A 881 subject cohort had muscle strength measured with standardized testing. Vitamin D status analyses were conducted on 499 subjects, low levels of vitamin D were defined as serum below 250H-vitamin D below 50 nmol/L. Statistical analyses were adjusted for height, body fat, and weight. The study does not provide an explanation for the difference of the finding between the sexes.
It was also found that vitamin D levels higher than 50 nmol/L was associated with the strongest female subjects, the finding was not evident in males. Studies show that vitamin D increases levels of IGF-1 which is a growth factor that increases muscle strength, levels of which are different between the sexes. Researchers say that based on data they still can’t conclude that females who get the vitamin D through food, sun, or supplement will get stronger muscles, although their association could mean that, according to the researchers.