Date of Award


Document Type


Degree Name

Medical Doctor (MD)

First Advisor

Ben Hur Mobo


Background: In 2004, the Accession Medical Standards Analysis and Research Activity of the U.S. Army proposed the Assessment of Recruit Motivation and Strength (ARMS) study to determine whether those passing an initial screening fitness test were less likely to be injured during basic training than those unable to pass the test. Since 2005, qualified Army recruits who passed the ARMS test, but did not meet the body fat standard, were given a body fat waiver. Study Aims: To evaluate if female Army recruits who exceed the allowable percent body fat, but successfully pass the ARMS fitness test, have the same hazard of lower extremity stress fracture compared with similarly fit female recruits who are weight and body fat qualified. Methods: Health records of 1,716 female recruits enrolled in the ARMS study from May 2004 to December 2006 and meeting eligibility criteria were reviewed. Stress fractures were identified by ICD-9 codes. The Kaplan-Meier estimator was used to analyze stress fracture-free survival for different weight and percent body fat categories. Multivariate analysis and stratified analyses were completed using Cox Proportional Hazards Models. Results: A total of 358 female recruits were diagnosed with lower extremity stress fractures (21%). The hazard of lower extremity stress fracture in female recruits receiving an ARMS waiver compared to weight and body fat qualified recruits was 1.54 (CI 1.25 1.88, p<0.001). Rapid fitness index and age were also significantly associated with hazard of lower extremity stress fracture. Race and smoking status were not found to be significantly associated. Conclusion: Female recruits who exceed the Armys allowable percent body fat have an increased hazard of lower extremity stress fracture as compared to weight and body fat qualified female recruits. However, for highly fit female recruits, there is no association between body fat percentage and hazard of lower extremity stress fracture.


This thesis is restricted to Yale network users only. This thesis is permanently embargoed from public release.