Figure 2.

Data collection and processing sequence. For the 3 heart rate analysis groups, the data were recorded in the heart rate monitor while the subject remained at rest. The signal was transferred to the software via infrared, where it was converted to text for later analysis. The TXT file was opened in a spreadsheet where the data underwent several mathematical treatments, in the follow order: identification of artifacts and ectopic beats, and correction of the dubious points (i.e. by exclusion, substitution or interpolation techniques). After these steps, the sample base was selected for HRV analysis, either by selecting the 256 points of greatest stability or the last 5 min of the recorded signal (10 min). Finally, these selections were exported to the Kubios HRV to calculate the different HRV indices.