Effects of High-Dose Vitamin D on Hormones, Neuromuscular Function, Cognition, and Body Composition in Athletes

NCT07641075 | Recruiting

• 2 other identifiers: KB-05/2017Institute of Sport Sciences
• Study Type: interventional
• Target: 200
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to evaluate the effects of high-dose vitamin D3 supplementation on selected physiological, neuromuscular, and cognitive parameters in athletes. At the baseline visit, participants will undergo a series of assessments at the Functional Research Laboratory at AWF Katowice, including a 10 mL venous blood sample collection, body composition analysis (via InBody and DEXA scans), neuromuscular function evaluation using tensiomyography (TMG), and computerized cognitive tests via the Vienna Test System. Following baseline testing, participants will be randomly assigned to either the vitamin D3 group or the placebo group. The active group will receive a daily dose of 4,000 IU of vitamin D3 (1 capsule with dinner), while the control group will receive an identical placebo. The intervention period will last for 4 or 8 weeks. Upon completion of the supplementation period, all baseline assessments will be repeated to evaluate the post-intervention changes.

Conditions

Vitamin D 25-Hydroxylase Deficiency; Vitamin D Deficiency/Insufficiency

Keywords

vitamin D; athletes; coggnitive function; neuro-muscular function; hormones; speed; performance

Outcome Measures

Primary Outcomes (1)

• Serum 25-Hydroxyvitamin D Concentration

  Description: Serum concentration of 25-hydroxyvitamin D \[25(OH)D\] measured using a validated laboratory method to assess vitamin D status. Unit of Measure: ng/mL

  8-weeks

Secondary Outcomes (3)

• Corsi Block-Tapping Test - Block Time

  8-weeks

• Corsi Block-Tapping Test - Reverse Span Score

  8-weeks

• Corsi Block-Tapping Test - Unweighted Block Span

  8-weeks

Other Outcomes (2)

• Countermovement Jump Height

  8-weeks

• Sprint Performance

  8-weeks

Study Arms (2)

Vitamin D3 supplemented group

EXPERIMENTAL

Participants in this arm will receive vitamin D3 supplementation at a total daily dose of 4,000 IU. The supplement will be administered 1 capsule in the evening (with dinner). The intervention period will last for either 4 or 8 weeks.

Dietary Supplement: Vitamin D supplementation

Placebo supplementation group

PLACEBO COMPARATOR

Participants in this arm will receive placebo supplementation. The supplement will be administered capsule in the evening (with dinner). The intervention period will last for either 4 or 8 weeks.

Dietary Supplement: Placebo

Interventions

Vitamin D supplementation DIETARY_SUPPLEMENT

Vitamin D3 will be administered orally in the form of capsules. Participants will ingest a total daily dose of 4,000 IU, split into two doses: 1 capsule (4,000 IU) in the evening with dinner. The intervention will be carried out daily for a duration of either 4 or 8 weeks. Supplementation compliance will be monitored by the research team through capsule counting during follow-up visits.

Vitamin D3 supplemented group

Placebo DIETARY_SUPPLEMENT

An identical placebo will be administered orally in the form of capsule, matching the active vitamin D3 supplement in appearance, size, color, and taste. Participants will ingest 1 placebo capsule in the evening with dinner daily for a duration of either 4 or 8 weeks.

Placebo supplementation group

Eligibility Criteria

• Age: 17 Years - 60 Years
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• a minimum of 8 years of training experience,
• absence of injuries in the 6 months leading up to the assessments,
• consistent engagement in training sessions a minimum of 5 times per week over the last 6 months.

You may not qualify if:

• vitamin D supplementation within one month prior to the study,
• use of multivitamin supplements,
• intestinal disorders.

Sponsors & Collaborators

• The Jerzy Kukuczka Academy of Physical Education in Katowice: lead

Study Sites (1)

The Jerzy Kukuczka Academy of Physical Education in Katowice

Katowice, Mikołowska 72a, 40-065, Poland

RECRUITING

MeSH Terms

Conditions

Vitamin D Hydroxylation-Deficient Rickets, Type 1B; Vitamin D Deficiency

Condition Hierarchy (Ancestors)

Avitaminosis; Deficiency Diseases; Malnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases

Central Study Contacts

Małgorzata Michalczyk, Profesor

CONTACT

+48535016532; m.michalczyk@awf.katowice.pl

Małgorzata Michalczyk, Profesor

CONTACT

535016532; m.michalczyk@awf.katowice.pl

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: assistant profesor

Study Record Dates

• First Submitted: May 20, 2026
• First Posted: June 11, 2026
• Study Start: July 1, 2025
• Primary Completion: July 10, 2025
• Study Completion (Estimated): December 31, 2028
• Last Updated: June 11, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL
• Time Frame: Start data- 20.05.2026 End- 31.12.2028

Locations

PL (1)