Effects of 7-day intake of hydrogen-rich water on physical performance of trained and untrained subjects
Timón R et al. · Biol Sport. 2021;38(2):269–275.
What kind of evidence is this?
Human
Randomized double-blind placebo-controlled crossover study
Exercise and recovery
H₂-rich water
Not reported in this record.
Not reported in this record.
Methods at a glance
Trained amateur cyclists and untrained adults
37 recruited; analyzed groups reported as 12 trained cyclists and 15 untrained participants
7 days per condition in a crossover design
Nano-bubble hydrogen-rich water, 1,920–2,240 mL/day (six or seven 320 mL bottles), consumed immediately after each hydrogenation cycle
H₂ dissolved in water — H₂ only, not Brown’s gas.
1.9 ppm dissolved H₂; pH 7.5 and oxidation-reduction potential −600 mV reported.
Not applicable — oral water, not gas inhalation.
No O₂ was co-delivered as part of the intervention.
Placebo purified water produced and consumed with the same portable-bottle procedure
Outcomes and reported result
Incremental peak-oxygen-uptake test, maximal anaerobic cycling test, power, fatigue index, lactate and perceived exertion
Only the trained cyclists showed higher anaerobic peak and mean power and a lower fatigue index after H₂ water. Untrained participants did not show these changes. Aerobic performance did not improve; trained cyclists had lower lactate after the aerobic test.
Dose, methods, full results, funding and conflict statement checked in the open-access full text; independent appraisal remains incomplete.
A reported association, difference or mechanism is not automatically a clinical benefit. Null findings, outcome type, study design and precision all matter.
Cautions and applicability
Small crossover subgroups and several outcomes. The authors reported no conflicts; a company lent the portable bottles and public regional funding supported the study.
Trained amateur cyclists and untrained adults under the reported short intervention and laboratory tests.
Not reported in this record.
Not reported in this record.
Not reported in this record.
No single-study GRADE certainty rating is assigned. Certainty is assessed by important outcome across a complete eligible evidence set, not by attaching a final grade to one source.
Sources and record status
PMID: 34079172 · DOI: 10.5114/biolsport.2020.98625
Open-access full text is available through PMC.
Open-access PMC full text and PubMed bibliographic record.
2026-08-10