Effects of High-concentration Hydrogen+Oxygen Gas Inhalation on Lower Limb Hemodynamics, Muscle Flexibility, Joint Range of Motion, and Vertical Jump Height: Study Using a Single-blind Crossover Study
Masaki Tamura; Takuya Aso; Mitsugu Hachisu; Hitomi Kitai; Kanji Furuya; Takeyuki Sanbe; Naoya Nishinaka · Physical Therapy Japan. 2024;51(4):93-100.
Study at a glance
Ten healthy men inhaled a hydrogen-oxygen mixture and ambient air on separate visits. Most measurements, including flexibility and jump height, showed no clear difference. One exploratory comparison of change in blood-flow velocity favored the gas mixture; this small study does not demonstrate a physical-performance or clinical benefit.
Human
10 healthy adult men; mean age 25.7 ± 2.9 years.
One hour of nasal-cannula source mixture from Hycellvator ET100, with participants resting supine or prone. · Source mixture approximately 68% H₂ / 32% O₂. Actual inspired H₂ fraction not reported.
1 hour per condition; at least 7 days between conditions (mean 8.1, range 7–14 days); outcomes immediately before and after.
Main repeated-measures analyses found no significant effects or interactions for vessel diameter, blood-flow velocity, flexibility, joint range or vertical jump. Exploratory after/before peak blood-flow-velocity ratio: 1.14 ± 0.23 with H₂/O₂ versus 0.94 ± 0.14 with air (P = 0.02; reported r = 0.71). Other ratio outcomes were not significant, including vertical jump (P = 0.15). This does not establish exercise recovery or clinical benefit.
Only 10 healthy men and short-term physiological measurements. Single blinding, limited allocation details and unmatched oxygen complicate interpretation. The positive exploratory velocity ratio sits alongside mostly null main analyses. Ratio tests included unpaired/rank-sum methods despite the crossover design. Microvascular flow and recovery after exercise were not directly assessed.
What kind of evidence is this?
Human
Randomized single-blind two-period crossover experiment, with five participants initially assigned to each sequence.
高濃度水素+酸素ガス吸入が下肢血流動態，筋柔軟性，関節可動域，垂直飛び高に与える影響
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
10 healthy adult men; mean age 25.7 ± 2.9 years.
10 randomized and analyzed; 5 initially assigned to each crossover sequence.
1 hour per condition; at least 7 days between conditions (mean 8.1, range 7–14 days); outcomes immediately before and after.
One hour of nasal-cannula source mixture from Hycellvator ET100, with participants resting supine or prone.
Hydrogen–oxygen mixture, not pure H₂: approximately 68% H₂ and 32% O₂ at the generator.
Source mixture approximately 68% H₂ / 32% O₂. Actual inspired H₂ fraction not reported.
Gas flow not reported in the checked full text.
Approximately 32% O₂ at the generator; ambient-air comparator not oxygen matched.
Ambient air delivered through a nasal cannula; oxygen composition was not matched to the intervention mixture.
Outcomes and reported result
Multiple hemodynamic and physical-function outcomes; no prospectively specified primary-endpoint hierarchy reported.
Main repeated-measures analyses found no significant effects or interactions for vessel diameter, blood-flow velocity, flexibility, joint range or vertical jump. Exploratory after/before peak blood-flow-velocity ratio: 1.14 ± 0.23 with H₂/O₂ versus 0.94 ± 0.14 with air (P = 0.02; reported r = 0.71). Other ratio outcomes were not significant, including vertical jump (P = 0.15). This does not establish exercise recovery or clinical benefit.
The available main full text was reviewed for methods, results, limitations and declarations. Remaining source-specific uncertainties are stated in this record.
No adverse events reported.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Only 10 healthy men and short-term physiological measurements. Single blinding, limited allocation details and unmatched oxygen complicate interpretation. The positive exploratory velocity ratio sits alongside mostly null main analyses. Ratio tests included unpaired/rank-sum methods despite the crossover design. Microvascular flow and recovery after exercise were not directly assessed.
10 healthy adult men; mean age 25.7 ± 2.9 years. Findings apply only to the studied design and exposure; no treatment or device recommendation.
Showa University Research Institute for Sport and Exercise Sciences research grant, fiscal year 2021.
HelixJapan supplied the hydrogen–oxygen generator; this support appears in the conflict-of-interest section.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
Source ID: doi-10.15063-rigaku.12478 · DOI: 10.15063/rigaku.12478
Complete Japanese-language publisher article on J-STAGE in HTML, including both tables.
AI-assisted editorial review of the available main full text, 29 October 2026. The source version and access limitations are stated in this record. No independent clinical or statistical assessment has been performed.
Full publisher HTML: Introduction; Subjects and methods 1–7, including randomization, washout, device composition and statistics; Results; Tables 1-2; Discussion and limitations; Conclusion; Acknowledgements; Conflict of interest/funding statement; references.
AI-assisted editorial review of the available main full text, 29 October 2026. Complete Japanese-language publisher article on J-STAGE in HTML, including both tables.
Trial registration not reported. Showa University ethics approval 22-122-A; written consent reported.
29 October 2026
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