The Valsalva Manoeuvre, Physiology and Clinical Examples
Authors: L. Pstras, K. Thomaseth, J. Waniewski, I. Balzani, F. Bellavere
DOI / Source: https://doi.org/10.1111/apha.12639
Date: 03 December 2015
Reading level: Intermediate
Why This Matters for Freedivers
Many freedivers try to equalise with a “Valsalva-like” push early on, and this paper explains why that can be a bad habit: it spikes pressure in the chest and head, changes blood pressure and heart rate, and can make you feel dizzy or stressed—especially if you strain hard. Understanding the Valsalva response helps you choose gentler equalisation methods and avoid unnecessary strain that wastes oxygen and increases risk.
Synopsis
The Valsalva manoeuvre is a forced exhale against a closed airway (think “trying to blow out while the nose and mouth are blocked”). In medicine it’s used as a simple test because it reliably creates a big, predictable chain reaction in the cardiovascular system. This review explains that chain reaction and why small differences in how you do it (how hard you strain, how long, body position, how full your lungs are) can produce very different results.
The key driver is pressure. When you strain, pressure rises in the chest and abdomen, which temporarily changes how blood moves back to the heart and how the heart pumps. Your body then tries to protect blood pressure using fast reflexes—mainly the baroreflex (pressure sensors in the arteries), plus input from lung stretch receptors and, later, chemoreceptors.
Clinicians describe four classic phases. First, at the start of strain, blood pressure briefly rises because pressure is “transmitted” to the arteries, and heart rate may dip. Then, during continued strain, venous return to the heart is reduced, stroke volume drops, and blood pressure falls; your body answers by increasing heart rate and tightening blood vessels to recover pressure. When you release the strain, blood pressure suddenly drops again for a moment as pressures normalize and the circulation “rearranges.” Finally, in recovery, venous return floods back, stroke volume jumps, blood vessels are still tight for a short while, and blood pressure overshoots—triggering a reflex slowing of the heart.
The review also highlights practical risks. Valsalva is usually safe in clinics, but strong or repeated straining can cause dizziness, fainting, rhythm issues, and rare complications—especially in people prone to blood pressure swings. For divers, the important takeaway is that “hard pushing” isn’t just an ear trick: it’s a whole-body event that can increase stress, disrupt calm, and potentially set you up for poor equalisation or unsafe sensations at the worst time (right before or during descent).
Abstract
The Valsalva manoeuvre is a forced expiratory effort against a closed airway and is widely used in medicine to assess cardiovascular and autonomic function. The pressure changes produced by the manoeuvre create a complex, phase-dependent pattern of blood pressure and heart rate responses driven mainly by baroreflex control, with contributions from pulmonary stretch receptors and chemoreceptors. This review summarizes the physiology and pathophysiology of the manoeuvre, explains how technical factors (strain level, duration, body position, breathing pattern) influence the response, and presents clinical examples of normal and abnormal haemodynamic patterns.