Girl Power: Vitamin D Increases Muscle, Force in Girls

MANCHESTER, United Kingdom—Vitamin D significantly increases muscle power and force in adolescent girls, according to a new study in the February issue of the Journal of Clinical Endocrinology & Metabolism (JCEM).

The body produces vitamin D naturally via exposure to direct sunlight; however, vitamin D deficiency has become common in the United States and has a negative impact on muscle and bone health, which can lead to osteoporosis and rickets.

“We know vitamin D deficiency can weaken the muscular and skeletal systems, but until now, little was known about the relationship of vitamin D with muscle power and force,” said the study’s lead author Kate Ward, PhD, of the University of Manchester. “Our study found that vitamin D is positively related to muscle power, force, velocity and jump height in adolescent girls.”

Researchers followed 99 adolescent girls between the ages of 12 and 14 and took blood samples to measure the girls’ serum levels of vitamin D. Many were found to have low levels of vitamin D despite not presenting any symptoms.

Researchers used jumping mechanography to measure muscle power and force. According to Ward, this method of testing is ideal as the muscles required to jump are those most often affected in subjects with vitamin D deficiency. Girls without vitamin D deficiency performed significantly better in these tests.

“Vitamin D affects the various ways muscles work and we’ve seen from this study that there may be no visible symptoms of vitamin D deficiency,” Ward said. “Further studies are needed to address this problem and determine the necessary levels of vitamin D for a healthy muscle system.”