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Updated: Feb 13, 2026

Autonomic Function Following Concussion in Youth Athletes: An Exploration of Heart Rate Variability Using 24-hour Recording Methodology
Published on: September 21, 2018
Origins of the power of the low frequency heart rate variability bandwidth
Daniel Roach1, Robert Sheldon1
1Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Canada.
Purpose:
We hypothesized that heart period (HP) variability in the low frequency (LF) band is due to transient fluctuations of about 10 s in HP sequences, associated with fluctuations in blood pressure.
Methods:
10 healthy subjects, mean age 36 y, had HP and blood pressure acquired for 10 min each. Nonrandom HP fluctuations (ripples) lasting 6.7-20 s were detected using time-scrambled surrogate sequences as controls.
Results:
Ripples were 99 ± 40 ms in amplitude, in concatenates 23.4 ± 7.4 s long. They co-occurred with similar blood pressure ripples with amplitudes 5 ± 5 mm Hg, correlating with them with r2 = 0.68 ± 0.10, slope 23.9 ± 10.8 ms/mm Hg, at an optimum lag of 2.16 ± 0.63 beats. A second HP structure consisting of transient tachycardias of 140 ± 53 ms lasting 15.1 ± 6.1 occurred singly. Together the two structures contributed 84% ± 8% of the total power in the LF band.
Conclusion:
The LF band is caused by two types of HP structures that occur at discrete times.
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