Researchers at Baylor University in Waco, Texas set out to see if vitamin D supplementation improved muscle strength in athletes. They identified several studies that had measured serum vitamin D levels and compared them to muscle strength in healthy athletes between the ages of 18- and 45-years-old. The studies lasted four weeks to six months and used vitamin D supplements that ranged from 600IU to 5000IU a day. Results showed that while vitamin D2 was ineffective at improving muscle strength, supplements of vitamin D3 were associated with improved muscle strength. Improvements ranged from 1.37% to 18.75%.
Elizabeth Somer, M.A.,R.D.
Chiang C, Ismaeel A, Griffis R, et al: Effects of vitamin D supplementation on muscle strength in athletes. Journal of Strength and Conditioning Research 2016;June 28th.