Vitamin D supplementation and athletic performance in male collegiate and recreational, intramural basketball players

Deficient and insufficient levels of serum 25(OH)D, defined as levels below 30ng/ml, have been reported to negatively affect muscular performance and function, immune function, cognitive function, and other measures vital to perform in sports and athletics. Initial research has shown that athletes, especially those who practice and compete indoors, tend to have deficient and insufficient levels of vitamin D. However, the effects of supplementation with vitamin D3 on athletic performance measures in collegiate and recreational, intramural athletes has not been studied. This study examined 18 college aged males, both collegiate and recreational, intramural basketball players in a double-blind, placebo controlled trial, where neither the study participants nor researchers were aware of treatment, either vitamin D3 supplementation or placebo. Blood samples were taken and analyzed for 25(OH)D using liquid chromatography, tandem mass spectrometry at baseline and after 8 weeks of supplementation. Pre- and post-tests consisted of the vertical jump, to assess power, 20 m sprint time trial, to assess speed, and 5-10-5 agility drill time trial, to assess agility. The results indicated that collegiate and recreational, intramural basketball players were deficient in 25(OH)D at baseline, at 19.33 ng/mL (9.46). Vitamin D3 supplementation was effective at significantly increasing 25(OH)D levels from 21.10 ng/ml (9.27), an insufficient level, to 41.1 ng/ml, a sufficient level. Placebo did not significantly increase 25(OH)D levels, although levels did increase 18.25 ng/ml (10.30) to 27.88 ng/ml (7.77). However there were no significant differences in pre and post athletic performance measurements of the vertical jump height, 20 m sprint time, and 5-10-5 agility drill time. In conclusion, 4,000 IU of vitamin D3 supplementation, as expected, significantly increased 25(OH)D levels, but was ineffective in increasing athletic performance.