Abstract
Muscle weakness has been recognized as a hallmark feature of vitamin D deficiency for many years. Until recently, the direct biomolecular effects of vitamin D on skeletal muscle have been unclear. Although in the past, some reservations have been raised regarding the expression of the vitamin D receptor in muscle tissue, this special issue review article outlines the clear evidence from preclinical studies for not only the expression of the receptor in muscle but also the roles of vitamin D activity in muscle development, mass, and strength. Additionally, muscle may also serve as a dynamic storage site for vitamin D, and play a central role in the maintenance of circulating 25-hydroxy vitamin D levels during periods of low sun exposure. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.