Report of a Randomized Placebo-Controlled Trial of the Effects of Oral NADH on Physical Endurance Levels

Background: Nicotinamide adenine dinucleotide hydride [NADH] is a vital coenzyme involved in cellular energy production and redox regulation. Oral NADH supplementation has shown promise in enhancing physical and mental performance; however, its direct effects on exercise endurance and related biochemical markers in healthy individuals remain understudied.

Objective: This double-blind, placebo-controlled, randomized study aimed to evaluate the impact of oral NADH supplementation on physical endurance, aerobic capacity, and key metabolic markers (NADH, NAD+, ATP, and phospho-AMPKα1) in healthy, untrained young adults.

Methods: Sixteen healthy male medical students aged 20–22 years were randomly assigned to receive either 40 mg/day of sublingual NADH or placebo for three weeks. Physical endurance was assessed using the PWC170 cycle ergometer test to estimate VO2max. Heart rate, blood pressure, and pulse pressure were monitored both before and after exercise. Blood samples were analyzed for NADH, NAD+, ATP, and phospho-AMPKα1 levels in leukocytes.

Results: After three weeks, the NADH group demonstrated significant improvements in PWC170 [+25.6%] and VO2max (+23.9%) compared to both the baseline and placebo groups [p < 0.05]. Heart rate recovery post-exercise improved, and systolic blood pressure decreased, suggesting enhanced cardiovascular efficiency and reduced stress response. However, no significant changes were observed in the levels of NADH, NAD+, ATP, or phospho-AMPKα1 in leukocytes, possibly due to increased cellular utilization during physical exertion or tissue-specific effects.

Conclusion: Oral NADH supplementation significantly enhances physical endurance, aerobic capacity, and cardiovascular recovery in healthy young adults under stress, without altering leukocyte metabolic markers. Further research is warranted to explore tissue-specific metabolic effects and the underlying molecular mechanisms.

Introduction

Nicotinamide Adenine Dinucleotide Hydride (NADH) is a natural, body-owned substance, more simply known as coenzyme 1. It is a biological form of hydrogen that, upon reaction with oxygen, creates ATP, energy for every cell in the body. In the body, most NADH is found in the heart, brain, and muscles, which are also the largest energy consumers.

NADH is a crucial molecule for cellular metabolism, particularly in redox reactions. It serves as an electron carrier in many biochemical reactions, primarily in anabolic processes such as fatty acid synthesis and nucleotide synthesis.

NADH participates in over 1,000 metabolic processes that occur constantly in the body. It plays a decisive role in cell regulation and DNA repair [1] as well as being a stimulator of the cellular immune system [2]. Due to its high redox potential, NADH has an enormous antioxidative capacity.

Here’s some scientific information about NADH and its mechanism of action:

NADH is essential for various metabolic pathways, including biosynthesis of lipids and nucleotides, detoxification reactions in the liver, and maintenance of cellular antioxidant defenses [3]. NADH participates in redox reactions as a reducing agent. It donates electrons to other molecules, reduce them, and is oxidized to NAD⁺. This electron transfer is vital for the synthesis of biomolecules and the neutralization of reactive oxygen species (ROS), thereby protecting cells from oxidative damage. NADH provides reducing equivalents for fatty acid and cholesterol synthesis. Antioxidant defence: NADH fuels the regeneration of reduced glutathione (GSH), an important antioxidant molecule that scavenges ROS [3]. NADH supports the activity of cytochrome P450 enzymes in the liver, which are involved in the detoxification of xenobiotics and drugs.

In vitro studies have strongly suggested that NADH influences the metabolism of a cell, particularly the production of ATP. In a double-blind, placebo-controlled, FDA-approved clinical trial, ENADA/NADH was demonstrated to improve the energy level of subjects suffering from chronic fatigue syndrome [4]. Another study found that patients suffering from chronic fatigue syndrome show an ATP deficiency in their muscle tissue after physical exercise, as measured by nuclear magnetic resonance [5]. There is also evidence that NADH penetrates the cell membrane and possibly the mitochondrial membrane [6].

Dysregulation of NADH metabolism has been implicated in various diseases including cancer, metabolic disorders, and neurodegenerative diseases. Targeting NADH-dependent pathways is a potential strategy for therapeutic interventions. Modulating NADH metabolism or antioxidant defenses through exercise training or pharmacological interventions may enhance exercise endurance and performance by increasing the capacity of skeletal muscles to produce and utilize NADH, thereby improving energy metabolism and antioxidant defenses. Pharmacological agents targeting NADH-producing enzymes or antioxidant pathways may have potential as exercise performance enhancers; however, their efficacy and safety require further research.

In summary, NADH plays a multifaceted role in cellular metabolism and antioxidant defense mechanisms that are essential for exercise endurance. Recently, it was shown that taking oral NADH may raise the level of NAD+, which partially explains some mechanisms of the NADH effect on different metabolic pathways [7], but there has been no investigation in humans.

Moreover, NADH supplementation has been shown to have a positive effect on physical and mental performance in highly conditioned athletes; however, the mechanisms of NADH action are still not clearly understood. Recent studies have revealed that AMP-activated protein kinase (AMPK) plays a significant role in this process. AMPK regulates energy expenditure by modulating NAD+ metabolism and promoting mitochondrial health, and multiple newly discovered targets of AMPK are involved in various aspects of mitochondrial homeostasis, including mitophagy, by regulating the SIRT family and PPAR [8]. We hypothesized that oral NADH supplementation might influence AMPK activity.

Understanding the interplay between NADH metabolism, energy production, and oxidative stress regulation may provide insights into strategies for optimizing exercise performance and enhancing endurance. We propose that oral NADH administration may have a positive influence on mitochondrial metabolism, increase ATP and NAD+ levels through different pathways, and improve physical endurance and overall health.

Aim

We set out to investigate the effect of sublingual NADH tablets (Kingnature, Switzerland) on tolerance to physical activity and to study changes in the concentration of NADH, NAD+, ATP, and phospho-AMPKα1-activated kinase (AMPK) in blood leukocytes of practically healthy people aged 20–25 years.

Materials and Methods

Participants

16 practically healthy male volunteers, students of the 3rd year of the medical university who did not play any sports, took part in the study.

All volunteers combined study with work, ate irregularly, and periodically lacked sleep. The age of the volunteers was 20–22 years (on average—20), height ranged from 169 to 185 cm (on average—180 cm), body weight at the first examination was 65–85 kg (on average—74.8 kg), and at the second examination was 65–84 kg (on average—74.6 kg). Volunteers were randomly divided into two groups of eight people each: experimental and control groups. There were no significant differences in age or anthropometric indicators between groups. The study was conducted following the guidelines of a double-blind study.

The volunteers in the main group took sublingual NADH tablets (Kingnature, Switzerland) twice a day for three weeks at a dose of 20 mg (two tablets per day, a total of 40 mg) from the day after the test for the level of tolerance to the dosed exercise. Volunteers from the control group received a placebo according to the same scheme.

Before conducting the first examination, the volunteers were informed of the purpose, tasks, and organization of the study, familiarized with the examination methods, and familiarized with the characteristics of the dietary supplement [NADH Original Instant Power^®]. They also provided informed consent for their voluntary participation in the study.

The bioethical standards of the Declaration of Helsinki, Council of Europe Convention on Human Rights and Biomedicine (1977), the relevant WHO resolutions, and laws of Ukraine were followed during the research.

Organization and Research Methods

The examination was performed in the first half of the day. Before the first examination, the volunteers were informed about the purpose, tasks, organization, and methods of the study and familiarized with the characteristics of the dietary supplement (NADH Original Instant Power^®). The examinations were initiated after obtaining informed consent for voluntary participation in the study.

Immediately before the examination, the height and body weight of the volunteers were measured using the “Rostomira mechanical floor scale with electronic medical scales RPVE-2000”. Thereafter, the volunteer filled out the questionnaire (see Appendix No. 1) and was examined by a doctor who permitted functional testing with physical exertion.

The PWC170 test (cycle ergometric variant, according to Karpman) was chosen as a functional test for tolerance to physical exertion for assessing the level of physical performance. The test allows for the determination of both the level of aerobic physical capacity and the level of maximum oxygen consumption (V0₂ max).

The physiological basis of the PWC170 test is a linear relationship between the power of physical work and heart rate in the range of 170–190 beats per minute, but the load at which the heart rate reaches 170 beats per minute may be too great for the subject, so modifications of this test are used. In the practice of diagnosing the level of physical working capacity, the modification of the PWC170 test with the use of two load levels, at which the heart rate does not reach 170 beats*min-1, has proven itself well. The power of the first load was determined based on the body weight and level of physical training of the subject.

The power of the second load is set based on the increase in heart rate after the first load. In our study, we used tables of approximate values of the load power on a bicycle ergometer to determine PWC170 in healthy, untrained individuals (Appendix No. 2).

The PWC170 test was conducted as follows:

The subject received instructions on how to conduct the test and sat on a bicycle ergometer (KETTLER Ergometer E3) in a comfortable position. The power of the first load was set, and the subject, without a preliminary warm-up, pedaled for 5 minutes at a speed of 60 turns per minute.

Immediately after pedaling, the heart rate was determined and the power of the second load was set using the appropriate table. Three minutes after the end of the first session, the patient began pedaling, overcoming the level of the second load for another 5 minutes at a speed of 60 turns per minute. Heart rate was determined immediately after pedaling.

The study was not limited to the PWC170 test but was supplemented by measurements of heart rate and blood pressure at rest, immediately before the start of the test, and monitoring at the 1st, 2nd, 3rd, and 4th minutes of recovery after the second test load to assess the effect of the nutraceutical on the course of early recovery after dosed physical exertion.

The heart rate was determined simultaneously by three methods each time: by palpation of the left common carotid artery for 10 seconds [to represent the heart rate in beats for 1 minute, the result of counting in 10 seconds was multiplied by 6], using an automatic tonometer (one-X automatic tonometer), and an ECG in the second standard lead when registering a chest rheogram. The last two methods made it possible to eliminate the possible error in palpatory heart rate determination in 10 seconds.

The safety of functional testing with physical exertion was ensured by monitoring the electrical activity and pumping function of the heart by recording the thoracic rheogram using a rheograph (computer diagnostic complex “ReoCom HAI-Medika”). For direct testing, six assistants were involved in accordance with the methodology described above and were protected by the certificate of registration of copyright for scientific work [9].

The level of physical capacity was determined by extrapolation using a graphical method in a two-dimensional Cartesian coordinate system. The value of the power of the physical load in watts was plotted on the abscissa, and the heart rate beats per minute on the ordinate. A graph was constructed on a plane by drawing a straight line through two points, each of which corresponded to the heart rate (HR) value at the end of the corresponding load (coordinates of the first point, W1 and HR1; the second, W2 and HR2). From the point at which this straight line crossed the horizontal drawn at the level of the heart rate value of 170 beats per minute, a straight line perpendicular to the abscissa was drawn, and in this way the value of the load power was obtained, at which the examined heart rate would reach 170 beats per minute; that is, PWC170 was determined.

The maximum oxygen consumption (MSC) was calculated according to the following formula for untrained healthy people [10]:

VO₂ max = 2,2 × PWC170 + 1070

The obtained value of MSC in ml×min-1 was normalized by body weight, and the value of specific MSC was also obtained, which made it possible to compare the level of MSC regardless of the body weight of the subject.

Statistical data processing was performed using the SPSS Statistics program using non-parametric methods.

Blood Tests

Blood samples were collected twice: at the beginning of the study and after 3 weeks of taking either the placebo or the food supplement. Venous blood was collected before meals in 2.4 ml Sarstedt monovials containing (ethy)nediaminetetraacetic acid (EDTA-K) stabilizer. Whole blood was centrifuged for 5 minutes at 2500 g, and the buffy coat was collected. Thereafter, the cells were frozen in liquid nitrogen and stored until the following parameters were measured using immunoenzymatic assay, fluorometric, and statistical methods: SPSS Statistics (Version 17) and Microsoft Excel 2003 Software with the application of Student’s t-test. The results were presented as M±m. Differences between the average values were considered statistically significant at p < 0.05.

NADH and NAD+ levels were measured using the NAD+/NADH Assay Kit (Sigma Aldrich, Merck, Germany), according to the manufacturer’s recommendations [11].

ATP level was determined using the ATP Colorimetric/Fluorometric Assay Kit (Sigma Aldrich, Merck, Germany) according to manufacturer recommendations [12].

The level of phospho-AMPKα1-activated kinase was determined using DuoSet IC Human phospho-AMPKα1 (T183) ELISA, according to the manufacturer’s recommendations [13].

Results

The PWC170 Test Results

The team of researchers who conducted the test examinations provided all individual protocols for the first and second examinations, which contained:

• A report on the dynamics of changes in heart rate and blood pressure during testing

• A report on the course of recovery after exercise according to heart rate and blood pressure indicators

• values of PWC170, VO₂ max, and a specific MSC, as determined by the results of the first and second tests.

An array of data for statistical analysis was formed based on the results of studies presented in individual examination protocols.

To analyze the effect of oral intake of NADH on the level of physical endurance, information about the participants of the examination regarding the intake of NADH or placebo was disclosed, and two groups were formed: the main (“NADH”) and the control (“control”).

The summarized results of the study are presented in the tables, which present the average values of indicators reflecting the level of tolerance to physical exertion, detected at the time of the first and second examinations in the main (NADH) and control (control) groups (See Tables I–III). The effect of the health ingredient on physical performance, the level of functional reserves, and the course of recovery after dosed physical exertion are illustrated in the form of graphs in the corresponding figures.

Table I. The Effect of the NADH Food Supplement on the Level of PWC170 and VO₂ Max

		NADH		Control
		Before	After	Before	After
PWC170	watt	165,9 ± 9,7	208,4 ± 8,2^*	185,0 ± 9,9	175,6 ± 8,7
VO2 max	ml × min-1	1233,7 ± 36,6^	1528,6 ± 20,1^*	1477,0 ± 40,1	1456,4 ± 26,5
VO2 max/b.w.	ml·min−1·kg−1	17,1 ± 1,1	21,3 ± 0,2^*	19,1 ± 1,2	18,8 ± 1,1

Table II. Heart Rate During Exercise and in the First Minutes of Recovery After the PWC170 Test

		NADH		Control
		Before	After	Before	After
f0	min−1	92,3 ± 1,4	87,8 ± 1,2	86,3 ± 2,5	79,5 ± 3,4
f1	min−1	114,8 ± 4,6	116,3 ± 2,7^	127,5 ± 4,7	126,0 ± 3,4
f2	min−1	182,3 ± 3,7	159,8 ± 2,4^*	174,0 ± 3,4	179,3 ± 2,8
f2.1	min−1	140,3 ± 2,6	134,3 ± 2,1^*	140,3 ± 2,7	147,8 ± 2,2
f2.2	min−1	136,5 ± 2,9	121,5 ± 2,7^*	123,8 ± 2,4	135,8 ± 3,2
f2.3	min−1	126,0 ± 1,7	114,0 ± 1,9^*	120,0 ± 2,1	121,5 ± 3,1

Table III. Blood Pressure During Exercise and in the First Minutes of Recovery After the PWC170 Test

		NADH		Control
		Before	After	Before	After
SBP0	mm Hg	148,6 ± 3,4^	137,0 ± 3,1*	136,9 ± 3,5	131,6 ± 2,9
SBP1	mm Hg	154,3 ± 2,9	152,9 ± 2,4	158,8 ± 2,8	155,8 ± 2,9
SBP2	mm Hg	156,3 ± 3,0	155,4 ± 3,1	151,3 ± 3,3	161,3 ± 3,4
SBP2.1	mm Hg	148,0 ± 2,9	154,0 ± 3,1	143,3 ± 3,2	151,8 ± 2,6
SBP2.2	mm Hg	137,4 ± 2,6	146,9 ± 2,5	135,8 ± 2,4	138,8 ± 2,5
SBP2.3	mm Hg	131,8 ± 2,8	135,5 ± 2,6	132,3 ± 2,6	140,5 ± 2,8
DBP0	mm Hg	86,9 ± 1,6	85,3 ± 1,1	79,0 ± 2,6	71,5 ± 2,5
DBP1	mm Hg	85,6 ± 1,9	89,0 ± 1,6	83,1 ± 1,6	76,5 ± 1,8
DBP2	mm Hg	79,1 ± 1,4	79,3 ± 1,3	80,7 ± 1,6	78,6 ± 1,5
DBP2.1	mm Hg	68,6 ± 1,9	79,0 ± 1,6	77,6 ± 1,5	72,7 ± 1,8
DBP2.2	mm Hg	77,8 ± 1,1	73,4 ± 1,5	77,4 ± 1,6	74,5 ± 1,9
DBP2.3	mm Hg	74,1 ± 1,3	79,1 ± 1,4	69,9 ± 1,7	75,5 ± 1,6

Data on the effect of NADH on PWC170 and VO₂ max are shown in Table I and Figs. 1–3. The analysis of the study results revealed that during the first examination (before taking the food supplement in the main group or placebo in the control group), the tolerance to physical exertion according to the PWC170 level in the control group was slightly higher than that in the main group (185.0 ± 9.9 watts vs. 165. 9 ± 9.7 watts), and the average value of the VO₂ max indicator was significantly lower in the main group compared to the average VO₂ max of the control group (1233.7 ± 36.6 ml·min⁻¹ vs. 1477.0 ± 40.1 ml·min⁻¹, respectively). At the same time, this indicator normalized to body weight (VO₂max/b.w.) was slightly lower in the main group (17.1 ± 1.1 ml·min⁻¹·kg⁻¹ vs. 19.1 ± 1.2 ml·min⁻¹·kg⁻¹ in the control group), but the difference of 2 ml·min⁻¹·kg⁻¹ was not statistically significant.

Fig. 1. The influence of NADH on tolerance to physical exertion according to the value of PWC170.

Fig. 2. The Influence of NADH on maximal oxygen consumption.

Fig. 3. Influence of NADH on maximum oxygen consumption normalized to body weight.

Three weeks later (second examination), PWC170, VO₂ max, and VO₂ max/b.w. in the control group were slightly lower than those in the placebo group, but the difference was statistically significant. In the main group, three weeks after taking NADH, the PWC170 value increased by 42.5 watts, which was an increase of 25.6%, and the VO₂max and VO₂ max/m.t. increased by 294.9 ml·min⁻¹ (a 23.9% increase) and 4.2 ml·min⁻¹·kg⁻¹ (a 24.6% increase). The indicators PWC170, VO₂max, and VO₂ max/b.w. after the second examination in the main group were significantly higher compared to the control group and significantly higher than before taking the food supplement.

In our study, the state of central hemodynamics was assessed based on heart rate and blood pressure. Table II shows the average heart rate values in the groups before testing, after the first and second loads, and during recovery. The graphs in Fig. 4 show the dynamics of changes in this parameter of central hemodynamics in both groups during testing and in the early recovery period. Figs 4.1 and 4.2 present the same graphs separately for the main and control groups. In the main group, the heart rate after the second exercise was significantly lower at the second examination, that is, after taking the nutraceutical for three weeks, compared to the first examination, that is, before taking the supplement. Heart rate recovery during the second examination was faster than that during the first examination. In the control group, placebo administration did not affect the nature of heart rate changes; the heart rate dynamics were the same during the first and second examinations.

Fig. 4. Heart rate dynamics during testing and recovery after the PWC170 test.

Fig. 4.1. Dynamics of heart rate during testing and recovery after the PWC170 test (main group).

Fig. 4.2. Dynamics of heart rate during testing and recovery after the PWC170 test (control group).

Table III shows the average blood pressure values in the groups before testing, after the first and second loads, and during recovery.

The graphs in Fig. 5 show the dynamics of the changes in SBP and DBP in both groups under load during testing and in the early recovery period. Figs. 5.1 and 5.2 present the same graphs separately for the main and control groups.

Fig. 5. BP dynamics during testing and recovery after the PWC170 test.

Fig. 5.1. BP dynamics during testing and recovery after the PWC170 test (main group NADH).

Fig. 5.2. BP dynamics during testing and recovery after the PWC170 test (control group).

In both groups, the SBP level at relative rest (SBP₀) at the time of the first examination was higher than the age norm. At the same time, the main group had significantly higher SBP than the control group. Before the second examination, the level of SBP₀ in both groups was slightly higher than the age norm, but in the main group it was significantly lower than before the first, and in the control group there was a tendency to decrease.

The presence of hypertension in volunteers can be explained by the effect of several stress factors on their bodies, particularly chronic emotional stress associated with a significant educational load and insufficient sleep time in combination with part-time work.

The tendency to normalize blood pressure with a decrease in SBP₀ after 3 weeks of taking NADH by 7.8% or taking a placebo (3.9%) against the background of the stressor factors mentioned above may indicate the anti-stressor effect of NADH and the same but smaller placebo effect.

The correct assessment of the reaction of blood pressure to exercise is based on the analysis of changes in blood pressure, blood pressure (BP), and pulse blood pressure (PsBP). Normal is a normotonic reaction, manifested by an increase in PsBP under the influence of physical exertion. Such an increase in normotonic reaction occurs due to an increase in BPS, which is adequate for the power of the load and a decrease in BPS within normal limits.

Data on the effect of NADH on PsBP and the dynamics of changes in this parameter of central hemodynamics in both groups during exercise, during testing, and during the early recovery period are shown in the Table IV and Figs. 6.1 and 6.2. In the main group, there was a normotonic response to physical activity with a power that corresponded to W2, both before and after NADH administration.

Table IV. Pulse Blood Pressure During Exercise and in the First Minutes of Recovery After the PWC170 Test

		NADH		Control
		Before	After	Before	After
PsBP0	mm Hg	61,8 ± 1,2	51,8 ± 1,1	57,9 ± 1,4	60,1 ± 1,3
PsBP1	mm Hg	68,6 ± 1,2	63,9 ± 1,6	75,6 ± 1,6	79,3 ± 1,2
PsBP2	mm Hg	77,1 ± 1,4	76,1 ± 1,3	70,6 ±1,4	82,6 ± 1,4
PsBP2.1	mm Hg	70,6 ± 1,2	75,0 ± 1,1	65,6 ± 1,8	79,2 ± 1,2
PsBP2.2	mm Hg	59,6 ± 0,6	73,5 ± 1,0	58,4 ± 1,3	64,3 ± 1,4
PsBP2.3	mm Hg	57,6 ± 0,4	56,4 ± 1,9	62,4 ± 0,4	65,0 ± 1,0

Fig. 6.1. Dynamics of PsBP during testing and recovery after the PWC170 test (main group NADH).

Fig. 6.2. Dynamics of PsBP during testing and recovery after the PWC170 test (control group).

However, at the first examination, PsBP values in the 2nd and 3rd minutes of recovery were lower than those of PsBP0, reflecting the weakened ability of the cardiovascular system to adapt to physical exertion. The course of recovery during the second examination demonstrated an increase in the functional capabilities of the cardiovascular system following NADH administration.

In the control group, we observed a hypertensive type of reaction to physical exertion during the first and second examinations, which, in the absence of intensive physical training, indicates overstrain of adaptive reserves under the influence of social and household stressors.

Blood Test Results

Levels of NADH, NAD+, ATP, and phospho-AMPKα1 in leukocytes of healthy individuals were measured at the beginning of the study and after 3 weeks of taking placebo or NADH (Kingnature, Switzerland).

As shown in Fig. 7, NADH, NAD+, ATP, and phospho-AMPKα1 levels did not change significantly during the study.

Fig. 7. Levels of NADH (A), NAD+ (B), phospho-AMPKα1 (C) and ATP (D) in the leukocytes of healthy people at the beginning of the study and after 3 weeks of taking a placebo or NADH (Kingnature, Switzerland).

In a study of NADH, NAD+, ATP, and phospho-AMPKα1 levels in the blood leukocytes of healthy volunteers after taking NADH and a placebo for 2 weeks, no significant changes were observed.

Particularly, the dispersion of NADH concentrations in the measured samples after supplementation was slightly higher than that in the placebo group. At the same time, the average level in the group of patients who took NADH was slightly lower (6,19 microM/ml) than in the placebo group (7,90 microM/ml). This can be explained by the fact that in energy exchange during physical exertion, NADH can be actively used for the respiratory chain of the mitochondria [14]. Moreover, the activity of metabolic processes in leukocytes and the state of the immune system as a whole are suppressed during stress due to physical exertion [15]. Almost the same situation was observed in NAD+ concentrations of these volunteers—the average level in the group of patients who took NADH was slightly higher (6,20 microM/ml) than in the placebo group (5,42 microM/ml).

The level of phospho-AMPKα1 was slightly lower in the NADH group. It can be supposed that exercise-induced inactivation of phospho-AMPKα1 disrupts individual immune cell function [16] and thus may be linked to exercise-induced immunosuppression, and NADH is actively used in cell protection mechanisms.

At the same time, we observed that the average ATP level in the group receiving NADH after 3 weeks of treatment was higher (3.84 ng/μL) than that in the placebo group (1.78 ng/μL).

These data indicated that the levels of NADH, NAD+, ATP, and phospho-AMPKα1 in leukocytes did not change significantly in response to NADH supplementation. Although significant positive effects on different physical parameters were observed in the PWC170 test, it can be assumed that there were positive changes in muscle or heart cells, and these molecules need to be further investigated in other cells and tissues.

Conclusions

NADH was administered twice a day for 3 weeks at a dose of 20 mg, the level of physical performance and tolerance to physical exertion (endurance). NADH has a positive effect on a person’s aerobic capacity even with long-term exposure to stressful factors and the absence of physical training. The use of 40 mg of the food supplement daily for 3 weeks by volunteers (non-athlete students during the period of intensive training) led to an increase in the VO₂ max level by 25.6% and by 23.9% in the level of maximum oxygen consumption per 1 kg of body weight. NADH has a positive effect on the state of central hemodynamics and contributes to the normalization of blood pressure in young people with signs of arterial hypertension. The use of NADH for three weeks at a daily dose of 40 mg led to an increase in the functional reserves of the cardiovascular system in people who did not engage in physical training. The levels of NADH, NAD+, ATP, and phospho-AMPKα1 in leukocytes did not change significantly in response to NADH supplementation, which may be related to different protective mechanisms against stress, and these molecules need to be further investigated in other cells and tissues.