Related Experiment Video
Updated: Aug 17, 2026

Autonomic Function Following Concussion in Youth Athletes: An Exploration of Heart Rate Variability Using 24-hour Recording Methodology
Published on: September 21, 2018
Influence of head-down and lateral decubitus neck flexion on heart rate variability
C M Lee1, R H Wood, M A Welsch
1Department of Kinesiology, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
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.
Related Concept Videos
Guidelines For Measuring Vital Signs
Before taking a patient's vital signs, a nurse would consider and assess the patient's comfort level and ensure appropriate equipment is available.
Factors Influencing Heart Rate
Let us explore the significant factors affecting heart rate, including age, body temperature, posture, acute pain, chemical influences,...
Assessment of apical radial pulse
The A-R pulse assessment involves simultaneous evaluation of the apical and radial pulses. When the apical and radial pulse rates vary, this assessment helps identify a pulse deficit.
Pre-Procedural Preparation
Assessment of blood pressure in brachial artery(one-step method)
Prepare for the Procedure:
Special considerations while measuring blood pressure
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
Imbalances in Cardiac Output
CHF can occur due to the failure of either side of the heart. Left-side failure leads to pulmonary congestion—the right side continues to send blood...

