Vitamin D Deficiency and Myopathy

The association between vitamin D deficiency, myalgia, and muscle weakness is well known. However, the molecular basis of vitamin D’s effects on skeletal muscle is incompletely understood and evolving. Case reports in humans describe profound muscle weakness, muscle pain, and type II fiber atrophy in subjects with severe vitamin D deficiency. Animal studies employing models of vitamin D deficiency and aberrant vitamin D signaling have helped to characterize this association. In vitro studies have identified specific pathways by which vitamin D modulates myocytes and influences contraction and anabolism. This chapter discusses clinical aspects of the association between vitamin D deficiency and myopathy, its effects on muscle weakness, muscle pain, physical performance, and falls.