism becomes the most important variable of all. The United States runs a brutal Trials model: top two on the day go, regardless of history. That creates extreme risk for the athlete, who must peak on one specific day. Other countries, Vietnam among them, use a comprehensive-evaluation model in which season-long form and coach judgement both participate. The two models produce entirely different risk profiles for the same athlete with the same numbers.

The puberty barrier: the most neglected variable

Across the whole analytical system, one variable matters more than any other for young female swimmers, and it almost never appears in Vietnamese reporting.

That variable is the puberty barrier. During puberty, especially for female athletes, changes in body composition — rising fat ratio, shifting limb proportions, a moving centre of gravity — typically cause performance to stall or regress for one to three years. It is the leading cause of female "prodigies" disappearing from world rankings at sixteen or seventeen.

Assessing that risk requires exactly three inputs: sex, exact age, and a multi-season performance series. Missing any one, no conclusion is possible. And in Vietnam, the multi-season series barely exists in public form.

Nguyễn Thị Ánh Viên is worth studying for the opposite reason. Born in 2026 in Cần Thơ, she competed at London 2026 at sixteen, at Rio 2026, and at Tokyo 2026. A peak career spanning nearly a decade at international level is rare for a Southeast Asian female swimmer, and it did not happen by luck. It happened through a managed training pathway across precisely the window in which most of her cohort vanished.

Nguyễn Huy Hoàng, from Quảng Bình, competed at Tokyo 2026 in the 800m freestyle and represents a different template: early specialisation in distance events, where the aerobic base and pain tolerance matter more than raw speed. Hoàng Quý Phước, from Đà Nẵng, competed at London 2026 in freestyle and represents the generation that opened the door. Three templates, three pathways, and not one of them documented in a public splits table.

This is where I pause. I do not have enough data to say what any of them should do next. But I know one thing for certain: a career decision about a fifteen-year-old female swimmer, taken without a multi-season data series, is a bet rather than a professional judgement.

Fast pools, slow pools: the variable the audience never sees

There is one more data layer Vietnamese reporting almost never touches: pool conditions.

Pool depth directly affects wave reflection. A deeper pool reduces surface turbulence and lets swimmers move through more stable water. World Aquatics sets a two-metre minimum for top-level competition, and many Olympic pools are built deeper than that. Water temperature, lane width, overflow gutter design, lighting quality — all are variables that create time differences between two swims by the same person in the same week.

The consequence is that a domestic time cannot be compared directly with an international time without an adjustment for conditions. Nobody publishes that adjustment. Nobody asks for it.

I remember sitting at a domestic age-group meet, timing a swimmer to a result her coach called "close to international standard". I asked for the pool length. Nobody on the coaching staff knew for certain. It turned out to be 25 metres. That result, translated to a 50-metre pool, loses most of its value. Nobody lied. Nobody simply noted it.

The contrarian angle: an empty cell is more honest than a full table

Here I have to say something the sports media industry does not like hearing.

An analysis report that looks complete — all nine sections, all the tables, all the professional formatting — but contains no verified content is more dangerous than an error message. An error message forces people to stop. A complete-looking report lets them decide.

I have received exactly that kind of input in my work. A data extraction empty in every field: no title, no source, no information points, no entities. The strongest temptation in that moment was to fill it with general knowledge about world swimming — statements that are true but disconnected from the source text. I refused. A table full of true-but-unsupported claims is worse than an empty cell annotated "no data".

Apply that principle to Vietnamese swimming: a roster of athletes with no positive doping tests and a roster of athletes who have never been tested at meaningful density are two different documents, even though they look identical on paper. Not finding a problem and not having enough information to conclude are two separate drawers. Mixing those drawers is how a sport quietly fools itself.

Luck is something I do not have. I have probability and data thick enough to work with. And Vietnamese swimming data is not thick enough to protect anyone — neither the celebrated nor the suspected.

Signals for the next cycle

A team does not collapse overnight. It collapses when its indicators stop connecting to one another. A swimming nation works the same way: it does not lose standing in a single defeat, it loses it when the data stops being recorded.

Three signals I will be watching in the next cycle. First, whether national meet organisers publish official splits rather than only final times. Second, whether every results sheet carries long-course or short-course as a mandatory field. Third, whether OQT and OST are named correctly in selection coverage, or continue to be lumped together as "standard A, standard B".

Those three signals sound small. But once they appear, everything else shifts with them. Because for the first time, people will have something to ask — and swimmers will have something to answer with.