Vibration therapy, which involves standing on a vibrating plate for a short period of time every day or couple of days, has been suggested to potentially prevent and treat the bone-thinning disease osteoporosis. Previous studies involving animals showed impressive results - after therapy, animals' bone-mineral density (BMD) increased more than those obtained with exercise. Results from a few preliminary studies in patients (e.g. postmenopausal women and children with cerebral palsy) have also been described as encouraging. Yet the current study on human patients found that this form of therapy had no effect on bone.

Dr. Saila Torvinen and colleagues from Tampere University Hospital in Finland studied 56 healthy adult volunteers, aged 19 to 38 years old. Volunteers participated in either vibration therapy or the "control" therapy. Vibration therapy consisted of whole-body vibration for four minutes per day, three to five days a week, and over a period of eight months. Bone effects were measured at the beginning and end of study by two methods: peripheral quantitative computed tomography (PQCT) and dual-energy x-ray absorptiometry (DEXA). Serum markers of bone turnover were also studied at the study's beginning and at 3, 6, and 8 months.

The researchers also looked for an effect on muscle. At the beginning and end of the study, volunteers performed five tests that measured items like vertical jump, grip strength, and postural sway.

For those undergoing vibration therapy, none of the tests revealed any effect on bone at any site in these young, healthy volunteers. The only change was seen in the volunteers' vertical jump height, which increased by 7.8% in the vibration vs. control group.

Yet the pioneer of vibration-therapy, Dr. Clinton Rubin (New York University, Stony Brook) criticized several aspects of this study.

• Rubin's animal studies showed vibration therapy's benefits while using a vibration magnitude that was 50 times greater than those used in Torvinen's study - that is a huge discrepancy. Rubin points out that more is not necessarily better since too much stimulus may shut the system down. "In fact, I worry that the signals used in this study (or imposed by their device) may actually cause damage, as vibration is considered a key pathogen in low back pain, as shown in helicopter pilots and truck drivers." He compares the "dosing" of vibration therapy to the "dosing" of drugs - "…one dose may be beneficial, but another (not necessarily lower) may be ineffective, and yet another may be deleterious."
  
• He questions whether eight months is long enough to give the therapy a chance since bone adaptation is a long process. Rubin's group is currently running a study spanning several years. Even osteoporosis trials with drugs like bisphosphonates and parathyroid hormone (PTH) run for years.
  
• According to an interview with Joint and Bone's Rheumawire, Rubin explains: "I'm not sure I understand why anyone would choose to examine young, healthy subjects." Vibration therapy is thought to work because "it provides a surrogate for a stimulus that is no longer there…In the elderly or in children with cerebral palsy, the muscle wasting ends up denying what we believe is a key regulatory stimulus to the bone…and the [vibration therapy] signal 'replaces' that. In a young, healthy population, there is no reason to suspect that such a regulatory signal is missing, so the vibration is simply perceived as noise." He says that it is like trying bisphosphonates or PTH in a young, healthy population; "I can't imagine that they would do anything (good, anyway)."