Heart rate variability in athletes: relationship with central and peripheral performance

Purpose: To investigate relationships between heart rate variability (HRV) and peripheral and central performance measures, 17 cross-country (X-C) ski ers and seven canoeists were studied before and after a training period of 7 months. Methods: For the skiers and canoeists respectively, leg and arm p eak torque (Tq), time to peak torque (TiTq), and total work (Wrk) were meas ured in an isokinetic dynamometer. Maximal oxygen uptakes ((V) over dot O-2 max) were obtained from treadmill tests. Power spectral analysis of HRV was performed on electrocardiographic recordings in the resting supine positio n and after a tilt to yield power in the low-frequency (0.04-0.15 Hz) and h igh-frequency (0.15-0.45 Hz) components of HRV. Results: The change in norm alized LF-variability in standing (Delta LFnT) correlated (P < 0.01) with t he changes in TiTq (r = 0.63). max lactate (r = -0.631), and (V) over dot O -2max (r = -0.53). The change in absolute LFT was inversely correlated with the change in Tq. Subjects who improved (V) over dot O-2max, were characte rized by consistently higher high-frequency and total HRV than subjects wit h deteriorated aerobic capacity (P < 0.05). Conclusion: The results suggest that improved measures of both peripheral and central (aerobic) work capac ities were associated with a reduction of low-frequency HRV in the tilted p osition. High-frequency and total HRV did not change in proportion with cha nges in muscle performance or aerobic capacity, but the ability to further improve (V) over dot O-2max. with training in these already fit subjects se emed to depend on their average levels of these FIRM measures, interpreted to reflect parasympathetic activity.