Shannon Stadelman '12

Effect of Vitamin D Status on Anaerobic Performance in College Basketball Players

Vitamin D deficiency is prevalent among athletes especially during the winter months in the northern hemisphere (1). In a previous study with male cross-country runners, Vitamin D levels were inadequate in December in 40% of runners and by February, 100%.

Purpose: to 1) determine if a supplement of 2000 IUs/day of vitamin D for 90 days was sufficient to maintain optimal serum D3 status (> 75 µmol/L) in male basketball players, and 2) observe if D3 status correlated with anaerobic performance.

Methods: IRB approval and informed consent were obtained. Twenty male basketball players participated. Blood collections and anaerobic performance tests [vertical jump and an agility T-test] were conducted in October and January; D3 was measured using an ELISA kit (ALPCO). Subjects were assigned to either vitamin D or thiamin (as placebo). Data were analyzed using repeated measures analysis of variance. Surveys were completed pre and post-study to assess supplement use, tanning, and compliance.

Results: Overall, 10 players had less than optimal levels of serum D3 (<75 µmol/L) in October and 12 players in January. Vitamin D levels between the groups were not statistically different. All subjects improved their vertical jump and agility T-test scores after 90 days, but there was no difference between groups (p = 0.66 for agility T-test and p = 0.95 for vertical jump). No significant differences were obtained for any of the performance measures (vertical jump, agility T test) between the treatment and control groups. Review of post-study surveys indicated that less than 15% of subjects reported taking the supplement 80-100% of time, and 45% reported taking the supplement <40% of the time. Supplements including vitamin D, even taken irregularly, appear to have prevented the dramatic drop in serum D3 levels that typically occurs during the winter months.

Conclusions: No differences were observed between initial and final D3 serum levels in the vitamin D supplement group due to poor compliance. Measures to ensure compliance are essential to determine whether vitamin D status plays a role in anaerobic performance.

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Effect of Vitamin D Status on Anaerobic Performance in College Basketball Players

Research Advisors: Amy Olson PhD, RDN, LD and Manuel Campos, PhD, Biology