Hydrogen gas inhalation prior to high-intensity training reduces attenuation of nitric oxide bioavailability in male rugby players
Zhao Y, Li C, Zhou S, Xu Z, Huang X, Wen L. · PeerJ. 2024;12:e18503.
Study at a glance
Human
High-level professional male rugby players with at least six years of professional training.
Mask inhalation for 20 minutes beginning one hour before training on each of six training days during the H₂ week. · 66.7% H₂ and 33.3% O₂ from a Wuduoyun X9 hydrogen–oxygen ventilator. The article does not report total gas output at the mask.
20 minutes before each daily high-intensity session for six days; day 7 was rest.
NO, L-arginine/BH4, 8-OHdG, IL-6 and selected antioxidant comparisons favored the H₂/O₂ week. Supplementation-by-time interactions were null for NOS, eNOS, protein carbonyls, IL-1β and IL-10; the article states H₂ did not significantly alter changes in oxidative-damage markers overall. No athletic-performance or injury endpoint was tested.
Biomarker study in 22 male athletes with numerous comparisons and no clinical or performance endpoint. The intervention added oxygen as well as H₂, total flow was omitted and the washout week used lower-intensity rather than no training. Public funding was reported and the authors declared no conflicts.
What kind of evidence is this?
Human
Randomized double-blind placebo-controlled crossover trial
Exercise and recovery
Inhaled H₂
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
High-level professional male rugby players with at least six years of professional training.
24 enrolled and randomized; two withdrew because of injury, leaving 22 completing both periods.
20 minutes before each daily high-intensity session for six days; day 7 was rest.
Mask inhalation for 20 minutes beginning one hour before training on each of six training days during the H₂ week.
Brown's gas / oxyhydrogen — the generator supplied 66.7% H₂ and 33.3% O₂, not H₂ alone.
66.7% H₂ and 33.3% O₂ from a Wuduoyun X9 hydrogen–oxygen ventilator. The article does not report total gas output at the mask.
Not reported — absolute H₂ flow in mL/min cannot be calculated because total flow was not stated.
33.3% O₂ was co-delivered, but absolute O₂ flow cannot be calculated without total flow.
Compressed normal air through a blinded apparatus; one lower-intensity training week separated the two intervention weeks.
Outcomes and reported result
NO, NOS/eNOS, L-arginine, tetrahydrobiopterin, oxidative-damage markers, total antioxidant capacity and IL-1β, IL-6 and IL-10.
NO, L-arginine/BH4, 8-OHdG, IL-6 and selected antioxidant comparisons favored the H₂/O₂ week. Supplementation-by-time interactions were null for NOS, eNOS, protein carbonyls, IL-1β and IL-10; the article states H₂ did not significantly alter changes in oxidative-damage markers overall. No athletic-performance or injury endpoint was tested.
The complete PeerJ/PMC article, protocol, every biomarker family, null interactions, gas composition, withdrawals, funding and declarations were checked; the earlier automatic record is superseded by this manual full-text extraction.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Biomarker study in 22 male athletes with numerous comparisons and no clinical or performance endpoint. The intervention added oxygen as well as H₂, total flow was omitted and the washout week used lower-intensity rather than no training. Public funding was reported and the authors declared no conflicts.
Professional male rugby players under this one-week pre-training biomarker protocol.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 39703911 · DOI: 10.7717/peerj.18503
Open-access full article on PeerJ and PubMed Central.
PeerJ and PMC full article, supplementary training schedule and PubMed metadata; full-text and article-status check completed 8 August 2026.
10 August 2026
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