The Effect of Vitamin D Supplementation on Muscle Power in Elite Cyclist

This study has suspended participant recruitment.
(Trial was suspended due to obligations by researcher.)
Sponsor:
Collaborator:
Mid America Athletic Trainers Association
Information provided by (Responsible Party):
Oklahoma State University
ClinicalTrials.gov Identifier:
NCT01518725
First received: January 18, 2012
Last updated: December 11, 2012
Last verified: December 2012
  Purpose

The purpose of this study is to evaluate the change in vitamin D status with the change in muscular strength and muscular power in highly trained athletes over a 9-month study period. The investigators hypothesize that the greatest muscular strength and power gains will be demonstrated in the athletes who achieve and maintain a 25(OH)-D > 50 ng/mL (but < 100 ng/mL) over the 6 month study duration.

This hypothesis will be tested by carrying out the following specific aims: Aim 1. to determine the extent to which increasing serum 25(OH)D to > 50 ng/mL is associated with improved muscular power by assessing specific performance measures (e.g. Vertical Jump Test and Wingate test) relative to lean body mass; and Aim 2. to examine the correlation between vitamin D status and muscular power over time.


Condition Intervention Phase
Muscle Power
Dietary Supplement: Vitamin D
Dietary Supplement: Placebo
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Pharmacodynamics Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: The Effect of Vitamin D Supplementation on Muscle Power in Elite Cyclist

Resource links provided by NLM:


Further study details as provided by Oklahoma State University:

Primary Outcome Measures:
  • Change in Vitamin D status from baseline to 3 months and 6 months [ Time Frame: Up to 6 months ] [ Designated as safety issue: Yes ]
    Non fasting blood samples will be used for the evaluation of vitamin D metabolites. Venous blood (~5 cc) will be collected from the non-dominant arm by a trained phlebotomist, centrifuged at 2,000 rpm and serum stored at -80° C. Two vitamin D metabolites, 25 (OH) D and 1,25 (OH)2 D and serum PTH will be assessed.

  • Change in Power Output from baseline to 3 months and 6 months [ Time Frame: Up to 6 months ] [ Designated as safety issue: No ]
    Power will be assessed using a Vertical Jump Test and a Wingate Power Test.


Secondary Outcome Measures:
  • Sun Exposure Questionnaire [ Time Frame: Up to 6 months ] [ Designated as safety issue: No ]
    Participants will complete a sun exposure questionnaire (SEQ) to estimate vitamin D synthesis. The SEQ is a 2 point questionnaire that assesses exposure in a week's time period. Sun exposure can be calculated by day and by week. This questionnaire is currently in press.

  • Skin Tone Measurement [ Time Frame: Up to 6 months ] [ Designated as safety issue: No ]
    Skin tone will be assessed using the SmartProbe 400 for skin color measurement (IMS, Inc., Portland, ME). The measurement will be performed on the inner and outer portion of the forearm (dominant arm).

  • Food Frequency Questionnaire [ Time Frame: Up to 6 months ] [ Designated as safety issue: No ]
    A food frequency questionnaire (FFQ) will estimate dietary vitamin D intake. The FFQ is a 12 point questionnaire that assesses vitamin D supplement usage and the intake of foods that are vitamin D rich.


Estimated Enrollment: 60
Study Start Date: January 2012
Estimated Study Completion Date: July 2014
Estimated Primary Completion Date: July 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Vitamin D Supplementation
The vitamin D supplementation will consist of 100 mcg of vitamin D/d, to be taken throughout the day. Participants will achieve 100 mcg by taking 2 x 25 mcg capsules per day. One will be taken at each time point (i.e., morning and evening) throughout the day.
Dietary Supplement: Vitamin D
The vitamin D supplementation will consist of a capsule of 100 mcg of vitamin D/d, to be taken throughout the day. Participants will achieve 100 mcg by taking 2 x 25 mcg capsules per day. One will be taken at each time point (i.e., morning and evening) throughout the day. They will take the vitamin D supplement for the 6 month intervention period
Other Name: Cholecalciferol
Placebo Comparator: Gel-like Substance
Participants in the placebo group will receive a capsule containing the inactive ingredients that include cellulose and silica to create a gel-like substance
Dietary Supplement: Placebo
Participants in the placebo group will receive a capsule containing the inactive ingredients that include cellulose and silica to create a gel-like substance

Detailed Description:

Study will be advertised through flyers at the training facilities and by word of mouth. Researchers will schedule meeting with club members at the training facilities. At the meetings, the researchers will give an explanation of the study and address any concerns or questions that they may have. Cyclist will have an opportunity to sign up for participation on a sign-up sheet or e-mail the PI directly to minimize any chance of coercion. Meetings will take place in the training facilities in Tulsa, Oklahoma or the Oklahoma City Metropolitan Area. At this time, subjects will complete an informed consent along with demographic, anthropometric and health history, sunlight exposure, calcium and food frequency questionnaires and PAR Q. All subjects will be asked to fill out the questionnaires in the training facilities at various locations to ensure privacy. After completion of the appropriate questionnaires, cyclist will be have venous blood from the dominant arm (i.e., ~ 5 cc of blood) collected by a licensed medical professional and serum samples stored for future analysis of vitamin D metabolites (i.e., 25-OH-vitamin D and 1,25-OH-vitamin D) and parathyroid hormone (PTH) concentrations. The cyclist's arm will be cleaned with an alcohol swab, the blood will be drawn into a sterile vacutainer using a sterile needle. At the completion of blood collection, the arm will again be cleaned using sterile gauze and covered by a band aid to minimize the risk of infection. Samples will be placed on ice in an ice chest until they are processed in the Nutritional Sciences laboratories at Oklahoma State University. Subjects will then undergo skin tone analyses followed by evaluation of specific performance measures of muscular strength and power. These performance measures include: vertical jump test and a Wingate Power Test. All testing and blood collection will take place at the training facilities.

Within 4 weeks of completing the baseline assessment, the investigators will meet with the cyclist at their training facilities. Participants will be randomly assigned to placebo or the vitamin D supplemented group. The vitamin D supplementation will consist of 100 mcg of vitamin D/d, to be taken throughout the day. Participants will achieve 100 mcg by taking 2 x 25 mcg capsules per day. One will be taken at each time point (i.e., morning and evening) throughout the day. Currently, there is no evidence suggesting that athletes require more vitamin D then the general population for their age. Although we do not anticipate that the dose of vitamin D used in this study, will produce intoxication (150 ng/mL), subjects who exceed 100 ng/ml (i.e., upper end of the normal range) at any time will be asked to discontinue the study. Studies that have demonstrated the benefits of vitamin D supplementation on muscular strength and muscular power have combined vitamin D with calcium. Therefore, all subjects (placebo and vitamin D supplemented group) will be given a commercially available supplement of calcium and instructed to take with breakfast. The calcium supplement is in the form of calcium citrate (500 mg per capsule).

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Elite Cyclist (level 1,2 or 3)

Exclusion Criteria:

  • Currently prescribed vitamin D without physician approval to participate in study
  • Participants who respond "yes' to PAR-Q and do not get physician approval to participate in study
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT01518725

Locations
United States, Oklahoma
Oklahoma State University
Stillwater, Oklahoma, United States, 74078
Sponsors and Collaborators
Oklahoma State University
Mid America Athletic Trainers Association
Investigators
Principal Investigator: Rachel A Hildebrand, M.Ed Oklahoma State University
Principal Investigator: Brenda Smith, PhD Oklahoma State University
  More Information

No publications provided

Responsible Party: Oklahoma State University
ClinicalTrials.gov Identifier: NCT01518725     History of Changes
Other Study ID Numbers: ED11189
Study First Received: January 18, 2012
Last Updated: December 11, 2012
Health Authority: United States: Institutional Review Board

Keywords provided by Oklahoma State University:
Muscle Power
Vitamin D
Vitamins
Cholecalciferol

Additional relevant MeSH terms:
Cholecalciferol
Vitamin D
Ergocalciferols
Vitamins
Micronutrients
Growth Substances
Physiological Effects of Drugs
Pharmacologic Actions
Bone Density Conservation Agents

ClinicalTrials.gov processed this record on April 17, 2014