Your watch recorded extra swimming distance: did you swim farther, or was the GPS wrong?

You finish an announced competition with 1,500 meters and the watch shows 1,640 meters. The difference may suggest a bad navigation, but the number alone does not allow closing the discussion. Before turning the data into technical diagnosis, it is necessary to ask how it was obtained.

A review of 2026 precisely examines the construction of these measures in open water sports and proposes ways to better analyze the swimming stage in the triathlon.

What the review found

Seelhöfer et al. included 20 studies with satellite positioning technologies. Only one was swimming; most investigated sports such as surfing and sailing. The report of technical aspects was classified as low in eight studies, intermediate in ten and high in two. Methodological diversity prevented a meta-analysis.

The authors propose an evaluation model that considers sensor positioning, sampling frequency, signal quality and processing. It is a proposal based on the literature, not a test that validates all commercial clocks or determines their universal error.

Recorded distance is the result of a measurement

To reconstruct a trajectory, the system uses successive position estimates. If each point contains some error, the final design may incorporate displacements that did not happen. At the same time, a real path can present curves and deviations that increase the distance effectively traveled.

Therefore, precision of the device and navigation of the athlete are explanations that need to be examined separately. Compare the recorded route with the design of the competition, observe unlikely points and consider the behavior of the signal helps to formulate better questions.

The review highlights difficulties related to submersion and acquisition conditions. A visually convincing chart does not eliminate these limitations. It is also not enough for the system to present many decimal places: screen resolution and measurement quality are different characteristics.

Editorial example: three interpretations for the same difference

Imagine three situations with distance recorded above the nominal. In the first, the trajectory shows a broad and coherent deviation before a buoy. In the second, instant jumps appear incompatible with human speed. In the third, the design is plausible, but there is no independent measurement of the path of competition.

The three deserve different interpretations. The first can guide a review of navigation; the second suggests a problem in registration; the third preserves uncertainty about the origin of the difference. The same final result in meters does not produce the same explanation.

This also affects the calculated pace. If the distance changes artificially, the time by 100 meters derived from it changes together. An apparent improvement may be partially linked to the way the distance was estimated.

What does that teach the swimmer?

Use the record to investigate, not to decide on your own whether the competition was short, whether you swam wrong or if conditioning has changed. The comparison gains value when it combines official time, trajectory, context and repetition under similar conditions.

For the trainer, the technology opens questions about navigation and distribution of the pace. For the researcher, it requires transparency on data acquisition and processing. The fact that the review found only one swimming study shows that there is still an important space for specific validation.

Measuring more does not guarantee better understanding. Gain appears when we know the question the sensor can answer and the degree of confidence that the answer allows.

Cada um no seu ritmo. Juntos no caminho.