MOTS-C in Sapa: Mitochondrial Energy Regulation and the Physiology of Endurance Exercise
Featured Answer
What is the proposed role of MOTS-c in endurance exercise?
MOTS-c is a 16-amino-acid mitochondrial-derived peptide encoded within the mitochondrial 12S ribosomal RNA region. Preclinical research suggests that it participates in metabolic signaling involving folate and purine metabolism, AMP-activated protein kinase (AMPK), and pathways associated with cellular energy regulation. Research published in 2025 further reported associations between endogenous MOTS-c, aerobic exercise capacity, and skeletal-muscle mitochondrial respiration, alongside mechanistic findings in endurance-trained mice.
These findings support scientific interest in MOTS-c as a possible component of exercise-responsive mitochondrial signaling. They do not establish that administering MOTS-c improves endurance in humans, increases maximal oxygen uptake, or substitutes for established endurance training.
Key Takeaways
- MOTS-c is a mitochondrial-derived peptide, not a conventional mitochondrial enzyme or a direct fuel source.
- Foundational research linked MOTS-c to folate-cycle and purine metabolism, with downstream AMPK activation in experimental systems.
- AMPK is an energy-sensitive signaling kinase that coordinates aspects of cellular metabolism; it does not independently determine endurance performance.
- PGC-1α is involved in the regulation of mitochondrial biogenesis and oxidative metabolism. Its relationship with MOTS-c is supported by experimental research, but the pathway should not be treated as a fully established linear mechanism in humans.
- A 2025 study reported associations between endogenous MOTS-c levels and aerobic capacity in human participants, alongside endurance-training experiments in mice. Observational associations cannot prove that MOTS-c causes superior performance.
- Exercise itself activates numerous overlapping adaptations, including changes in mitochondrial function, substrate use, cardiovascular delivery, and muscle recruitment.
- As of the evidence reviewed for this article, published clinical efficacy and safety results from completed trials administering native MOTS-c to humans remain unavailable.
- The strongest conclusion is that MOTS-c is a promising research target in mitochondrial and exercise biology, not a clinically established endurance-enhancing intervention.
1. Introduction: Mitochondria as Energy Regulators and Signaling Organelles
Endurance exercise depends on the coordinated ability of the cardiovascular system, lungs, skeletal muscles, and metabolic pathways to sustain ATP production over time. Mitochondria play a central role because they generate much of the ATP required for prolonged aerobic activity through oxidative phosphorylation. Their function, however, extends beyond energy conversion.
Mitochondria also respond to changes in nutrient availability, cellular energy demand, oxidative stress, and exercise-related signals. These responses can alter gene expression, metabolic enzyme activity, mitochondrial quality control, and communication with other cellular compartments. The broader concept of mitochondrial signaling therefore treats the organelle as both an energy-producing system and a participant in the regulation of physiological adaptation [1].
Mitochondrial-derived peptides have emerged as one potential component of this signaling network. Unlike most conventional peptides encoded by nuclear genes, these molecules originate from short open reading frames within mitochondrial DNA. Humanin was one of the first described examples, followed by MOTS-c, which was characterized as a peptide encoded within the mitochondrial 12S rRNA region [1,2].
MOTS-c has attracted interest because experimental studies connect it with metabolic regulation, skeletal-muscle biology, and responses to exercise-related stress. Researchers are investigating whether it helps coordinate the response between mitochondrial signals and cellular energy demand.
That hypothesis is scientifically interesting, but the distinction between a signaling mechanism and a proven performance intervention is essential. Evidence that a peptide changes a pathway in cells or improves an exercise-related outcome in mice does not establish that administering the peptide will produce the same outcome in humans.
2. What Is MOTS-c?
MOTS-c stands for mitochondrial open reading frame of the 12S rRNA type-c. It is a 16-amino-acid peptide encoded within the mitochondrial genome’s MT-RNR1 region. The foundational 2015 study by Lee and colleagues identified MOTS-c as a biologically active peptide associated with metabolic homeostasis and insulin sensitivity [2].
The discovery expanded the traditional view of mitochondrial DNA. Although mitochondrial DNA is best known for encoding components involved in mitochondrial protein synthesis and oxidative phosphorylation, the identification of short peptide-encoding sequences suggested that it may also contribute to signaling through small bioactive molecules.
In the original experimental work, MOTS-c affected metabolic processes involving the folate cycle and de novo purine biosynthesis. The researchers linked these changes to activation of AMPK and reported metabolic effects in cultured cells and mice [2].
Three concepts should be separated when interpreting this literature:
- Endogenous MOTS-c: The peptide produced naturally within biological systems and measured in experimental tissues or circulation.
- Exogenous MOTS-c: Synthetic or externally administered material used in experimental studies, including preclinical animal research.
- Clinical intervention: Administration to humans within a properly designed clinical study that measures safety, pharmacokinetics, and meaningful outcomes.
Evidence from one category does not automatically validate another. Measuring endogenous MOTS-c in an athlete after exercise does not show that administering a synthetic peptide improves the athlete’s performance. Likewise, an effect observed after administration to mice does not establish human safety or an effective human dose.
3. ATP Production and the Bioenergetics of Endurance Exercise
ATP is the immediate energy currency used to support muscle contraction, ion transport, biosynthesis, and many other cellular functions. During prolonged aerobic exercise, mitochondria generate ATP by oxidizing substrates such as carbohydrates and fatty acids. The relative contribution of these substrates changes with exercise intensity, duration, training status, nutrition, and other physiological variables.
Glycolysis provides ATP through the breakdown of glucose and can operate rapidly when energy demand rises. Mitochondrial oxidative metabolism can sustain a large share of ATP production during prolonged aerobic activity, provided that oxygen delivery, substrate availability, and mitochondrial function meet the demands of the working muscles.
Endurance performance is not determined by mitochondria alone. It also depends on maximal oxygen uptake, cardiac output, pulmonary function, oxygen transport, muscle capillarization, motor-unit recruitment, movement economy, thermoregulation, and the athlete’s ability to sustain a given fraction of their physiological capacity.
This integrated physiology matters when evaluating MOTS-c. Even if a molecular intervention changes one aspect of mitochondrial signaling, the resulting effect on whole-body endurance may be small, absent, or dependent on other limiting factors. A change in cellular metabolism is not equivalent to a measurable improvement in running speed, cycling power, or time to exhaustion.
For research, a useful hierarchy separates molecular outcomes, mitochondrial function, muscle physiology, and whole-body performance. Each level addresses a different question, and evidence at one level cannot simply replace evidence at another.
4. The MOTS-c–Folate–Purine–AMPK Connection
The foundational study by Lee and colleagues proposed that MOTS-c influences metabolic homeostasis partly through the folate cycle and de novo purine biosynthesis, ultimately affecting AMPK signaling [2]. This pathway is important because purine metabolism is connected to nucleotide synthesis and cellular energy sensing.
In the reported experimental system, MOTS-c inhibited a step associated with the folate cycle and its linked purine-biosynthesis pathway. This was associated with the accumulation of 5-aminoimidazole-4-carboxamide ribonucleotide, commonly abbreviated AICAR. AICAR-related signaling can activate AMPK, a kinase involved in coordinating cellular responses to energy stress [2].
AMPK helps cells respond when energy demand and energy availability become mismatched. Depending on the tissue and conditions, AMPK activation can influence glucose uptake, lipid metabolism, energy-consuming biosynthesis, and other processes involved in maintaining cellular energy balance.
However, AMPK is not a simple on-off switch for endurance. It integrates multiple signals and operates within a wider network that includes calcium-dependent signaling, p38 MAPK, nutrient-sensing pathways, redox responses, and transcriptional regulators. Its effects depend on the magnitude, duration, cellular location, and context of activation.
Furthermore, a pathway identified in cultured cells or experimental animals should not be assumed to operate with the same magnitude or importance in human skeletal muscle during real-world exercise. The original findings establish a mechanistic basis for further investigation, not a complete description of MOTS-c physiology in humans.
AMPK activation can indicate that a cell has engaged an energy-regulatory response. It does not, by itself, demonstrate increased mitochondrial capacity, improved oxygen uptake, faster race times, or better recovery. Researchers should measure the outcome relevant to the claim rather than using a molecular marker as a substitute for performance data.
5. AMPK, PGC-1α, and Mitochondrial Adaptation
PGC-1α, or peroxisome proliferator-activated receptor gamma coactivator 1-alpha, is a transcriptional coactivator involved in the regulation of mitochondrial biogenesis and oxidative metabolism. It interacts with multiple transcription factors and signaling pathways to influence the expression of genes associated with energy metabolism.
Exercise can activate signaling networks that influence PGC-1α and other regulators of skeletal-muscle adaptation. Repeated training may lead to changes in mitochondrial content, oxidative enzyme activity, substrate utilization, capillary supply, and the ability to sustain work at a given intensity.
AMPK is one of several signals that can interact with pathways regulating PGC-1α. The relationship is not exclusive: calcium-dependent signaling, p38 MAPK, redox-sensitive pathways, and other regulators also contribute to exercise-induced adaptations.
The 2025 study by Feng and colleagues reported that endurance training was associated with enhanced skeletal-muscle mitochondrial respiration and MOTS-c secretion, with experimental findings implicating the AMPK/PGC-1α pathway [3]. The work supports further investigation of MOTS-c as a potential participant in exercise-responsive mitochondrial signaling.
It does not establish that the pathway is the only explanation for training adaptation. Nor does it prove that exogenous MOTS-c can reproduce the complex, repeated physiological stimulus of endurance exercise.
Endurance training changes many systems simultaneously. The heart adapts to deliver oxygen, muscles remodel their oxidative machinery, the nervous system coordinates movement, and metabolic regulation adjusts to repeated demands. A single peptide is unlikely to capture the full complexity of these adaptations.
6. How Endurance Exercise Challenges Cellular Energy Regulation
During endurance exercise, ATP turnover increases substantially in active muscle. The magnitude of the challenge depends on exercise intensity, duration, recruitment of muscle fibers, substrate availability, and training status.
Several interconnected processes respond to this demand:
- Energy sensing: Cells respond to changes in adenine nucleotide status and other signals associated with ATP demand.
- Substrate regulation: Carbohydrate and fat metabolism adjust to the intensity and duration of exercise.
- Mitochondrial respiration: Oxidative phosphorylation responds to substrate supply, oxygen availability, and cellular demand.
- Calcium signaling: Repeated muscle contractions generate signals that influence metabolic regulation and gene expression.
- Redox signaling: Reactive oxygen species can act as signals as well as potential sources of cellular damage, depending on concentration and context.
- Transcriptional adaptation: Repeated exercise stimuli alter the expression of genes associated with mitochondrial and metabolic function.
MOTS-c is being investigated within this broader context of metabolic stress and adaptive signaling. Some experimental studies suggest that it can influence pathways relevant to glucose handling and muscle function. The unresolved question is how much endogenous MOTS-c contributes to the normal human training response, and whether that contribution can be isolated from other pathways.
This question is difficult because exercise simultaneously activates multiple signaling networks. Demonstrating that MOTS-c levels change after exercise is not enough to establish that MOTS-c is necessary or sufficient for the resulting adaptation.
7. What the 2025 Endurance Study Adds
Feng and colleagues published Endurance training enhances skeletal muscle mitochondrial respiration by promoting MOTS-c secretion in Free Radical Biology and Medicine in 2025 [3]. The study examined the relationship between MOTS-c, aerobic exercise capacity, and skeletal-muscle mitochondrial function.
The research included observations involving marathon runners and sedentary participants, as well as endurance-training experiments in mice. The authors reported a close relationship between serum MOTS-c levels and aerobic exercise capacity in the human comparison. In the mouse experiments, long-term endurance training was associated with changes in serum MOTS-c and skeletal-muscle mitochondrial respiration.
The authors further reported findings consistent with MOTS-c-related signaling and activation of the AMPK/PGC-1α pathway in the context of endurance training [3]. These results provide a mechanistic basis for examining whether MOTS-c participates in communication between exercise stress and mitochondrial adaptation.
Several interpretive limits remain important:
- Association is not causation. A relationship between circulating MOTS-c and aerobic capacity does not show that higher MOTS-c caused better endurance.
- Human observation differs from intervention. Measuring a naturally occurring peptide is not equivalent to administering synthetic MOTS-c to participants.
- Animal training studies have limited generalizability. Results in mice help identify mechanisms but do not establish the magnitude or direction of effects in human athletes.
- Biomarkers are not performance guarantees. A circulating peptide concentration may reflect training exposure, physiological status, or other variables without directly determining performance.
- Pathway involvement is not pathway exclusivity. Even when AMPK/PGC-1α signaling is implicated, other mechanisms may contribute to the observed response.
The study is an important addition to the literature, but it should be understood as a combination of human observational evidence and experimental animal research rather than a clinical trial demonstrating that administered MOTS-c improves endurance in people.
8. Endogenous MOTS-c and the Meaning of an Exercise-Responsive Biomarker
A biomarker is a measurable characteristic that may reflect a biological process, exposure, or physiological state. Endogenous MOTS-c has been investigated as a potential marker of metabolic status and exercise-related responses.
Earlier reviews of mitochondrial-derived peptides and exercise described evidence that acute high-intensity exercise can change the concentrations of MOTS-c and humanin in human skeletal muscle or plasma. They also noted that evidence for chronic training-related changes was not fully consistent across studies, potentially reflecting differences in training mode, duration, intensity, participant characteristics, and sampling methods [4].
This variability is not unusual in exercise biology. A biomarker may change immediately after a single session, return toward baseline during recovery, or show a different pattern after repeated training. Blood concentrations may also differ from concentrations within skeletal muscle, and a single measurement may not capture the timing of the underlying biological response.
For MOTS-c, researchers should distinguish at least three questions:
- Does exercise change endogenous MOTS-c concentrations under specified conditions?
- Do baseline or exercise-related MOTS-c measurements correlate with training status, metabolic health, or aerobic capacity?
- Does changing MOTS-c itself alter exercise adaptation or performance?
The first two questions can be investigated using observational and biomarker studies. The third requires stronger causal evidence, such as appropriately designed intervention studies. A positive answer to one question does not automatically answer the others.
9. Mitochondrial Respiration: What the Measurements Actually Mean
Mitochondrial respiration describes oxygen-dependent processes associated with ATP production and other metabolic functions. Researchers may assess respiration in isolated mitochondria, permeabilized muscle fibers, cultured cells, or other experimental systems. Each approach captures different aspects of mitochondrial function.
Measurements of oxygen consumption can help characterize respiratory capacity under defined conditions. However, higher oxygen consumption is not always equivalent to greater efficiency or better endurance. Interpretation depends on the experimental protocol, substrates supplied, coupling between respiration and ATP synthesis, tissue preparation, and the biological question.
For example, a study may report greater maximal respiratory capacity under laboratory conditions. This finding can support the conclusion that a measured preparation has greater capacity under those conditions, but it does not automatically establish that a participant can sustain a higher race pace.
Whole-body endurance depends on more than mitochondrial respiration. Oxygen delivery, blood volume, cardiac output, muscle perfusion, ventilatory function, movement economy, thermoregulation, and motivation can all influence performance. A molecular intervention that affects one component may not improve the integrated outcome if another component remains limiting.
In MOTS-c research, mitochondrial respiration should therefore be considered a mechanistic endpoint rather than a complete proxy for endurance performance. Future studies would benefit from measuring cellular and whole-body outcomes in parallel.
10. Glucose Handling, Fat Oxidation, and Metabolic Flexibility
Endurance exercise requires flexible use of energy substrates. Carbohydrate oxidation can support high rates of ATP production, while fat oxidation contributes substantially during many forms of prolonged, lower-intensity exercise. The relative contribution of each substrate depends on intensity, duration, training adaptation, nutritional status, and individual physiology.
The original MOTS-c research linked the peptide to glucose utilization, AMPK signaling, and improved insulin sensitivity in experimental systems. In mice, MOTS-c treatment was associated with protection against diet-induced metabolic dysfunction under the conditions studied [2]. These findings contributed to interest in MOTS-c as a possible regulator of metabolic homeostasis.
However, glucose handling, fat oxidation, and metabolic flexibility are related but distinct outcomes. Improved glucose clearance in an animal model does not establish that an endurance athlete can oxidize more fat at a given workload, spare more glycogen, or maintain a faster pace.
Metabolic flexibility is commonly used to describe the capacity to adjust substrate use in response to physiological demands, such as fasting, feeding, or exercise. It requires measurements that characterize the change in substrate utilization under defined conditions. A single metabolic marker is rarely sufficient to establish the full phenotype.
For MOTS-c, future research would need to determine whether any observed changes in glucose handling translate into meaningful differences in exercise metabolism and whether those differences are reproducible in humans.
11. Mitochondrial Stress Signaling and Mitohormesis
Mitohormesis describes the concept that a moderate stressor can trigger adaptive responses that improve the ability to tolerate subsequent challenges. Exercise is a familiar example: acute physiological stress activates signaling pathways that can contribute to beneficial adaptation when training and recovery are appropriately balanced.
Mitochondrial-derived peptides have been proposed as part of the signaling network involved in these responses. MOTS-c is of particular interest because experimental findings connect it with metabolic regulation and exercise-related pathways [4].
Nevertheless, the mitohormesis concept should not be interpreted as meaning that all mitochondrial stress is beneficial or that increasing one stress-associated signal will necessarily improve health. Responses depend on the magnitude, duration, timing, and biological context of the stressor. Excessive stress, insufficient recovery, or underlying disease can produce adverse rather than beneficial outcomes.
The relationship between exercise and MOTS-c may also be bidirectional. Exercise could influence endogenous peptide expression, while the peptide may participate in signaling processes associated with adaptation. Establishing the causal importance of this relationship requires experiments that can distinguish correlation from necessity and sufficiency.
One important research question is whether MOTS-c is a mediator of exercise adaptation, a marker of the adaptation process, or both. The current evidence does not fully resolve that distinction in humans.
12. Why MOTS-c Is Not an Established Exercise Mimetic
The term exercise mimetic is sometimes used in commercial discussions of experimental metabolic compounds. It can imply that a substance reproduces the benefits of exercise without the exercise itself. This is a much stronger claim than demonstrating that a compound influences a pathway also activated by exercise.
Exercise is a complex physiological stimulus involving repeated muscle contraction, cardiovascular loading, changes in substrate use, neural adaptation, bone loading, thermoregulation, and interactions among multiple organ systems. A peptide associated with one component of this response cannot be assumed to reproduce the whole system.
Preclinical research suggests that MOTS-c treatment can affect metabolic outcomes and exercise-related measures in mice. Reviews have also discussed similarities and differences between MOTS-c-related effects and exercise-induced adaptations [4]. These findings support continued investigation but do not establish a clinically meaningful exercise-mimetic effect in humans.
Several questions would need to be answered before such a claim could be supported:
- Does administered MOTS-c reach relevant tissues in humans at a predictable exposure?
- Does it produce a reproducible biological effect at a tolerable exposure?
- Does the intervention improve validated endurance outcomes compared with an appropriate control?
- Are any effects sustained, clinically meaningful, and independent of changes in body weight or other confounders?
- What are the short- and long-term safety implications?
Until these questions are addressed, describing MOTS-c as a proven substitute for endurance training would go beyond the evidence.
Exercise and an experimental peptide may influence some of the same signaling pathways while producing different effects across tissues and time scales. Demonstrating overlapping molecular activity is a starting point for mechanistic research, not proof that the interventions are interchangeable.
13. Human Evidence: Observational Studies Versus Administration Trials
The human evidence for MOTS-c requires particular care because many studies measure the peptide that people naturally produce rather than administering the peptide as an intervention.
Observational research may examine circulating MOTS-c in relation to age, metabolic health, physical activity, or exercise capacity. Such studies can help generate hypotheses and identify possible biomarkers, but they cannot by themselves determine whether MOTS-c causes a particular outcome.
To establish the effects of administered MOTS-c in humans, investigators need controlled studies that evaluate pharmacokinetics, safety, tolerability, and prespecified efficacy outcomes. The findings must also be published in sufficient detail for independent assessment.
As of the evidence reviewed for this article, completed, published clinical trials demonstrating the safety or endurance-enhancing efficacy of administered native MOTS-c in humans remain unavailable. A registered or recruiting trial is evidence that research is planned or underway, not evidence that a treatment works.
It is also important not to confuse native MOTS-c with a related or modified peptide analog. Results for a distinct molecule cannot automatically be attributed to native MOTS-c because sequence modifications can alter biological activity, exposure, metabolism, and safety.
Consequently, the human evidence currently supports interest in endogenous MOTS-c as a biological signal. It does not establish a safe, effective, or clinically validated MOTS-c intervention for endurance performance.
14. Research Limitations and Methodological Challenges
MOTS-c research faces several challenges that are common in emerging peptide biology, as well as specific problems related to measuring small mitochondrial-derived peptides.
Measurement validity
Biomarker studies depend on reliable and specific analytical methods. Differences in sample handling, assay specificity, calibration, and laboratory procedures can complicate comparisons between studies. Investigators should report methods in sufficient detail to support reproducibility.
Tissue versus circulation
A blood concentration may not directly represent the concentration or activity of MOTS-c within skeletal muscle. Researchers should avoid assuming that circulating measurements fully capture local signaling or mitochondrial function.
Training heterogeneity
Endurance athletes differ in training volume, intensity distribution, recent exercise exposure, nutrition, recovery, age, and baseline fitness. These variables can influence both biomarker concentrations and performance outcomes.
Small samples and multiple outcomes
Mechanistic studies often measure numerous molecular and physiological outcomes. Small samples can produce imprecise estimates, while multiple comparisons can increase the likelihood of chance findings unless the analysis is appropriately designed and interpreted.
Translation across species
Animal studies are valuable for investigating mechanisms and testing hypotheses that cannot initially be studied in humans. However, differences in metabolism, physiology, exercise behavior, and experimental conditions limit direct translation.
Intervention uncertainty
Without published human administration studies, important questions about exposure, biological activity, adverse effects, and interactions remain unanswered. Mechanistic plausibility cannot replace these data.
15. What Future MOTS-c Endurance Studies Should Measure
Future research would benefit from linking molecular outcomes to functional measurements rather than treating biomarker changes as sufficient evidence of benefit.
| Research domain | Potential measurements | Key interpretation question |
|---|---|---|
| Molecular signaling | MOTS-c concentration, AMPK-related signaling, PGC-1α-associated markers | Does the molecular response precede or predict a meaningful physiological change? |
| Mitochondrial function | Respiration, oxidative capacity, mitochondrial content, and appropriate functional assays | Does the measured change reflect greater capacity, altered substrate use, or a different aspect of metabolism? |
| Whole-body physiology | Maximal oxygen uptake, ventilatory thresholds, exercise economy, and substrate oxidation | Does the molecular effect translate into a reproducible physiological difference? |
| Performance | Time trials, time to exhaustion, sustainable power, or validated sport-specific outcomes | Is any difference meaningful for actual exercise performance? |
| Safety and tolerability | Adverse events, clinical laboratory measures, exposure data, and follow-up | Are any observed benefits accompanied by acceptable and adequately characterized risks? |
Strong studies would prespecify primary outcomes, use appropriate control groups, report effect estimates with confidence intervals, and distinguish exploratory analyses from confirmatory tests. Where an administered intervention is studied, safety and pharmacokinetics should be established before claims about athletic benefit are considered.
16. Statistics: Quantitative Findings and Their Limits
| Finding | Reported detail | Interpretation |
|---|---|---|
| MOTS-c peptide length | 16 amino acids | A defining molecular feature of the peptide characterized in the foundational study [2]. |
| Foundational publication | 2015, Cell Metabolism | Established the peptide’s proposed role in metabolic regulation through cell and animal experiments [2]. |
| Endurance-training study | Published online in December 2024; journal issue dated February 2025 | Reported human associations and experimental findings from endurance-trained mice, not a human MOTS-c administration trial [3]. |
| Published clinical efficacy evidence for administered native MOTS-c | No completed, published human efficacy results identified in the evidence reviewed for this article | Human safety, effective exposure, and endurance benefits remain unestablished. |
Statistical caution: These figures describe the peptide’s molecular characteristics and the publication history of the evidence. They are not estimates of the size of a performance benefit. No numerical increase in human endurance, maximal oxygen uptake, or time-trial performance can be inferred from these findings.
17. Frequently Asked Questions
1. What is MOTS-c?
MOTS-c is a 16-amino-acid mitochondrial-derived peptide encoded within the mitochondrial 12S rRNA region. It has been studied for possible roles in metabolic regulation, skeletal-muscle biology, and mitochondrial signaling.
2. How is MOTS-c connected to AMPK?
Foundational experimental work linked MOTS-c to changes in folate and purine metabolism associated with AMPK activation. AMPK helps cells respond to energy stress, but its activation alone does not prove improved endurance or athletic performance.
3. What is the proposed role of PGC-1α?
PGC-1α is a transcriptional coactivator involved in the regulation of mitochondrial biogenesis and oxidative metabolism. Experimental research has implicated AMPK/PGC-1α signaling in the relationship between endurance training and MOTS-c, but this should not be interpreted as a fully established linear pathway in human exercise physiology.
4. Does exercise increase endogenous MOTS-c?
Some research reports changes in endogenous MOTS-c following acute exercise or in association with endurance training. Findings can vary with the study design and participant characteristics. A change in circulating concentration does not establish that MOTS-c causes the training adaptation.
5. Does MOTS-c improve endurance in humans?
That has not been established. Human observational associations and animal experiments provide a rationale for further study, but published clinical efficacy results from trials administering native MOTS-c to humans remain unavailable in the evidence reviewed here.
6. Is MOTS-c an exercise mimetic?
Calling MOTS-c a proven exercise mimetic overstates the evidence. Some experimental findings overlap with pathways involved in exercise adaptation, but endurance exercise produces integrated cardiovascular, muscular, metabolic, and neurological effects that cannot be assumed to be reproduced by one peptide.
7. What did the 2025 endurance study show?
The study by Feng and colleagues reported associations between endogenous MOTS-c and aerobic exercise capacity in human participants, alongside endurance-training experiments in mice that implicated MOTS-c-related signaling in skeletal-muscle mitochondrial function. It did not demonstrate that administering MOTS-c improves endurance in humans.
8. Does improved mitochondrial respiration always mean better performance?
No. Mitochondrial respiration is one component of endurance physiology. Whole-body performance also depends on oxygen delivery, cardiovascular function, substrate availability, movement economy, thermoregulation, and other factors. The relevance of a respiratory measurement depends on the method and context.
9. Is MOTS-c the same as a MOTS-c analog?
No. An analog is a distinct or modified molecule that may have different biological properties. Findings for one analog cannot automatically be attributed to native MOTS-c, and each intervention requires its own safety and efficacy evidence.
10. Is the safety of administered MOTS-c established in humans?
No. Without completed, published human administration studies, the safety profile, pharmacokinetics, interactions, and tolerability of native MOTS-c remain insufficiently characterized. Preclinical findings cannot substitute for clinical safety data.
11. Can MOTS-c replace endurance training?
There is no clinical evidence supporting that conclusion. Exercise produces adaptations across multiple physiological systems, while current MOTS-c research is primarily mechanistic, observational, and preclinical.
12. What evidence would establish an endurance benefit?
Appropriately designed human clinical trials would need to evaluate safety and exposure, use suitable control groups, and measure validated endurance outcomes such as maximal oxygen uptake, exercise economy, or standardized performance tests. Molecular pathway changes alone would not be sufficient.
18. Related Articles
- Vietnam Peptides Knowledge Hub — Explore research-oriented articles on peptide biology, metabolic regulation, and evidence interpretation.
- Peptide Research FAQ — Review general questions about research peptides and responsible interpretation of product information.
- Peptide Products and Research Categories — Browse related product categories and educational resources.
- Personalized Peptide Plans — Explore the site’s goal-based content while distinguishing commercial information from clinical evidence.
19. Related Research Products
MOTS-C 20mg
This product page relates directly to the peptide discussed in this article. Product descriptions should be distinguished from peer-reviewed experimental findings. The current literature does not establish that a commercial research-grade MOTS-c product improves human endurance, enhances mitochondrial function in athletes, or is safe for human administration.
SLU-PP-332 5mg
SLU-PP-332 is a separate experimental compound investigated in preclinical research related to exercise-associated metabolic pathways. It is not MOTS-c, and findings for one compound should not be transferred to the other. Its inclusion provides related-category navigation rather than a recommendation or evidence of clinical efficacy.
20. Related Plan
Longevity Plan
Explore the site’s longevity research-plan category for related educational content. This commercial resource should not be interpreted as a clinically validated MOTS-c protocol or as evidence that experimental peptides improve mitochondrial function, aging outcomes, or endurance in humans.
21. Scientific References
- Picard M, Wallace DC, Burelle Y. The rise of mitochondrial medicine. Mitochondrion. 2016;30:105–116. https://doi.org/10.1016/j.mito.2016.07.003
- 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
- Feng Y, Rao Z, Tian X, et al. Endurance training enhances skeletal muscle mitochondrial respiration by promoting MOTS-c secretion. Free Radical Biology and Medicine. 2025;227:619–628. Published online December 18, 2024. https://doi.org/10.1016/j.freeradbiomed.2024.12.038
- Merry TL, Chan A, Woodhead JST, et al. Mitochondrial-derived peptides and exercise. Biochimica et Biophysica Acta (BBA) – General Subjects. 2021. Review of mitochondrial-derived peptide responses to exercise and proposed roles in exercise adaptation. Read the review
- Kim SJ, Mehta HH, Wan J, et al. Mitochondrial peptides modulate mitochondrial function during cellular stress. Refer to the foundational MOTS-c literature and subsequent mechanistic studies for the distinction between cellular effects and whole-organism outcomes. PubMed literature search
- Herzig S, Shaw RJ. AMPK: guardian of metabolism and mitochondrial homeostasis. Nature Reviews Molecular Cell Biology. 2018;19:121–135. https://doi.org/10.1038/nrm.2017.95
- Egan B, Zierath JR. Exercise metabolism and the molecular regulation of skeletal muscle adaptation. Cell Metabolism. 2013;17(2):162–184. https://doi.org/10.1016/j.cmet.2012.12.012
- ClinicalTrials.gov. Search results for MOTS-c intervention studies. Trial registration should be distinguished from published trial results. Search ClinicalTrials.gov
22. Conclusion
MOTS-c offers an intriguing research perspective on the relationship between mitochondrial signaling, cellular energy regulation, and endurance exercise. Foundational experiments connected the peptide to folate and purine metabolism and AMPK-related signaling. More recent work has linked endogenous MOTS-c with aerobic exercise capacity and reported mechanistic findings involving endurance training and skeletal-muscle mitochondrial respiration.
The evidence must nevertheless be interpreted at the correct level. Cellular pathway changes are not equivalent to greater mitochondrial capacity, animal exercise outcomes are not proof of human efficacy, and observational biomarker associations do not establish causality. As of the evidence reviewed here, completed, published human trials demonstrating that administration of native MOTS-c improves endurance or is safe for this purpose remain unavailable.
The next phase of research should connect molecular measurements to validated physiological and performance outcomes while establishing exposure and safety in humans. Until such data are available, MOTS-c is best understood as an experimental mitochondrial-derived peptide with promising mechanistic research, not a proven endurance-enhancing intervention or substitute for established training practices.