A Valsalva maneuver is an effort to exhale without letting air escape through the nose or mouth. People often use a Valsalva maneuver during some common activities, such as straining to have a bowel movement or blowing a stuffy nose.
A Valsalva maneuver is not normally harmful. But it may cause irregular heart rhythms in some people who have certain types of heart disease.
A person may be asked to do a Valsalva maneuver during certain medical tests or exams. During the test, a person is asked to try to breathe using the stomach muscles and diaphragm but not let any air out through the nose or mouth.