Shoulder Injuries in Vietnamese Swimming: The Gap Is in the Logbook, Not in the Pool

In June 2026, at a youth training camp in northern Vietnam, I stood at the edge of lane two and counted the stroke rate of a seventeen-year-old swimmer in the 200m butterfly. At the 150m mark, the range of motion in his right arm narrowed and his torso tilted left to compensate for the rotation axis. That afternoon I opened the centre's medical log and found exactly three lines for that case: date, name, and a short note — "right shoulder pain, three days off". No weekly training volume, no butterfly metres, no date for when the pain first appeared. I asked for the squad's workload tracking sheet. The centre did not have one.

At Lach Tray, I learned to read injuries from the first numbers, and that lesson followed me onto the lanes: an injury only becomes data when it has a baseline to compare against. Those three lines in the logbook are not data. They are memory.

Swimming carries the largest training volume of any individual sport. A national-team swimmer typically trains twice a day, six days a week, accumulating roughly forty to sixty kilometres of pool distance. The shoulder joint rotates through a wider arc than any other joint in the sport; a ninety-minute session can contain more than two thousand shoulder rotations. Sports-medicine reviews published in specialist journals over many years land in the same band: forty to seventy per cent of competitive swimmers experience shoulder pain at some point in their careers, with butterfly and backstroke showing the highest rates.

At most training centres in Vietnam, none of those figures are recorded. Names such as Nguyen Huy Hoang, a two-time Olympian, or Nguyen Thi Anh Vien, who also competed at two Olympic Games, show that Vietnamese swimming has reached the big stage. The system behind them has not kept pace. A typical centre has three to five coaches covering four age groups, no dedicated sports-science unit, no one assigned to data entry, and a pool that must be shared between the junior squad and the national team. Under those conditions, workload logging is treated as an optional chore rather than a mandatory duty.

I once built a load-monitoring system for forty-three footballers, logged one hundred and twenty-seven injuries over four months, and used it to flag eight high-risk cases before they broke down, cutting the squad's days lost by twenty-three per cent. That method does not belong to football. It belongs to any sport with a sufficiently large volume of repeated movement — and swimming sits at the top of that list.

Injury mechanisms in swimming split cleanly by stroke. Butterfly and backstroke load the shoulder with the arm overhead, where the subacromial space is narrowest; this is the region compressed repeatedly during every stroke cycle. Breaststroke creates a valgus load on the inner knee, which is why breaststroke knee pain has a mechanism quite different from running knee pain. Freestyle and butterfly drive the kick from the lumbar spine, making low-back pain the third common presentation, particularly among fifteen- to eighteen-year-olds whose spines are still developing.

What the three groups share: none of them appear in a single session. They accumulate across hundreds of sessions. Injury in swimming does not begin in the shoulder; it begins on the blank page of the workload logbook. When the log records only "shoulder pain, three days off", nobody can know how much the seventeen-year-old's butterfly metres rose in the preceding fortnight, or how many months ago the previous episode occurred. Every intervention that follows must rest on guesswork.

The widely accepted rule for safe load progression in sports medicine is no more than ten per cent per week, with a deload week after every three to four weeks of increase. The rule sounds simple, but it can only be enforced when baseline numbers exist. A coach cannot know he is exceeding ten per cent if he does not have last week's figure. That is why I spend most of my time not diagnosing shoulder cases, but persuading centres to log workload before it becomes a shoulder case.

Every collapse has a graph, and every graph has a break point. On the lanes, the break point usually sits in the third week of a continuously rising load, when the first pain appears but is not yet enough to slow the swimmer down — so it is ignored.

Most of the debate around injuries to Vietnamese swimmers blames poor arm technique, body type, young athletes being "not tough enough", or competition psychology. The first three explanations may each hold some truth, but none has a baseline against which to test itself. A swimmer's technique becomes a cause only when someone can demonstrate that shoulder rotation range narrowed abruptly while training volume stayed flat. I have never seen that kind of data inside a Vietnamese training centre.

One coach once rejected a ten-day progressive loading protocol for his reserves because he "needed to win the opening match". An empty stadium, a golden rule bent out of shape, and the body pays — not that day, but in week four. The trap in swimming is harsher: no scoreboard lights up to warn that a shoulder joint is crossing its threshold. There is only the stopwatch, and a stopwatch does not measure soft tissue.

The body is a closed system, but data is the key that opens it. A usable swimming log needs four columns: total metres per session, metres by stroke, average heart-rate intensity, and a one-to-ten self-rating for shoulder, back and knee. Those four columns, kept consistently for three years, would tell a centre exactly which region of which athlete tends to cross its threshold at which stage of the training cycle. The cost is close to zero. The cost of not doing it is already written in that three-line logbook.

Vietnamese swimming is rising on individual talent and the persistence of a handful of coaches, not on a system. If nobody sits down over the next three years to fill in those four columns, every gain in performance will continue to be paid for with the shoulders of seventeen-year-olds.