Changes In Parameters Of Bone And Body Composition In Females Undergoing U.S. Army Basic Training

Abstract

U.S. Army initial entry training (IET) requires soldiers to undergo a vigorous nine week basic training course designed to enhance physical strength, endurance and function to prepare them for combat operations. However, there is little known about the effect of this type of training on bone parameters. PURPOSE To observe the response of bone and lean tissue mass (LM) to strenuous physical training in a cohort of IET soldiers, and to explore the association between LM and bone area (BA), bone mineral content (BMC), and bone mineral density (BMD). METHODS 151 female soldiers (age 21.4 ± 3.4 years) underwent dual x-ray absorptiometry scanning before and after nine weeks of basic training. A total body scan provided BA, BMC, BMD and LM measures for the total body (TB), the upper extremities (UE), and the lower extremities (LE). Data were analyzed using paired sample t-tests and Pearson's correlation coefficients. RESULTS Total body BMD decreased from 1.20 ± 0.08 to 1.19 ± 0.08 g/cm2 (p<0.001). Total body LM increased from 39.38 ± 4.30 to 41.84 ± 4.42 kg (p<0.001), and was not significantly correlated with parameters of bone. Total body BMC and BA did not change significantly. Extremity data are presented in the following table:TableThe observed changes in LM were positively correlated with changes in BA for the UE (r=.52) and LE (r=.32) (both p<0.001). CONCLUSION This study provides evidence for the influence of physical training on bone acquisition in the skeletally mature female. Lower extremity bone area increases in response to short term, strenuous, weight bearing activity without a concomitant increase in BMD or BMC. Increases in bone area in the extremities are positively associated with increases in lean tissue mass. At this time it is unknown if significant changes in soft tissue composition result in artifactual variability in measures of bone.