Effect of Hydrogen-rich Water During Tapering on Recovery After Functional Overreaching in Basketball Players

Effect of Hydrogen-rich Water Supplementation During Tapering on Recovery After Functional Overreaching in Competitive Male Basketball Players: A Randomized, Double-blind, Placebo-controlled Paralel-group Trial

The goal of this clinical trial is to evaluate whether hydrogen-rich water supplementation during tapering improves recovery after functional overreaching in competitive male basketball players aged 18-35 years. The main questions it aims to answer are:

• Does hydrogen-rich water improve autonomic recovery after functional overreaching?
• Does hydrogen-rich water improve recovery in biochemical, performance, and subjective feeling outcomes during tapering?

Researchers will compare hydrogen-rich water to placebo (water containing no molecular hydrogen) to determine whether molecular hydrogen improves recovery after accumulated fatigue has been induced by functional overreaching. Participants will:

• Complete a training cycle including normal training, functional overreaching, and tapering.
• Consume hydrogen-rich or placebo water daily during the one-week tapering period.
• Undergo repeated testing of autonomic nervous system, blood biochemical markers, performance, and subjective soreness.

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy Active Athletes
• Intervention / Treatment: Dietary supplement: Hydrogen-rich water; Dietary supplement: Placebo water

Detailed Description

The study consists of an initial screening and entry testing phase, followed by one week of normal training, two weeks of functional overreaching, and one week of tapering. During the functional overreaching period, training load is increased to approximately 120-130% of normal training load to induce accumulated fatigue. During the tapering period, training volume is reduced to approximately 50-60% of normal training volume to support recovery and performance rebound.

The molecular hydrogen is administered only during the tapering period. Participants in the experimental group consume 2.5 L per day of hydrogen-rich water. The total daily dose is divided into 0.5 L in the morning, 1.5 L around training, and 0.5 L in the evening. Participants in the placebo group consume visually matched placebo water according to the same total daily intake and timing schedule. Supplementation adherence is monitored using logs, dose counts, and attendance records. Participants are randomly assigned in a 1:1 ratio to either the experimental group or the placebo group. Randomization is performed using a block scheme and a computer random number generator.

Testing is performed at multiple time points: entry laboratory testing, baseline after normal training, post-functional overreaching, and post-taper. The primary interval for evaluation is the change from post-functional overreaching to post-taper. Statistical analysis is based on a t-test or analysis of variance. Data that not follow a normal distribution are treated using a logarithmic transformation or analyzed using nonparametric tests. The significance level is set at 0.05.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jakub Krejci, PhD; Email: jakub.krejci@upol.cz
• Study Contact Backup: Name: Jan Kvas; Phone Number: +420774678756; Email: jan.kvas01@upol.cz

Study Locations

• Czechia
  • Olomouc, Czechia, 77111
    • Palacky University, Faculty of Physical Culture
    • Contact: Jan Kvas; Phone Number: +420774678756; Email: jan.kvas01@upol.cz

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Competitive male basketball players.
• Signed informed consent.
• Completion of entry medical and laboratory screening.

Exclusion Criteria:

• Acute injury or infection.
• History or presence of relevant cardiovascular, respiratory, metabolic, or other disease that may affect the study results.
• Use of medication affecting recovery markers or study results.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Hydrogen-rich water; Hydrogen-rich water administered at a dose of 2.5 L per day during a one-week tapering period.	Dietary supplement: Hydrogen-rich water; Hydrogen-rich water with molecular hydrogen concentration >1.0 ppm.; Other Names: Tirtan generator (Nutristamina, Ostrava, Czech Republic)
Placebo Comparator: Placebo water; Placebo water administered at a dose of 2.5 L per day during a one-week tapering period.	Dietary supplement: Placebo water; Tap water without molecular hydrogen.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
RMSSD	The root mean square of successive differences of RR intervals (RMSSD) is used as an index of parasympathetic activity and is calculated from an ECG using heart rate variability analysis.	One-week change between post-overreaching and post-taper.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Creatine kinase	Blood creatine kinase concentration is used as a marker of muscle damage.	One-week change between post-overreaching and post-taper.
High-sensitivity C-reactive protein	High-sensitivity C-reactive protein concentration is used as a marker of systemic inflammatory.	One-week change between post-overreaching and post-taper.
Cortisol	Blood cortisol concentration is used as a marker of physiological stress response.	One-week change between post-overreaching and post-taper.
Testosterone	Blood testosterone concentration is used as a marker related to anabolic-catabolic balance.	One-week change between post-overreaching and post-taper.
Urea	Blood urea concentration is used as a marker related to metabolic and protein-turnover stress.	One-week change between post-overreaching and post-taper.
Leukocytes	Blood leukocyte count is used as a marker of immune-related response to training.	One-week change between post-overreaching and post-taper.
Lymphocytes	Blood lymphocyte count is used as a marker of immune-related response to training.	One-week change between post-overreaching and post-taper.
Neutrophils	Blood lymphocyte count is used as a marker of imflammatory response to training.	One-week change between post-overreaching and post-taper.
Reactive strength index	Reactive strength index is used as an marker of neuromuscular function of the lower limbs and is measured using a drop jump.	One-week change between post-overreaching and post-taper.
Hangrip test	Handgrip test is used as a marker of forearm muscle strength and is measured using a dynamometer.	One-week change between post-overreaching and post-taper.
20-m sprint	20-m sprint test is used to assess linear speed.	One-week change between post-overreaching and post-taper.
Repeated sprint	20 x 15 m repeated sprint test is used to asses repeated sprint ability.	One-week change between post-overreaching and post-taper.
Agility T-test	Agility T-test is used to assess planned change-of-direction performance.	One-week change between post-overreaching and post-taper.
Basketball jump shot accuracy test	Basketball jump shot accuracy test is used to assess basketball-specific performance.	One-week change between post-overreaching and post-taper.
Muscle soreness	Muscle soreness is assessed subjectively using a visual analog scale, which is represented by a 100 mm line marked 0 (no pain) and 100 (worst imaginable pain).	One-week change between post-overreaching and post-taper.

Collaborators and Investigators

• Sponsor: Palacky University
• Investigators: Principal Investigator: Jan Kvas, Palacky University

Study record dates

Study Major Dates

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

Study Registration Dates

• First Submitted: July 15, 2026
• First Submitted That Met QC Criteria: July 15, 2026
• First Posted (Actual): July 20, 2026

Study Record Updates

• Last Update Posted (Actual): July 20, 2026
• Last Update Submitted That Met QC Criteria: July 15, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: tapering; heart rate variability; basketball; molecular hydrogen; functional overreaching
• Other Study ID Numbers: FTK_2026_13

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