Two-week continuous supplementation of hydrogen-rich water increases peak oxygen uptake during an incremental cycling exercise test in healthy humans: a randomized, single-blinded, placebo-controlled study
Hori A et al. · Med Gas Res. 2020;10(4):163–169.
Study at a glance
Human
Healthy university students able to complete an incremental cycling test
Acute experiment: 500 mL once, 30 minutes before cycling. Two-week experiment: 500 mL on each weekday for 10 doses (5 L total), with the final dose 30 minutes before testing. · Dissolved H₂: 4.3 ± 0.9 ppm in the acute experiment and 5.9 ± 0.2 ppm in the 2-week experiment.
Single-dose crossover sessions at least 24 hours apart; separate 2-week parallel experiment
The single dose did not significantly change peak oxygen uptake or peak load. After 2 weeks, the H₂-water group had a greater increase in weight-adjusted peak oxygen uptake than placebo; peak-load change showed only a statistical trend. Lactate and measured redox responses did not differ.
Small pilot experiments, single blinding, different designs for acute and 2-week questions, and no direct measurement of maximal oxygen uptake. Two authors were MiZ employees and the company supplied a resource.
What kind of evidence is this?
Human
Two experiments: randomized single-blind crossover acute test and randomized single-blind parallel 2-week test
Exercise and recovery
H₂-rich water
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
Healthy university students able to complete an incremental cycling test
Acute experiment: 9 participants (6 men, 3 women); 2-week experiment: 20 men (10 H₂ water, 10 placebo)
Single-dose crossover sessions at least 24 hours apart; separate 2-week parallel experiment
Acute experiment: 500 mL once, 30 minutes before cycling. Two-week experiment: 500 mL on each weekday for 10 doses (5 L total), with the final dose 30 minutes before testing.
H₂ dissolved in water — H₂ only, not Brown’s gas.
Dissolved H₂: 4.3 ± 0.9 ppm in the acute experiment and 5.9 ± 0.2 ppm in the 2-week experiment.
Placebo water prepared with the same handling procedure
Outcomes and reported result
Peak oxygen uptake, peak cycling load, respiratory and circulatory variables, perceived exertion, lactate, oxidative stress and antioxidant activity
The single dose did not significantly change peak oxygen uptake or peak load. After 2 weeks, the H₂-water group had a greater increase in weight-adjusted peak oxygen uptake than placebo; peak-load change showed only a statistical trend. Lactate and measured redox responses did not differ.
Methods, result tables, funding and conflicts checked in the open-access full text; independent appraisal remains incomplete.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Small pilot experiments, single blinding, different designs for acute and 2-week questions, and no direct measurement of maximal oxygen uptake. Two authors were MiZ employees and the company supplied a resource.
Healthy young university students completing the reported incremental cycling protocol.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 33380582 · DOI: 10.4103/2045-9912.304223
Open-access full text is available through PMC.
Open-access PMC full text and PubMed bibliographic record.
10 August 2026
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