Aerobic exercise does not increase muscle mass and strength, and does not improve balance, and is therefore less comprehensive in its effects on the multiple risk factors for osteoporotic fracture. Additionally, there is no evidence in young women to support the isolated use of aerobic training that does not involve high impact forces as a means tomaintain or augment femoral bone density, whereas programs that include resistance training and/or high impact training have been shown to benefit the skeleton at this clinically vital site. Therefore, the most economical prescription with the broadest benefits for body composition and bone health as well as neuromuscular function would appear to be resistance training as the exercise modality