Vitamin D Supplementation and Muscle Characteristics in Trained Subjects

Healthy Subjects, Trained Clinical Trial

Official title:

Effects of 12 Weeks of Vitamin D Supplementation on Muscle Characteristics in Trained Subjects

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02599675
• Other study ID #: Trainsome 2015#006
• Status: Completed
• Phase: N/A
• First received: November 5, 2015
• Last updated: September 7, 2017
• Start date: November 2015
• Est. completion date: February 28, 2017

Study information

• Verified date: March 2017
• Source: Inland Norway University of Applied Sciences
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 71
• Est. completion date: February 28, 2017
• Est. primary completion date: February 28, 2017
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 40 Years

Eligibility

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

Related Conditions & MeSH terms

• Healthy Subjects, Trained

Intervention

Dietary Supplement:
• Vitamin D3
Vitamin D3 dissolved in olive oil, encapsuled
• Placebo
Olive oil, encapsuled

Locations

Country	Name	City	State
Norway	Lillehammer University College	Lillehammer

Sponsors (2)

Lead Sponsor	Collaborator
Inland Norway University of Applied Sciences	Sykehuset Innlandet HF

Country where clinical trial is conducted

Norway, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Other	Training diary	Diary that includes information on type of training, duration and intensity performed	From 1 month prior to study to post test (w12)
Other	Vitamin D-intake diary	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	From 1 month prior to study to post test (w12)
Other	Sun exposure diary	Diary that includes information on exposure to solarium or sun in countries south of Norway	From 1 month prior to study to post test (w12)
Primary	Lower body maximal dynamic strength	Changes in the ability of lower body muscles to exert maximal force during a dynamic movement	wk 0, wk12
Primary	Muscle fiber composition	Changes of the muscle fiber composition of musculus vastus lateralis in a 2X to 2A direction, measured using mRNA profiling	wk0, wk12
Secondary	Gene expression in muscle	Changes in RNA abundances in musculus vastus lateralis, measured at the level of single genes	wk0, wk12
Secondary	Vitamin D in blood	Changes in levels of 25(OH)D in blood	wk0, wk12
Secondary	Steroid hormones in blood	Changes in levels of steroid hormones in blood	wk0, wk12
Secondary	Muscular endurance	Changes in the ability of muscles to perform repeated dynamic contractions at submaximal loads (50% of 1 repetition maximum)	wk0, wk12
Secondary	Upper body maximal dynamic strength	Changes in the ability of upper body muscles to exert maximal force during dynamic movements	wk0, wk12