The effects of +Gz force on the bone mineral density of fighter pilots.
OBJECTIVE
Bone is a metabolically active tissue which responds to high strain loading. The purpose of this study was to examine the bone response to high +Gz force loading generated during high performance flying.


METHODS
The bone response to +Gz force loading was monitored in 10 high performance RAAF pilots and 10 gender-, age-, height-, weight-matched control subjects. The pilots were stationed at the RAAF base at Pearce, Western Australia, all completing the 1-yr flight training course. The pilots flew the Pilatus PC-9 aircraft, routinely sustaining between 2.0 and 6.0 +Gz. Bone mineral density (BMD) and bone mineral content (BMC) were measured at baseline and 12 mo, using the Hologic QDR 2000+ bone densitometer.


RESULTS
After controlling for change in total body weight and fat mass, the pilots experienced a significant increase in BMD and BMC for thoracic spine, pelvis, and total body, in the magnitude of 11.0%, 4.9%, and 3.7%, respectively. However, no significant changes in bone mineral were observed in the pilots lumbar spine, arms or legs. The control group experienced a significant decrease in pelvic BMC, with no other bone mineral changes observed at any site.


CONCLUSIONS
These findings suggest that site specific BMD is increased in response to high +Gz forces generated during high performance flying in a PC-9.
School of Biomedical and Sport Science, Edith Cowan University, Joondalup, Perth, Australia. f.morris@cowan.edu.au
F L
FL
Naumann
K L
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Bennell
J D
JD
Wark
D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D000337:Aerospace Medicine; D015519:Bone Density / Q000502:physiology*; D001846:Bone Development / Q000502:physiology; D003720:Densitometry; D005260:Female; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000502:physiology; D008297:Male; D008889:Military Personnel; D016273:Occupational Exposure / Q000009:adverse effects; D010384:Pelvic Bones / Q000502:physiology; D013904:Thoracic Vertebrae / Q000502:physiology