Vitamin D3 supplementation makes soccer training more effective
You should not exaggerate the effect, but according to Polish researchers it is there: if you give hard training soccer players extra vitamin D during the winter months, they become just a bit fitter than if they don't use vitamine D supplements.
Even in sunny Spain, during the winter the concentration of vitamin D in the soccer players' blood drops to a level that makes doctors usually prescribe vitamin D supplements. [Clin Nutr. 2012 Feb;31(1):132-6.] This is not only due to the small amount of sun, but probably also because frequent and heavy physical exercise increases the need for vitamin D.
For that reason, Polish sports scientists at the University Clinical Center of Gdansk wondered what happens if you supplement soccer players with extra vitamin D during an intensive training period in the winter months. The players had relatively low vitamin D levels.
The researchers had 36 young soccer players train 8 weeks intensively between January and March. 20 of them took 5000 IU vitamin D3 [125 micrograms] every morning, 16 players received a placebo.
Supplementation with vitamin D [SG] increased the vitamin D level by 119 percent. In the placebo group [PB], however, the vitamin D level decreased slightly further.
Both groups responded positively to the training, the figure below shows. It applies to all players, whether they take vitamin D or not.
When the researchers split their data, and looked at the vitamin D users and the placebo users as separate groups, they saw a clear difference on 1 variable: the VO2max. This increased by 20 percent among vitamin D users. In the other group that was 13 percent.
"According to our study, it may be assumed that vitamin D can have a positive, though moderate, effect on aerobic performance in players who apply high-intensity training in the form of small-sided games during limited exposure to sunlight", the researchers write.
"The study can be highly applicable for coaches who plan training loads for youth and adult soccer players. Apart from considering high intensity training in the form of small-sided games, they should also control vitamin D concentration in players."
"Subjects with low vitamin D levels should be supplemented with 4000-5000 IU/day during at least 4 weeks."
"These recommendations especially concern players who practice in winter in countries with low solar radiation."
"The limited amount of literature on the subject should induce both scientists and coaches to further research the effect of vitamin D deficiency and supplementation among athletes and their aerobic performance."
J Hum Kinet. 2018 Mar 23;61:63-72.
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