To characterize the heart rate variability parameters which best discriminate sedentary from athletes, in order to comprehend the regulatory mechanisms involved. Chronotropic activity is modulated by the autonomic nervous system through its sympathetic and parasympathetic branches, as a result of this dynamic interaction cardiac cycles are affected, changing heart rate variability in both time and frequency domains. A 16-minute ECG recording was collected from each one, and classic parameters of heart rate variability and the pNNx family