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The effects of vitamin D on skeletal muscle function and cellular signaling.
It is thought that every cell in the body expresses the vitamin D receptor, and therefore vitamin D may play a role in health and homeostasis of every organ system, including skeletal muscle. Human, animal, and cell culture studies have collectively shown that vitamin D affects muscle strength and function. Vitamin D functions in a plethora of cellular processes in skeletal muscle including calcium homeostasis, cell proliferation, cell differentiation, fiber size, prevention of fatty degeneration, protection against insulin resistance and arachidonic acid mobilization. These processes appear to be mediated by several signaling pathways affected by vitamin D. This review aims to explore the effects of vitamin D on skeletal muscle in each model system and to delineate potential cell signaling pathways affected by vitamin D.
https://www.ncbi.nlm....pubmed/21397021
Vitamin D and Its Role in Skeletal Muscle
Molecular mechanisms of vitamin D action in muscle tissue include genomic and non-genomic effects via a receptor present in muscle cells. Knockout mouse models of the vitamin D receptor provide insight into understanding the direct effects of vitamin D on muscle tissue. Vitamin D status is positively associated with physical performance and inversely associated with risk of falling. Vitamin D supplementation has been shown to improve tests of muscle performance, reduce falls, and possibly impact on muscle fiber composition and morphology in vitamin D deficient older adults.
https://www.ncbi.nlm....45/?tool=pubmed
Vitamin D and human skeletal muscle.
Vitamin D deficiency is an increasingly described phenomenon worldwide, with well-known impacts on calcium metabolism and bone health. Vitamin D has also been associated with chronic health problems such as bowel and colonic cancer, arthritis, diabetes and cardiovascular disease. In recent decades, there has been increased awareness of the impact of vitamin D on muscle morphology and function, but this is not well recognized in the Sports Medicine literature. In the early 20th century, athletes and coaches felt that ultraviolet rays had a positive impact on athletic performance, and increasingly, evidence is accumulating to support this view. Both cross-sectional and longitudinal studies allude to a functional role for vitamin D in muscle and more recently the discovery of the vitamin D receptor in muscle tissue provides a mechanistic understanding of the function of vitamin D within muscle. The identification of broad genomic and non-genomic roles for vitamin D within skeletal muscle has highlighted the potential impact vitamin D deficiency may have on both under-performance and the risk of injury in athletes. This review describes the current understanding of the role vitamin D plays within skeletal muscle tissue.
https://www.ncbi.nlm....pubmed/19807897
Vitamin D: extent of deficiency, effect on muscle function, bone health, performance, and injury prevention.
Vitamin D deficiencyis increasingly being identified in children, adolescents, and adults. Primary production of the active form of vitamin D occurs via a photolytic reaction induced by ultraviolet radiation B. Vitamin D has important effects on bone and muscle as well as on the immune system. Isolation ofa vitamin D receptor on muscle cells has been accompanied by studies showing receptor polymorphisms and age-related functional changeswhich have an effect on muscle performance. Insufficient levels havebeen associated with increased risk of stress fractures, decreased muscle performance, and increased sick days. Although there is still debate about the appropriate levels of vitamin D, studies have suggested a minimal level of 32 ng/ml. Supplementation serves as an inexpensive option associated with reduction in both morbidity and financial costs.
https://www.ncbi.nlm....pubmed/20945707
Vitamin D and skeletal muscle tissue and function.
This review aims to summarize current knowledge on the role of vitamin D in skeletal muscle tissue and function. Vitamin D deficiency can cause a myopathy of varying severity. Clinical studies have indicated that vitamin D status is positively associated with muscle strength and physical performance and inversely associated with risk of falling. Vitamin D supplementation has shown to improve tests of muscle function, reduce falls, and possibly impact on muscle fiber composition and morphology in vitamin D deficient older adults. Molecular mechanisms of vitamin D action on muscle tissue include genomic and non-genomic effects via a receptor present in muscle cells. Genomic effects are initiated by binding of 1,25-dihydroxyvitamin D [1,25(OH)(2)D] to its nuclear receptor, which results in changes in gene transcription of mRNA and subsequent protein synthesis. Non-genomic effects of vitamin D are rapid and mediated through a cell surface receptor. Knockout mouse models of the vitamin D receptor provide insight into understanding the direct effects of vitamin D on muscle tissue. Recently, VDR polymorphisms have been described to affect muscle function. Parathyroid hormone which is strongly linked with vitamin D status also may play a role in muscle function; however, distinguishing its role from that of vitamin D has yet to be fully clarified. Despite the enormous advances in recent decades, further research is needed to fully characterize the exact underlying mechanisms of vitamin D action on muscle tissue and to understand how these cellular changes translate into clinical improvements in physical performance.
https://www.ncbi.nlm....pubmed/18727936
https://www.ncbi.nlm....pubmed/20538161
Acho que muitas deles vão contra essa sua teoria então...