Dalquist’s 2015 paper4 reports that it is plausible that vitamin D has a role to play in power output of muscle tissue so it is important that the aspiring strength athlete seeking to maximise their performance has adequate levels of vitamin D on board. So the question is just how common therefore is vitamin D deficiency amongst the athletic population? In a meta-analysis by Farrokhyar5 which contained a total of 2313 athletes it was shown that just over half, 56% of athletes had inadequate vitamin D levels and that this was more likely to occur in athletes that lived >400N latitude4. Therefore for those athletes who live in areas of decreased sunlight it is important to ensure you know your vitamin D levels and you supplement accordingly if you are seeking to maximise your strength levels.
Now before you run off and start sun baking for hours on end and start popping vitamin D pills all day it is important to recognise that not one nutrient is going to be the panacea for a strength athlete. Yes, vitamins are essential for normal metabolism, growth and maintenance of human tissue and performance has been demonstrated to improve when deficiencies are addressed, the fat soluble vitamins A, D, E and K are stored in fat in the body which means levels can accumulate, in particular vitamin A which can pose a health risk6. Vitamin D whilst less likely to reach undesirably high levels (one study had subjects ingest 10,000IU daily for 5 months with no toxic effects7), it is still important to be safe when supplementing with the fat soluble vitamins. So how do I know if I have insufficient vitamin D levels and if so what are the recommended daily intakes for Vitamin D?
A blood test with a vitamin D assay is the clearest way to determine vitamin D status however for the power/strength athlete it is unlikely that these tests are readily available as these sports such as Powerlifting and Olympic Weight Lifting aren’t supported to the likes of more mainstream sports such as football or basketball. Therefore some signs of possible vitamin D insufficiency are a history of stress fractures, frequent respiratory illness, skeletal pain or clear signs of overtraining8. Now for the elite powerlifter for example skeletal or joint pain may just be as a result of the tremendous loads lifted by the athlete so this will need to be taken into consideration when using symptoms as a way of determining inadequate vitamin D status. One interesting fact for the strength/power athlete community, which has a tendency to attract the larger athlete, is the role bodyfat levels can have on Vitamin D status. For the heavyweight athletes with relatively high bodyfat levels it has been demonstrated that Vitamin D status may be effected as the vitamin D can be stored deep in the subcutaneous fat decreasing its ability to be converted to Vitamin D when required, such as in the winter months8.
Whilst the US Recommended Daily Intake for Vitamin D is 600IU it appears clear in the body of evidence that this recommendation is well below what is required for the athlete. The recommendation is to obtain 5-30min of sun exposure as close to solar midday as possible on the arms, legs and back. The lower ranges for fair skinned athletes and the upper ranges for darker skinned athletes. For the athlete confined to most of their time being spent indoors such as the Powerlifter or Olympic Lifter the recommended supplementation dose is between 2000-3000IU a day. Some reports of significantly higher “loading” doses to address insufficiencies in vitamin D have been demonstrated but should only be conducted under the strict supervision of an experienced health care practitioner. Apart from sunlight or supplements other sources of Vitamin D can be found in fatty/oily fish, fortified milk and cereals as well as yoghurt and eggs9.
All strength athletes are seeking ways to maximise their power and whilst the evidence appears to be leaning towards the importance of adequate Vitamin D levels it must be remembered that it is unlikely that just one vitamin will dramatically change an athlete’s performance unless they had significant deficiencies to begin with. If the athlete is eating a full, balanced diet inclusive of appropriate sports nutrition supplementation and gaining adequate sun exposure this should be adequate to maintaining Vitamin D status. However, particularly during winter months or for the athlete living in the far northern or southern regions of the world, vitamin D supplementation in the vicinity of 2000-3000IU a day is likely to maintain adequate vitamin D status.
1. Hamilton, B. Review Vitamin D and Human Skeletal Muscle Scand J Med Sci Sports 2010: 20: 182–190
2. Cannell J et al, Athletic Performance and Vitamin D Medicine & Science in Sports & Exercise April 2009
3. Sato Y, et al. Low-dose vitamin D prevents muscular atrophy and reduces falls and hip fractures in women after stroke: a randomized controlled trial. Cerebrovasc Dis 2005: 20: 187–192.
4. Dalquist et al. Plausible ergogenic effects of vitamin D on athletic performance and recovery Journal of the international Society of Sports Nutrition 2015 12:33
5. Farrokhyar et al. Prevalence of Vitamin D Inadequacy in Athletes: A Systematic-Review and Meta-analysis Sports Medicine March 2015
6. Gastelu, D, Hatfield F. Sports Nutrition International Sports Science Association 2000
7. Vieth R, Why the optimal requirement for Vitamin D3 is probably much higher than what is recommended for adults The Journal of Steroid Biochemistry and Molecular Biology, 2004 89-90(1-5), 575-579
8. Larson-Meyer E, The importance of Vitamin D for Athletes Sports Science Exchange (2015) Vol 28, no. 148, 1-6
9. Willis K Should we be concerned about the vitamin D status of athletes? International Journal of Sport Nutrition and Exercise Metabolism, 2008, 18, 204-224.