Impact Loading Effect on Bone Biomarkers in Female Runners

This study is a randomized, cross-over intervention study that will evaluate the effect of brief, high-impact loading exercises on biomarkers of bone metabolism in energy-restricted, eumenorrheic female runners. Volunteers will complete two, 5-day experimental conditions in a randomized order separated by one menstrual cycle (approximately 3 weeks). Experimental conditions will include a dietary intervention of energy intake equal to 30 kcal/kg of fat-free mass/d using controlled diets and an exercise intervention of daily treadmill running with or without an additional 50 impact loading exercises.