Spinal shrinkage due to +Gz forces
Hämäläinen, O.; Vanharanta, H.; Hupli, M.; Karhu, M.; Kuronen, P.; Kinnunen, H.
Aviation Space and Environmental Medicine 67(7): 659-661
1996
ISSN/ISBN: 0095-6562 PMID: 8830946 Document Number: 459316
Background: Fighter pilots frequently complain of inflight pain in the cervical or lumbar spine. As to the cervical spine, there is evidence that repeated exposures to high +Gz forces and inflight neck pain may cause premature cervical disk degeneration. Whether inflight lumbar pain caused by high +Gz forces has a similar effect on the lumbar spine has not been studied. Hypothesis: The aim of the study was to investigate whether high +Gz forces during aerial combat maneuvering reduces the body height. Investigation to determine whether any long-term degenerative changes occur in the lumbar spine was beyond the scope of this study. Methods: The body height of 20 junior fighter pilots was measured before and after 30 min of recumbent rest and after high-G flights. A special measuring device was used. Measurements were also made with the pilots sitting fully equipped in a fighter aircraft on the ground. Results: Maneuvering under high +Gz forces for 40 min caused a 4.9 mm decrease in body height. Recumbent rest before flights increased body height by 2.5-3.5 mm, and sitting in an aircraft returned body height to the values measured before rest. Conclusions: The findings indicate that +Gz forces place a high stress on the spinal column. Therefore, the work of a fighter pilot can be considered to be physically demanding with respect to the spinal column.