[Polar S810 as an alternative resource to the use of the electrocardiogram in the 4-second exercise test].
BACKGROUND
The 4-second exercise test (T4s) evaluates the cardiac vagal tone during the initial heart rate (HR) transient at sudden dynamic exercise, through the identification of the cardiac vagal index (CVI) obtained from the electrocardiogram (ECG).


OBJECTIVE
To evaluate the use of the Polar S810 heart rate monitor (HRM) as an alternative resource to the use of the electrocardiogram in the 4-second exercise test.


METHODS
In this study, 49 male individuals (25 +/- 20 years, 176 +/-12 cm, 74 +/- 6 kg) underwent the 4-second exercise test. The RR intervals were recorded simultaneously by ECG and HRM. We calculated the mean and the standard deviation of the last RR interval of the pre-exercise period, or of the first RR interval of the exercise period, whichever was longer (RRB), of the shortest RR interval of the exercise period (RRC), and of the CVI obtained by ECG and HRM. We used the Student t-test for dependent samples (p < or 0.05) to test the significance of the differences between means. To identify the correlation between the ECG and the HRM, we used the linear regression to calculate the Pearson's correlation coefficient and the strategy proposed by Bland and Altman.


RESULTS
Linear regression showed r(2) of 0.9999 for RRB, 0.9997 for RRC, and 0.9996 for CVI. Bland e Altman strategy presented standard deviation of 0.92 ms for RRB, 0.86 ms for RRC, and 0.002 for CVI.


CONCLUSIONS
Polar S810 HRM was more efficient in the application of T4s compared to the ECG.
Pimentel
Alan Santos
AS
Laboratório de Avaliação Motora, Universidade Federal de Juiz de Fora.
Alves
Eduardo da Silva
Eda S
Alvim
Rafael de Oliveira
Rde O
Nunes
Rogério Tasca
RT
Costa
Carlos Magno Amaral
CM
Lovisi
Júlio Cesar Moraes
JC
Perrout de Lima
Jorge Roberto
JR
D000328:Adult; D004562:Electrocardiography / Q000295:instrumentation*; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation* / Q000379:methods; D004812:Epidemiologic Methods; D005080:Exercise Test / Q000295:instrumentation* / Q000379:methods; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D014630:Vagus Nerve / Q000502:physiology