 Sample Size Determination The inclusion of 32 participants 16 in both groups would give the study 80 power to detect a clinically significant additional increase of 22 with WBV assuming a 9 increase of BMD in the PTH alone group and 11 increase in the combined PTHWBV group, and assuming a SD of the BMD increase of 2. Allowing for a 20 dropout rate, the plan is to include 40 participants 20 in each group. From previous research on WBV by one of the investigators TM, statistically significant differences were found in bone formation markers and in muscle strength at 3 months between the WBV and control groups with a sample size of 35. The number of participants in the latter pilot work is reassuringly consistent with the sample size calculations. The number needed to be included is far less 34 than the actual number of patients treated with PTH in the recruiting departments in a similar time period last year. 