The Effects of Vitamin D Supplementation on Aerobic Fitness in Athletes

The Effects of Vitamin D Supplementation on VO2max in Athletes: a Randomised, Double-blind, Placebo-controlled Trial

The primary aim of the study is to identify if vitamin D3 supplementation influences VO2max in athletes.

Secondary aims are to determine if vitamin D3 supplementation impacts on measures of muscle function, lung function, body composition, immune function and the self-reported incidence of upper respiratory tract infection.

This double-blind, randomised, placebo-controlled trial is of parallel design and will aim to recruit a total of 50 athletes randomised into either a placebo or treatment group for a 12-week intervention.

Inclusion Criteria:

• Athletes whose sport does not primarily consist of an anaerobic component
• Apparently healthy
• Over the age of 18

Exclusion Criteria:

• Resting arterial hypertension
• Individuals who are not an athlete at a University/local sports team
• Athletes who predominantly utilise anaerobic energy systems
• Athletes under the age of 18
• Those that have consumed a supplement containing vitamin D (greater than 400IU/day) or iron supplements for up to 30 days prior to starting the study
• Those with health conditions identified by the screening questionnaire
• Individuals that are on prescribed medication that is known to affect vitamin D metabolism
• Those following a vegan diet
• Those with a physical disability that would prevent successful completion of the exercise test
• Those who have either had a sun holiday in the 4 weeks prior to starting the study
• Those planning a sun holiday during the intervention period