Drinking hydrogen water enhances endurance and relieves psychometric fatigue: a randomized, double-blind, placebo-controlled study 1

Combined use of hydrogen-rich water and enzyme-digested edible bird's nest improves PMA/LPS-impaired wound healing in human inflammatory gingival tissue equivalents

Gingival wound healing plays a critical role in maintaining oral health. However, this process can be delayed by oxidative stress and excessive inflammatory responses. In this study, we established a human inflammatory gingival tissue equivalent (iGTE) to investigate the inhibitory effects of hydrogen-rich water (HW), enzyme-digested edible bird's nest (EBND) and sialic acid (SA) on PMA (an inducer of oxidative free radicals)- and LPS (an inflammatory stimulus)-impaired wound healing. The iGTE was constructed by human gingival fibroblasts (hGFs), keratinocytes and macrophages under three-dimensional conditions. Wounds in the iGTE and hGF/keratinocyte monolayers were created by mechanical injury. Tissues and cells were pretreated with HW, EBND, and SA, and then exposed to the inflammatory and oxidative environment induced by PMA (10 ng/mL) and LPS (250 ng/mL). The inflammatory cytokines IL-6 and IL-8 were quantitatively analyzed by ELISA. Histopathological image analysis was performed by HE and immunofluorescence staining. In the iGTE, PMA/LPS significantly reduced the epithelial thickness while causing a decrease in K8/18, E-cadherin, laminin and elastin expression and an increase in COX-2 expression along with ulcer-like lesions. In mechanically scratched hGFs and keratinocyte monolayers, PMA/LPS significantly impaired wound healing, and promoted the secretion of IL-6 and IL-8. Pretreatment of HW, EBND, and SA significantly suppressed PMA/LPS-induced wound healing delay and inflammatory responses in cell monolayers, as well as in the iGTE. Remarkably, the combined use of HW and EBND exhibited particularly robust results. Combined use of HW and EBND may be applied for the prevention and treatment of wound healing delay.

Can molecular hydrogen supplementation enhance physical performance in healthy adults? A systematic review and meta-analysis

Background

Physical exertion during exercise often leads to increased oxidative stress and inflammatory responses, significantly affecting physical performance. Current strategies to mitigate these effects are limited by their effectiveness and potential side effects. Molecular hydrogen (H₂) has gained attention for its antioxidant and anti-inflammatory properties. Studies have suggested that H2 supplementation contributes to antioxidant potential and anti-fatigue during exercise, but the variance in the observations and study protocols is presented across those studies.

Objective

This systematic review and meta-analysis aimed to comprehensively characterize the effects of H₂ supplementation on physical performance (i.e., endurance, muscular strength, and explosive power), providing knowledge that can inform strategies using H2 for enhancing physical performance.

Methods

We conducted a literature search of six databases (PubMed, Web of Science, Medline, Sport-Discus, Embase, and PsycINFO) according to the PRISMA guidelines. The data were extracted from the included studies and converted into the standardized mean difference (SMD). After that, we performed random-effects meta-analyses and used the I 2 statistic to evaluate heterogeneity. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the quality of the evidence obtained from this meta-analysis.

Results

In total, 27 publications consisting of 597 participants were included. The search finally included aerobic endurance, anaerobic endurance, muscular strength, lower limb explosive power, rating of perceived exertion (RPE), blood lactate (BLA), and average heart rate (HRavg) in the effect size (ES) synthesis. The ES of H2 on aerobic endurance, including V̇O2max (SMD = 0.09, p = 0.394; I 2 = 0%) and aerobic endurance exercise (SMD = 0.04, p = 0.687; I 2 = 0%), were not significant and trivial; the ES of H2 on 30 s maximal anaerobic endurance (SMD = 0.19, p = 0.239; I 2 = 0%) was not significant and trivial; the ES of H2 on muscular strength (SMD = 0.19, p = 0.265; I 2 = 0%) was not significant and trivial; but the ES of H2 on lower limb explosive power (SMD = 0.30, p = 0.018; I 2 = 0%) was significant and small. In addition, H2 reduces RPE (SMD = -0.37, p = 0.009; I 2 = 58.0%) and BLA (SMD = -0.37, p = 0.001; I 2 = 22.0%) during exercise, but not HRavg (SMD = -0.27, p = 0.094; I 2 = 0%).

Conclusion

These findings suggest that H2 supplementation is favorable in healthy adults to improve lower limb explosive power, alleviate fatigue, and boost BLA clearance, but may not be effectively improving aerobic and anaerobic endurance and muscular strength. Future studies with more rigorous designs are thus needed to examine and confirm the effects of H2 on these important functionalities in humans.

Systematic review registration

http://www.crd.york.ac.uk/PROSPERO.

Hydrogen Water: Extra Healthy or a Hoax?-A Systematic Review

Hydrogen-rich water (HRW) has emerged as a novel approach in the field of health and wellness. It is believed to have therapeutic antioxidant properties that can neutralize harmful free radicals in the human body. It has also been shown to be beneficial in mitigating oxidative stress-induced damage through its anti-inflammatory and anti-apoptotic pathways. We aim to conduct a systematic review to evaluate the potential benefits of hydrogen-rich water. The review protocol was uploaded on PROSPERO. After the initial search criteria, the articles were reviewed by two blinded investigators, and a total of 25 articles were included in the systematic review. The potential benefits of hydrogen-rich water on various aspects of health, including exercise capacity, physical endurance, liver function, cardiovascular disease, mental health, COVID-19, oxidative stress, and anti-aging research, are a subject of growing interest and ongoing research. Although preliminary results in clinical trials and studies are encouraging, further research with larger sample sizes and rigorous methodologies is needed to substantiate these findings. Current research needs to fully explain the mechanisms behind the potential benefits of hydrogen-rich water. Continued scientific exploration will provide valuable insights into the potential of hydrogen-rich water as an adjunctive therapeutic approach in the future.

Acute effect of hydrogen-rich water on physical, perceptual and cardiac responses during aerobic and anaerobic exercises: a randomized, placebo-controlled, double-blinded cross-over trial

Molecular hydrogen (H2 gas) dissolved in water to produce Hydrogen-Rich Water. Hydrogen-Rich Water (HRW) is considered as ergogenic aid in different exercise modes. However, acute pre-exercise HRW ingestion effect is unclear regarding athlete performance. This study aimed at investigating acute effect of HRW ingestion on aerobic and anaerobic exercise performance. Twenty-two male amateur middle-distance runners volunteered to participate in this study. In a randomized, double-blind study design, all players ingested 500 mL of HRW or placebo (PLA) supplement 30 min before the start of the tests. Over 4 days, maximal aerobic speed of Vameval test (MAS), time to exhaustion at MAS (Tlim), squat jump (SJ), counter-movement jump (CMJ) and five jump test (5JT) were evaluated. Also, rate of perceived exertion (RPE) and peak heart rate (HRpeak) were measured during the aerobic tests. For Vameval test, HRW ingestion improved MAS, HRpeak and RPE compared with the placebo condition. For Tlim test, HRW ingestion demonstrated improvements in time to exhaustion, RPE and HRpeak. However, no significant change was observed between HW and placebo conditions in SJ, CMJ, 5JT. 500 mL of HRW can significantly improve HRpeak, time to exhaustion, RPE, with no significant effect on MAS, jumping performance in amateur endurance athletes.

Molecular Hydrogen Therapy-A Review on Clinical Studies and Outcomes

With its antioxidant properties, hydrogen gas (H2) has been evaluated in vitro, in animal studies and in human studies for a broad range of therapeutic indications. A simple search of "hydrogen gas" in various medical databases resulted in more than 2000 publications related to hydrogen gas as a potential new drug substance. A parallel search in clinical trial registers also generated many hits, reflecting the diversity in ongoing clinical trials involving hydrogen therapy. This review aims to assess and discuss the current findings about hydrogen therapy in the 81 identified clinical trials and 64 scientific publications on human studies. Positive indications have been found in major disease areas including cardiovascular diseases, cancer, respiratory diseases, central nervous system disorders, infections and many more. The available administration methods, which can pose challenges due to hydrogens' explosive hazards and low solubility, as well as possible future innovative technologies to mitigate these challenges, have been reviewed. Finally, an elaboration to discuss the findings is included with the aim of addressing the following questions: will hydrogen gas be a new drug substance in future clinical practice? If so, what might be the administration form and the clinical indications?

Effects of molecular hydrogen supplementation on fatigue and aerobic capacity in healthy adults: A systematic review and meta-analysis

Background

Fatigue is oftentimes induced by high-intensity exercise potentially via the exceeded amount of reactive oxygen species, leading to diminished functions (e.g., aerobic capacity) and increased risk of injuries. Studies indicate that molecular hydrogen (H₂), with antioxidant and anti-inflammatory properties, may be a promising strategy to alleviate fatigue and improve aerobic capacity. However, such effects have not been comprehensively characterized.

Objective

To systematically assess the effects of in taking H₂ on fatigue and aerobic capacity in healthy adults.

Methods

The search was conducted in August 2022 in five databases. Studies with randomized controlled or crossover designs that investigated the rating of perceived exertion (RPE), maximal oxygen uptake (VO_2max), peak oxygen uptake (VO_2peak), and endurance performance were selected. The data (mean ± standard deviation and sample size) were extracted from the included studies and were converted into the standardized mean difference (SMD). Random-effects meta-analyses were performed. Subgroup analysis was used to analyze potential sources of heterogeneity due to intervention period, training status, and type of exercise.

Results

Seventeen publications (19 studies) consisting of 402 participants were included. The pooled effect sizes of H₂ on RPE (SMD_pooled = -0.38, 95%CI -0.65 to -0.11, p = 0.006, I ² = 33.6%, p = 0.149) and blood lactate (SMD_pooled = -0.42, 95% CI -0.72 to -0.12, p = 0.006, I ² = 35.6%, p = 0.114) were small yet significant with low heterogeneity. The pooled effect sizes of H₂ on VO_2max and VO_2peak (SMD_pooled = 0.09, 95% CI -0.10 to 0.29, p = 0.333, I ² = 0%, p = 0.998) and endurance performance (SMD_pooled = 0.01, 95% CI -0.23 to 0.25, p = 0.946, I ² = 0%, p > 0.999) were not significant and trivial without heterogeneity. Subgroup analysis revealed that the effects of H₂ on fatigue were impacted significantly by the training status (i.e., untrained and trained), period of H₂ implementation, and exercise types (i.e., continuous and intermittent exercises).

Conclusions

This meta-analysis provides moderate evidence that H₂ supplementation alleviates fatigue but does not enhance aerobic capacity in healthy adults.

Systematic review registration

www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022351559.

Molecular Hydrogen Reduces Electromagnetic Pulse-Induced Male Rat Reproductive System Damage in a Rodent Model

Infertility has got to be a broadly concerned social issue these days, in which the malefactor cannot be overlooked. Numerous studies have shown that electromagnetic pulse (EMP) radiation may have seriously damaging effects on reproductive health, through nonthermal effects and oxidative stress. Molecular hydrogen, a selective hydroxyl radical scavenger, explains the protective effects against many diseases closely associated with oxidative damage, such as ionizing radiation (IR). We sought to characterize the beneficial effects of molecular hydrogen on the male reproductive system in a rodent EMP exposure model. The 8-week-old male Sprague-Dawley rats were exposed to EMP (peak intensity 1000 kV/m, pulse edge 20 ns, pulse width 200 ns, 1 Hz, and 200 pulses), with or without hydrogen-rich water. The pathological structure of the testis, the rate of apoptosis of the testis, the serum testosterone level, the sperm parameters, and the activity of the antioxidant enzymes of the testis were measured. Then, transcriptomic and untargeted metabolomic analyses were applied to uncover the underlying mechanism. Exposure to EMP increased testicular apoptosis rate and apoptosis protein level, decreased sperm viability and motility, decreased serum testosterone levels, and diminished testicular antioxidant capacity. Molecular hydrogen-alleviated damage decreased the testicular apoptosis rate and apoptosis protein level, increased sperm motility, increased serum testosterone levels, and improved antioxidative capacity. Omics results showed that molecular hydrogen has a strong influence on metabolic pathways, and EMP affects mainly oxidative phosphorylation, TNF signaling pathways, and cytokine-receptor interactions. The mechanism of molecular hydrogen's effect may be related to the reversal of some metabolite levels. These observations warrant molecular hydrogen as an innovative approach for potential protection against EMP.

Effects of pre-exercise H2 inhalation on physical fatigue and related prefrontal cortex activation during and after high-intensity exercise

Objective: In this study, we examined the effects of pre-exercise H₂ gas inhalation on physical fatigue (PF) and prefrontal cortex (PFC) activation during and after high-intensity cycling exercise.

Methods: Twenty-four young men completed four study visits. On the first two visits, the maximum workload (W_max) of cycling exercise of each participant was determined. On each of the other two visits, participants inhaled 20 min of either H₂ gas or placebo gas after a baseline test of maximal voluntary isometric contraction (MVIC) of thigh. Then participants performed cycling exercise under their maximum workload. Ratings of perceived exertion (RPE), heart rate (HR) and the PFC activation by using functional near-infrared spectroscopy (fNIRS) was measured throughout cycling exercise. The MVIC was measured again after the cycling.

Results: It was observed that compared to control, after inhaling H₂ gas, participants had significantly lower RPE at each workload phase (p < 0.032) and lower HR at 50% W_max, 75% W_max, and 100% W_max during cycling exercise (p < 0.037); the PFC activation was also significantly increased at 75 and 100% W_max (p < 0.011). Moreover, the H₂-induced changes in PF were significantly associated with that in PFC activation, that is, those who had higher PFC activation had lower RPE at 75% W_max (p = 0.010) and lower HR at 100% W_max (p = 0.016), respectively.

Conclusion: This study demonstrated that pre-exercise inhalation of H₂ gas can alleviate PF, potentially by maintaining high PFC activation during high-intensity exercise in healthy young adults.

Effects of hydrogen water and psychological treatment in a sample of women with panic disorder: a randomized and controlled clinical trial

Research suggests that inflammation is an important mediator in the pathophysiology of anxiety disorders. In addition, women are more likely to develop an anxiety and depression disorder, in comorbidity with a wide spectrum of diseases related to the immune system. In recent years, hydrogen-rich water has emerged as a promising therapeutic strategy to prevent and intervene in stress-related disorders, due to its antioxidant and anti-inflammatory properties. The present study aims to analyze the effects of psychological treatment and a hydrogen-rich drink on the severity of anxiety and depression, pro-inflammatory cytokine levels, the cortisol awakening response, and general health state in a sample of women with panic disorder. This is a completely randomized, placebo-controlled study. The treatment group simultaneously received psychological treatment and 1.5 L of hydrogenated water for three months, compared to the control group that received psychological treatment and placebo. The results show that the treatment group was not significantly better than the control group. But there was a further reduction in measured pro-inflammatory cytokine scores, improving body pain and physical health. When between-group treatment effects were removed, psychological treatment significantly decreased measured variables, including cytokines and cortisol. The results support the presence of a maladaptive inflammatory process in women with panic disorder.

Molecular Hydrogen as a Medical Gas for the Treatment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Possible Efficacy Based on a Literature Review

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disorder that is characterized by fatigue that persists for more than 6 months, weakness, sleep disturbances, and cognitive dysfunction. There are multiple possible etiologies for ME/CFS, among which mitochondrial dysfunction plays a major role in abnormal energy metabolism. The potential of many substances for the treatment of ME/CFS has been examined; however, satisfactory outcomes have not yet been achieved. The development of new substances for curative, not symptomatic, treatments is desired. Molecular hydrogen (H₂) ameliorates mitochondrial dysfunction by scavenging hydroxyl radicals, the most potent oxidant among reactive oxygen species. Animal experiments and clinical trials reported that H₂ exerted ameliorative effects on acute and chronic fatigue. Therefore, we conducted a literature review on the mechanism by which H₂ improves acute and chronic fatigue in animals and healthy people and showed that the attenuation of mitochondrial dysfunction by H₂ may be involved in the ameliorative effects. Although further clinical trials are needed to determine the efficacy and mechanism of H₂ gas in ME/CFS, our literature review suggested that H₂ gas may be an effective medical gas for the treatment of ME/CFS.

Hydrogen-Rich Water Prevents Dehydration-Induced Cellular Oxidative Stress and Cell Death in Human Skin Keratinocytes

Hypohydration is linked to increased risk of a variety of diseases and can be life-threatening, especially in elderly populations. Dehydration induces cellular damage partially through the production of reactive oxygen species (ROS) in cells, tissues and organs. Hydrogen molecules are known to convert ROS to harmless water. Therefore, theoretically hydrogen-rich water (HW) might eliminate dehydration-induced ROS and reverse its harmful effects in cells. In this in vitro study, we demonstrated that air-drying for 5 min could induce ROS generation in both nucleus and cytoplasm of human keratinocytes HaCaT as quantified by CellROX® Green/Orange reagents (Thermo Fisher Scientific, Waltham, Massachusetts, U.S.), respectively. Conversely, when the air-drying time was increased to 10 and 20 min, HaCaT cells lost the ability to produce ROS. Scanning electron microscopic (SEM) images showed that 10 min air-drying could induce severe membrane damage in HaCaT cells. PrestoBlue assay showed that, when HaCaT cells were air-dried for 20 min, cell viability was decreased to 27.6% of the control cells 48 h later. However, once HaCaT cells were pretreated with HW-prepared media, dehydration-induced intracellular ROS, cell membrane damage and cell death were significantly reduced as compared with double distilled water (DDW) under the same conditions. In conclusion, our data suggested that HW can decrease dehydration-induced harmful effects in human cells partially through its antioxidant capacity.

The Role of Hyperthermia in Methamphetamine-Induced Depression-Like Behaviors: Protective Effects of Coral Calcium Hydride

Methamphetamine (METH) abuse causes irreversible damage to the central nervous system and leads to psychiatric symptoms including depression. Notably, METH-induced hyperthermia is a crucial factor in the development of these symptoms, as it aggravates METH-induced neurotoxicity. However, the role of hyperthermia in METH-induced depression-like behaviors needs to be clarified. In the present study, we treated mice with different doses of METH under normal (NAT) or high ambient temperatures (HAT). We found that HAT promoted hyperthermia after METH treatment and played a key role in METH-induced depression-like behaviors in mice. Intriguingly, chronic METH exposure (10 mg/kg, 7 or 14 days) or administration of an escalating-dose (2 ∼ 15 mg/kg, 3 days) of METH under NAT failed to induce depression-like behaviors. However, HAT aggravated METH-induced damage of hippocampal synaptic plasticity, reaction to oxidative stress, and neuroinflammation. Molecular hydrogen acts as an antioxidant and anti-inflammatory agent and has been shown to have preventive and therapeutic applicability in a wide range of diseases. Coral calcium hydride (CCH) is a newly identified hydrogen-rich powder which produces hydrogen gas gradually when exposed to water. Herein, we found that CCH pretreatment significantly attenuated METH-induced hyperthermia, and administration of CCH after METH exposure also inhibited METH-induced depression-like behaviors and reduced the hippocampal synaptic plasticity damage. Moreover, CCH effectively reduced the activity of lactate dehydrogenase and decreased malondialdehyde, TNF-α and IL-6 generation in hippocampus. These results suggest that CCH is an efficient hydrogen-rich agent, which has a potential therapeutic applicability in the treatment of METH abusers.

Effects of carbohydrate-electrolyte dissolved alkaline electrolyzed water on physiological responses during exercise under heat stress in physically active men

Purpose

This study investigated the effects of 1400 mL intake of alkaline electrolyzed water (AEW) or purified water (PW) into which carbohydrate-electrolyte (CE) was dissolved on improving physiological responses during exercise under heat stress.

Methods

This double-blinded, crossover randomized controlled trial included 10 male participants who completed two exercise trials in a hot environment (35 °C, ambient temperature, and 50% relative humidity) after consuming CE-dissolved PW (P-CE) or CE-dissolved AEW (A-CE). The exercise trial consisted of running for 30 min on a treadmill (at an intensity corresponding to 65% of heart rate reserve adjusted for heat stress conditions) and repeated sprint cycling (10 × 7-s maximal sprint cycling), with a 35-min rest interval between the two exercises, followed by a 30-min post-exercise recovery period. Before and after running, and after cycling, the participants drank P-CE (hydrogen concentration of 0 ppm, pH 3.8) or A-CE (0.3 ppm, pH 4.1). Blood samples were obtained before, during (rest interval between running and cycling), and post-exercise.

Results

Repeated sprint performance and oxidative stress response did not differ between the P-CE and A-CE trials. A-CE consumption significantly attenuated the increase in blood lactate concentration during the running exercise but not during repeated sprint cycling under heat stress conditions.

Conclusion

Our findings suggested that A-CE did not significantly affect repeated sprint performance; however, the attenuated elevation in blood lactate by A-CE ingestion implies a partial enhancement of endurance performance during submaximal exercise under heat stress.

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A-CE did not enhance repeated sprint performance in a hot environment.

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A-CE failed to decrease oxidative damage induced by exercise in a hot environment.

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Blood lactate response during submaximal running was attenuated by drinking A-CE.

Formulation and Characterization of an Effervescent Hydrogen-Generating Tablet

Hydrogen, as a medical gas, is a promising emerging treatment for many diseases related to inflammation and oxidative stress. Molecular hydrogen can be generated through hydrogen ion reduction by a metal, and magnesium-containing effervescent tablets constitute an attractive formulation strategy for oral delivery. In this regard, saccharide-based excipients represent an important class of potential fillers with high water solubility and sweet taste. In this study, we investigated the effect of different saccharides on the morphological and mechanical properties and the disintegration of hydrogen-generating effervescent tablets prepared by dry granulation. Mannitol was found to be superior to other investigated saccharides and promoted far more rapid hydrogen generation combined with acceptable mechanical properties. In further product optimization involving investigation of lubricant effects, adipic acid was selected for the optimized tablet, due to regulatory considerations.

Prenatal Molecular Hydrogen Administration Ameliorates Several Findings in Nitrofen-Induced Congenital Diaphragmatic Hernia

Oxidative stress plays a pathological role in pulmonary hypoplasia and pulmonary hypertension in congenital diaphragmatic hernia (CDH). This study investigated the effect of molecular hydrogen (H₂), an antioxidant, on CDH pathology induced by nitrofen. Sprague-Dawley rats were divided into three groups: control, CDH, and CDH + hydrogen-rich water (HW). Pregnant dams of CDH + HW pups were orally administered HW from embryonic day 10 until parturition. Gasometric evaluation and histological, immunohistochemical, and real-time polymerase chain reaction analyses were performed. Gasometric results (pH, pO_2, and pCO₂ levels) were better in the CDH + HW group than in the CDH group. The CDH + HW group showed amelioration of alveolarization and pulmonary artery remodeling compared with the CDH group. Oxidative stress (8-hydroxy-2′-deoxyguanosine-positive-cell score) in the pulmonary arteries and mRNA levels of protein-containing pulmonary surfactant that protects against pulmonary collapse (surfactant protein A) were significantly attenuated in the CDH + HW group compared with the CDH group. Overall, prenatal H₂ administration improved respiratory function by attenuating lung morphology and pulmonary artery thickening in CDH rat models. Thus, H₂ administration in pregnant women with diagnosed fetal CDH might be a novel antenatal intervention strategy to reduce newborn mortality due to CDH.

Hydrogen medicine: A rising star in gas medicine

Gas medicine, including O2, NO, H2S, CO, CH4, has played important roles in prevention and treatment of diseases for a long time. Molecular hydrogen (H2), the smallest diatomic molecule in nature, has become a rising star in gas medicine in the past decades. Many studies have shown that H2 has preventive and therapeutic effects on various diseases through its selective antioxidant activity. H2, as a non-toxic gas for the human body and convenience to obtain, has provided a great possibility to be used widely. Currently, the main difficulties in hydrogen medicine are lack of definitive clinical evidence and the molecular basis of hydrogen effects. In this paper, the authors have conducted a comprehensive review and analysis of these issues, and also proposed the possibility of developing Hydrogen Biology and Hydrogen Medicine as new disciplines of biology and medicine.

Nature's marvels endowed in gaseous molecules I: Carbon monoxide and its physiological and therapeutic roles

Nature has endowed gaseous molecules such as O2, CO2, CO, NO, H2S, and N2 with critical and diverse roles in sustaining life, from supplying energy needed to power life and building blocks for life's physical structure to mediating and coordinating cellular functions. In this article, we give a brief introduction of the complex functions of the various gaseous molecules in life and then focus on carbon monoxide as a specific example of an endogenously produced signaling molecule to highlight the importance of this class of molecules. The past twenty years have seen much progress in understanding CO's mechanism(s) of action and pharmacological effects as well as in developing delivery methods for easy administration. One remarkable trait of CO is its pleiotropic effects that have few parallels, except perhaps its sister gaseous signaling molecules such as nitric oxide and hydrogen sulfide. This review will delve into the sophistication of CO-mediated signaling as well as its validated pharmacological functions and possible therapeutic applications.

Hydrogen Gas as an Exotic Performance-Enhancing Agent: Challenges and Opportunities

BACKGROUND

Hydrogen gas (H₂) has entered the world of experimental therapeutics approximately four and a half decades ago. Over the years, this simple molecule appears to drive more scientific attention, perhaps due to a dualism of H₂ affirmative features demonstrated in numerous in vitro, animal and human studies on one side, and still puzzling mechanism(s) of its biological activity on the other. Up to this point, H₂ was scrutinized for more than 170 different disease models and pathologies, and many research groups across the world have lately started to dynamically investigate its conceivable performance-enhancing potential.

METHODS

We outlined here the studies indexed in leading research databases (PubMed, Web of Science, SCOPUS, JSTORE) that explored the effects of hydrogen on exercise performance, and also addressed important restraints, open questions, and windows of opportunities for forthcoming research and possible H₂ enactment in exercise physiology. About two dozen trials have been identified in this domain, with most of the trials published during the past 5 years, while drinking hydrogen-rich water recognized as the most convenient method to deliver H₂ in both animal and human studies.

RESULTS

Either administered as an inhalational gas, enteral hydrogen-rich water, or intravenous hydrogen-rich saline, H₂ seems to favorably affect various exercise performance outcomes and biomarkers of exercise-associated fatigue, inflammation, and oxidative stress. Not all studies have shown corroborative effects, and it appears that the gold-standard protocol for applying H₂ in the field of exercise science does not exist at the moment, with studies markedly differ in the dose of H₂ administered, the duration of treatment, and the source of hydrogen.

CONCLUSION

H₂ is a newfangled and rather effective performance-enhancing agent, yet its promising ergogenic potency has to be further validated and characterized in more well-controlled, appropriately sampled and longterm mechanistic trials. Also, appropriate regulation of hydrogen utilization in sport as an exotic medical gas may require distinctive legislative actions of relevant regulatory agencies in the future.

Direct Targets and Subsequent Pathways for Molecular Hydrogen to Exert Multiple Functions: Focusing on Interventions in Radical Reactions

Molecular hydrogen (H₂) was long regarded as non-functional in mammalian cells. We overturned the concept by demonstrating that H₂ exhibits antioxidant effects and protects cells against oxidative stress. Subsequently, it has been revealed that H₂ has multiple functions in addition to antioxidant effects, including antiinflammatory, anti-allergic functions, and as cell death and autophagy regulation. Additionally, H₂ stimulates energy metabolism. As H₂ does not readily react with most biomolecules without a catalyst, it is essential to identify the primary targets with which H₂ reacts or interacts directly. As a first event, H₂ may react directly with strong oxidants, such as hydroxyl radicals (•OH) in vivo. This review addresses the key issues related to this in vivo reaction. •OH may have a physiological role because it triggers a free radical chain reaction and may be involved in the regulation of Ca2+- or mitochondrial ATP-dependent K+-channeling. In the subsequent pathway, H₂ suppressed a free radical chain reaction, leading to decreases in lipid peroxide and its end products. Derived from the peroxides, 4-hydroxy-2-nonenal functions as a mediator that up-regulates multiple functional PGC-1α. As the other direct target in vitro and in vivo, H₂ intervenes in the free radical chain reaction to modify oxidized phospholipids, which may act as an antagonist of Ca2+-channels. The resulting suppression of Ca2+-signaling inactivates multiple functional NFAT and CREB transcription factors, which may explain H₂ multi-functionality. This review also addresses the involvement of NFAT in the beneficial role of H₂ in COVID-19, Alzheimer's disease and advanced cancer. We discuss some unsolved issues of H₂ action on lipopolysaccharide signaling, MAPK and NF-κB pathways and the Nrf2 paradox. Finally, as a novel idea for the direct targeting of H2, this review introduces the possibility that H₂ causes structural changes in proteins via hydrate water changes.

Hydrogen Rich Water Consumption Positively Affects Muscle Performance, Lactate Response, and Alleviates Delayed Onset of Muscle Soreness After Resistance Training

ABSTRACT

Botek, M, Krejčí, J, McKune, A, Valenta, M, and Sládečková, B. Hydrogen rich water consumption positively affects muscle performance, lactate response, and alleviates delayed onset of muscle soreness after resistance training. J Strength Cond Res XX(X): 000-000, 2021-Positive outcomes of hydrogen rich water (HRW) supplementation on endurance performance have been shown, but the effects of HRW in resistance training are unclear. The aim of this study was to assess the effects of 1,260 ml of HRW intake on physiological, perceptual, and performance responses to a resistance training and after 24 hours of recovery. This randomized, double-blinded placebo-controlled cross-over study included 12 men aged 23.8 ± 1.9 years. Subjects performed a half squat, knee flexion, and extension exercises with the load set at 70% of 1 repetition maximum for 3 sets (10 reps/set). Lunges were performed with a load of 30% of body mass for 3 sets (20 reps/set). Time of each set, lactate, and ratings of perceived exertion were assessed mid-way through exercise and immediately after the exercise. Creatine kinase, muscle soreness visual analog scale ratings, countermovement jump, and heart rate variability were evaluated before the training and at 30 minutes, 6, and 24 hours of recovery. Lunges were performed faster with HRW compared with placebo (p < 0.001). Hydrogen rich water reduced lactate at mid-way and immediately after the exercise (HRW: 5.3 ± 2.1 and 5.1 ± 2.2, placebo: 6.5 ± 1.8 and 6.3 ± 2.2 mmol·L-1, p ≤ 0.008). Visual analog scale ratings were significantly lower with HRW (26 ± 11 vs. 41 ± 20 mm, p = 0.002) after 24 hours of recovery. In conclusion, an acute intermittent HRW hydration improved muscle function, reduced the lactate response, and alleviated delayed onset of muscle soreness.

Two-week continuous supplementation of hydrogenrich water increases peak oxygen uptake during an incremental cycling exercise test in healthy humans: a randomized, single-blinded, placebo-controlled study

The various beneficial effects of the intake of molecular hydrogen (H2) have been demonstrated in the field of sports science. Although supplementation of H2 has been reported to increase mitochondrial metabolism in animal studies, the effects of the administration of H2 on aerobic capacity during exercise in humans are still not clear. We investigated whether a single or 2-week continuous intake of H2-rich water (HW) enhanced the aerobic capacity during incremental exercise in healthy humans. In this randomized, single-blinded, placebo-controlled experimental study, the participants performed an incremental cycling exercise to measure peak oxygen uptake and peak load before and after a single (500 mL) or a 2-week supplementation (total 5 L) of HW. In the latter experiment, the participants drank the 500 mL of HW on all weekdays (i.e., 10 times). The single intake of HW did not significantly increase peak oxygen uptake and peak load, and did not significantly alter the responses in oxidative stress, antioxidant activity, and lactate levels. However, importantly, the 2-week continuous consumption of HW significantly augmented peak oxygen uptake and tended to increase the peak load without any significant changes in lactate levels, oxidative stress, and antioxidant responses. In conclusion, the continuous supplementation of HW potentially augments the aerobic capacity, implying that continuous supplementation of H2 might help improve aerobic exercise performance and physical health. This study protocol was approved by the Ethical Committee of Chubu University (approval No. 260086-2) on March 29, 2018.

Molecular hydrogen (H2 ) as a potential treatment for acute and chronic fatigue

Many diseases as well as acute conditions can lead to fatigue, which can be either temporary or chronic in nature. Acute fatigue develops frequently after physical exercise or after alcohol hangover, whereas microbial infections such as influenza or COVID-19 and chronic diseases like Parkinson's disease or multiple sclerosis are often associated with chronic fatigue. Oxidative stress and a resulting disturbance of mitochondrial function are likely to be common denominators for many forms of fatigue, and antioxidant treatments have been shown to be effective in alleviating the symptoms of fatigue. In this study, we review the role of reactive oxygen and nitrogen species in fatigue and the antioxidant effects of the intake of molecular hydrogen. We propose that molecular hydrogen is well suited for the treatment of temporary and chronic forms of oxidative stress-associated fatigue.

Acute ingestion of hydrogen-rich water does not improve incremental treadmill running performance in endurance-trained athletes

There is emerging evidence that hydrogen-rich water (H2-water) has beneficial effects on the physiological responses to exercise. However, few studies investigate its ergogenic potential. This randomized controlled trial examined the effects of H2-water ingestion on physiological responses and exercise performance during incremental treadmill running. In a double-blind crossover design, 14 endurance-trained male runners (age, 34 ± 4 years; body mass, 63.1 ± 7.2 kg; height, 1.72 ± 0.05 m) were randomly assigned to ingest 2 doses of 290-mL H2-water or placebo on each occasion. The first bolus was given before six 4-min submaximal running bouts, and the second bolus was consumed before the maximal incremental running test. Expired gas, heart rate (HR), and ratings of perceived exertion (RPE) were recorded; blood samples were collected at the end of each submaximal stage and post maximal running test. Cardiorespiratory responses, RPE, and blood gas indices were not significantly different at each submaximal running intensity (range: 34%–91% maximal oxygen uptake) between H2-water and placebo trials. No statistical difference was observed in running time to exhaustion (618 ± 126 vs. 619 ± 113 s), maximal oxygen uptake (56.9 ± 4.4 vs. 57.1 ± 4.7 mL·kg−1·min−1), maximal HR (184 ± 7 vs. 184 ± 7 beat·min−1), and RPE (19 ± 1 vs. 19 ± 1) in the runners between the trials. The results suggest that the ingestion of 290 mL of H2-water before submaximal treadmill running and an additional dose before the subsequent incremental running to exhaustion were not sufficiently ergogenic in endurance-trained athletes.

Novelty Acute ingestion of H2-water does not seem to be ergogenic for endurance performance. A small dose of H2-water does not modulate buffering capacity during intense endurance exercise in athletes.

Application of Molecular Hydrogen as a Novel Antioxidant in Sports Science

Molecular hydrogen (H₂) is a colorless, tasteless, odorless, and minimal molecule with high flammability. Although H₂ has been thought to be an inert gas in living bodies for many years, an animal study reported that inhalation of H₂ gas decreased oxidative stress and suppressed brain injury caused by ischemia and reperfusion injury due to its antioxidant action. Since then, the antioxidant action of H₂ has attracted considerable attention and many studies have reported on its benefits. Most studies have reported the effects of H₂ on diseases such as cancer, diabetes, cerebral infarction, and Alzheimer's disease. However, little is known regarding its effects on healthy subjects and exercise. Thus far, including our study, only 6 studies have explored the effect of H₂ on exercise. H₂ is the smallest molecule and therefore can easily penetrate the cellular membrane and rapidly diffuse into organelles. H₂ is thought to be able to selectively reduce hydroxyl radicals and peroxynitrite and does not affect physiologically reactive species. H₂ can be supplied to the body through multiple routes of administration, such as oral intake of H₂ water and H₂ bathing. Therefore, H₂ may be a potential alternative strategy for conventional exogenous antioxidant interventions in sports science. The purpose of this review is to provide evidence regarding the effects of H₂ intake on changes in physiological and biochemical parameters, centering on exercise-induced oxidative stress, for each intake method. Furthermore, this review highlights possible future directions in this area of research.

The Effects of 24-Week, High-Concentration Hydrogen-Rich Water on Body Composition, Blood Lipid Profiles and Inflammation Biomarkers in Men and Women with Metabolic Syndrome: A Randomized Controlled Trial

PURPOSE

Metabolic syndrome is associated with several medical risk factors including dyslipidemia, hyperglycemia, and obesity, which has become a worldwide pandemic. The sequelae of this condition increase the risk of cardiovascular and neurological disease and increased mortality. Its pathophysiology is associated with redox dysregulation, excessive inflammation, and perturbation of cellular homeostasis. Molecular hydrogen (H₂) may attenuate oxidative stress, improve cellular function, and reduce chronic inflammation. Pre-clinical and clinical studies have shown promising effects of H₂-rich water (HRW) on specific features of metabolic syndrome, yet the effects of long-term, high-concentration HRW in this prevalent condition remain poorly addressed.

METHODS

We conducted a randomized, double-blinded, placebo-controlled trial in 60 subjects (30 men and 30 women) with metabolic syndrome. An initial observation period of one week was used to acquire baseline clinical data followed by randomization to either placebo or high-concentration HRW (> 5.5 millimoles of H₂ per day) for 24 weeks.

RESULTS

Supplementation with high-concentration HRW significantly reduced blood cholesterol and glucose levels, attenuated serum hemoglobin A1c, and improved biomarkers of inflammation and redox homeostasis as compared to placebo (P < 0.05). Furthermore, H₂ tended to promote a mild reduction in body mass index and waist-to-hip ratio.

CONCLUSION

Our results give further credence that high-concentration HRW might have promising effects as a therapeutic modality for attenuating risk factors of metabolic syndrome.

Hydrogen gas: from clinical medicine to an emerging ergogenic molecule for sports athletes 1

H₂ has been clinically demonstrated to provide antioxidant and anti-inflammatory effects, which makes it an attractive agent in exercise medicine. Although exercise provides a multiplicity of benefits including decreased risk of disease, it can also have detrimental effects. For example, chronic high-intensity exercise in elite athletes, or sporadic bouts of exercise (i.e., noxious exercise) in untrained individuals, result in similar pathological factors such as inflammation, oxidation, and cellular damage that arise from and result in disease. Paradoxically, exercise-induced pro-inflammatory cytokines and reactive oxygen species largely mediate the benefits of exercise. Ingestion of conventional antioxidants and anti-inflammatories often impairs exercise-induced training adaptations. Disease and noxious forms of exercise promote redox dysregulation and chronic inflammation, changes that are mitigated by H₂ administration. Beneficial exercise and H₂ administration promote cytoprotective hormesis, mitochondrial biogenesis, ATP production, increased NAD⁺/NADH ratio, cytoprotective phase II enzymes, heat-shock proteins, sirtuins, etc. We review the biomedical effects of exercise and those of H₂, and we propose that hydrogen may act as an exercise mimetic and redox adaptogen, potentiate the benefits from beneficial exercise, and reduce the harm from noxious exercise. However, more research is warranted to elucidate the potential ergogenic and therapeutic effects of H₂ in exercise medicine.