Influence of head-down and lateral decubitus neck flexion on heart rate variability

C. M. Lee, R. H. Wood, M. A. Welsch

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The purpose of this study was to examine the response of heart rate variability (HRV), a noninvasive index of autonomic control, to head-down neck flexion (HDNF), which engages both otoliths and neck muscle afferents, and to lateral decubitus neck flexion (LNF), in which neck afferents are activated, whereas otolith afferent input is not. HRV and forearm blood flow were evaluated in participants lying prone, during HDNF, lying in the lateral decubitus position, and during LNF. Compared with the prone position, HDNF resulted in lower high-frequency (46.9 ± 7.1 vs. 62.3 ± 6.2) and higher low-frequency (53.1 ± 7.1 vs. 37.7 ± 6.2) power, expressed as normalized units, along with higher low-frequency-to-high-frequency ratio (1.65 ± 0.3 vs. 0.78 ± 0.2), whereas LNF resulted in no alterations in HRV indexes. Furthermore, there were no significant differences in forearm blood flow or vascular resistance among any of the positions. Our data suggest that otolith organs influence autonomic modulation of the heart, supporting previous studies reporting that HDNF elicits increased sympathetic outflow. These data further suggest that HDNF results in a parasympathetic withdrawal from the heart in addition to sympathetic activation.

Original languageEnglish
Pages (from-to)127-132
Number of pages6
JournalJournal of Applied Physiology
Volume90
Issue number1
DOIs
StatePublished - 2001

Keywords

  • Autonomic
  • Muscle afferents
  • Otoliths

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