Validity of the polar S810 to measure R-R intervals in children

Intervals between two consecutive cardiac beats (R-R intervals) and the subsequent analysis of heart rate variability (HRV) obtained simultaneously from the Polar S810 heart rate monitor (HRM) and an electrocardiogram (ECG) in a supine position were compared in twelve children (age 9.6+/-0.9 years) before and after protocol correction. R-R intervals were significantly different between the ECG and the HRM uncorrected and corrected signal (p < 0.001, effect size [ES] = 0.005, and 0.005, respectively). However, the bias (95% confidence interval) was 0.80 (-124.76-123.16) ms and 0.80 (-12.76-11.16) ms, respectively. HRV parameters derived from both signals were not different (p>0.05) and well correlated (r>0.99, p<0.05), except SD2 (p<0.05, ES= 0.000; r = 0.99). These data support the validity of the Polar S810 HRM to measure R-R intervals and make the subsequent HRV analysis in a supine position in children.