Hydrogen-Rich Water Decreases Muscle Damage and Improves Power Endurance in Elite Athletes: A Randomized, Double-Blinded, Placebo-Controlled Trial

Abstract

Background

Physical activity significantly increases the production of reactive oxygen species in the body. Molecular hydrogen has been shown to have safe and effective antioxidant properties on athletes. However, research on elite athletes is scarce.

Methods

A randomized, double-blinded, placebo-controlled trial was conducted with 22 female elite athletes participating in handball and skeleton sports. The first group received hydrogen-rich water (HRW)-generating tablets, whereas the second group consumed a visually and organoleptically similar placebo. Various assessments were performed during HRW intake, such as anthropometric and biochemical measurements, stress, and recovery parameters, as well as biomechanical testing.

Results

HRW consumption resulted inan increase in muscle mass and a reduction in fat mass (p < 0.05). However, HRW did not significantly affect stress or recovery rates, as determined by the Recovery-Stress Questionnaire-Sport questionnaire. However, the HRW group exhibited a significant increase in torque, particularly after an intensive exercise test (p < 0.05). Moreover, HRW intake led to a reduction in total creatine kinase, vitamin C, and beta-carotene contents (p < 0.05), whereas the vitamin E and interleukin-10 levels increased compared with baseline levels (p < 0.05).

Conclusion

The HRW-generating tablets were found to be safe and well-tolerated by the participants. These tablets also exerted ergogenic effects by reducing body fat percentage, increasing muscle mass percentage, improving maximal torque, decreasing muscle damage, and positively modulating the exercise-induced inflammatory and antioxidant responses to exercise. Although the mechanism of action of HRW remains unclear, these effects observed indicate its potential for diverse applications in high-performance sports.

INTRODUCTION

Physical exertion is a fundamental component of athletic training and competition, yet it is also a significant instigator of reactive oxygen species (ROS) production in the body [1]. ROS, including free radicals and reactive oxygen intermediates, are generated during exercise due to increased oxygen consumption and metabolic activity, leading to oxidative stress [2]. While ROS play essential roles in cellular signaling and adaptation to exercise, excessive ROS production can overwhelm endogenous antioxidant defenses, resulting in oxidative damage to cellular macromolecules such as proteins, lipids, and DNA [3].

In recent years, hydrogen has emerged as a promising therapeutic agent with potential antioxidant, anti-inflammatory, and anti-apoptotic effects [4]. Molecular hydrogen (H₂) can selectively neutralize highly reactive ROS, such as hydroxyl radicals (^•OH) and peroxynitrite (ONOO⁻), without affecting less reactive species essential for cellular signaling, such as superoxide (O^2•−) and hydrogen peroxide (H₂O₂) [5,6]. The ability of H₂ to selectively scavenge harmful ROS while preserving beneficial signaling molecules makes it an attractive candidate for mitigating oxidative stress and its associated detrimental effects in athletes [7].

Various methods have been developed to deliver H₂ to the body, including inhalation, injection, and ingestion of hydrogen-rich water (HRW) [8]. Among these methods, HRW has gained popularity as a convenient and accessible means of H₂ administration, particularly in sports settings [9]. HRW is produced by dissolving molecular hydrogen gas in water using electrolysis or by reacting magnesium with water to generate H₂ gas [10]. The resulting water contains dissolved molecular hydrogen at supersaturated concentrations, which can then be consumed as a beverage [11].

While several studies have investigated the effects of HRW on exercise performance and recovery, most of these studies have focused on recreational or amateur athletes, with limited research conducted on elite athletes [12]. Elite athletes represent a unique population with distinct physiological and performance characteristics, making it essential to evaluate the efficacy and safety of HRW specifically in this population [12]. Athletes in sports such as handball and skeleton face unique physiological demands that make them ideal for studying the potential benefits of HRW. Handball requires sustained exercise above the anaerobic threshold, which significantly increases oxidative stress due to elevated ROS production. This can contribute to lipid peroxidation when antioxidant defenses are insufficient to counteract the increased pro-oxidant load. Similarly, skeleton involves high-speed anaerobic performance, which places significant oxidative and inflammatory stress on the body. These characteristics make these elite athletes an excellent model for assessing HRW’s capacity to mitigate exercise-induced oxidative stress and support performance and recovery.

This study aims to fill this gap in the literature by investigating the effects of HRW consumption on various physiological, biochemical, and performance parameters in elite female athletes participating in handball and skeleton. A randomized double-blinded, placebo-controlled trial was conducted to assess the impact of HRW on muscle mass, body composition, stress and recovery parameters, and biomechanical performance. Additionally, biochemical markers of oxidative stress, inflammation, and antioxidant status were measured to elucidate the potential mechanisms underlying the observed effects of HRW.

The findings of this feasibility and pilot study have the potential to contribute valuable insights into the role of HRW as a biologically active supplement in sports medicine, with implications for optimizing athletic performance, enhancing recovery, and minimizing the negative effects of oxidative stress associated with intense physical training and competition. Moreover, the results may inform the development of evidence-based strategies for integrating HRW supplementation into the training and recovery regimens of elite athletes, thereby maximizing their competitive potential and overall well-being.

MATERIALS AND METHODS

A randomized, double-blinded, placebo-controlled trial was conducted with the participation of 22 female international-level athletes who provided informed consent. The research protocol was approved by the local ethics committee of the approved by the institutional review board the Federal Research and Clinical Center of Sports Medicine and Rehabilitation (protocol 2 dated 10/24/2022). Informed consent was submitted by all subjects when they were enrolled. Among them, 16 were handball players and 6 were skeleton athletes, with a median age of 24.5 (20; 28) years. At the commencement of the study, all athletes were in the special training phase, which focused primarily on speed and strength development.

For the study, the athletes were randomly assigned to two groups using simple fixed randomization (computer-generated random numbers). This method ensured that each participant had an equal 50% probability of being assigned to either group. To maintain blinding, the placebo tablets were designed to be visually and organoleptically identical to the HRW tablets, including their effervescence and taste profile. Neither the participants nor the researchers involved in data collection and analysis were aware of group assignments to minimize bias. Moreover, all athletes were at the same stage of preparation and maintained normal patterns of supplementation, with the only new intervention being HRW.

The first group (n = 10) received the biologically active H₂-producing supplement “Drink HRW,” manufactured by Natural Health Products Inc., New Westminster, Canada. The tablets contain some organic acids that serve as proton donors (i.e., H⁺), and non-ionic, zero valent, metallic magnesium which, once dissolved in water, reacts with the acids (i.e., H⁺) to produce H₂ gas according to the reaction: Mg + 2H⁺ + Mg²⁺ + H₂ (g). Subjects were instructed to place one tablet in 500 mL of room temperature water and ingest within ≈ 3 minutes twice daily. This provided a total daily dose of H₂ of around 8 mg. The athletes in the second group (n = 12) received a placebo containing magnesium oxide, manufactured by NuEra Nutraceutical Inc., United States, which had similar physicochemical and organoleptic properties to the HRW. In this case, the effervescence was created by the production of CO₂ via the reaction of organic acids with bicarbonate. The duration of supplementation for both groups was 28 days.

At the beginning and end of the study, the athletes underwent measurement of anthropometric indicators with an analysis of body composition. The validated Russian version of the Recovery-Stress Questionnaire for Athletes (RESTQ-76 Sport) [13] was employed to evaluate stress levels and the effectiveness of post-exercise recovery processes.

Additionally, the athletes underwent biomechanical testing to assess the peak isometric strength and endurance of the posterior thigh muscles via knee flexion. Specifically, prior to warm-up, athletes performed five three-second attempts of maximal voluntary contraction with a five-second rest between each attempt. Their highest peak torque from these attempts represented their maximum torque, while the average torque of the five attempts was used to estimate their muscular endurance at or near peak force. Following this, athletes completed a warm-up by running on the treadmill for 7-10 minutes until reaching 80% of their age-predicted maximum heart rate. The peak and average isometric torque of the athletes were then retested, the same as before the warm-up. This same procedure was then repeated following 28 days of supplementation with either placebo or HRW.

The study also involved comprehensive laboratory testing for all participants, during which biological samples were collected at three time points: baseline, after 28 days of supplementation with either placebo or HRW, and one-week post-intervention. Blood sampling was performed in the morning, after an overnight fast. The blood samples were analyzed for the following biomarkers: tumor necrosis factor-alpha, interleukins 6 (IL-6), 8 (IL-8), and 10 (IL-10), creatine kinase (CK), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), coenzyme Q10, vitamins C and E, beta-carotene, glutathione, and malondialdehyde (MDA). Thus, the study evaluated the cytokine profile, antioxidant status, and oxidative stress markers. Fig. 1 illustrates the study design and timeline for the biological markers.

Fig. 1.

Timeline testing of the biological samples at three different periods, baseline, immediately after 28 days of hydrogen-rich water (HRW) supplementation, and 1-week post-intervention.

Statistical analysis of the data was performed using the IBM SPSS Statistics 27.0 software package (IBM Co.). To assess the applicability of parametric tools, the normality of the distribution of variables was tested using the Shapiro-Wilk and Kolmogorov-Smirnov tests with the Lilliefors correction. Non-parametric statistical methods were employed for data analysis when the distribution of variable values deviated from normal. Descriptive statistics for quantitative data were presented as medians and quartiles, while qualitative characteristics were described in terms of absolute and relative frequencies with their corresponding confidence intervals. Comparative intergroup analysis was conducted using the nonparametric Mann-Whitney U test, and within-group analysis utilized the nonparametric Friedman test. The statistical significance of differences between parameters in the dynamics of observation was established using the nonparametric Wilcoxon test for the comparison of two time points and the Bonferroni-Holm correction for multiple comparisons for comparison of three time points.

RESULTS

During this placebo-controlled study, none of the observed athletes reported any side effects that could be attributed to the consumption of HRW, and there were no cases of a decline in exercise tolerance. This indicates the absence of significant restrictions on its inclusion in the medical and biological support programs during the various stages of the annual training cycle.

1. Evaluation of anthropometric indicators before and after the consumption of HRW

Following the 28-day intervention, no statistically significant changes were observed in body composition in the placebo group. However, 28 days of HRW led to statistically significant decreases in relative percentage and absolute body fat content, along with increases in both percentage and absolute muscle mass content (Table 1).

Table 1.

Within-group differences in anthropometric indicators for HRW and placebo groups

Indicator	HRW group				Placebo group
	Before intake Me (Q1; Q3)	After intake Me (Q1; Q3)	p-value		Before intake Me (Q1; Q3)	After intake Me (Q1; Q3)	p-value
Body weight (kg)	64.85 (60.13; 68.93)	66.20 (61.03; 68.85)	0.103		67.40 (60.08; 77.03)	66.60 (60.88; 76.95)	0.969
Body mass index (kg/m2)	21.46 (20.67; 22.37)	21.85 (20.83; 22.55)	0.386		22.36 (22.12; 23.83)	22.63 (21.75; 23.58)	0.937
Waist circumference (cm)	74.00 (69.75; 74.00)	73.00 (69.50; 75.25)	0.726		72.50 (70.00; 79.00)	71.50 (70.00; 77.50)	0.172
Hip circumference (cm)	97.00 (93.50; 102.00)	98.50 (94.75; 102.00)	0.263		99.00 (95.25; 105.00)	97.00 (94.38; 105.00)	0.307
Waist-to-hip ratio	0.74 (0.72; 0.77)	0.75 (0.71; 0.77)	0.314		0.75 (0.73; 0.76)	0.75 (0.72; 0.76)	0.575
Absolute content of body fat (kg)	10.10 (9.70; 12.10)	10.25 (8.93; 11.35)	0.052		13.35 (11.15; 16.10)	12.60 (11.18; 14.68)	0.271
Body fat mass percentage (%)	15.44 (14.49; 21.92)	15.30 (12.75; 20.28)	0.028*		19.93 (17.33; 21.72)	19.37 (16.98; 20.85)	0.308
Absolute content of muscle mass (kg)	31.00 (25.28; 33.13)	31.36 (26.93; 34.03)	0.017*		30.25 (27.48; 34.25)	30.45 (27.43; 34.20)	0.638
Body muscle mass percentage (%)	47.48 (43.03; 48.46)	47.92 (44.10; 49.42)	0.017*		45.06 (44.23; 47.09)	45.24 (43.63; 46.37)	0.875

HRW: hydrogen-rich water, Me: median, Q: quartile.

*Indicates statistically significant differences (p < 0.05).

2. Assessment of stress and recovery levels before and after HRW intake

To analyze the potential effects of HRW on stress response and the effectiveness (speed) of recovery processes following training loads, only those parameters of the RESTQ-Sport Questionnaire reflecting “sport-specific stress”, “sport-specific recovery”, “general stress”, and “general recovery” were utilized (Fig. 2).

Fig. 2.

Comparison of stress and recovery parameters in the hydrogen-rich water (HRW) and placebo groups before and after 28 days of supplementation. Box plots represent the median, interquartile range, and overall data spread for the following RESTQ-Sport parameters: (A) Sport-specific stress, (B) Sport-specific recovery, (C) General stress, and (D) General recovery. Statistical comparisons were conducted within each group over time and between groups at each time point. No statistically significant differences (ns, p > 0.05) were observed in any parameter across conditions.

No statistically significant differences were found during the dynamic observation of the participants in either the HRW or placebo groups (p > 0.05).

3. Assessment of biochemical values before and after HRW intake

Compared to baseline values, statistically significant reductions were observed in the levels of CK, vitamin C, and beta-carotene following 28 days of HRW intake. Conversely, HRW intake led to an increase in the levels of vitamin E and IL-10 (Table 2).

Table 2.

Within-group differences in laboratory parameter values for the HRW and placebo groups

Parameter	HRW					Placebo
	Before intake Me (Q1; Q3)	Immediate post intake Me (Q1; Q3)	One-week post intake Me (Q1; Q3)	p-value		Before intake Me (Q1; Q3)	Immediate post intake Me (Q1; Q3)	One-week post intake Me (Q1; Q3)	p-value
CK (IU/L)	116.5 (85.3; 177.3)	108.5 (66.8; 130.8)	87.5 (72.3; 101.5)	0.016*		165.0 (78.8; 280.3)	124.0 (81.3; 232.8)	102.5 (73.0; 134.8)	0.432
Coenzyme Q10 (ng/mL)	767.3 (708.2; 1,177.5)	752.0 (622.0; 932.2)	798.3 (651.5; 930.3)	0.150		911.0 (752.7; 1,069.8)	797.7 (732.2; 976.1)	855.7 (736.1; 1,111.9)	0.558
Vitamin C (µg/mL)	13.4 (10.9; 15.1)	10.4 (7.8; 12.3)	8.4 (7.1; 9.3)	< 0.001*		12.5 (11.9; 13.7)	9.1 (8.4; 10.4)	8.3 (7.2; 9.8)	0.001*
Vitamin E (µg/mL)	7.3 (7.2; 8.1)	10.1 (8.3; 10.9)	15.1 (10.7; 17.5)	0.007*		9.6 (8.2; 11.8)	10.0 (8.4; 11.9)	11.3 (10.3; 15.8)	0.368
Beta-carotene (ng/mL)	390.8 (305.1; 596.2)	462.9 (313.3; 509.5)	315.6 (162.9; 394.9)	0.006*		470.4 (356.6; 535.9)	400.7 (324.1; 500.6)	388.0 (261.0; 490.7)	0.105
IL-6 (pg/mL)	1.6 (1.5; 2.7)	3.6 (3.0; 4.2)	3.6 (2.7; 4.0)	0.061		2.7 (1.9; 4.8)	3.9 (3.3; 5.0)	3.6 (1.9; 4.1)	0.205
IL-8 (pg/mL)	5.7 (4.7; 8.0)	7.6 (3.8; 8.9)	5.1 (4.3; 6.8)	0.407		3.7 (2.6; 7.5)	4.6 (3.2; 6.6)	6.2 (3.5; 8.9)	0.472
IL-10 (pg/mL)	5.3 (4.7; 6.0)	5.2 (4.8; 5.5)	12.9 (11.2; 13.5)	0.001*		5.6 (5.1; 6.3)	5.2 (4.3; 6.1)	11.9 (8.3; 13.3)	< 0.001*
Glutathione (µmole/L)	901.0 (809.8; 927.3)	834.0 (786.8; 895.3)	793.5 (768.8; 880.0)	0.273		816.5 (709.5; 871.8)	836.5 (798.5; 905.5)	781.5 (756.0; 860.0)	0.558
Glutathione peroxidase (IU/L)	4,548.0 (4,342.5; 4,975.0)	4,941.0 (4,505.5; 6,013.5)	4,767.5 (4,590.0; 5,033.5)	0.067		4,988.0 (4,525.0; 5,425.8)	4,760.0 (4,387.8; 5,434.0)	5,216.5 (4,849.5; 5,338.0)	0.054
Glutathione reductase (IU/g)	7.0 (6.8; 7.1)	7.0 (6.7; 7.2)	7.3 (6.9; 7.5)	0.154		7.2 (6.9; 7.4)	7.1 (6.8; 7.3)	7.2 (6.9; 7.4)	0.779
Malonaldehyde (nmole/mL)	0.8 (0.7; 1.1)	0.9 (0.9; 1.1)	0.9 (0.6; 1.3)	0.670		0.8 (0.6; 1.2)	0.9 (0.8; 0.9)	1.0 (0.9; 1.1)	0.205
Superoxide dismutase (IU/mL)	178.0 (173.0; 196.5)	181.5 (176.5; 184.5)	184.0 (176.3; 194.3)	0.497		178.0 (174.0; 195.0)	191.0 (179.8; 198.0)	185.5 (178.0; 194.0)	0.978

HRW: hydrogen-rich water, Me: median, Q: quartile, CK: creatine kinase, IL: interleukin.

*Indicates statistically significant differences (p < 0.05).

In the placebo group, significant but opposite dynamics were observed in only two parameters: a decrease in vitamin C levels and an increase in IL-10 levels (Table 2), indicating similar changes in content compared to both groups.

Following the one-week post-intervention levels of CK and vitamin E in the HRW group remained consistent with the last day of HRW intake. In contrast, there was a slight decrease in these parameters over the same time frame in the placebo group.

All the statistically significant changes reported in Table 2 are detailed in Fig. 3, which demonstrates the results of pairwise comparison of parameters in HRW or placebo groups at different comparative time periods.

Fig. 3.

The results of pairwise comparison of laboratory parameters in hydrogen-rich water (HRW) or placebo groups at different observation periods (p < 0.05). Each cell shows p-values for pairwise comparisons at different time periods. Cells where the p-value was less than 0.05 are highlighted in green, cells where the p-value is significantly more than 0.05 are highlighted in red, and p-value of about 0.05 is indicated in transitional color. CK: creatine kinase, IL: interleukin.

4. Assessment of biomechanical parameters of hamstring muscles before and after 28 days of HRW intake

HRW intake for 28 days resulted in a statistically significant increase in maximum torque values after but not before warm-up by approximately 12.6%. (p = 0.018) (Fig. 4A). However, no statistically significant changes were observed in the within-group comparison of the mean torque values in the HRW group (Fig. 4B).

Fig. 4.

Dynamics of maximum and mean torque values before and after the warmup before and after either (A, B) hydrogen-rich water or (C, D) placebo. ns: no statistically significant differences.

Similarly, there were no statistically significant differences in either the maximum or mean torque values in the placebo group (p > 0.05) (Fig. 4C, 4D).

DISCUSSION

The literature discusses both the presence and absence of positive effects of HRW, primarily in terms of its antioxidant properties [7]. HRW was well-tolerated in our study, with no adverse effects or unexpected outcomes reported by any of the athlete. In our study, no statistically significant correlations were found between body mass index (BMI) and the waist-to-hip ratio, both before and after supplementation. Although this contradicts findings from previous findings [14], the previous reports that did find changes in BMI dynamics by HRW involved patients with metabolic syndrome rather than elite athletes. Sim et al. [15] also reported no difference in BMI in healthy subjects between patients receiving HRW and those receiving a placebo. Importantly, however, our study did report reductions in body fat percentage and increases in muscle mass, which is consistent with other studies [16]. These improvements in body composition suggest potential applications of HRW in managing metabolic conditions such as diabetes, where it has shown promise in clinical studies [17]. These effects may be partially explained by molecular hydrogen’s potential to modulate the expression of fibroblast growth factor 21 [18]. This hormone regulates lipid metabolism, enhances energy expenditure, and promotes the browning of white adipose tissue. By inducing this hormone, H₂ may contribute to reductions in body fat mass and increases in muscle mass through improved metabolic efficiency, as well as anti-inflammatory and antioxidant actions. Improvements in body composition also suggest the potential use of HRW for those with diabetes, which have shown clinically improvements.

We also evaluated the effects of HRW on various markers of recovery. Although we did not detect any statistically significant changes, this does not exclude the possible benefits from HRW. The absence of statistically significant changes may be attributed to the fact that these athletes had relatively low baseline stress levels. Thus, it is unlikely and perhaps undesirable for HRW to reduce stress further since it is already in the optimal hormetic/eustress range [7]. In contrast, if a higher level of stress were exerted that would be outside the beneficial homeostatic range of hormesis, then HRW may have had a stress-reductive effect on oxidative stress. Other studies have shown that HRW can indeed help decrease psychometric fatigue during exercise [19], improve heart recovery in female athletes [20], as well as decrease overall anxiety in healthy subjects [21]. Additionally, there could have been certain inaccuracies that might have arisen during the administration of the extensive questionnaire or, alternatively, the validity of the unverified Russian translation of the RESTQ-Sport Questionnaire.

We also observed that compared to placebo, HRW resulted in a notable decrease in total blood CK levels. This may indicate a reduction in muscle fiber damage induced by intensive exercise (exercise-induced muscle soreness). This, in turn, may contribute to a decrease in the intensity of delayed-onset muscle soreness and faster recovery after intense workouts, consequently improving exercise tolerance [22,23]. Indeed, several studies on HRW also demonstrate decreases in muscle soreness and improved recovery [24,25].

The potential antioxidant effect of HRW was also evaluated in our study. We did not observe any significant changes in glutathione, GPx, GR, SOD, and MDA, as reported in previous studies [14-16,19,26-28]. However, this was a group of healthy, elite-level athletes who were not experiencing excessive levels of stress as noted by the RESTQ-sport questionnaire, or heightened levels of oxidative stress since all markers were within normal ranges. Generally, HRW only reduces oxidative stress when there is an excessive level of free radicals [7].

Moreover, it is well-recognized that ROS play key signaling roles in mediating the benefits of exercise [3]. This may explain why antioxidant supplementation can hamper exercise training adaptations. Thus, it is important to recognize that HRW does not pose the same risk as conventional antioxidants in neutralizing beneficial ROS or impairing training adaptations [2]. At the same time, a meta-analysis on hydrogen with exercise indicates that molecular hydrogen may confer favorably modulating effects on the antioxidant/oxidative status in exercise [29].

Additionally, the increase in blood serum vitamin E (alpha-tocopherol) content observed in our study may indicate a reduced need for its direct antioxidant action during the intake of HRW. Alternatively, an increased vitamin E level may indicate improved redox cycling of vitamin C, which is known to restore the oxidized form of Vitamin E. Vitamin E is known to play an active role in stabilizing cell membranes and, most importantly, mitochondria, which is associated with energy efficiency [30-32]. The observed multidirectional change in the vitamins E and C within the HRW group in this study may represent key mediating mechanisms underlying the ergogenic effects of HRW consumption [33].

Furthermore, it is worth noting that researchers have repeatedly reported the immunomodulatory properties of vitamin E [31,34,35]. Although the exact mechanism of this action is not yet fully understood, it is reasonable to speculate that the increase in serum levels of vitamin E during the intake of HRW may also impact the effectiveness of the immune response, which is often diminished in elite athletes due to high-intensity training loads [36-38].

We also monitored the effects of HRW on various inflammatory markers during the intervention. Like ROS, inflammation also plays a dual role in exercise training as a moderate amount activates important signaling cascades that mediate the beneficial adaptations to exercise [39]. In contrast, an excessive amount leads to muscle damage and prolonged recovery time. Importantly, HRW did not blunt the exercise-induced increase in IL-6 [39]. However, HRW did result in a mild increase in IL-10, which has anti-inflammatory effects. This highlights the modulatory effects of molecular hydrogen on the inflammatory response, which is important for exercise adaptations [7].

The significant increase in torque following an exercise warm-up performed within a single biomechanical testing procedure after 28 days of HRW supplementation supports the growing hypothesis of hydrogen’s ergogenic effects. This phenomenon is likely attributed to a reduction in muscle fatigue induced by HRW [7,9,40].

The effects of HRW may be partly attributed to its ability to modulate the Nrf2/Keap1 pathway, a critical regulator of cellular antioxidant defenses [41]. H₂ exerts mild oxidative stress by transiently increasing ROS levels, which activates Nrf2 by disrupting its interaction with Keap1, a cytosolic inhibitor that facilitates its degradation [41]. Once released, Nrf2 translocates to the nucleus and promotes the expression of genes encoding antioxidant enzymes, such as SOD, GPx, and heme oxygenase-1. This hormetic mechanism primes cells for improved redox homeostasis and resilience to oxidative challenges. Furthermore, H₂-mediated modulation of mitochondrial function may enhance mitophagy and biogenesis, improving mitochondrial quality control. These mitohormetic effects not only mitigate oxidative damage but also support exercise recovery by maintaining cellular energy efficiency and reducing inflammatory signaling, as reflected by the elevated levels of anti-inflammatory cytokine IL-10 observed in this study.

This study has several limitations that should be considered when interpreting the findings. Although we observed several statistically significant changes in various parameters, the small sample size, inclusion of athletes from only two sports (skeleton and handball), and the exclusive participation of female athletes may limit the generalizability of our findings. Additionally, the relatively short observation period and lack of long-term follow-up data preclude conclusions about the sustained effects of HRW supplementation. The study was also conducted at a single center, which may reduce its applicability to broader populations. The limited sample size also precluded subgroup analyses, such as comparing effects between handball and skeleton athletes or exploring variations based on training volume or intensity, which could have provided additional insights. Furthermore, although we randomized the subjects, we did not collect data on menstrual cycles, which could act as a confounding variable.

Despite these limitations, the data obtained during the study bring forth specific questions that will guide future research design. For instance, can hydrogen, as a biologically active supplement, induce overall clinically significant changes? What should be the optimal duration of administration to achieve long-term effects? Would alternating intermittent courses of intervention be optimal not only during the preparatory period but also during competitive periods? What is the optimal dose, frequency, and duration of HRW supplementation? The implementation of studies following such designs will provide insights into the physiological mechanisms triggered by hydrogen in response to intense training and competition stressors [12].

The findings from this study indicate that HRW may have beneficial and ergogenic effects as evidenced by reduced percent body fat, increased percent muscle mass, and improvement in maximal torque after warm-up. Mechanistically this was accompanied with reductions in muscle damage (CK), and modulation of the antioxidant and inflammatory responses. Furthermore, the absence of any side effects in the elite athletes confirms the safety of using this dietary supplement in sports. Unfortunately, a definitive explanation of the mechanism of action of HRW is not currently possible and requires further research. However, based on the comprehensive assessment of the effectiveness and safety of the HRW-producing tablet in elite female national and international-level athletes, its positive effects have been established. Therefore, the use of HRW-producing tablets may be recommended for the medical, biological, and ergogenic support of athletes.

Funding Statement

• Funding: This study was founded by a grant provided by VILOVIT LLC. (Moscow, Russia).