Validity of a temple-mounted photoplethysmography-based heart rate sensor compared with a chest-strap reference during swimming in adolescent competitive swimmers

This study aims to evaluate the validity of a photoplethysmography-based optical heart rate sensor worn at the temple during swimming, using an electrocardiogram-based chest strap as the criterion reference. Heart rate will be recorded concurrently from both devices during standardized swimming trials designed to represent common training and competitive scenarios, including continuous swimming, interval-based swimming, and mixed-stroke swimming tasks. Agreement between devices will be assessed across a range of exercise intensities and swimming conditions using agreement-based statistical methods. The results are expected to provide practical insights into the applicability of optical heart rate monitoring as an alternative to chest-strap devices in competitive swimming, particularly in adolescent athletes.