INTRODUCTION: Limited research is available on the bone health of female warfighters graduating from combat leadership courses like the US Army Ranger Training Course since combat roles opened to women in 2015. This investigation aimed to characterise the bone density, microarchitecture and strength of a small cohort of these female elite warfighters (FEW) to aid in understanding the physical resilience necessary for women to succeed in such courses.
METHODS: FEW (n=11) were assessed for body composition and whole-body areal bone mineral density (aBMD) and content (BMC) by DXA, bone microarchitecture at two distal tibia sites by high-resolution peripheral quantitative CT (HR-pQCT) and health and lifestyle outcomes by survey. Two female comparison cohorts (CC) of Army basic combat trainees were matched (3:1), to provide context to the FEW.
RESULTS: FEW were similar to CC1 and CC2 in height, and lower in body fat (p<0.05). FEW whole-body aBMD and BMC were higher than CC1 (both p<0.01, Cohen's D=0.233 and 0.785, respectively). HR-pQCT measures demonstrated greater total density (13.4%; p=0.01), bone volume fraction (12.9%; p=0.03) and 26.0% higher estimated failure load (p<0.01) in the FEW compared with CC1 at the metaphysis. At the diaphysis, FEW tibiae had 10.2% higher estimated compressive stiffness and 10.3% higher estimated failure load (both p<0.05) than CC2 with no differences in other bone health measures. Lifestyle and health factors were similar between groups.
CONCLUSIONS: Greater BMC and more favourable bone properties at the distal tibia were observed in the FEW compared with basic combat trainees, supplementing previous findings of exceptional body composition of women graduating from elite combat leadership courses. Considering the prevalence of BSI in female warfighters, further study is warranted to determine how bone status affects probability of course success.