MOTS-C in Sapa: Why Hypoxia and Altitude Adaptation Do Not Establish a Peptide Performance Benefit

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Why do hypoxia and altitude adaptation not establish a MOTS-c performance benefit?

Hypoxia activates complex physiological responses involving oxygen sensing, hypoxia-inducible factors (HIFs), cardiovascular regulation, mitochondrial remodeling, and metabolic adaptation. MOTS-c has been investigated as a mitochondrial-derived signal involved in cellular energy regulation and stress responses. However, showing that a peptide participates in a hypoxia-related pathway—or improves a specific outcome in an animal model—does not prove that administering it improves endurance, aerobic capacity, or athletic performance in humans.

A 2026 study reported that MOTS-c alleviated persistent cardiac dysfunction in mice following simulated high-altitude exposure, with findings implicating PINK1/Parkin-mediated mitophagy. This is relevant preclinical evidence for a potential cardioprotective mechanism, not proof of an endurance-enhancing effect in people. Human studies must separately establish safety, exposure, efficacy, and meaningful performance outcomes.

1. Introduction: The Difference Between Biological Plausibility and Performance Evidence

Altitude physiology offers a useful framework for examining claims about experimental mitochondrial-derived peptides. When people ascend to high altitude, the lower barometric pressure reduces the partial pressure of inspired oxygen. This can reduce arterial oxygenation and increase the physiological challenge associated with exercise. Over time, the body responds through multiple processes that influence ventilation, circulation, oxygen transport, and tissue metabolism.

At the cellular level, reduced oxygen availability can affect oxygen-sensitive signaling pathways, mitochondrial function, redox balance, and gene expression. Because MOTS-c has been investigated in relation to mitochondrial signaling, AMPK activity, metabolic homeostasis, and cellular stress responses, it is reasonable to ask whether it participates in responses to hypoxia or altitude exposure.

However, a plausible mechanism is not the same as an established performance benefit. A molecule may participate in a protective response to physiological stress without increasing an athlete’s maximal oxygen uptake, sustainable power, running speed, or time-trial performance. It may also influence a pathological response to prolonged hypoxia without improving the normal acclimatization process in healthy people.

These distinctions are especially important when interpreting research that combines different experimental models. A cell study can identify molecular interactions. An animal study can test whether an intervention affects a physiological outcome under controlled conditions. A human observational study can identify associations between a biomarker and a phenotype. A clinical intervention trial is needed to establish whether administering a substance produces a meaningful benefit in people.

The central question is therefore not simply whether MOTS-c is involved in hypoxia-related biology. It is whether the available evidence supports a causal, safe, reproducible, and clinically meaningful performance benefit from administering MOTS-c to humans. At present, that conclusion has not been established.

2. What Hypoxia Means in Exercise and Altitude Physiology

Hypoxia refers to inadequate oxygen availability relative to tissue requirements. It can occur in different settings, including high-altitude exposure, some disease states, and local changes in oxygen balance during exercise. These conditions are not physiologically identical.

At altitude, reduced barometric pressure lowers the partial pressure of inspired oxygen. The resulting physiological challenge affects oxygen uptake and delivery throughout the body. During exercise, working muscles also experience changes in local oxygen availability because oxygen consumption rises substantially as ATP demand increases. The relationship between oxygen delivery and demand depends on exercise intensity, blood flow, capillary exchange, mitochondrial activity, and other factors [1,2].

Researchers distinguish several related concepts:

• Environmental hypoxia: Reduced oxygen availability associated with the surrounding environment, such as high altitude or simulated altitude.
• Local tissue hypoxia: Reduced oxygen availability within a particular tissue relative to its metabolic needs.
• Acclimatization: Physiological changes that develop during continued exposure to an environmental condition, including altitude.
• Training adaptation: Changes resulting from repeated exercise stimuli and recovery, which may occur at sea level or under hypoxic conditions.
• Pathological hypoxia: Oxygen deficiency associated with disease or tissue dysfunction, which may trigger protective and harmful responses simultaneously.

These categories matter because an intervention that protects cardiac tissue during a pathological response to prolonged altitude exposure does not automatically improve endurance training adaptation. Similarly, a molecular pathway activated during exercise-induced changes in muscle oxygenation may not behave identically during prolonged environmental hypoxia.

Hypoxia is also not uniformly beneficial. Some adaptive responses improve oxygen delivery or help cells maintain function, while sustained or severe hypoxia can impair organ function, alter mitochondrial metabolism, and increase physiological stress. A compound associated with one protective response should not be assumed to reproduce all beneficial aspects of acclimatization.

3. How the Body Adapts to Altitude

Altitude acclimatization is an integrated response involving multiple organ systems. Early responses include increased ventilation and changes in cardiovascular regulation. With continued exposure, renal and hormonal mechanisms contribute to changes in fluid balance and red blood cell production. The magnitude and timing of these adaptations vary with altitude, duration of exposure, individual physiology, and health status [3].

Ventilatory responses

Reduced arterial oxygenation stimulates peripheral chemoreceptors, increasing ventilation. This helps improve oxygen uptake but also changes carbon dioxide levels and acid-base balance. Ventilatory acclimatization develops over time and contributes to the overall response to sustained altitude exposure.

Hematological adaptation

Hypoxia-related signaling can increase erythropoietin production and stimulate red blood cell production. Over time, changes in hemoglobin concentration and oxygen-carrying capacity may contribute to acclimatization. The response is neither instantaneous nor identical in all individuals.

Cardiovascular and pulmonary responses

Altitude exposure changes cardiovascular demands, and hypoxic pulmonary vasoconstriction can increase pulmonary arterial pressure. With sufficiently prolonged or severe exposure, maladaptive responses can occur, including pulmonary hypertension and cardiac strain in susceptible settings. The effects of altitude must therefore be interpreted in relation to exposure intensity and duration, not assumed to be uniformly beneficial.

Skeletal-muscle and metabolic responses

Skeletal muscle adjusts to changes in oxygen availability through complex changes in substrate utilization, mitochondrial function, oxygen-sensing pathways, and gene expression. These responses can differ between acute exposure, chronic exposure, and repeated exercise in hypoxia. Some adaptations may support function under low-oxygen conditions, while others may reduce oxidative capacity or contribute to muscle loss during prolonged stress [2].

Because acclimatization depends on several interacting systems, no single biomarker or peptide can be assumed to reproduce the complete response. Establishing a role for MOTS-c in one component of this process would still leave the overall performance question unanswered.

4. HIF Signaling: A Key but Context-Dependent Hypoxia Response

Hypoxia-inducible factors (HIFs) are transcription factors that help cells respond to changes in oxygen availability. Under oxygenated conditions, oxygen-sensitive regulatory enzymes contribute to the degradation of HIF-α subunits. When oxygen availability falls, these regulatory processes change, allowing HIF signaling to influence the expression of genes involved in adaptation.

HIF-regulated processes include aspects of erythropoiesis, angiogenesis, glucose transport, and glycolytic metabolism. These responses can support oxygen delivery or help cells generate energy under conditions in which oxidative metabolism is constrained [2].

However, HIF signaling does not simply switch on all beneficial endurance adaptations. Some HIF-related responses favor glycolytic energy production, while endurance-trained muscle also depends on a high capacity for oxidative metabolism. Reviews of skeletal-muscle physiology note that HIF responses vary with acute exercise, chronic training, and environmental hypoxia, and that prolonged endurance training may attenuate certain acute HIF-1α responses [2].

This complexity is relevant to peptide research. If a peptide affects AMPK, mitochondrial quality control, or another stress-related pathway, that does not prove it reproduces the appropriate HIF response for every altitude condition. Nor does it demonstrate that the net effect is improved athletic performance.

Researchers must distinguish a molecular response that is compatible with adaptation from an intervention that improves the whole organism’s ability to exercise. The former can support a mechanistic hypothesis; the latter requires direct physiological evidence.

5. MOTS-c: Origin and Proposed Biological Functions

MOTS-c, or mitochondrial open reading frame of the 12S rRNA type-c, is a 16-amino-acid mitochondrial-derived peptide encoded within the mitochondrial 12S ribosomal RNA region. Its discovery expanded interest in short peptides encoded by mitochondrial DNA and in communication between mitochondria and the nucleus [4].

The foundational study by Lee and colleagues, published in Cell Metabolism in 2015, linked MOTS-c to metabolic homeostasis and insulin sensitivity through experimental work involving cells and mice. The study implicated changes in folate-cycle and de novo purine-biosynthesis pathways, with downstream involvement of AMPK signaling [4].

Subsequent preclinical research has investigated MOTS-c in relation to glucose handling, metabolic stress, aging-associated changes, inflammation, skeletal-muscle function, and exercise-related biology. Reviews describe proposed interactions with AMPK, SIRT1, PGC-1α, and nuclear stress-response pathways [5].

These findings provide a basis for continued investigation, but the level of evidence differs substantially across claims. A mechanism identified in a cell model is not equivalent to a replicated physiological effect in an animal. An animal outcome is not equivalent to a validated clinical benefit in a human population.

It is also necessary to distinguish endogenous MOTS-c from administered MOTS-c. Endogenous MOTS-c is naturally produced and may be measured in blood or tissue. Exogenous MOTS-c refers to peptide supplied from outside the body in an experimental intervention. The concentration, timing, tissue distribution, and biological context of an administered peptide may differ from those of the endogenous signal.

Consequently, a correlation between naturally occurring MOTS-c and a physiological outcome does not establish that administering a synthetic product will reproduce the association—or produce a beneficial outcome at all.

6. AMPK and PGC-1α: Shared Biology Does Not Prove Equivalent Effects

AMP-activated protein kinase (AMPK) is an energy-sensitive kinase involved in coordinating cellular responses to changes in energy status. Depending on the tissue and context, AMPK signaling can influence glucose uptake, lipid metabolism, and the regulation of energy-consuming processes.

PGC-1α is a transcriptional coactivator involved in the regulation of mitochondrial biogenesis and oxidative metabolism. It interacts with multiple signaling pathways and transcription factors to coordinate changes in gene expression associated with cellular energy use.

Exercise can activate signaling pathways that influence AMPK and PGC-1α. Experimental studies have also implicated these pathways in some of the reported metabolic effects of MOTS-c [4,5]. This overlap makes the peptide relevant to exercise physiology research.

However, three claims must remain separate:

• Mechanistic overlap: MOTS-c and exercise may influence some of the same signaling pathways in experimental systems.
• Physiological adaptation: Repeated exercise produces integrated changes in muscle, cardiovascular function, substrate metabolism, and other systems.
• Performance benefit: A particular intervention measurably improves a validated outcome, such as time-trial performance or maximal oxygen uptake, in a defined human population.

The first claim does not establish the second, and neither automatically establishes the third. Even if an intervention changes AMPK activity or a PGC-1α-associated marker, the resulting effect on endurance depends on many additional variables, including oxygen delivery, muscle recruitment, training status, substrate availability, and recovery.

7. The 2026 High-Altitude MOTS-c Study: What It Actually Demonstrated

A particularly relevant study, published in Free Radical Biology and Medicine in 2026, examined MOTS-c in cardiac dysfunction that persisted after high-altitude exposure. The investigators used a mouse model in which animals were exposed to simulated altitude corresponding to approximately 6,000 metres for 10 days, followed by a 10-day period at a lower simulated altitude of approximately 400 metres [6].

The researchers reported that cardiac dysfunction persisted during the de-acclimatization period and was accompanied by mitochondrial dysfunction and reduced MOTS-c expression. Exogenous MOTS-c administered during de-acclimatization alleviated the measured cardiac dysfunction in the mouse model. Mechanistic experiments implicated the PINK1/Parkin pathway, which participates in mitophagy—the selective removal of damaged mitochondria [6].

The study also reported reduced circulating MOTS-c in patients with high-altitude heart disease and in patients with acute coronary syndrome. These human observations are relevant to biomarker research, but they do not establish that low MOTS-c caused the conditions or that administering MOTS-c would improve clinical outcomes in those patients [6].

This research adds meaningful evidence to the preclinical literature. It links MOTS-c to mitochondrial quality control in a specific model of cardiac dysfunction following altitude exposure. Nevertheless, its implications must be kept within the scope of the experimental design.

The study does not establish that MOTS-c:

• Improves maximal oxygen uptake in humans.
• Increases endurance performance in trained athletes.
• Improves the normal acclimatization process in healthy people at altitude.
• Prevents acute mountain sickness or other altitude-related illnesses in humans.
• Reproduces the integrated physiological benefits of endurance training.
• Is safe or effective when administered to people for performance enhancement.

These outcomes were not established by the reported mouse intervention and human biomarker observations. The correct interpretation is narrower: MOTS-c showed a potential protective effect against persistent cardiac dysfunction in a particular animal model, with evidence implicating mitochondrial quality control.

8. Why Cardioprotection Is Not the Same as Endurance Enhancement

Cardiac function is essential for exercise, but improving one cardiac outcome does not automatically improve endurance performance. The heart, lungs, blood, vasculature, skeletal muscle, and nervous system work together to determine how effectively the body delivers and uses oxygen during exercise.

A cardioprotective intervention may reduce injury, preserve a measured aspect of cardiac function, or improve mitochondrial quality in a disease model. Those outcomes may be clinically valuable in their own right. They are nevertheless different from showing that a healthy athlete can sustain a greater workload or perform better in competition.

The distinction can be illustrated by considering several outcome categories:

• Cardiac injury or dysfunction: Whether a pathological change in cardiac structure or function is reduced.
• Mitochondrial quality: Whether mitochondrial damage, turnover, or function changes under the experimental conditions.
• Aerobic capacity: The integrated ability of the body to take up, transport, and use oxygen during exercise.
• Exercise performance: Whether a person completes a defined task faster, sustains a greater workload, or performs better on a validated test.
• Clinical benefit: Whether the intervention produces an improvement that matters to health or function in the target population, with acceptable risks.

These outcomes may be related, but they are not interchangeable. For example, preserving cardiac function in a model of altitude-associated injury does not necessarily change the limiting factor in a healthy athlete’s endurance performance.

Furthermore, an intervention that benefits a stressed or diseased system may have a different effect in a healthy system. Biological responses depend on baseline status, the type of stress, and the degree of dysfunction present. Results from a pathological model should therefore not be generalized automatically to healthy performance enhancement.

9. The 2023 Human Study: A Direct Test of the Endurance Claim

A preliminary study by Domin and colleagues examined whether circulating MOTS-c concentrations were associated with muscle strength and aerobic capacity in physically active adults. The study included 20 participants—17 men and three women—with a median age of approximately 30 years. The participants underwent body-composition assessment, countermovement-jump testing, and cardiopulmonary exercise testing [7].

The researchers found positive associations between serum MOTS-c concentrations and several measures of lower-body muscle performance, including jump force and power. MOTS-c concentrations were also associated with measures of muscle mass. However, the study did not find a significant correlation between serum MOTS-c and peak oxygen uptake [7].

This result is particularly relevant to the present topic because peak oxygen uptake is a commonly used measure of integrated aerobic capacity. The finding does not prove that MOTS-c has no role in endurance physiology, but it does show why a proposed mechanistic relationship should not be treated as proof of an endurance benefit.

The study also has limitations. It was small, cross-sectional, and observational. The researchers measured endogenous MOTS-c rather than administering it as an intervention. Associations between a circulating biomarker, muscle mass, and strength can reflect several interacting factors and do not establish a causal effect.

The study therefore supports a restrained conclusion: in this small sample, endogenous MOTS-c was associated with selected measures of muscle strength and power but not with peak oxygen uptake. It did not test whether an administered MOTS-c product could improve either outcome.

10. Altitude Adaptation Is Not a Single Molecular Pathway

Altitude acclimatization is sometimes simplified into the idea that hypoxia activates a pathway that improves oxygen delivery and therefore improves performance. In reality, acclimatization is a dynamic process involving multiple physiological systems and trade-offs.

Increased ventilation can improve oxygen uptake but also changes carbon dioxide balance. Changes in red blood cell production may affect oxygen-carrying capacity over time, but they do not occur immediately. Hypoxic pulmonary vasoconstriction can support ventilation-perfusion matching in some contexts while increasing pulmonary vascular pressure. Skeletal muscle can remodel its metabolism in ways that help it cope with oxygen limitation, but prolonged hypoxia can also impair muscle function.

Human acclimatization studies have documented changes in arterial oxygenation, hemoglobin concentration, symptoms, and exercise performance over time at altitude. For example, the AltitudeOmics project followed 21 participants during 16 days at 5,260 metres and reported changes in several physiological and functional measures during acclimatization [3]. These observations describe an integrated human response to altitude exposure; they do not identify MOTS-c as the cause of the observed changes.

The presence of mitochondrial signaling in this response does not establish that a peptide intervention can reproduce it. Acclimatization develops through interacting systems and repeated exposure over time. A synthetic peptide may influence one pathway, but its effect on the total response must be tested directly.

Researchers should also distinguish adaptation from protection. An intervention that protects a tissue against injury following hypoxic exposure may not accelerate acclimatization, and an intervention that changes acclimatization biomarkers may not improve performance.

11. Endogenous MOTS-c Versus Administered MOTS-c

One of the most common interpretive errors in peptide research is to assume that a naturally occurring biomarker and an administered peptide are interchangeable.

Endogenous MOTS-c is produced within the body’s biological systems. Its concentration may vary with physiological state, tissue activity, metabolism, sampling time, and other factors. When researchers measure endogenous MOTS-c in people exposed to exercise or altitude, they are observing a biological signal in a particular context.

Administered MOTS-c is an intervention. It introduces a peptide from outside the body and raises separate questions about product identity, exposure, distribution, degradation, target engagement, biological effects, and safety. The relationship between an administered dose and tissue exposure cannot be inferred simply from a naturally occurring blood concentration.

These distinctions are essential when interpreting the 2026 high-altitude study. The investigators reported an experimental benefit after administration in mice, while their human observations concerned circulating MOTS-c levels in patient groups. The animal intervention and human biomarker data are complementary, but they answer different questions [6].

Similarly, the 2023 study linked endogenous MOTS-c concentrations to selected physical characteristics in a small group of active adults. It did not establish that administering MOTS-c increases muscle mass, strength, or aerobic capacity [7].

To establish the clinical effects of administered MOTS-c, researchers need appropriately designed human intervention studies that measure exposure, safety, and prespecified outcomes. A biomarker association cannot substitute for those trials.

12. Research Quality: How to Evaluate Claims About Hypoxia and MOTS-c

Evidence should be evaluated according to the question being asked. If the claim concerns a molecular mechanism, cell studies may be informative. If the claim concerns organ protection, a suitable animal or clinical model may provide relevant evidence. If the claim concerns human endurance enhancement, studies must measure endurance outcomes in people receiving the intervention.

For a claim that MOTS-c improves human endurance at altitude, a suitable study would need to specify the target population, intervention, comparator, exposure conditions, safety monitoring, and performance endpoint. Investigators would also need to distinguish effects on healthy athletic performance from effects on pathological cardiac dysfunction.

Without these elements, a claim may be biologically plausible but remain clinically unproven.

13. Why Biomarker Changes Do Not Guarantee Better Performance

Biomarkers are useful for investigating biological processes, but they are not automatically surrogate endpoints for clinical or performance outcomes. A surrogate endpoint must reliably predict the outcome of interest in the context in which it is used.

For MOTS-c, an increase in circulating concentration could reflect altered production, release, distribution, or clearance. It does not necessarily indicate that mitochondrial respiration has improved, that oxygen delivery has increased, or that exercise performance will change.

The 2023 study by Domin and colleagues provides a useful illustration: endogenous MOTS-c was associated with some measures of lower-body strength and power but not with peak oxygen uptake in the sample studied [7]. This finding cautions against using one biomarker as a general measure of athletic capability.

Likewise, an increase in a mitochondrial quality-control marker after an intervention would not by itself establish improved aerobic capacity. Researchers would need to show that the change is reproducible, biologically meaningful, and linked to the outcome of interest.

Even a statistically significant association may have limited practical relevance. Effect size, uncertainty, measurement quality, sample characteristics, and replication all matter when deciding whether a finding supports a real-world claim.

14. Clinical and Safety Questions Remain Open

Experimental findings do not establish the safety of administering MOTS-c to humans. Important questions include pharmacokinetics, tissue exposure, immunogenicity, dose-related effects, interactions with other substances, and potential short- or long-term adverse events.

Safety assessment is particularly important when a peptide is promoted for use under physiologically stressful conditions such as altitude exposure or strenuous exercise. Hypoxia and intense activity can place additional demands on cardiovascular, respiratory, and metabolic systems. An experimental compound should not be assumed safe simply because it appears protective in a particular animal model.

The 2026 high-altitude study investigated a specific model of cardiac dysfunction during de-acclimatization. It does not establish that administering MOTS-c is safe for healthy people traveling to altitude, competitive athletes, or people with pre-existing medical conditions [6].

Similarly, reduced circulating MOTS-c observed in patients with high-altitude heart disease does not establish that supplementation prevents the condition. Biomarker findings may reflect disease processes, physiological compensation, or other factors and require further investigation.

As of the evidence reviewed for this article, published clinical results establishing a safe and effective human MOTS-c intervention for endurance enhancement remain unavailable. Research-grade products should therefore not be treated as clinically validated performance agents.

15. What Future Studies Need to Establish

Future research should test the causal role of MOTS-c in hypoxia-related physiology and determine whether any effects translate into meaningful outcomes in humans.

• Mechanistic specificity: Which pathways are directly influenced by MOTS-c under hypoxic conditions, and which changes are secondary responses?
• Model relevance: Do findings from cell and animal models replicate in human tissues and physiological settings?
• Human exposure: What are the pharmacokinetic and safety characteristics of administered native MOTS-c?
• Population differences: Do effects differ between healthy individuals, trained athletes, people with metabolic disease, and patients with altitude-related pathology?
• Outcome selection: Does the intervention affect cardiac function, mitochondrial quality, acclimatization, aerobic capacity, or actual performance—and are those effects independently measured?
• Clinical significance: Are observed changes large enough to matter, durable over time, and accompanied by acceptable safety?
• Replication: Are the findings reproducible across independent research groups and suitable study designs?

Well-designed clinical research should separate mechanistic outcomes from performance outcomes and avoid treating a positive result in one domain as proof of efficacy in another. Studies should also report negative findings and uncertainty transparently.

16. Statistics: Key Findings and Their Context

Statistical caution: The figures above describe the design and findings of specific studies. They are not estimates of an endurance-enhancing effect. No percentage increase in human peak oxygen uptake, race performance, or altitude tolerance can be calculated from these data.

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21. Scientific References

1. Lundby C, Calbet JAL, Robach P. The response of human skeletal muscle tissue to hypoxia. Cellular and Molecular Life Sciences. 2009;66:3615–3623. PubMed
2. Lindholm ME, Rundqvist H. Skeletal muscle hypoxia-inducible factor-1 and exercise. Experimental Physiology. 2016;101(1):28–32. https://doi.org/10.1113/EP085318
3. Beall CM, et al. AltitudeOmics: the integrative physiology of human acclimatization to hypobaric hypoxia and its retention upon reascent. Journal of Applied Physiology. 2014. PubMed
4. Lee C, Zeng J, Drew BG, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism. 2015;21(3):443–454. https://doi.org/10.1016/j.cmet.2015.02.009
5. Wan W, Zhang L, Lin Y, et al. Mitochondria-derived peptide MOTS-c: effects and mechanisms related to stress, metabolism and aging. Journal of Translational Medicine. 2023;21:36. https://doi.org/10.1186/s12967-023-03885-2
6. Feng Z, Xing Y, Lou J, et al. MOTS-c attenuates cardiac dysfunction following high altitude exposure by promoting mitophagy. Free Radical Biology and Medicine. 2026;247:157–172. https://doi.org/10.1016/j.freeradbiomed.2026.01.064
7. Domin R, Pytka M, Żołyński M, et al. MOTS-c Serum Concentration Positively Correlates with Lower-Body Muscle Strength and Is Not Related to Maximal Oxygen Uptake—A Preliminary Study. International Journal of Molecular Sciences. 2023;24(19):14951. https://doi.org/10.3390/ijms241914951
8. Physiological Reviews. Molecular responses to acute exercise and their relevance for adaptations in skeletal muscle to exercise training. Physiological Reviews. 2023. https://doi.org/10.1152/physrev.00054.2021

22. Conclusion

Hypoxia and altitude adaptation provide a compelling context for investigating MOTS-c because both involve complex responses in mitochondrial function, cellular energy regulation, and stress signaling. Experimental research links MOTS-c to metabolic pathways that overlap with aspects of exercise and hypoxia biology, and the 2026 high-altitude mouse study adds evidence of a possible cardioprotective role during de-acclimatization.

However, the evidence does not establish that administering MOTS-c improves human endurance performance. The high-altitude study measured cardiac outcomes in mice, while human observations concerned circulating MOTS-c in clinical populations. A preliminary study of active adults also found no significant association between endogenous MOTS-c concentration and peak oxygen uptake.

The scientific conclusion is therefore specific: MOTS-c is a promising experimental target in mitochondrial signaling and hypoxia-related research, but its role as a human performance intervention remains unproven. Establishing such a benefit requires human studies that separately evaluate safety, exposure, aerobic capacity, and validated performance outcomes. Neither a shared molecular pathway nor a protective effect in an animal model can replace that evidence.