Effects of Eights Weeks of Vitamin D Supplementation on Physical Performance in a Physically Active Population




Markin, Kelsie

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<p><b>Context:</b> Vitamin D deficiency is common in the general and athletic population. It is indicated that vitamin D may play an important role in muscle function and physical performance. <b>Objective:</b> The purpose of this investigation is to determine if an eight- week supplementation of 50,000 IU of vitamin D3 will reverse deficiency in a physically active population. A secondary purpose of this investigation is to determine if vitamin D3 supplementation will increase musculoskeletal performance abilities in a 40-meter sprint, 1 RM bench press, and vertical jump height. <b>Design:</b> Double-Blinded, Randomized Controlled Clinical Trial <b>Setting:</b> Laboratory <b>Participants:</b> Twenty-nine physically active men (n=11) and women (n=18) (age =23.21 ± 1.52 yrs, weight =70.66±14.23 kg, height=171.18±9.03 cm) from Texas State University volunteered to participate in the investigation. <b>Interventions:</b> Subjects were randomized into two groups receiving either 50,000 IU of vitamin D3 for eight weeks or a placebo pill. Pre-supplementation serum 25(OH)D levels were measured to determine deficiency. Physical performance measures (1-RM bench press, 40 meter sprint, and vertical jump height) were assessed pre-supplementation and post-supplementation. Subjects met with the investigator one time each week for eight weeks to receive 50,000 IU vitamin D3 capsule or placebo capsule. Vitamin D blood serum levels were measured again at the end of the investigation’s eight-week supplementation period. <b>Main Outcome Measures:</b> The main outcomes measured in this investigation were serum 25(OH)D levels, 1-RM bench press, 40-meter sprint, and vertical jump height. <b>Results:</b> Total serum 25(OH)D concentration significantly increased in the vitamin D supplementation group after eight weeks of supplementation with 50,000 IU of vitamin D (p<0.00). At baseline testing 66% of the participants were vitamin D deficient. After eight weeks of supplementation all participants in the treatment group reached optimal values above 50ng/ml. There were no significant differences between the two groups in any of the performance tests measures over the eight week supplementation period (1RM bench press, p=0.583 ; vertical jump height, p=0.820; 40-meter sprint, p=0.969). <b>Conclusions:</b> Eight weeks of 50,000 IU of vitamin D supplementation one time per week significantly increased vitamin D serum levels and reverse vitamin D deficiency in a young, physically active population. Supplementation of vitamin D for eight weeks had no effect on physical performance measures.



Vitamin D, Muscle function


Markin, K. (2015). Effects of eights weeks of vitamin D supplementation on physical performance in a physically active population (Unpublished thesis). Texas State University, San Marcos, Texas.


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