Date of Award
Bachelor of Science Honours
Faculty of Communications, Health and Science
Dr Fiona Naumann
Previous research on exercise and bone mineral density (BMD) has established that increases in BMD are site specific, responding to unusual strain and particularly to high magnitude loading. The positive Gz forces generated during high performance flying provide all three variables. Naumann, Bennell and Wark (2000) investigated the effects of moderate gravitational force on the BMD of fighter pilots. The pilots in this study had significant increases in BMD and bone mineral content (BMC) for the thoracic spine, pelvis and total body. However, it is now suspected that the cervical spine, which was unable to be analysed at that time endures the majority of the compressive stresses during flight. This is due to the forces acting on the weight of the head, helmet and oxygen mask. The purpose of this research was to analyse the cervical spine bone response to moderate +Gz loading generated during high performance flying. The bone response to +Gz force loading was monitored in 9 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 8 month flight training course. The pilots flew the Pilatus PC-9 aircraft, routinely sustaining between 2.0 and 6.0 +Gz. BMD and BMC were measured for the cervical spine and whole body at baseline and 32 weeks, using the Hologic QDR 4500 bone densitometer. The pilots were found to have significantly greater increases in bone mass for total body BMC and cervical spine BMD. While not significant, thoracic BMD showed a definite increase in bone mass in comparison to the control group. No significant difference in bone mass existed between the two groups for any other measured site. The findings from this study support the principals of bone loading discussed and studied by so many researchers. This study has reinforced the notion of a site specific bone response to high magnitude and unaccustomed mechanical loading. Taking into account that an osteogenic response was found from flying under moderate +Gz force for a duration of 8 months, it is possible that such greater increases in bone mass are occurring for pilots flying at higher +Gz forces for greater lengths of time.
Grant, M. C. (2001). The Effect of Moderate +Gz Force on the Cervical Spine Bone Mineral Density in RAAF PC-9 Pilots. https://ro.ecu.edu.au/theses_hons/1006