Vitamin D, muscle recovery, sarcopenia, cachexia, and muscle atrophy.

The relevance of vitamin D to skeletal muscle metabolism has been highlighted in recent years. The interest arises from the important findings of studies demonstrating multiple effects of vitamin D on this tissue, which can be divided into genomic (direct effects) and non-genomic effects (indirect effects). Another important aspect to be considered in the study of vitamin D and muscle fiber metabolism is related to different expression of vitamin D receptor (VDR), which varies in muscle tissue depending on age, sex, and pathology. The correlation between low circulating levels of vitamin D and muscle metabolism disorders is documented in various contexts, including muscle recovery, atrophy, sarcopenia, and cachexia. The aim of this review was to analyze recent results of both in vitro and in vivo studies to address the relationship between vitamin D and skeletal muscle biology. The words muscle atrophy, muscle hypertrophy, sarcopenia, and cachexia were crossed over with vitamin D in a Pubmed search. All original contributions, along with reviews on the topic, were included, and no publications in the past 10 y were discarded. The papers retrieved different topics such as vitamin D in skeletal muscle; vitamin D in circulation; vitamin D, sarcopenia, and muscle atrophy; vitamin D and cachexia; and vitamin D and muscle recovery.