Effects of Sodium Bicarbonate on Endurance Performance

NCT07171047 | Completed

• 1 other identifier: BICARB_Haller
• Study Type: interventional
• Target: 19
• Locations: 1 country
• Sites: 1

Brief Summary

This study is investigating whether taking sodium bicarbonate, a common supplement used by endurance athletes, can improve cycling performance during prolonged exercise and in a time trial. Sodium bicarbonate may help reduce muscle acidity, which could delay fatigue and improve performance. The goal of this study is to determine if this supplement can help athletes perform better during long, intense efforts like those seen in real competitions. Participants in this study are well-trained cyclists who will complete two exercise trials in a laboratory setting. Each trial involves three hours of moderate cycling followed by a 20-30-minute time trial at maximum effort. Before each trial, participants will take either sodium bicarbonate or a placebo. The study will measure performance outcomes, such as time trial results, as well as physiological responses, including heart rate, oxygen use, and muscle fatigue. Researchers hope to better understand how sodium bicarbonate can help endurance athletes and provide guidelines for its use in competitive sports.

Conditions

Healthy; Athlete; Well-trained Athletes; Performance

Keywords

Bicarbonate; Endurance training; Cycling; Time trial

Outcome Measures

Primary Outcomes (1)

• Endurance performance

  Difference in time trial performance (average power in watts) between placebo and verum condition

  20-30 minutes, immediately after completion of the time trial for each condition (Placebo and Verum), assessed on test day 1 and test day 2 respectively, with a washout period of 3-7 days between appointments (test days).

Secondary Outcomes (16)

• Difference in questionnaire score - gastrointestinal symptoms

  6.5 hours (rest, breakfast, every 30min during 3-hour low-intensity, after TT) for each condition (Placebo and Verum), on test day 1 and test day 2 respectively, with a washout period of 3-7 days between appointments (test days).

• Difference in questionnaire score - Energy & Confidence

  3 hours (every 30min during 3-hour low-intensity) for each condition (Placebo and Verum), assessed on test day 1 and test day 2 respectively, with a washout period of 3-7 days between appointments (test days).

• Difference in questionnaire score - rate of perceived exertion

  3.5 hours (every 30min during 3-hour low-intensity, after TT) for each condition (Placebo and Verum), assessed on test day 1 and test day 2 respectively, with a washout period of 3-7 days between appointments (test days).

• Difference in blood count

  6.5 hours (rest, every 30min during 3-hour low-intensity, after TT) for each condition (Placebo and Verum), assessed on test day 1 and test day 2 respectively, with a washout period of 3-7 days between appointments (test days).

• Difference in pH & HCO3 kinetics

  6.5 hours (rest, breakfast, every 30min during 3-hour low-intensity, after TT) for each condition (Placebo and Verum), on test day 1 and test day 2 respectively, with a washout period of 3-7 days between appointments (test days).

Study Arms (2)

Placebo then Verum

OTHER

Placebo then Verum 3 hour low-intensity ride followed by a 16 km time trial for both conditions. Supplementation of Placebo or Verum before the exercise start.

Dietary Supplement: Placebo then Verum

Verum then Placebo

OTHER

Verum then Placebo 3 hour low-intensity ride followed by a 16 km time trial for both conditions. Supplementation of Placebo or Verum before the exercise start.

Dietary Supplement: Verum then Placebo

Interventions

Placebo then Verum DIETARY_SUPPLEMENT

Intake of 0.3 g/kg bodyweight of maltodextrin with hydrogel as placebo and 0.3 g/kg bodyweight of sodium bicarbonate with hydrogel as Verum

Placebo then Verum

Verum then Placebo DIETARY_SUPPLEMENT

Intake of 0.3 g/kg bodyweight of maltodextrin with hydrogel as placebo and 0.3 g/kg bodyweight of sodium bicarbonate with hydrogel as Verum

Verum then Placebo

Eligibility Criteria

• Age: 16 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• age 16-50 years
• well-trained cyclists
• Proof of physical fitness (e.g. sports medical examination required) for measurements with higher intensities (e.g. endurance tests, competition simulation)
• \>10h endurance training per week

You may not qualify if:

• Systemic disease or other known pathology in the organs: heart, lungs, kidney, stomach, spleen, liver, gall bladder, and intestines.
• Evidence of pulmonary disease: forced expiratory volume in one second/forced expiratory volume \< 70% with/without symptoms (cough, sputum) or other evidence of pulmonologic disease.
• Diabetes II.

Sponsors & Collaborators

• University of Salzburg: lead
• Red Bull Athlete Performance Center: collaborator

Study Sites (1)

Red Bull Athlete Performance Center

Thalgau, Salzburg, 5303, Austria

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Senior Researcher

Model Details: Double blinded two-intervention crossover study

Study Record Dates

• First Submitted: July 25, 2025
• First Posted: September 12, 2025
• Study Start: September 15, 2025
• Primary Completion: December 12, 2025
• Study Completion: December 12, 2025
• Last Updated: March 30, 2026

Record last verified: 2026-03

Locations

AU (1)