Effects of electrolyzed hydrogen water ingestion during endurance exercise in a heated environment on body fluid balance and exercise performance
Ito H, Kabayama S, Goto K. · Temperature. 2020;7(3):290–299.
Study at a glance
Human
Twelve trained triathletes, mean age 20.0 years, exercising in heat.
During 60 minutes of cycling at 65% of VO₂max in 32°C and 50% relative humidity, participants drank 2.0 mL/kg electrolyzed hydrogen water every 15 minutes, followed by an incremental test to exhaustion. · The article reports pH 9.7±0.2 for intervention water but does not report a measured numerical dissolved-H₂ concentration; the average consumed volume was 926±13 mL.
Two exercise trials at least three days apart; 60 minutes fixed-load cycling plus a post-rest incremental test.
Body mass fell by about 1.1 kg in both conditions. Plasma volume, osmolality, sodium, potassium, pH, lactate, bicarbonate, temperature changes and time to exhaustion did not differ between waters. Energy expenditure during fixed-load cycling was slightly lower with electrolyzed water (13.2 versus 13.7 kcal/min, p=0.04), without improved exercise performance.
Only 12 young trained athletes, acute crossover exposure, multiple physiological endpoints and no measured dissolved-H₂ concentration. The significant energy-expenditure difference was small and did not translate to time-to-exhaustion benefit. The work was funded by Nihon Trim Co., maker of the generator, and one author was a company employee involved in generator preparation and pH checking.
What kind of evidence is this?
Human
Randomized crossover exercise trial
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
Twelve trained triathletes, mean age 20.0 years, exercising in heat.
12 participants; all performed both water conditions.
Two exercise trials at least three days apart; 60 minutes fixed-load cycling plus a post-rest incremental test.
During 60 minutes of cycling at 65% of VO₂max in 32°C and 50% relative humidity, participants drank 2.0 mL/kg electrolyzed hydrogen water every 15 minutes, followed by an incremental test to exhaustion.
H₂ in alkaline electrolyzed drinking water — H₂ only, not Brown's gas.
The article reports pH 9.7±0.2 for intervention water but does not report a measured numerical dissolved-H₂ concentration; the average consumed volume was 926±13 mL.
Purified water made with the same generator, pH 7.4±0.1.
Outcomes and reported result
Body mass, plasma volume, serum osmolality, electrolytes, acid-base and lactate measures, skin and muscle temperature, energy expenditure and time to exhaustion.
Body mass fell by about 1.1 kg in both conditions. Plasma volume, osmolality, sodium, potassium, pH, lactate, bicarbonate, temperature changes and time to exhaustion did not differ between waters. Energy expenditure during fixed-load cycling was slightly lower with electrolyzed water (13.2 versus 13.7 kcal/min, p=0.04), without improved exercise performance.
The complete PubMed Central article, randomization, water preparation, volumes, environmental protocol, primary null findings, funding and conflict disclosure were checked.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Only 12 young trained athletes, acute crossover exposure, multiple physiological endpoints and no measured dissolved-H₂ concentration. The significant energy-expenditure difference was small and did not translate to time-to-exhaustion benefit. The work was funded by Nihon Trim Co., maker of the generator, and one author was a company employee involved in generator preparation and pH checking.
Acute hydration during endurance exercise in heat among trained young triathletes; no demonstrated performance or hydration benefit.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 33117861 · DOI: 10.1080/23328940.2020.1742056
Free full article on PubMed Central.
PubMed metadata and complete PubMed Central article; full-text extraction checked 8 August 2026.
10 August 2026
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