<![CDATA[Relay sprint performance is influenced by the efficiency and synchronization of baton exchanges, yet current evaluation methods remain largely subjective and fragmented. This study aimed to develop and evaluate an integrated Smart Relay Baton and multisensor wearable system for objective and real-time assessment of relay performance. A research and development approach based on the Borg–Gall model was employed, followed by a quasi-experimental pre–post design involving 241 sprint relay athletes. The system integrated accelerometer-based motion tracking within the baton and physiological monitoring through wearable sensors and smartwatch support, with synchronized data transmission via an MQTT-based IoT architecture. Key variables included transition time, entry speed, average acceleration, synchronization delay, heart rate response, rating of perceived exertion (RPE), and the Relay Performance and Orchestration Index (RPOI). Results showed pre–post changes in transition time (Cohen’s dz = −0.82), synchronization delay (dz = −0.74), entry speed (dz = 0.74), average acceleration (dz = 0.48), and RPOI (dz = 1.05). Heart rate during the exchange showed a small reduction (dz = −0.32), while 60-s heart rate recovery increased (dz = 0.54) and RPE decreased (dz = −0.75). These findings indicate that the integrated system can provide comprehensive, data-driven information on baton exchange and relay performance by combining movement and physiological measures. However, the observed changes represent within-participant differences and should not be interpreted as evidence of a causal effect of the system or as evidence of pedagogical effectiveness.]]>
