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Vitamin D Supplementation and Muscle Characteristics in Trained Subjects

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ClinicalTrials.gov Identifier: NCT02599675
Recruitment Status : Completed
First Posted : November 6, 2015
Last Update Posted : September 8, 2017
Sponsor:
Collaborator:
Sykehuset Innlandet HF
Information provided by (Responsible Party):
Inland Norway University of Applied Sciences

Brief Summary:
This study evaluates the effect of vitamin D supplementation on outcomes muscle performance and characteristics in 70 trained healthy individuals (18-40 years of age). Subjects will be allocated to ingest either vitamin D (35) or placebo (35) in a double-blinded fashion

Condition or disease Intervention/treatment Phase
Healthy Subjects, Trained Dietary Supplement: Vitamin D3 Dietary Supplement: Placebo Not Applicable

Detailed Description:

Vitamin D insufficiency compromises muscle functionality, leading to changes in muscle mass and strength, manifested at the cellular level. While this is increasingly recognized as a problem for individuals with vitamin D deficiency (typically 25(OH)D < 25 nmol/l), there is no general consensus for the remainder of the vitamin D-spectra. This lack of knowledge is probably linked to the variation in protocols of studies that have investigated the physiological role of vitamin D. These variations vary from aspects such as interventional vs observational studies to aspects related to subject characteristics such as age, health and training status. In this project, we will evaluate the effects of 12 weeks of vitamin D supplementation (2000 IU/day) on muscle performance and characteristics in 70 trained healthy individuals (18-40 years of age). Subjects will be allocated to either a vitamin D (35) or a placebo group (35) in a double-blinded manner. They will be instructed to continue their ordinary modes and frequency of training.

We anticipate baseline vitamin D levels in blood (and hence changes in vitamin D obtained through supplementation), measured as 25(OH)D, to be a major determinant of the efficacy of the intervention. This means that we expect individuals with low baseline levels of 25(OH)D to display more pronounced changes in functional and biological outcome measures than those with high baseline values. Such a scenario could be related to an inability of our protocol to increase blood levels of 25(OH)D in individuals with higher physiological levels of vitamin D (which essentially means that ingestion of vitamin D3 is leveled out or exceeded by elimination of vitamin D derivatives). Alternatively, it may be related to inabilities of tissues to respond to the resulting elevation in vitamin D levels. To study the individual variation in vitamin D responses, data on both functional and biological variables will be divided into quartiles based on baseline 25(OH)D-levels, whereupon comparisons will be made between the low-end and high-end quartile. Individual variation will also be assessed using a mixed model approach.


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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 71 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Effects of 12 Weeks of Vitamin D Supplementation on Muscle Characteristics in Trained Subjects
Study Start Date : November 2015
Actual Primary Completion Date : February 28, 2017
Actual Study Completion Date : February 28, 2017

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Vitamin D

Arm Intervention/treatment
Experimental: Vitamin D3
Vitamin D3 capsules for 12 weeks (2000 IU daily, equivalent to 50 ug)
Dietary Supplement: Vitamin D3
Vitamin D3 dissolved in olive oil, encapsuled
Other Name: cholecalciferol

Placebo Comparator: Placebo
Placebo capsules for 12 weeks (the number of daily capsules will match that of the vitamin D-group)
Dietary Supplement: Placebo
Olive oil, encapsuled




Primary Outcome Measures :
  1. Lower body maximal dynamic strength [ Time Frame: wk 0, wk12 ]
    Changes in the ability of lower body muscles to exert maximal force during a dynamic movement

  2. Muscle fiber composition [ Time Frame: wk0, wk12 ]
    Changes of the muscle fiber composition of musculus vastus lateralis in a 2X to 2A direction, measured using mRNA profiling


Secondary Outcome Measures :
  1. Gene expression in muscle [ Time Frame: wk0, wk12 ]
    Changes in RNA abundances in musculus vastus lateralis, measured at the level of single genes

  2. Vitamin D in blood [ Time Frame: wk0, wk12 ]
    Changes in levels of 25(OH)D in blood

  3. Steroid hormones in blood [ Time Frame: wk0, wk12 ]
    Changes in levels of steroid hormones in blood

  4. Muscular endurance [ Time Frame: wk0, wk12 ]
    Changes in the ability of muscles to perform repeated dynamic contractions at submaximal loads (50% of 1 repetition maximum)

  5. Upper body maximal dynamic strength [ Time Frame: wk0, wk12 ]
    Changes in the ability of upper body muscles to exert maximal force during dynamic movements


Other Outcome Measures:
  1. Training diary [ Time Frame: From 1 month prior to study to post test (w12) ]
    Diary that includes information on type of training, duration and intensity performed

  2. Vitamin D-intake diary [ Time Frame: From 1 month prior to study to post test (w12) ]
    Diary withthat includes information on approximate intake of vitamin D from sources other than the study-specific supplement, including ingestion of fish, seafood and vitamin D-supplement

  3. Sun exposure diary [ Time Frame: From 1 month prior to study to post test (w12) ]
    Diary that includes information on exposure to solarium or sun in countries south of Norway



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Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

- Individuals that have performed strength and / or endurance exercise training at least 3 X week for at least 6 months prior to the study


Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02599675


Locations
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Norway
Lillehammer University College
Lillehammer, Norway
Sponsors and Collaborators
Inland Norway University of Applied Sciences
Sykehuset Innlandet HF
Investigators
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Principal Investigator: Håvard Nygaard, MSc Inland Norway University of Applied Sciences

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Responsible Party: Inland Norway University of Applied Sciences
ClinicalTrials.gov Identifier: NCT02599675     History of Changes
Other Study ID Numbers: Trainsome 2015#006
First Posted: November 6, 2015    Key Record Dates
Last Update Posted: September 8, 2017
Last Verified: March 2017
Keywords provided by Inland Norway University of Applied Sciences:
Muscle
Vitamin D
Strength
Endurance
Muscle fiber
Additional relevant MeSH terms:
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Vitamin D
Ergocalciferols
Cholecalciferol
Vitamins
Micronutrients
Nutrients
Growth Substances
Physiological Effects of Drugs
Bone Density Conservation Agents
Calcium-Regulating Hormones and Agents