Research
Hormonal
Vitamin D supplementation improves muscle morphology (Type II fiber size) and function in deficient individuals, but evidence for performance benefits in healthy, non-deficient young athletes is limited.
For healthy young athletes, Vitamin D supplementation may not significantly boost strength or performance unless you are deficient. Focus on getting adequate sun exposure or dietary sources, and consider testing levels if you have risk factors (e.g., indoor lifestyle, high latitude).
ModerateQualifiesMEDIUM confidence
At the 2-year follow-up... in the vitamin D2-supplemented group the relative content and mean diameter of type II fibers increased, with the fiber size correlating with 25(OH)D levels... By far the majority of vitamin D studies have been performed on the elderly population... there is limited evidence for the impact of vitamin D on healthy young individuals.
Why this rating
Strong mechanistic and elderly data, but mixed/limited results in young athletic populations.
Source
Vitamin D and Human Skeletal Muscle
Bruce Hamilton · Scandinavian Journal of Medicine and Science in Sports · 2009
DOI 10.1111/j.1600-0838.2009.01016.x
narrative_reviewCited 273×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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- Vitamin D status influences muscle function through genomic mechanisms involving the Vitamin D Receptor (VDR) and non-genomic rapid calcium handling.Strong
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