Endurance-trained cyclists had higher heart rate variability (SDNN) at rest (89.9 vs 59.1 ms, P<0.05) and during head-up tilt compared to sedentary controls, with no spectral differences.
Cross-Sectional (n=21)
Does endurance training alter autonomic heart rate modulation (HRV) at rest and during head-up tilt compared to a sedentary lifestyle?
Resting bradycardia in endurance athletes appears more related to intrinsic mechanisms than to modifications in autonomic control, as frequency domain HRV measures did not differ from sedentary controls.
Absolute Event Rate: 89.9% vs 59.1%
p-value: p=< 0.05
The purpose of the present study was to determine if autonomic heart rate modulation, indicated by heart rate variability (HRV), differs during supine rest and head-up tilt (HUT) when sedentary and endurance-trained cyclists are compared. Eleven sedentary young men (S) and 10 trained cyclists (C) were studied. The volunteers were submitted to a dynamic ECG Holter to calculate HRV at rest and during a 70 masculine HUT. The major aerobic capacity of athletes was expressed by higher values of VO2 at anaerobic threshold and peak conditions (P < 0.05). At rest the athletes had lower heart rates (P < 0.05) and higher values in the time domain of HRV compared with controls (SD of normal RR interval, SDNN, medians): 59.1 ms (S) vs 89.9 ms (C), P < 0.05. During tilt athletes also had higher values in the time domain of HRV compared with controls (SDNN, medians): 55.7 ms (S) vs 69.7 ms (C), P < 0.05. No differences in power spectral components of HRV at rest or during HUT were detected between groups. Based on the analysis of data by the frequency domain method, we conclude that in athletes the resting bradycardia seems to be much more related to changes in intrinsic mechanisms than to modifications in autonomic control. Also, HUT caused comparable changes in sympathetic and parasympathetic modulation of the sinus node in both groups.
Martinelli et al. (Fri,) conducted a cross-sectional in Healthy volunteers (n=21). Endurance training (cyclists) vs. Sedentary lifestyle was evaluated on Heart rate variability (SDNN) at rest (p=< 0.05). Endurance-trained cyclists had higher heart rate variability (SDNN) at rest (89.9 vs 59.1 ms, P<0.05) and during head-up tilt compared to sedentary controls, with no spectral differences.
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