Galectin-3 is a pleiotropic lectin that regulates multiple cellular processes in a multitude of tissue types. In bone, depending on its cellular localization, Galectin 3 has a dual and opposite role, as if on the one hand intracellular Galectin 3 promotes bone formation, on the other circulating Galectin 3 antagonizes osteoblast differentiation and increases osteoclast activity. In the present study, we demonstrate that Gal-3 is released in the extracellular environment from muscle cultured cells, and reveal the role of Gal-3 in muscle to bone crosstalk, as a factor able to impair bone homeostasis during muscle differentiation and following muscular activity