CONCLUSIONS Vitamin D supplementation positively affected lower limb muscle strength in athletes , but not upper limb muscle strength or muscle power .
Different muscle groups and functions may respond differently to vitamin D supplementation .
BACKGROUND Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle .
However , vitamin D deficiency is a global problem , including athletes .
Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results .
Therefore , we aim ed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta- analysis .
Low-Dose Vitamin D Prevents Muscular Atrophy and Reduces Falls and Hip Fractures in Women after Stroke: A Randomized Controlled Trial
OBJECTIVE Vitamin D supplementation is suggested to reduce the risk of falls among ambulatory or institutionalized elderly subjects . The present study was undertaken to address the reduced risk of falls and hip fractures in patients with long-st and ing stroke by vitamin D supplementation . METHODS Ninety-six elderly women with poststroke hemiplegia were followed for two years . Patients were r and omly assigned to one of the two groups , and 48 patients received 1,000 IU ergocalciferol daily , and the remaining 48 received placebo . The number of falls per person and incidence of hip fractures were compared between the two groups . Strength and tissue ATPase of skeletal muscles on the nonparetic side were assessed before and after the study . RESULTS At baseline , serum 25-hydroxyvitamin D levels were in the deficient range ( < 10 ng/ml ) in all patients ; and vitamin D treatment enhanced serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels .  Vitamin D treatment accounted for a 59 % reduction in falls ( 95 % CI , 28 - 81 % ; p = 0.003 ) . There were increases in the relative number and size of type II muscle fibers and improved muscle strength in the vitamin D-treated group . Hip fractures occurred in 4 of 48 placebo group and 0 in 48 vitamin D2 group during the 2-year study period ( log-rank , p = 0.049 ) . CONCLUSION Vitamin D may increase muscle strength by improving atrophy of type II muscle fibers , which may lead to decreased falls and hip fractures
CONCLUSIONS Vitamin D supplementation positively affected lower limb muscle strength in athletes , but not upper limb muscle strength or muscle power .
Different muscle groups and functions may respond differently to vitamin D supplementation .
BACKGROUND Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle .
However , vitamin D deficiency is a global problem , including athletes .
Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results .
Therefore , we aim ed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta- analysis .