Effects of Single Sodium Bicarbonate Supplementation on National-Level Finswimming Performance

NCT ID: NCT07135934

Last Updated: 2025-08-22

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 20 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-07-01
• Study Completion Date: 2026-12-20

Brief Summary

This randomized, double-blind, placebo-controlled crossover trial will investigate the acute effects of sodium bicarbonate supplementation on performance, stroke biomechanics, and selected physiological and perceptual responses during a simulated 200-meter Bi-Fins race in elite finswimmers.

Detailed Description

This randomized, double-blind, placebo-controlled, crossover study will examine the effects of sodium bicarbonate (NaHCO₃) supplementation on simulated finswimming performance and associated biomechanical, physiological, and perceptual responses in national-level finswimmers. Twenty participants, all active members of the Czech junior or senior national team, will complete three test sessions separated by a 48-hour recovery period without training sessions.

The first session will serve as a control with no intervention, while the second and third will involve ingestion of either sodium bicarbonate (NaHCO₃; 300 mg·kg-¹) or placebo (food-grade starch), administered in a randomized, counterbalanced order. The capsules will be indistinguishable in appearance, weight, and texture. Allocation concealment will be ensured: only a designated medical professional overseeing the health and safety of the participants will have access to the randomization codes. Neither the participants nor the investigators will be aware of the supplement condition during testing.

All sessions will be conducted under standardized conditions in a 25-meter indoor swimming pool (Aplikační centrum BALUO, Palacký University Olomouc) and will include a standardized warm-up followed by a 200-meter Bi-Fins time trial.

Blood samples for acid-base balance assessment will be collected at four time points: baseline (10 minutes before warm-up), 10 minutes after warm-up, 5 minutes before race start, and 3 minutes post-exercise. From these samples, variability in acid-base balance will be assessed, specifically using actual base excess (ABE; mmol/L), blood hydrogen ion concentration (pH; unitless), and bicarbonate concentration (HCO₃-; mmol/L). Blood lactate concentration (mmol/L) will be measured at two time points only: baseline (10 minutes before warm-up) and 3 minutes post-exercise.

Subjective perceptual responses will include:

1. rate of perceived exertion (RPE) using the Borg Category Ratio 1-10 scale, assessed immediately after the race, where higher scores indicate greater exertion;

2. gastrointestinal discomfort using the Borg Category Ratio 1-10 scale, assessed approximately 5 minutes before the race to avoid performance bias, where higher scores indicate worse discomfort; and

3. delayed-onset muscle soreness (DOMS) using a 10-centimeter visual analog scale (VAS; 0 cm = no soreness, 10 cm = extreme soreness) for both upper and lower limbs, where higher scores indicate greater soreness.

Stroke mechanics - stroke rate (SR; cycles/min) and stroke length (SL; meters/cycle) - will be analyzed from video recordings of the 200-meter trials.

The study will follow the Consolidated Standards of Reporting Trials (CONSORT) guidelines for crossover trials and has been approved by the Ethics Committee of the Faculty of Physical Culture, Palacký University Olomouc (Ref. No. 2/2024).

Statistical analysis will include repeated-measures analysis of variance (ANOVA) to compare conditions and time points. In case of violation of assumptions, appropriate corrections or non-parametric alternatives will be applied. Descriptive statistics, effect sizes (partial eta-squared, Cohen's d), and correlation coefficients (Pearson's r) will be used to support the interpretation of results. Data will be processed using International Business Machines Statistical Package for the Social Sciences (IBM SPSS) software and Microsoft Excel.

Conditions

Sport Performance; Acid Base Imbalance; Ergogenic Support; Sodium Bicarbonate; Water Sports; Biomechanics

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: TRIPLE

Study Groups

Placebo Comparator

Placebo: Food-grade starch Participants will ingest 300 mg·kg-¹ body mass of food-grade starch encapsulated in gelatin capsules 60-90 minutes prior to the simulated 200 m Bi-Fins race.

Dietary Supplement: Placebo Gelatin capsules filled with food-grade starch, indistinguishable in appearance from sodium bicarbonate capsules. Water is consumed ad libitum during ingestion.

Other Names: Placebo Capsules

Group Type: PLACEBO_COMPARATOR

Placebo

Intervention Type: DIETARY_SUPPLEMENT

Gelatin capsules each containing 1g food-grade starch

Sodium Bicarbonate (NaHCO₃)

Sodium Bicarbonate: NaHCO₃ Participants will ingest 300 mg·kg-¹ body mass of sodium bicarbonate encapsulated in gelatin capsules 60-90 minutes prior to the simulated 200 m Bi-Fins race.

Dietary Supplement: Sodium Bicarbonate Gelatin capsules containing sodium bicarbonate (NaHCO₃), matched in appearance, weight, and texture to placebo. Water is consumed ad libitum during ingestion.

Other Names: NaHCO₃ Capsules

Group Type: EXPERIMENTAL

Sodium Bicarbonate (NaHCO3)

Intervention Type: DIETARY_SUPPLEMENT

Gelatin capsules each containing 1g sodium bicarbonate (NaHCO₃)

Interventions

Sodium Bicarbonate (NaHCO3)

Gelatin capsules each containing 1g sodium bicarbonate (NaHCO₃)

Intervention Type: DIETARY_SUPPLEMENT

Placebo

Gelatin capsules each containing 1g food-grade starch

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

Inclusion Criteria

1. Member of a wider national selection in finswimming (junior or senior level)

2. Regular participation in competitive finswimming training (≥4 sessions per week)

3. Age between 15 and 30 years

4. Absence of chronic illness or injury

5. No use of medications or dietary supplements during the study period

6. Signed informed consent (for minors, also signed by a legal guardian)

Exclusion Criteria

1. History of gastrointestinal disorders affecting supplement tolerance

2. Presence of cardiovascular, metabolic, or musculoskeletal disorders

3. Current illness or acute infection

4. Regular use of substances that may interfere with acid-base balance

5. Refusal to comply with pre-test restrictions (e.g., 48 hours without training)

• Minimum Eligible Age: 15 Years
• Maximum Eligible Age: 30 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Palacky University

OTHER

Sponsor Role: lead

Responsible Party

Tomáš Michalica

Principal Investigator, Doctoral Researcher and Assistant Lecturer, Faculty of Physical Culture, Palacký University Olomouc

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Tomáš Michalica, Mgr.

Role: PRINCIPAL_INVESTIGATOR

Palacký University, Faculty of Physical Culture

Locations

Palacký University, Faculty of Physical Culture

Olomouc, Olomoucký kraj, Czechia

Site Status: RECRUITING

Countries

Czechia

Central Contacts

Tomáš Michalica, Mgr.

Role: CONTACT

tomas.michalica01@upol.cz

+420605320688

Zbyněk Svozil, Assoc. Prof.

Role: CONTACT

zbynek.svozil@upol.cz

+420 585 636 111

Facility Contacts

Tomáš Michalica, Mgr.

Role: primary

tomas.michalica01@upol.cz

+420605320688

Other Identifiers

FTK_2024_002

Identifier Type: -

Identifier Source: org_study_id