This paper outlines the progress that has been made in a study on human body dynamics during vibration therapy. At the Toronto Rehabilitation Institute, vibration therapy has been applied to spinal cord injured (SCI) patients in an effort to maintain the patients' bone density. Some clinical trials have not been successful, and thus a better understanding of human responses to vibration therapy is required to ascertain if and how it can be applied to maintain bone density in SCI subjects. Experiments with SCI and healthy subjects were conducted to determine the accelerations present in the lower extremities during vibration therapy. The results showed negligible differences between the responses of SCI and healthy subjects, but considerable differences between the responses of subjects with different body types. A mathematical model of a standing subject was also developed, and theoretical predictions using the model were found to match experimental data reasonably.