Purpose: Military recruits and distance runners share a special risk of stress fracture injury. Recent efforts by US and Israeli military-sponsored researchers have uncovered important mechanisms and practical low-cost interventions. This article summarizes key findings relevant to prevention of stress fracture, including simple strategies to identify and to mitigate risk.
Methods: Published research supported through the Bone Health and Military Medical Readiness research program and related military bone research was analyzed for contributions to preventing stress fracture in military recruits and optimizing bone health.
Results: Thousands of military recruits helped test hypotheses about predictors of risk, safer exercise regimens, and rest, nutrition, gait training, and technology interventions to reduce stress fracture risk. Concurrent cellular, animal, and human laboratory studies were used to systematically investigate mechanisms of mechanical forces acting on bone and interactions through muscle, hormonal and genetic influences, and metabolism. The iterative and sometimes simultaneous process of basic discovery and field testing produced new knowledge that will provide safer science-based physical training.
Discussion: Human training studies evaluating effects on bone require special commitment from investigators and funders due to volunteer compliance and attrition challenges. The findings from multiple studies indicate that measures of bone elasticity, fragility, and geometry are as important as bone mineral density in predicting fracture risk, with applications for new measurement technologies. Risk may be reduced by high intakes of calcium, vitamin D, and possibly protein (e.g., milk products). Prostaglandin E2, insulin-like growth factor 1, and estrogens are important mediators of osteogenesis, indicating reasons to limit the use of certain drugs (e.g., ibuprofen), to avoid excessive food restriction, and to treat hypogonadism. Abnormal gait may be a correctable risk factor. Brief daily vibration may stimulate bone mineral accretion similar to weight-bearing exercise. Genetic factors contribute importantly to bone quality, affecting fracture susceptibility and providing new insights into fracture healing and tissue reengineering.
1Telemedicine and Advanced Technology Research Center, Fort Detrick, MD; 2US Army Research Institute of Environmental Medicine, Natick, MA; and 3Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, ISRAEL
Address for correspondence: Karl E. Friedl, Ph.D., Telemedicine and Advanced Technology Research Center (TATRC), Building 1054, Fort Detrick, MD 21702-5012; E-mail: email@example.com.