Vitamin D Supplementation and Muscle Characteristics in Trained Subjects

NCT ID: NCT02599675

Last Updated: 2017-09-08

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 71 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2015-11-30
• Study Completion Date: 2017-02-28

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

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.

Conditions

Healthy Subjects, Trained

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: TRIPLE

Study Groups

Vitamin D3

Vitamin D3 capsules for 12 weeks (2000 IU daily, equivalent to 50 ug)

Group Type: EXPERIMENTAL

Vitamin D3

Intervention Type: DIETARY_SUPPLEMENT

Vitamin D3 dissolved in olive oil, encapsuled

Placebo

Placebo capsules for 12 weeks (the number of daily capsules will match that of the vitamin D-group)

Group Type: PLACEBO_COMPARATOR

Placebo

Intervention Type: DIETARY_SUPPLEMENT

Olive oil, encapsuled

Interventions

Vitamin D3

Vitamin D3 dissolved in olive oil, encapsuled

Intervention Type: DIETARY_SUPPLEMENT

Placebo

Olive oil, encapsuled

Intervention Type: DIETARY_SUPPLEMENT

Other Intervention Names

cholecalciferol

Eligibility 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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 40 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Sykehuset Innlandet HF

OTHER

Sponsor Role: collaborator

Inland Norway University of Applied Sciences

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Håvard Nygaard, MSc

Role: PRINCIPAL_INVESTIGATOR

Inland Norway University of Applied Sciences

Locations

Lillehammer University College

Lillehammer, , Norway

Countries

Norway

Other Identifiers

Trainsome 2015#006

Identifier Type: -

Identifier Source: org_study_id