The purpose of this study is to investigate the effects of vitamin D supplementation on biochemistry response and skeletal muscle synthesis in prolonged endurance exercise.

Endurance exercise mode will be used to evaluate the effects of vitamin D supplementation on cardiac biomarkers, metabolic hormones, oxidative damage, and inflammation responses. An independent samples and dose titration design will be used to assign 30 participants to the experimental group (n = 15) or placebo group (n = 15). All participants in the experimental group will have serum 25(OH)D concentrations higher than 48 ng/mL after supplementation period. After the prolonged endurance exercise test, the blood samples will be collected for analyzing biomarkers. Data will be analyzed by Two-way mixed design ANOVA.

Inclusion criteria:

• The volunteers included have conditions as stated below :

  1. male adult between 20-40 years old without any history of cardiovascular, liver, kidney and diabetes disease
  2. no acute sport injury
  3. male adult whose concentration of 25(OH)D is under 30 ng/mL, and maximal oxygen consumption is over 40 ml/kg/min
  4. did not participated in any clinical trials or research in the last 3 months before our experiment
  5. no supplements were taken during the experimental period
  6. were requested to maintain their regular daily life style and avoid alcohol intake

Exclusion Criteria:

• The volunteers were excluded if they have the situation stated below:

  1. history of cardiovascular, liver, kidney and diabetes disease
  2. acute sport injury
  3. their concentration of 25(OH)D is over 30 ng/mL, or maximal oxygen consumption is under 40 ml/kg/mint
  4. participated in any clinical trials or experimental research in the last 3 months before our experiment
  5. taking supplement during the experimental period
  6. did not maintain their regular eating habit or drink alcohol

A double-blind, matched-pair study design