The Underwater Phase: Where Vietnamese Swimming Drops Its Medals

The Underwater Phase: Where Vietnamese Swimming Drops Its Medals

At the final of the men's 200-meter breaststroke, I sat in the technical area behind the starting blocks, where the sight line drops straight onto the water and lets you see both the underwater phase and the finish. When the Vietnamese swimmer touched the wall, the scoreboard flashed 2 minutes 14.37 seconds. Fourth place. Exactly three-tenths of a second away from the bronze medal.

Three-tenths of a second. That is not the gap of a conceded goal, nor of a missed shot. It is a gap created by three underwater phases, each roughly one-tenth of a second shorter than the opponent's, adding up to something that could not be rescued in the final twenty meters. I have rewatched this clip eleven times, frame by frame, stopping at every point of surfacing.

Thirty years of watching water, from my 2026 reporting days at Thanh Nien newspaper to now, taught me a seemingly paradoxical lesson: the result of a lane is rarely decided in its loudest stretch. It is decided in the places the grandstand cannot see.

Data only recounts; tactics begin with mistakes. Today I will not praise a beautiful closing sprint. I start from a point of failure: the shortened underwater phase, and the way it was shortened tells us more than any medal about where Vietnamese swimming truly stands in the region.

Context: A sport measured by the naked eye

To Vietnamese audiences, swimming is a strange discipline. We have SEA Games gold medals, names carved into national memory, but most viewers read swimming through the scoreboard rather than through the mechanism that produces the number on it. The result is announced, emotions rise, and that is the end of it.

At the professional level, a 200-meter lane consists of five separable stages: the start, the underwater dolphin phase, surface swimming, turns, and the finish. Each stage can be measured in hundredths of a second. At SEA Games level, where the gap between a medal and fourth place is often under half a second, separating these stages is no longer academic. It is a matter of survival.

Vietnamese swimming competes regionally against three clear forces. Singapore owns a training system tied to a national training center and international scholarships; it treats swimming as a long-term spearhead sport. Thailand invests in school competition and private clubs, generating a deep pool of talent. Indonesia benefits from physical build and a line of speed swimmers raised from childhood.

Where does Vietnam stand in that picture? We have individually excellent swimmers, some SEA Games records, some historic moments. But if you look at the skeleton of the whole system — not just the peaks — the problem is not the closing sprint. It lies in the stages that television cameras seem to forget, and which professional coaches examine first.

I want to use this article to do something I have done many times with football: build the movement map first, fit the data in second, and only then draw a conclusion. In swimming, that map is a map of water — a three-dimensional space where each swimmer chooses how to leave a footprint. A swimmer's movement map is like a chess game: read the intention, predict the next move.

Core analysis: The underwater phase, where the gap is born

Four slices of a lane, measured in tenths of a second

Picture a 100-meter breaststroke lane split into four slices. The first is the start and the underwater phase after it, lasting roughly thirty meters at elite level. The second and third are the two surface-swimming stretches and the mid-pool turn. The fourth is the closing sprint to the wall.

At international level, the underwater phase after the start can reach fifteen meters before breaking the surface for the best swimmers. This is why swimming rules cap the underwater phase after the start at fifteen meters — a limit born precisely because the underwater phase is faster than surface swimming. Read as a map, water is a medium with different drag at different depths, and swimmers exploit that difference.

At SEA Games level, many Vietnamese swimmers can only stay under for roughly eight to ten meters before surfacing. That number sounds small, but summed across the underwater phases of a 200-meter lane, it becomes a gap measurable in time.

Let me use a simple calculation I employ in analysis. Suppose the underwater phase is about twenty percent faster than surface swimming. If you shorten the underwater phase by three meters per instance, and a 200-meter lane has three instances (after the start and after two turns), then nine meters are transferred from high speed to low speed. Nine meters at twenty percent slower is enough to produce nearly half a second.

Half a second. At the SEA Games, that is the entire distance between the podium and the void.

Why the underwater phase is shortened: four causes outside technique

When I say Vietnam goes under for less, I do not blame swimmers for laziness or coaches for isolated error. In analysis, I seek systemic causes before individual ones. Four causes explain most of the gap.

The first is specialized physical foundation. The underwater dolphin phase demands core strength and the ability to keep the ankles extended in a straight posture. This is a different kind of strength from the arm strength that most traditional swim sessions build. A swimmer with good endurance can still stay short underwater if the core and ankles have not been trained correctly.

The second is measurement practice in training. If the coaching staff only times the full lane without isolating the underwater phase, the problem never appears on the data sheet. You cannot fix what you do not measure. And you cannot measure what you do not separate.

The third is accumulated technical volume from youth. The underwater phase is a skill requiring thousands of correct repetitions to become reflex. If a swimmer begins serious underwater training at fifteen rather than nine, they will forever be one beat behind someone who began young.

The fourth, and in my view the most important, is how we imagine a lane. In popular perception, swimming is an arm race. The fastest swimmer is the one who pulls hardest. That view is partly right — but it neglects the stage that generates most of the differential at elite level.

Swimmer spotlight: The turn and the ankles

I want to dedicate a section to a detail I always watch in the water: the swimmer's ankles during the underwater phase.

Across many regional meets I have tracked, I noticed a pattern. Vietnamese swimmers with short underwater phases tend to flex their ankles during the dolphin kick, while those with long underwater phases keep the ankles extended, taut as a blade. The difference is so small it is hard to see with the naked eye on television, yet it changes the contact area with water and therefore the forward propulsion.

If I had to pick one metric to track Vietnamese swimming over the next two seasons, I would not pick medal count. I would pick average ankle angle in the underwater phase. It can be trained, measured, and improved within a shorter cycle than building a new academy.

Another detail closely tied to the underwater phase is the turn. In breaststroke and butterfly, the turn includes the underwater phase after the push-off. In freestyle and backstroke, the underwater phase after the turn is where arms and legs coordinate for momentum. A swimmer with a good turn but a short underwater phase loses most of the advantage just created. Conversely, a swimmer with a good underwater phase can compensate for an average turn.

I once watched a lane where the swimmer lost ground in the opening water, gradually closed the gap, and only won in the final twenty meters. When I broke down the data, the winner had gone farther underwater on all three occasions, and the closing sprint was a consequence — not the cause — of the win.

That is why I always tell young coaches: do not train the closing sprint while the underwater phase is still short. You are teaching a swimmer the skill of extra time while the match is decided in the opening ten minutes.

From underwater to finish: a chain of causation

The underwater phase does not exist in isolation. It sits in a chain that runs all the way to the finish.

A short underwater phase forces the swimmer to surface earlier. Surfacing earlier means more surface swimming. More surface swimming means more energy spent. More energy spent in the middle means less reserve for the end. And the end — the final twenty meters — is where medals are decided at SEA Games level.

That is a chain. A short underwater phase does not just lose its own time. It weakens what follows.

When I analyze, I try not to stop at the final number. The final number is the result of a chain of choices. To change the number, one must change the chain of choices. And the chain of choices changes only when the coach sees it.

The execution blind spot: We praise the wrong thing

This is the part I deliberated longest, because it touches a habit deeply embedded in how we watch sport.

In any sport, audiences are served what can be seen. In swimming, that means clear arm pulls, flashing scoreboards, closing sprints. This is not wrong. But it creates an attention bias: we praise the part of the race that is televised and overlook the part that is not.

In football, this bias makes people praise strikers and ignore holding midfielders. In swimming, it makes people praise arms and ignore ankles. The nature of the problem is the same.

The second blind spot is subtler. For years I have watched Vietnam produce swimmers with good closing sprints, sometimes the best in the region. This is a real asset. But it can become a trap when it becomes the only model. When younger generations learn from the sprint model, they optimize for the end and neglect the beginning. The result is swimmers who are excellent in the part of the race where the fewest points remain available.

I am not saying the sprint does not matter. I am saying: if you have only one asset and it lies at the end, the best way to use it is to make sure you still have reserve when you reach the end. And that reserve is created in the underwater phase.

I do not believe in hunches. I believe in asking how many variables that hunch has absorbed. When a coach says a swimmer "has good water feel," I always want to translate that sentence into measurable variables. Good water feel, in the end, is a metaphor for a mechanism trained enough to become automatic.

Closing: A question to verify

Next season, when regional meets take place, I will carry a specific metric: the average length, in meters, of the underwater phase after the start for Vietnamese swimmers.

If that number improves and the gap in the final twenty meters does not worsen, we are heading the right way. If that number stays flat while we still win at the end, we are winning with something that can run dry. And if that number improves but medals do not come, at least we know we are measuring the right place and need another cycle.

Vietnamese swimming does not lack talent. It lacks a way of measuring that respects every stage of the lane. And in sport, respect is usually repaid in time.

Technical afterword: Why I wrote this

I entered the data world with the memory of 2026, when a misrecorded number forced me to issue a correction in the middle of the night. My 2026 mistake reminded me that data is a mirror, not a lamp. It reflects what happened; it does not illuminate the road ahead by itself.

This article does not aim to claim Vietnamese swimming will win or lose. It only proposes a way of looking. When we grow used to measuring the whole path, from leaving the block to touching the wall, we will stop being surprised by three-tenths-of-a-second gaps. Because that gap is not born in the final minute. It was born in silence, beneath the surface, in the opening seconds before the grandstand could shout.

Appendix: Four terms to remember

Underwater phase: the stretch where the swimmer moves beneath the surface after the start or a turn, using the dolphin kick. It is the stage with higher speed than surface swimming at the same energy cost.

Turn: the stretch where the swimmer contacts the pool wall, pushes off, and changes direction. A good turn time is usually under half a second.

Finish: the final action of touching the wall to end the lane. It is the most precisely timed stage.

DPS (distance per stroke): the metric measuring how far each stroke cycle carries the swimmer. Higher DPS indicates better technical efficiency, and is often more important than stroke count.

A final note on method

I always try to write analysis as a map before writing it as commentary. That is, I define the space first — water, underwater phase, turn, finish — then fit the data into each cell, and only then draw a tactical conclusion.

This method sometimes slows the writing. But it has an advantage: it makes it hard for me to reach a wrong conclusion because I have fallen in love with a story. In sport, stories are seductive. Data, by contrast, is rather dry. And precisely because it is dry, data is useful.

Some ask why I chose to analyze swimming when most of my writing career is tied to football. The answer lies in the fact that I see water in every sport. Football is a space with a vertical and a horizontal axis, with gaps and with timing. Swimming is the same, except the medium is thicker — in swimming, the space is not a pitch but the very medium you move through. Once you are used to reading movement in water, you can read movement on a pitch more easily.

Thirty years taught me that people rarely lose where they are paying the most attention. They lose where they have forgotten. In Vietnamese swimming, that forgotten place lies beneath the surface, in the seconds before the grandstand could shout.