This study was conducted to compare R-R intervals and the subsequent analysis of heart rate variability (HRV) obtained from the Polar S810 heart rate monitor (HRM) (Polar Electro Oy) with an electrocardiogram (ECG) (Physiotrace, Estaris, Lille, France) during an orthostatic test.
A total of 18 healthy men (age: 27.1 ± 1.9 yr; height: 1.82 ± 0.06 m; mass 77.1 ± 7.7 kg) performed an active orthostatic test during which R-R intervals were simultaneously recorded with the HRM and the ECG recorder The two signals were synchronized and corrected before a time domain analysis, the fast Fourier transform (FFT) and a Poincaré plot analysis. Bias and limits of agreement (LoA), effect size (ES), and correlation coefficients were calculated.
R-R intervals were significantly different in the supine and standing position between the ECG and the HRM uncorrected and corrected signal (P < 0.05, ES = 0.000 and 0.006, respectively). The bias ± LoA, however, were 0.9 ± 12 ms. HRV parameters derived from both signals in both positions were not different (P > 0.05) and well correlated (r > 0.97, P < 0.05), except root mean square of difference (RMSSD) and SD1 in standing position (P < 0.05, ES = 0.052 and 0.057; r = 0.99 and 0.98, respectively).
Narrow LoA, good correlations, and small effect sizes support the validity of the Polar S810 HRM to measure R-R intervals and make the subsequent HRV analysis in supine position. Caution must be taken in standing position for the parameters sensitive to the short-term variability (i.e., RMSSD and SD1).
1Faculty of Sport Sciences, University of Lille, Ronchin, FRANCE; and 2Department of Kinesiology, University of Montreal, Montreal, CANADA
Address for correspondence: Laurent Bosquet, Department of Kinesiology, University of Montreal, CP 6128, succ. centre ville, Montreal, QC, Canada H3C 3J7; E-mail: firstname.lastname@example.org.
Submitted for publication September 2005.
Accepted for publication December 2005.