Treatment for childhood cancer interferes with normal bone maturation such that maximal peak bone mass may never be attained by some survivors of childhood cancer. In adults, deficits in bone mineral density are usually approached via pharmacologic intervention, the long term safety of which remains uncertain. In childhood cancer survivors, a randomized trial evaluating the effectiveness of vitamin D and calcium supplementation among ALL survivors is currently underway;however, few other interventions have been offered for this at risk population. Pharmacologic interventions do not take into account the responsiveness of bone to mechanical stimuli provided by the external environment. Recent evidence demonstrates that low magnitude, high frequency mechanical stimulation can improve bone quantity and quality, perhaps providing an alternative or adjunct to pharmacologic intervention in populations where additional medications are either contraindicated or not acceptable to the individuals at risk. There is a need for an evaluation of the potential of this low burden intervention. This application proposes a prospective double blind randomized clinical trial of low magnitude, high frequency mechanical (LMHF) stimulation for childhood cancer survivors whose bone mineral density is one or more standard deviations below the mean for their age and gender. A two arm parallel allocation of participants to either the intervention or control group will be utilized for a one year trial. Participants will be asked to stand on a "vibrating plate" for 10 minutes twice per day during the entire year of the trial. Participants in the control arm will stand on a placebo device that contains a voice box that mimics the sound of the vibrating place. If the intervention arm demonstrates significant improvement in bone mineral density (BMD), participants in the control arm will be offered the intervention at the conclusion of the study. PUBLIC HEALTH RELEVANCE: Interventions to improve BMD and prevent early onset osteoporosis and fracture are essential to promote long, productive lives, free from persistent pain and/or disability. Current treatments for BMD decrements among childhood cancer survivors are limited to those who can tolerate a pharmacologic agent, and to those whose physical abilities allow a vigorous weight bearing physical activity. This innovative intervention is portable, safe, cost-effective, and of low burden to the cancer survivor. It has the potential to be used either alone or as an adjunct to other interventions to improve BMD in this at risk population.