Temporal cross-correlation between Polar® heart rate monitor interface board and ECG to measure RR interval at rest

BACKGROUND: A Polar heart rate monitor is a device that measures RR intervals, but has not been correlated to accurately measure the series of RR interval signals between the ECG and the Polar® Heart Rate Monitor Interface (HRMI) Board at rest. OBJECTIVE: The aim of the study was to evaluate the temporal cross-correlations between the Polar® HRMI Board and an ECG to measure the series of RR intervals at rest. METHODS: The sample consisted of eighteen healthy male subjects and they were instructed to lie in the supine position at rest while breathing normally and a time window of the last 2 min was recorded to analyse RR intervals were obtained for each subject with a Polar® HRMI Board and an ECG. Cross-correlation analysis of RR interval signals between methods and reliability was expressed by Bland and Altman analysis. RESULTS: The cross-correlation was excellent, resulting in a mean of 0.98 ± 0.01 and no lag or delay between the signals. The bias was 0.03 ± 0.08 s or 8.0% for MeanRRi from Polar® HRMI Board and ECG, no significant difference. CONCLUSIONS: The Polar® HRMI Board is acceptable for assessment of serial RR intervals. The results support the reliability of the Mean RR interval compared to a resting ECG.