Swimming is one of the best full-body workouts, but traditional optical heart rate monitoring is subject to significant inaccuracies underwater due to water currents and body position. However, the latest line of professional sports watches released by Venus Smart Shop uses a fusion algorithm combining multi-wavelength sensors and accelerometers to improve underwater heart rate monitoring accuracy to 92% (compared to fitness trackers).

The challenges of underwater monitoring lie in the fact that water absorbs most light, and arm movements create motion artifacts. The new-generation solution employs a three-color LED combination of “green, red, and infrared” light. The green light offers strong resistance to interference in superficial blood vessels, while the red light is used to compensate for blood flow in deeper layers. At the same time, the watch’s built-in six-axis accelerometer captures stroke frequency in real time and uses AI models to filter out motion noise. Tests by the professional review agency SwimOutlet show that for freestyle, breaststroke, and butterfly strokes, the average deviation between the new smartwatch’s heart rate data and that of a chest-strap heart rate monitor is only ±3.2 bpm. Furthermore, the watch can automatically recognize stroke types and calculate the SWOLF efficiency index (a composite score of swimming distance and stroke count), helping swimmers optimize their technique.

If you’re a swimming enthusiast or a competitive swimmer, the professional-grade smartwatch recommended by Venus Smart Shop will be your best underwater coach, providing data-driven insights for every stroke.