Essentially, subjects will have a baseline assessment (WBV1) of their bone turnover marker response to a week-long period of whole body vibration (10 minutes/day), followed by a "washout period" of 5 weeks during which bone turnover is expected to return to normal. Following this, there will be a period of 6 weeks of treatment with risedronate (1 mg/kg/week). Immediately following this will come a second assessment (WBV2) of the bone turnover marker response to a week-long period of whole body vibration (10 minutes/day) as previously.