Effect of autonomic blockade on power spectrum of heart rate variability during exercise

John H. Warren, Rory S. Jaffe, Cheryl E. Wraa, Charles L Stebbins

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


To validate power spectral analysis of heart rate variability (HRV) as an autonomic indicator during exercise, ten males performed four identical progressive cycling tests during infusions of saline, esmolol (β1-blocker), glycopyrrolate (muscarinic blocker), or both drugs. Power spectra were constructed from the recorded electrocardiogram by Fourier algorithm and integrated for low-frequency power (LF) and high-frequency power (HF). Four different LF bands (0.004-0.1, 0.004-0.15, 0.05-0.1, and 0.05-0.15 Hz) and two different HF bands (0.1-1.0 and 0.15-1.0 Hz) were evaluated. The parasympathetic index, HF, decreased exponentially with workload and was attenuated by glycopyrrolate and combined treatments with both HF frequency bands measured. Whereas some sympathetic indexes (LF/total power and LF/HF) did reflect expected increases in sympathetic nerve activity associated with progressive increases in work intensity, none of the measured increases responded appropriately to autonomic blockade. It is concluded that HRV is a valid technique for noninvasive measurement of parasympathetic tone during exercise, but its validity as a measure of sympathetic tone during exercise is equivocal.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number2 42-2
StatePublished - 1997


  • β-adrenergic receptor antagonism
  • Humans
  • Muscarinic receptor antagonism

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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