Design of a Wearable Heart Rate Monitor with Wireless Data Transmission for Sports Medicine at Nigerian Universities

Wearable heart rate monitoring during athletic training and competition is standard practice in sports medicine globally, but affordable locally developed wearable devices for Nigerian university sports medicine programmes are absent from the market. This study designs a wearable heart rate monitor with wireless data transmission intended for sports medicine applications at Nigerian university athletic programmes. The device is built around a MAX30102 optical heart rate sensor using green light photoplethysmography for continuous heart rate measurement, managed by an ESP32 microcontroller that provides both Bluetooth Low Energy and Wi-Fi connectivity. Heart rate data are streamed in real time at one-second intervals to a companion Android smartphone application displaying a live heart rate trace, training zone indicators based on athlete maximum heart rate profiles, and session data logging for post-exercise analysis. The device is housed in a silicone wristband enclosure weighing less than 35 grams with IPX4 splash resistance for training use. Battery capacity of 120 mAh provides eight hours of continuous monitoring. Bluetooth transmission range was confirmed at fifteen metres. Accuracy validation was conducted on thirty student athletes at the University of Nigeria Nsukka Sports Science department, comparing wearable readings against a Polar H10 chest strap reference during treadmill exercise protocols at different intensities. Mean absolute error was 2.6 beats per minute, with accuracy declining slightly above 160 beats per minute. The study recommends incorporation of R-R interval analysis for heart rate variability assessment and further ruggedization testing. Keywords: wearable heart rate monitor, sports medicine, photoplethysmography, ESP32, university athletics.