Vietnamese Swimming: From Data to Tactics – Lessons from Mistakes

Vietnamese Swimming: From Data to Tactics – Lessons from Mistakes That moment happened at SEA Games 31, when Nguyen Thi Anh Vien touched the wall in the 400m freestyle with a time of 4 minutes 12.34 seconds. The entire stadium erupted, but I wasn't looking at the electronic scoreboard. I was looking at my stopwatch – it was 0.7 seconds off from the official result. I knew I had just witnessed a mistake in how we read data, and that's when I realized: Vietnamese swimming is improving, but the way we analyze it is still swimming against the current. Swimming is a sport of numbers. From stroke rate, stroke length, to start angle, everything can be measured. But in over a decade of following national teams, I've noticed a paradox: we have more data than ever, yet we have less real understanding of tactics. Coaches still rely on feel, analysts get stuck in dry spreadsheets, and athletes have to figure out the most effective way to swim on their own. This article is not a report of achievements. It is a tactical dissection, based on tracking data from recent SEA Games, Olympics, and national championships. I will point out the systemic mistakes I have observed, and more importantly, how we can fix them. Let's start with a number: 58%. That's the percentage of time that Vietnamese freestyle swimmers spend in the glide phase of each stroke cycle, according to data I collected from 12 top athletes at the 2026 national championships. This number is 12% higher than the Asian average for the same distances. At first glance, this seems good – a long glide is often considered a sign of efficient technique. But when I looked closer, I found that most of that glide time comes from athletes reducing their stroke rate too much, rather than optimizing the length of each stroke. They are swimming slower, not because they are stronger, but because they are afraid of getting tired. This is a classic tactical mistake that I call the 'glide trap'. It stems from a common misconception in Vietnamese coaching: that a longer stroke is always better than a faster stroke. In reality, according to my research, the best performers in the 200m and 400m events typically maintain a stroke rate of 0.8 to 0.9 cycles per second, while Vietnamese athletes only reach 0.6 to 0.7. As a result, they lose continuous propulsion, and when they need to accelerate in the final 50m, they no longer have the energy to change their rhythm. I remember the 200m freestyle final at SEA Games 31. Singapore's Joseph Schooling swam with an average stroke rate of 0.92 cycles per second throughout the 200m. He didn't glide long, but each of his strokes had powerful propulsion thanks to an optimal elbow angle. Meanwhile, our Vietnamese athlete, despite having a good physique, swam at a rate of 0.65. The result was that Schooling finished in 1 minute 46.12 seconds, while our athlete only managed 1 minute 50.45 seconds. The 4-second difference didn't come from physical fitness, but from a tactical mistake. Data only tells the story; tactics begin with mistakes. This phrase has followed me for 10 years in this profession. And the biggest mistake I see in Vietnamese swimming is not in individual technique, but in how we build training programs. Most training centers still apply the 'swim more to be better' method, with volumes up to 80-100km per week for young athletes. This is completely contrary to modern trends worldwide, where teams like Australia or the US only train 50-60km per week but focus on the quality of each stroke. I had the opportunity to talk with an Australian coach who once worked in Vietnam. He told me: 'Your athletes swim a lot, but they swim wrong. They don't know how to feel the water, they just know how to hit the water.' That statement startled me. I started reviewing slow-motion videos and realized that most Vietnamese athletes have a technical flaw in the pull phase: they pull their arm too early, don't keep the elbow high, causing the propulsion to be dispersed. This is a common mistake that coaches often overlook because they only look at results, not at movement. Summer without football is when high pressing reveals its skeleton. In swimming, summer is when major competitions take place, and it's also when tactical mistakes are most exposed. I spent the summer of 2026 analyzing all the competitions of the Vietnamese swimming team at SEA Games 32. The results were alarming: in 10 finals, we only won 2 gold medals, and both came from Anh Vien's specialty events – she has already retired. The young athletes replacing her not only lack experience, but also lack racing tactics. A typical example is the men's 400m individual medley. Young athlete Nguyen Huy Hoang, who was expected to succeed Anh Vien, swam the first 100m backstroke too fast, with a time of 1 minute 02 seconds, 3 seconds faster than planned. As a result, he exhausted himself in the 100m breaststroke and finished with a time 5 seconds slower than his best ability. When I reviewed the data, I saw that Huy Hoang had been swept along by the pace of the Indonesian swimmer, who swims backstroke very fast. He had no specific strategy, no idea how to distribute his energy. This is not Huy Hoang's fault, but the fault of a training system that didn't teach him how to read a race. An athlete's movement map is like a chess game: read the intention, predict the next move. In swimming, the movement map is the speed distribution over each 50m. I plotted the speed graphs of 20 swimmers in the 200m freestyle at the 2026 national championships. The results showed a very clear pattern: most Vietnamese athletes swim the first 50m too fast (2-3% faster than average speed), then drop off suddenly in the third 50m, and only slightly increase in the final 50m. This is a 'swim fast then die' pattern, contrary to the optimal pattern of world-class swimmers, where they swim the first 50m 1-2% slower than average, maintain a steady pace in the middle, and accelerate strongly in the final 50m. My mistake in 2026 reminded me that data is a mirror, not a lamp. I once wrote an analysis of Anh Vien's breaststroke technique, based on tracking data from a sensor device. I concluded that her elbow angle was too low, and suggested a correction. But later I realized that I hadn't accounted for Anh Vien's arm length – she has longer arms than average, so a lower elbow angle is normal. That article was criticized by a veteran coach, and I learned a deep lesson. Since then, I never make tactical conclusions based on just one data source. I always cross-check with at least two independent sources, and I always ask: does this data truly reflect the context? In swimming, context is everything. A 50m freestyle swimmer will have a completely different technique than a 1500m freestyle swimmer. But I see that many Vietnamese coaches still apply a common training plan for all distances. They don't distinguish between sprint and endurance swimming, leading to sprinters losing their explosiveness, and endurance swimmers lacking stamina. This is a tactical mistake at the systemic level. I don't believe in intuition. I believe in how many variables that intuition has been loaded with. When I analyze a race, I don't just look at the result; I look at the entire process: reaction time at the start, underwater time after the dive, number of dolphin kicks, turn angle, stroke rate, stroke length, and most importantly, speed distribution. All these variables create a complete picture of an athlete's tactics. A successful pressing move starts with recognizing how the opponent doesn't want to be broken. In swimming, this means we must recognize the opponent's weaknesses. For example, if an athlete has poor turn technique, we can accelerate in the approach phase to create distance. If an athlete tends to slow down in the final 50m, we can swim slower in the middle to save energy for a sprint finish. But I rarely see Vietnamese athletes having specific tactics for each opponent. They usually swim by feel, and as a result, they are passive in the race. Stepping into the Vietnamese football data world, I learned to be silent in front of numbers. In swimming, I learned the same thing. Data doesn't speak for itself. It needs to be interpreted, placed in context. A 0.7-second difference could be due to equipment error, or it could be due to an athlete changing technique. We cannot jump to conclusions. The transfer market is a huge error map. The wise look for blind spots, not treasure. In swimming, the 'transfer market' is the generational transition. We are witnessing the departure of the Anh Vien generation, and the rise of a new generation. But this new generation is facing a big problem: they don't have a systematic training program to develop tactics. They are taught how to swim, but not how to race. I spent 6 months analyzing data from 30 young athletes aged 16 to 20 at key training centers. The results showed a worrying pattern: most of these athletes have good results in youth competitions, but when they join the national team, they cannot improve their times. The reason is not physical fitness, but because they don't know how to adjust tactics when facing stronger opponents. They are used to swimming alone, used to leading, and when they face pressure from opponents, they don't know what to do. This is a psychological issue, but also a tactical one. In swimming, tactics are not just about energy distribution, but also about the ability to read the race, to adapt to the opponent's pace. A good swimmer is one who knows when to swim fast, when to swim slow, and when to make a sudden acceleration. This requires training not only physically, but also mentally. I propose a solution: we need to build a tactical analysis system for swimming, similar to what has been done in football. We need analysts who specialize in tracking each athlete, recording all their races, and providing detailed analysis of strengths, weaknesses, and ways to improve. We need to teach athletes how to read data, how to understand their own bodies, and how to build tactics for each race. I tested this method with a group of 5 young athletes at the Da Nang National Sports Training Center. I taught them how to use stopwatches, how to keep training diaries, and how to analyze their own races. After 3 months, their times improved by an average of 2%, a significant number. More importantly, they became more confident, they began to understand that winning doesn't just come from swimming fast, but also from swimming smart. I'm not saying we should completely copy foreign models. Each country has its own sports culture, and we need to find a path that suits our conditions. But we need to change our mindset. We cannot continue to rely on feelings, on the personal experience of each coach. We need to build a system based on data, based on science, and based on serious tactical analysis. My mistake in 2026 reminded me that data is a mirror, not a lamp. The mirror reflects reality, while the lamp illuminates the path. We need both. We need data to see the current state, and we need tactics to find the way forward. Vietnamese swimming is at a crossroads. We can continue swimming in the old rut, or we can embrace change, embrace learning from mistakes, and build a brighter future. The final question I want to ask is: do we have the courage to look into that mirror? Do we have the humility to admit we were wrong, and the determination to fix it? I believe the answer is yes. I have seen positive signals from young athletes, from young coaches, and from sports managers. They are eager for change, and they are looking for new methods. Our task, as analysts, is to provide them with the necessary tools. Swimming is not just a sport of numbers. It is a sport of decisions. Each stroke is a decision, each breath is a decision, each turn is a decision. And those decisions need to be based on data, on analysis, and on a deep understanding of oneself and the opponent. Only then can we swim faster, smarter, and more successfully. I will continue to follow, continue to analyze, and continue to share what I learn. Because I believe that, with perseverance and science, Vietnamese swimming will not just be a sport, but a national pride.