Effects of Whole-Body Vibration Training Combined With Cyclic Hypoxia on Bone Mineral Density in Elderly People

Abstract

Moderate intermittent hypoxia (IH) protocols may help to restrain osteoclastic activity and/or stimulate osteoblastic activity. Therefore, whole-body vibration (WBV) combined with IH exposure may provide the most effective treatment for osteoporosis. The present randomised controlled trial investigated if normobaric IH exposure combined with WBV training over an 18-week period for the elderly is more effective in increasing/maintaining bone mineral density when compared to WBV training or resting in normoxia. Healthy elderly persons (n=32) were randomly assigned to a: Hypoxia-Whole Body Vibration group (HWBV; n=10), Normoxic-Whole Body Vibration group (NWBV; n=11) or Control group (CON; n=10). The HWBV group performed WBV treatment under normobaric hypoxic conditions (16.1% FiO2). A vibration session included 4 bouts of 30 s (12.6 Hz in frequency and 4 mm in amplitude with 120º of knee flexion) with 1 min. rest between bouts. The NWBV group performed the same vibration treatment as the hypoxia group but under normoxic conditions. Proximal femur and whole body bone mineral density (BMD; g·cm-2) were measured using dual-energy X-ray absorptiometry. After 18 weeks, the HWBV group showed a significant 3.77% increment in BMD for the whole body (p<0.05) compared to those in the NWBV (-0.91%) and CON (0.97%) groups. In the analysis of the proximal femur, trochanter BMD in the HWVB group increased significantly (0.61%; p=0.05) compared to the CON group (-1.54%). The NWBV group had a significantly increased BMD of Trochanter (1.15%; p=0.037). Normobaric IH combined with WBV training improved BMD values in the whole body and proximal femur regions of the elderly more than the isolated WBV treatment.