The Missing Split Time Column in Vietnamese Swimming Data

On the electronic board at the pool inside the My Dinh National Sports Complex, the results of the men's 200m individual medley final stayed up for about thirty seconds and then went dark. I managed to photograph it: eight names, eight final times, not a single split column. Back in my seat in the stands, I opened the spreadsheet I had built that morning. The 50m column was empty. The 100m column was empty. The 150m column was empty. My equipment was working. What was missing belonged to the organisers.

I have grown used to empty cells like that. More than twenty years of watching swimming, from notebooks kept at the poolside in Hanoi to a full move into sports data analysis, taught me one uncomfortable thing: most conclusions written about Vietnamese swimming are published without enough data to hold them up. Data only recounts; tactics begin with mistakes. To see a mistake, you need every 50m segment to compare. Domestic result sheets rarely give you that.

Vietnamese swimming has a very recognisable results structure. Few athletes reach international standards, and at every SEA Games or Asian Games expectations concentrate on a handful of names. Nguyen Thi Anh Vien once carried most of Vietnamese swimming's gold medals in the regional arena over many years. Nguyen Huy Hoang then became the standard-bearer in the distance freestyle events.

SEA Games 31 took place in Hanoi from 12 to 23 May 2026, with swimming held in the pool of the My Dinh National Sports Complex. For the first time in many Games, Vietnamese swimming competed in a home pool. Home advantage brought a clear psychological edge, and it also exposed something rarely discussed: the quality of the data infrastructure.

Watching how major swimming federations publish results, I see a systematic gap. At world level, result sheets come with 50m splits, reaction times off the start, and in some cases underwater segment data as well. At many domestic meets, what appears is largely the final time and the placing. The distance between those two levels of information is the distance between a news item and an analysis.

The shortage goes beyond journalism. Without splits, academies in Vietnam have no yardstick to judge a swimmer's monthly progress. A swimmer who improves a 1500m time by three seconds over a training block may have gained seven seconds in the finishing laps, losing the rest at the turns. Reading only the total, a coach struggles to know whether to keep the current programme or change direction. Professionals feel this most sharply; spectators barely see it.

The 1500m freestyle is the sum of thirty 50m segments. Two swimmers who touch the wall at the same moment may have swum two entirely different races. One starts slowly, builds evenly and finishes with the fastest lap of the field. The other blasts the first 400m and fades over the last 200m. A final result sheet cannot tell those two apart. Split times can.

The consequences do not stop at reading a race. Without splits, a coach cannot tell where a swimmer is breaking down in order to adjust the training plan. In a 200m event, the gap between an opening lap that is too fast and a fading finish is often only a few tenths of a second, yet it decides the entire effort-distribution strategy. I once sat beside a young coach through an entire final. He hand-timed every 50m segment. Manual timing error usually lands around a few tenths of a second, enough to erase the signal you are looking for.

Technical work suffers more. Starts and underwater segments carry large weight in short events. The 15m rule allows a swimmer to stay underwater for a maximum of 15m after the start and after each turn. Within that window, dolphin-kick technique, entry angle and kick count all feed directly into the time. To assess them you need reaction time, the moment of surfacing and stroke count. Domestic result sheets contain none of that.

Turn data behaves the same way. A turn half a second slower, multiplied by the number of turns in an event, creates a gap that cannot be recovered on the flat. Over 1500m, the accumulated cost of each turn is the most important variable nobody can read. Seeing it requires cumulative time at every 50m mark.

At meets that do publish data, I usually spend the evening after a final cross-checking. The organisers' sheet is one source, the federation's summary is another, and when the two disagree I record the discrepancy instead of choosing whichever suits the story I am writing. The method is slow. One analysis costs three extra hours of verification. It is a cost I accept, because I have already paid for skipping it.

Women's events pay twice. Fewer female swimmers reach international standards in each event, so heats and finals are often merged into a single session with few swims to compare. Without splits, analysis of women's swimming tends to be folded into the men's frame, even though stroke rate, arm span and the distribution of effort in short races differ. Folding them together is the quickest way to erase the character of an entire group of events.

Without data, arguments about the rules also become hollow. How many dolphin kicks are optimal off the start, what entry angle, how long a rest interval between two swims — all of it needs measurement to answer. Lacking measurement, the argument turns on the credibility of the speaker rather than on evidence. Sound opinions get ignored and familiar ones get repeated.

Talent identification is affected too. When only final times exist, selectors naturally pick the swimmer with the best current result and pass over a junior with an outstanding finishing burst but a weak start. Signals like that only surface when a time is broken into segments. For a swimming nation with a small pool of athletes, every missed profile costs years.

The case of Nguyen Huy Hoang at the 2026 Asian Games shows what complete data is worth. According to the Games' official results, the swimmer born in 2026 in Quang Binh took bronze in the men's 1500m freestyle in 15 minutes 08.35 seconds. My point lies in the part that follows the result sheet: at meets that publish splits, an analyst can compare how he distributed his effort against the rivals in the same medal race. Without that part, we know the final number, not how it was built.

My own experience taught me this through a fall. In 2026, writing about the World Cup quarter-final between Belgium and Brazil, I reported Belgium as registering 21 successful presses when the real figure was 14. I wrote from memory, cross-checked nothing, and a reader caught it the same night. My 2026 mistake reminds me that data is a mirror, not a lamp. A mirror only reflects what you put in front of it. An empty input reflects nothing.

Since then I have applied a personal rule: every figure passes two independent sources, and any cell that cannot be verified is marked "insufficient information to assess" rather than filled by inference. The rule sounds dry, but it is the line between analysis and guesswork. In Vietnam's swimming data files, the proportion of empty cells is high enough that many articles should stop at that note.

Suppose a meet published full splits. Effort distribution appears first: whether the closing 200m is faster or slower than the average of the three preceding segments. Then comes technical efficiency, when stroke rate rises while speed does not, meaning the distance covered per stroke is shrinking. Then the cost of turns, the total time lost at each wall touch. None of those can be derived from a final time, however precisely that time is measured.

Back to the men's 200m medley final. Behind me sat a group of parents waiting for their children. One asked: "Which part of the race was he weak in?" I could not answer. Rewatching the race, I would only say he entered the water a little deep on the backstroke leg, and that was an observation by eye, not data. To turn observation into conclusion I need the empty cells in my spreadsheet.

The off-season is when old data is most valuable. When there are no new races, an analyst has to return to result sheets from previous seasons and look for patterns. For Vietnamese swimming, the pool of publicly available data is too thin for that work to be done at the level of a sport. In football, I once spent an entire summer measuring nothing but the distance between a team's centre-backs and its goalkeeper. With domestic swimming, I do not have enough data to begin.

The instinctive reaction is to demand more data. I am not certain that is the right answer, or at least not a sufficient one. More figures without a verification process produces false confidence, not understanding.

Electronic timing costs little for a national-level organiser. The blockage is habit and the requirement to publish: who records, who checks, where it is published, how long it is kept. Without that chain of responsibility, new equipment only changes the look of the empty cell.

One more risk is usually overlooked. When split sheets appear, the analytical crowd tends to sanctify every tenth of a second, while lane-measurement error, timing-station error and water conditions can match the margin under discussion. That is why I always ask how a figure was produced. Stepping into Vietnam's sports data world, I learned to stay silent in front of numbers. Silent first to check, speaking afterwards.

Looked at from the other direction, publishing split times benefits several parties. Organisers gain technical credibility. Coaches gain a tool. Journalists gain material. Athletes gain evidence to negotiate sponsorship with concrete progress rather than a placing alone. None of them pays a large price for one correctly recorded data column.

An empty cell honestly recorded is worth more than one filled with a guess. In swimming, where most readers cannot measure for themselves, the analyst is the only link holding that line.

Based on my experience following domestic swimming meets, the first task for next season is not buying more equipment but requiring 50m splits in official results. With one properly recorded column at every final, within a few seasons we would have an effort-distribution map of the whole sport. A swimmer's movement map is like a chess game: read the intention, predict the next move. Until that map exists, an analyst can only describe the move already played.