Modern basketball requires high-intensity physical performance, making stamina one of the key factors influencing athletes^ achievements. A decline in stamina can negatively affect concentration, coordination, and overall player performance, while also increasing the risk of injury due to uncontrolled training loads. Despite its importance, monitoring athletes^ physical condition is still often carried out manually and subjectively through visual observations and verbal reports. This makes it difficult to guarantee the objectivity and accuracy of the collected data. Therefore, this study aims to design a real-time stamina monitoring system for basketball players using Internet of Things (IoT) technology based on the ESP8266 microcontroller. The research method applied a prototype engineering approach through iterative development, starting from initial design, testing, and improvement based on user evaluation. The MAX30102 sensor is employed to measure heart rate and oxygen saturation, while the MPU6050 sensor detects running speed. Data are transmitted via Wi-Fi to a MySQL-based web dashboard. The results show that the system is capable of continuously recording physiological data and providing informative visualizations. Testing indicated that the system responds stably, with data accuracy sufficient for use as a monitoring aid during training sessions. Trials on five players demonstrated that the system could classify stamina into three categories (fit, tired, needs rest) with an average accuracy of 96.8%. A user evaluation (n = 7) yielded a score of 4.39 out of 5.00 (excellent). The system effectively assists coaches in making training decisions and reduces the risk of injury due to overtraining.
