Effect of Pre-exercise Inhalation of Molecular Hydrogen on Metabolic Response During Graded Exercise in Healthy Women

Effect of Repeated Pre-exercise Inhalation of Molecular Hydrogen on Metabolic Response During Graded Exercise in Healthy Women: A Randomized, Double-blind, Placebo-controlled Crossover Trial

The goal of this clinical trial is to evaluate if molecular hydrogen can reduce the metabolic response during graded exercise in healthy women aged 18-30 years. The main questions it aims to answer are:

• Does molecular hydrogen reduce the respiratory exchange ratio?
• Does molecular hydrogen reduce oxygen uptake?

Researchers will compare molecular hydrogen to a placebo (ambient air containing no molecular hydrogen) to see if molecular hydrogen reduces the metabolic response.

Participants will:

• Inhale molecular hydrogen for 60 minutes each day for 7 days.
• Undergo an exercise testing twice after a two-week washout period.

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy Adult Females
• Intervention / Treatment: Other: Molecular hydrogen; Other: Placebo

Detailed Description

This crossover trial examines the effect of repeated inhalation of molecular hydrogen on the metabolic response during graded exercise in healthy female participants. Each participant undergoes two experimental interventions (molecular hydrogen and placebo) in random order, separated by a two-week washout period. The order of the interventions is randomized using a computer random number generator. Each intervention consists of 7 days, during which participants inhale either molecular hydrogen or placebo gas for 60 minutes daily under resting conditions. Molecular hydrogen is produced by electrolysis of water and mixed with ambient air in the chamber to achieve a hydrogen concentration of 3.75 % which is below the lower explosive limit. This gas is administered via a face mask connected to an Ambu bag system with a one-way valve to ensure standardized delivery. Placebo is produced by pumping ambient air without molecular hydrogen. Molecular hydrogen is colorless, odorless, and tasteless, making it indistinguishable from placebo by human senses. On the 7th day of each intervention, participants undergo a graded exercise test on an bicycle ergometer immediately following the final inhalation session. The protocol consists of 8 incremental steps with the workload increasing from 0.5 to 2.25 W/kg. Outcome measures collected at rest before exercise and during exercise include cardiorespiratory variables, capillary blood biomarkers, and perceived exertion. Statistical analysis is based on a two-way analysis of variance for repeated measures, and p < 0.05 is considered statistically significant.

• Study Type: Interventional
• Enrollment (Estimated): 22
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Tereza Rysava; Phone Number: +420585636154; Email: tereza.rysava01@upol.cz
• Study Contact Backup: Name: Jakub Krejci, PhD; Email: jakub.krejci@upol.cz

Study Locations

• Czechia
  • Olomouc, Czechia, 77111
    • Palacky University, Faculty of Physical Culture
    • Contact: Tereza Rysava; Phone Number: +420585636154; Email: tereza.rysava01@upol.cz

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy female participants.
• Regular menstrual cycle with exercise testing scheduled outside the menstrual phase.
• Signed informed consent.

Exclusion Criteria:

• Pregnancy or breastfeeding.
• History or presence of cardiovascular disease.
• History or presence of respiratory disease.
• Regular use of medications affecting metabolism.
• Use of dietary supplements affecting metabolism within 14 days prior to intervention.
• Strenuous physical activity within 24 hours prior to exercise testing.
• Any contraindication to exercise testing or study participation determined by a physician.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Molecular hydrogen; Molecular hydrogen inhalation for 60 minutes daily for 7 days.	Other: Molecular hydrogen; Gas mixture containing 3.75% molecular hydrogen and ambient air.; Other Names: H2 Air-Blend Generator (H2 Medical Technologies, Ostrava, Czech Republic)
Placebo Comparator: Placebo; Ambient air inhalation for 60 minutes daily for 7 days.	Other: Placebo; Ambient air without molecular hydrogen.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Respiratory exchange ratio	Respiratory exchange ratio is measured using an Ergostik analyser (Geratherm Respiratory, Bad Kissinger, Germany) breath by breath during the exercise, and the average is calculated for 6-minute segments for subsequent analysis.	Change after 2 weeks of crossover.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Oxygen uptake	Oxygen uptake is measured using an Ergostik analyser (Geratherm Respiratory, Bad Kissinger, Germany) breath by breath during the exercise, and the average is calculated for 6-minute segments for subsequent analysis.	Change after 2 weeks of crossover.
Carbon dioxide production	Carbon dioxide production is measured using an Ergostik analyser (Geratherm Respiratory, Bad Kissinger, Germany) breath by breath during the exercise, and the average is calculated for 6-minute segments for subsequent analysis.	Change after 2 weeks of crossover.
Minute ventilation	Minute ventilation is measured using an Ergostik analyser (Geratherm Respiratory, Bad Kissinger, Germany) breath by breath during the exercise, and the average is calculated for 6-minute segments for subsequent analysis.	Change after 2 weeks of crossover.
Breathing frequency	Breathing frequency is measured using an Ergostik analyser (Geratherm Respiratory, Bad Kissinger, Germany) breath by breath during the exercise, and the average is calculated for 6-minute segments for subsequent analysis.	Change after 2 weeks of crossover.
Heart rate	Heart rate is continuously recorded during the exercise using a Polar H10 chest strap (Polar, Kempele, Finland), and the average is calculated for 6-minute segments for subsequent analysis.	Change after 2 weeks of crossover.
Blood lactate concentration	Capillary blood lactate concentration is assessed at baseline (resting condition) and during the final minute of each exercise step using a Lactate Scout device (EKF Diagnostics, Barleben, Germany).	Change after 2 weeks of crossover.
Rating of perceived exertion	Participants are asked to subjectively rate their perceived exertion at specified time points - at rest and subsequently in the last minute of each exercise step. The Borg's scale 6-20 is used, where 6 means "no exertion" and 20 means "maximal exertion".	Change after 2 weeks of crossover.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Blood glucose concentration	Capillary blood glucose concentration is assessed at baseline (resting condition) and during the final minute of each exercise step using an Accu-Chek Inform II device (Roche Diagnostics, Manheim, Germany).	Change after 2 weeks of crossover.

Collaborators and Investigators

• Sponsor: Palacky University
• Investigators: Principal Investigator: Tereza Rysava, Palacky University

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: June 8, 2026
• First Submitted That Met QC Criteria: June 8, 2026
• First Posted (Actual): June 12, 2026

Study Record Updates

• Last Update Posted (Actual): June 12, 2026
• Last Update Submitted That Met QC Criteria: June 8, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: metabolic response; molecular hydrogen
• Additional Relevant MeSH Terms: Inorganic Chemicals; Elements; Gases; Hydrogen
• Other Study ID Numbers: FTK_2026_14

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD that underlie results in a publication.
• IPD Sharing Time Frame: Beginning 1 month after the publication of results with no end date.
• IPD Sharing Access Criteria: Anonymized IPD will be uploaded to an open-access data repository.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No