Children with osteogenesis imperfecta (OI) have impaired bone strength, fractures, weak muscles and limited mobility. Mild to moderate forms of OI (type 1 and 4) may benefit from muscle training that leads to secondary improvement in bone strength (osteogenic treatment). Recent studies in children with cerebral palsy but also OI suggest that Whole Body Vibration Training (WBVT) improves mobility and also bone strength. No randomized controlled trials exist in OI children. This randomized controlled pilot study assesses the effect of 5 months WBVT (2 x 9min/day) on muscle function, mobility, bone structure and density. 24 children \>5 years with OI type 1 and 4 with limited mobility (CHAQ Score ≥0.13) will be randomized into a WBVT group and a control group matched by gender and pubertal stage. Main outcome measure is the change in tibial volumetric BMD, secondary outcomes include a variety of bone, mobility and dynamic muscle function variables.