Heart rate variability
ECTOPIC BEATS
ECG assessment was carried out at baseline and post-intervention, in a supine position on a stationary bench. Three ECG electrodes were placed over the left fifth intercostal space, the right fifth intercostal space and over the manubrium. Once the ECG signal was acceptable, participants were informed that they should rest for 10 minutes, alone in the examination room, before the ECG would be recorded for minimum 5 minutes. Participants were instructed not to talk or move excessively, to turn off their mobile phones, and to relax as much as possible. The ECG-assessments were recorded at a sampling frequency of 1000 Hz and stored on a computer. Each 300 s ECG-recording was inspected for ectopic beats and artifacts, as well as for the correct identification of each R-peak by the software, and non-sinus beats and other artifacts were corrected by interpolation [