(NaturalNews) Insufficient blood levels of vitamin D may cause adolescent girls to have weaker muscles, according to a new study in theThe research team was composed of scientists from Longsight Health Centre in Manchester, the University of Manchester, Saint Mary's Hospital for Women & Children in Manchester and Novotec Medical GmBH in Pforzheim, Germany."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," lead researcher Kate Ward said. "Our study found that vitamin D is positively related to muscle power, force, velocity and jump height in adolescent girls."The researchers measured vitamin D blood levels from 99 girls between the ages of 12 and 14, all of them students at the same inner city, multi-ethnic Manchester school. They found that 75 percent of the participants had vitamin D levels lower than optimal, although none were yet exhibiting any symptoms of deficiency.Deficiency of vitamin D is well known to lead to hampered calcium absorption, which can cause the weakening of bones and lead to fractures and osteoporosis. Newer research suggests that it may also increase the risk of cancer, heart disease and autoimmune disorders.The researchers also measured each participant's muscle strength and force through a variety of jumping exercises. They found a direct correlation between vitamin D blood levels and the girls' performance on the muscle strength tests."These data highlight the importance of vitamin D status on muscle function in adolescent girls. Sub-optimal force might have implications for long-term bone development," the researchers wrote.Scientists and medical professionals believe that vitamin D deficiency is widespread, particularly among darker skinned people living far from the equator, whose bodies cannot synthesize enough of the vitamin from the weak winter sunlight. Recent studies suggest that as many as 55 percent of apparently healthy U.S. adolescents might be vitamin D deficient.Sources for this story include: www.nutraingredients.com