Abstract des Autors

Heart rate is often lower in athletes than nonathletes. These differences are related to an alteration in autonomic nervous system avtivity and particularly to a higher parasympathetic and/or lower sympathetic nervous system activity. To evaluate the influence of parasympathetic and sympathetic nervous system activity on heart rate, we studied 8 athletes, national rugby players, age range 19-24 years, and 8 non-athletes, age range 18-26 years. We considered parasympathetic nervous system indices: 1) the peak to peak variation in heart period during regular breathing (VHP), the ratio of HR before/HR after atropine (0.03 mg/kg ev), and the difference of HR before - HR after atropine in millisecond (PC). A sympathetic nervous system index was derived from the ratio of HR before/HR after propranolol (0.15 mg/kg ev). These parameters were obtained in the morning, in a quite room, during supine and tilted (80ø) position. Parasympathetic and sympathetic indices were similar between the two groups. Therefore, the autonomic nervous system activity in athletes does not appear different in respect to non-athletes. However, heart rate was lower in athletes than non-athletes both in supine and standing position (p<0.05) and even the HR after atropine plus propranolol infusion was significantly lower in athletes than non-athletes, pointing to a lower intrinsic sino-atrial pacemaker activity in athletes. In conclusion, the autonomic nervous system activity in athletes does not appear different compared to non-athletes. The lower heart rate observed in athletes, therefore might be related to a lower intrinsic sinoatrial node pacemaker activity. Verf.-Referat