Final answer:
The Valsalva maneuver in flight physicals is used to test ear and sinus function during pressure changes by increasing intra-abdominal pressure through muscle contractions.
Step-by-step explanation:
For flight physicals, the Valsalva maneuver is a technique used to examine the functionality of the ear and sinus during changes in air pressure, as often experienced during flight. This technique involves a voluntary contraction of the diaphragm and abdominal wall muscles and closing of the glottis, which increases intra-abdominal pressure. While commonly associated with facilitating defecation, in aviation medicine, the maneuver is employed to assess whether the Eustachian tubes are open and can equalize pressure in the middle ear. Under normal circumstances, it can help prevent middle ear pain and possible damage when ambient pressure changes rapidly, such as during ascent and descent in flights.