Vietnamese Swimming: The Data Gap and the Analyst's Dilemma

In May 2026, I sat before a screen with a spreadsheet compiling Vietnam's swimming results at the SEA Games over more than a decade. The column of finishing times was full. The column for the first 50 metres, the column for stroke cycles per length, the column for underwater turn time — empty. I moved the cursor back and forth across the white cells, and it felt like reading a piece of music that had only a final note. Numbers do not lie, but they know how to hide something — and in Vietnamese swimming, what is hidden most carefully is the number itself. A swimming nation with athletes, medals and sponsorship contracts, yet operating on collective memory: remembering where someone stood on the podium, forgetting how they swam to get there. I am not writing this to criticise any federation or training centre. I am writing because over many years in this profession, I have fallen into the same trap many times: analysing a lane of swimming when the only thing in my hands was the final result. A decent swimming analysis must pass through nine dimensions — technique, performance and data, competition systems, the world map of each event, rules and anti-doping governance, an athlete's career trajectory, the risk profile, the media narrative, and the industry ripple. All nine require a minimum raw material: data points. When data points equal zero, the nine dimensions collapse into a single sentence — insufficient information to conclude. And that, precisely, is the state of Vietnamese swimming on the analysis desk. In swimming, every lane is a sequence of technical decisions divided into four clear parts: the start and underwater glide, the free-swimming stretch, the turns at the wall, and the final sprint. A swimmer can lose in the first 15 metres, or win at the last turn. But to know that, the analyst must have splits — segment speeds — not just the total printed on the scoreboard. This is the fundamental difference between swimming and athletics: in a 100-metre sprint, you win or lose in a single moment; in a swimming lane, the result is written as a book with several chapters, and each chapter can deliver a different verdict. Since my days as a reporter covering domestic meets, I have grown used to post-race press conferences. Coaches speak of spirit, of effort, of targets. No one offers a specific number for how much speed their athlete lost over the final 50 metres, or how many seconds their turn lagged behind a rival's. Not because they do not know, but because the data-collection system never existed to know. What troubles me most is not the shortfall itself, but how that shortfall disguises itself as information. Each time a Vietnamese swimmer wins a medal, the articles fill with the same numbers: time, ranking, national record. Those numbers are correct, but they are only the tip of an iceberg whose submerged part no one measures. We know an athlete swam the 200-metre breaststroke in two minutes twenty seconds, but we do not know how those two minutes twenty seconds were divided between arm strokes, leg kicks, and underwater glide. In deep swimming analysis, there is one principle I learned from the very blankness of my own spreadsheet: what a sport does not measure is often what it does not want to see. If you do not record splits, you will never have to admit that an athlete is losing from the underwater phase — where many medals are decided. If you do not record stroke cycles per length, you will never have to face the hard question: is your swimmer moving efficiently, or trying to compensate with brute force? Each swimming event has its own technical grammar, and each grammar demands its own kind of data. In freestyle, the decisive variable usually lies in the underwater phase after the start and after each turn — where the rules allow up to 15 metres before the head must surface. An athlete who uses the full 15 metres can create an advantage the naked eye cannot see. In breaststroke, everything revolves around rhythm: the rules allow only one leg kick per cycle, so efficiency lies in coordinating arms, legs and the glide. In backstroke, the start device and the first push decide a great deal, while in butterfly, the price of fatigue arrives earlier than in any other event. Without split data, the analyst cannot separate these things. We see only a total, like reading a student's grade-point average without knowing whether they excel at maths or literature. And in swimming, where the gap between gold and bronze can be three-tenths of a second, that blindness is a serious waste. I have replayed the SEA Games in my memory. There were finals where winner and loser were separated by one-hundredth of a second. The media called it a historic moment or a bitter regret. But with split data, the story would be different. Perhaps the loser did not lose in the swimming itself — they lost at the third turn, two-tenths slower, or in a start glide several metres shorter. One-hundredth of a second on the scoreboard is the outcome of a specific chain of technical decisions. Without data, all we have left is a vague faith in form and psychology. This matters even more when we look beyond the border. Swimming is a sport where the distance between nations is measured in hundredths of a second, and the leading swimming powers have turned data collection into an industry. In the top swimming nations, every training session is recorded; every technical change is measured before and after; every rival is profiled with splits for each segment. For them, a national record is not an end point but a benchmark against the world standard. For us, a national record is often the end of every question. And this is what I want to state most clearly: without data, all swimming analysis is merely inference legitimised by a confident tone. A writer can say this swimmer faded in the final stretch without proving it, because beside the pool, no one rebuts with a number. That asymmetry pushes even the most honest analyst toward two choices: say what is under-supported, or stay silent while louder voices take the stage. So what would a decent swimming data system look like? First, it needs splits at every 50-metre segment, at least at the 15-metre and 25-metre marks of the first half, to separate the start and the glide from the free swim. Second, it needs separate turn times at each wall, because a 200-metre race has three turns, and the accumulated error can reach half a second. Third, it needs stroke rate and distance per cycle, to distinguish an efficient swimmer from a strong one. Fourth — and this is the most neglected — it needs context: long course or short course, lane conditions, where the athlete sits in the training cycle, and who shares the lane. Without that fourth group of data, every comparison becomes meaningless. A time swum in a 25-metre short course cannot be compared directly with one in a 50-metre long course, because the different number of turns creates entirely different advantages. A result achieved in the low point of a training cycle says nothing about peak capability. And a record set without a rival of equal class cannot be judged like one set in a race that was forced to the final metre. Swimming is a sport of context, and separating a result from its context is the most common mistake of the hasty analyst. With all four data groups, reading a swimming result would change completely. A new national record would no longer be a single bright point, but the outcome of a specific improvement in the turn, or the glide, or the ability to hold stroke rate under fatigue. More importantly, it would allow a Vietnamese swimmer to be compared with regional and world standards in the proper language of the sport, rather than through a vague sense of level. We have figures to look at. Over the past decade, Vietnamese swimming has had faces who built a standing on the continental stage and won medals at regional Games. But even with the most successful athletes, the technical legacy remains faint — because no one systematically recorded how they produced their results. A mature sport does not only produce medals; it also produces understanding of how the medals were produced, so the next generation can start from there instead of starting again from zero. But here I must stop myself for a second, because I know the next trap is waiting: believing that having data means having the truth. Correlation is not causation. An athlete who improves turn times and simultaneously wins a medal does not mean the medal came from that turn — they may simply have been stronger at the right moment. Data is testimony, not a verdict. Every lane is a data point, but not every data point is a lane — and a good analyst is one who can tell the number that describes a single swim from the number that describes an entire sport. I must also acknowledge my own limits. There are things in swimming that data cannot measure: the competitive instinct in the final 25 metres, the tolerance for pain when the muscles burn, the calm before a race the whole stadium is waiting for. A good data system does not erase those things — it simply places them where they belong, so emotion cannot masquerade as evidence. And perhaps, for a swimming nation still wrestling with basic questions of coaching and investment, pursuing deep data sounds like a luxury. But I do not believe it is a luxury. That summer in Saigon, I learned that data also needs watering — it only lives when tended from the smallest things: a spreadsheet cell filled in after every session, a camera placed at the wall to time each segment, a habit of never compromising with the total. None of those requires a huge budget. They require discipline: accepting that the empty spreadsheet is a warning, not a harmless void. If I had to leave one question for the people of Vietnamese swimming, it would be this: do you want to win medals, or do you want to understand how you win them? Because those two goals lead to two different systems. One builds results on inspiration and talent. The other builds both on a notebook that is never left blank. I will sit with my spreadsheet for many more nights. And each time a cell is filled where there was a blank, I know Vietnamese swimming has moved forward one step — not on the medal table, but on a page that someone later can read to understand why the medal table looks the way it does.