Leg Muscle Usage on Tibial Elasticity During Running

摘要

Tibial stress fractures (TSFs) are a substantial problem in military training, but a means of predicting their occurrence remains elusive. Bone strength is key to the resistance of TSF, but bone density, a determinant of strength, is known not to predict TSF occurrence. Elasticity is nearly as important as density in determining bone strength but has not been tested in TSF, or even studied in runners. These basic validation studies will determine if modulators of tibial stress, such as heel-strike mechanics and surface incline, also modulate bone elasticity during running. Because these modulators may operate on the tibia via the muscles, we have combined ultrasound characterization of tibial elasticity with MRI monitoring of muscle recruitment during a running (training) protocol in health volunteers. We hypothesize that elasticity will be profoundly altered by our training constraints and that differential muscle recruitment effects the changes in bone material, this permitting subsequent application in groups with higher risks for TSF. This hypothesis is consistent with Frost's Utah paradigm of bone remodeling. Because of significant delays due to change in Principal Investigators and Protocal/Consent Form revisions, subject recruitment and data collection is on- going.