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College swimmers helped by daily 5,000 IU of Vitamin D in the fall – RCT Feb 2020

Effects of Seasonal Vitamin D3 Supplementation on Strength, Power, and Body Composition in College Swimmers

Int J Sport Nutr Exerc Metab, 1-9 2020 Feb 4, DOI: 10.1123/ijsnem.2019-0250
Michelle S Rockwell 1, Madlyn I Frisard 1, Janet W Rankin 1, Jennifer S Zabinsky 1, Ryan P Mcmillan 1, Wen You 1, Kevin P Davy 1, Matthew W Hulver 1


Indoor Athletes have lower Vitamin D levels

Overview Sports and vitamin D has the following summary
Athletes are helped by vitamin D by:

  1. Faster reaction time
  2. Far fewer colds/flus during the winter
  3. Less sore/tired after a workout
  4. Fewer micro-cracks and broken bones
  5. Bones which do break heal much more quickly
  6. Increased VO2 and exercise endurance Feb 2011
  7. Indoor athletes especially need vitamin D
  8. Professional indoor athletes are starting to take vitamin D and/or use UV beds
  9. Olympic athletes have used UV/vitamin D since the 1930's
  10. The biggest gain from the use of vitamin D is by those who exercise less than 2 hours per day.
  11. Reduced muscle fatigue with 10,000 IU vitamin D daily
  12. Muscle strength improved when vitamin D added: 3 Meta-analysis
  13. Reduced Concussions
    See also: Sports and Vitamin D category 273 items

Sports category in VitaminDWiki starts with

273 items in Sports category

Sports benefits from up to 50 ng (click on chart for details)
Sports benefit up to 50 ng @ /is.gd/Vitdsports
see also:
Overview Sports and vitamin D     Concussions
Military    Muscle    Overview Fractures and vitamin D
Vitamin D supplementation increases strength of lower muscles – Meta-analysis April 2019
Athletes helped by weekly 50,000 IU Vitamin D – RCT Aug 2019
College swimmers helped by daily 5,000 IU of Vitamin D in the fall – RCT Feb 2020
Shin splints decrease with vitamin D
Less muscle inflammation after exercise if high level of Vitamin D (50 ng) -July 2021 50 ng
Only 1 NCAA basketball player getting 10,000 IU vitamin D daily achieved 50 ng goal – Jan 2020 50 ng
NCAA trainers are getting on board the Vitamin D train (40-50 ng)– Nov 2019 50 ng
Is 50 ng of vitamin D too high, just right, or not enough 50 ng
The only independent predictor of aerobic power: Vitamin D - 2021
Olympic Committee consensus on Vitamin D, Omega-3, Zinc, etc– May 2018 not consdered "doping"
Some Foot and ankle problems are treated by Vitamin D – many studies
Typical stress fracture during US Navy training cost 14,953 dollars, most had less than 40 ng Vitamin D - June 2022
Vitamin D trials by military – all 4 found benefit – review Sept 2019
Vitamin D supplementation increases strength of lower muscles – Meta-analysis April 2019
Omega-3 helps muscles - many studies
The Meta-analysis of Sports and Vitamin D are listed here:

The purpose of this study was to evaluate the impact of fall season vitamin D3 supplementation on strength/power, body composition, and anabolic hormones in swimmers with optimal vitamin D status at summer's end. Male and female National Collegiate Athletic Association Division I swimmers (N = 19) with optimal 25-hydroxyvitamin D [25(OH)D] randomly received 5,000 IU of vitamin D3 (VITD) or placebo (PLA) daily for 12 weeks while participating in swimming and strength and conditioning training (August-November). Before and after the intervention, the participants underwent blood sampling for analysis of serum 25(OH)D, parathyroid hormone, total testosterone, free testosterone, sex hormone-binding globulin, and insulin-like growth factor 1, dual-energy X-ray absorptiometry, and strength/power testing (bench press, squat, dead lift, standing broad jump, vertical jump, and dips and pull-ups). Sex was used as a covariate for analyses.

  • The 25(OH)D was decreased by 44% in PLA (p < .05) and increased by 8% in VITD over the 12 weeks.
  • Fat-free mass increased in VITD (56.4-59.1 kg; p < .05), but not PLA (59.4-59.7 kg; p < .01).
    • Appears that added 2.7 kg of muscle if take Vitamin D, but only added 0.3 kg if placebo
  • Significant Group × Time interaction effects were observed for dead lift (F = 21.577, p < .01) and vertical jump (F = 11.219, p < .01), but no other strength/power tests.
  • Total testosterone decreased similarly in both groups, but free testosterone decreased and sex hormone-binding globulin increased only in PLA (p < .01).
  • There were no group differences or changes in insulin-like growth factor 1 with the intervention.

The findings suggest that vitamin D supplementation is an efficacious strategy to maintain 25(OH)D during the fall season training and to enhance some aspects of strength/power and fat-free mass in swimmers. Further research on the relationship between vitamin D and anabolic hormones is needed.

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