Measurement Properties of the Xiaomi Mi Band 5 for Resting Heart Rate: An Exploratory Study in Healthy Young Adult Men

Introduction. The Xiaomi Mi Band 5 (MB5) is a user-friendly device that offers a wide range of functionalities at a low cost. However, the measurement properties of the MB5 for assessing resting heart rate (RHR) measurement under different conditions have not yet been thoroughly examined. Objective. To analyze the measurement properties of the MB5 wrist-worn device for RHR measurement in healthy adults. Method. This validation study was designed to assess the measurement properties of the MB5 wearable device (global and Chinese version) in measuring RHR concurrently with a gold standard (electrocardiography, ECG). The study included 19 physically active male adults and was conducted in a laboratory setting under static conditions. Measurement properties were evaluated using mean absolute percentage error (MAPE), Lin’s concordance correlation coefficient (ρc), and Bland-Altman analysis. Moreover, two one-sided tests procedure was applied to test the statistical equivalence between the MB5 and the ECG within a pre-specified clinical margin of ±5 bpm. Results. Overall, MAPE was < 2%, and ρc > 0.97, demonstrating high concordance between MB5 and ECG measurements. Bland-Altman analysis further confirmed that all limits of agreement for RHR remained entirely within the pre-specified clinically acceptable margin under both supine and sitting conditions, with mean bias consistently < 1 bpm. Conclusion. The global and Chinese versions of the MB5 showed satisfactory measurement properties for assessing RHR, indicating potential utility for monitoring resting heart rate. Nonetheless, due to the exploratory nature of this study, these findings are strictly restricted to healthy young adult males under static conditions.