From the 3/08 Orthopaedic Research Society Annual Meeting-
Real simple, the researchers had young women push down on load cell attached to an oscilloscope 15m per session, 3X per week for 15 weeks. They did periodic BMD tests on the carpal bones of the wrist. All subjects increased bone mass at the conclusion. HOWEVER, at 7 weeks, the subjects actually showed a decrease!
Something to keep in mind when we are prescribing exercise. Always remember bone growth always lags behind muscle a little. Always keep the planned performance training model in the back of your mind, and cycle in periods of loading & unloading. Don't let your workouts become a survival of the fittest.