ORIGINAL ARTICLE  BODY COMPOSITION, NUTRITION AND SUPPLEMENTATION 

The Journal of Sports Medicine and Physical Fitness 2020 January;60(1):85-91

DOI: 10.23736/S0022-4707.19.09607-5

Copyright © 2019 EDIZIONI MINERVA MEDICA

language: English

Physical performance is not improved with vitamin D repletion: a randomized trial

Shane D. SCHOLTEN ¹ ✉, Derek D. FERLEY ², Chad B. BIRGER ³, Cortney DOWLING ⁴, Mikenzie MIKKELSON ⁵, Jesse SPRINGER ⁶, Nathan LUCS ⁷

¹ Exercise and Sport Sciences, Augustana University, Sioux Falls, SD, USA; ² Avera Sports Institute, Avera McKennan Hospital and University Health Center, Sioux Falls, SD, USA; ³ Human Resources, MetaBank, Sioux Falls, SD, USA; ⁴ Department of Chemistry, Liberty University, Lynchburg, VA, USA; ⁵ Department of Natural Sciences, Black Hills State University, Spearfish, SD, USA; ⁶ Department of Natural Sciences, University of Sioux Falls, Sioux Falls, SD, USA; ⁷ Department of Physical Therapy, Des Moines University, Des Moines, IA, USA

BACKGROUND: Studies enrolling physically active participants have used various vitamin D dosing strategies which can result in diverse post supplementation vitamin D status due to individual body weight and initial vitamin D status. Emerging evidence suggests serum 25(OH)D levels of 100-120 nmol/L are optimal for peak performance, however, studies generally administer the same dose for all participants regardless of initial 25(OH)D status and body weight. This approach will not likely get all participants to the optimal 25(OH)D level proposed for optimal physical performance. Therefore, it’s important to enroll vitamin D insufficient/deficient participants to observe the effects of vitamin D supplementation on physical performance. We assessed vitamin D repletion on markers of anaerobic performance in physically active adults by replenishing insufficient/deficient vitamin D to the target of 100-120 nmol/L suggested for optimal physical performance.
METHODS: We conducted a double-blind randomized control trial in 42 physically active participants, 18-42 years of age in the winter months. Physically active participants with insufficient/deficient 25(OH)D status (<75 nmol/L) were supplemented with an individualized dosing strategy to achieve 25(OH)D of 120 nmol/L with eight weeks of supplementation using the following formula: Dose (IU)=40•[Target 25(OH)D3 - Initial 25(OH)D3]•Body Weight (kg). A modified Wingate test, 10m and 40m sprints, vertical jump, hand grip strength, pushups, and isokinetic knee flexion and extension were assessed before and after repletion of 25(OH)D.
RESULTS: Thirty-nine out of 42 participants completed the study. Twenty-seven participants in the vitamin D group significantly increased 25(OH)D from 61 nmol/L to 123 nmol/L (P<0.001). 12 participants in the Placebo group had a significant decrease in 25(OH)D from 98 nmol/L to 83 nmol/L (P=0.02). Despite these changes in 25(OH)D status in each group, no significant changes in anaerobic performance markers were found.
CONCLUSIONS: These findings indicate that vitamin D repletion to levels sufficient for optimal physical performance does not improve anaerobic physical performance.

KEY WORDS: Muscle strength; Athletic performance; Vitamin D