Resistance training activates c-Myc (MYC) — the most powerful of the four Yamanaka epigenetic reprogramming factors in skeletal muscle — far more than endurance exercise, suggesting a unique epigenetic rejuvenating signal unique to lifting.
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c-Myc is also an oncogene: the pulsatile spike it creates after a workout (peaks ~3 hours, returns to baseline by ~24 hours) is biologically beneficial, but constitutive or chronic activation would be dangerous — which is precisely why recovery between sessions matters epigenetically, not just mechanically.
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Yamanaka factor activation makes muscle cells more 'plastic' — better able to adapt — rather than literally reversing age or regenerating tissue; the word 'rejuvenation' is scientifically imprecise and should be used with caution.
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mTOR, the master regulator of muscle growth, paradoxically rises with aging, suggesting its activity becomes dysregulated rather than depleted — raising the question of whether older muscle is stuck in an aberrant anabolic signaling state rather than a simply depleted one.
Protocols
Concrete recipes — what, when, how much, and why
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Prioritize resistance training to maximally activate the c-Myc Yamanaka factor pulse in skeletal muscle
WhatChoose compound resistance exercise (squats, leg extensions, multi-joint lifts) as the primary modality when the goal is activating epigenetic reprogramming pathways in aging muscle. Endurance exercise (cycling, running) also activates c-Myc but to a significantly lesser degree.
WhenAs the foundation of any exercise program oriented around muscle longevity and epigenetic adaptation, especially in aging individuals with anabolic resistance.
DoseStandard resistance exercise protocol (e.g., three sets of 10 reps on compound movements) was sufficient to induce a large c-Myc pulse in published studies. Total dose for maximal c-Myc has not been formally dose-optimized in published research.
For whomAdults, particularly older adults showing anabolic resistance or declining muscle adaptability. Anyone interested in the epigenetic anti-aging effects of exercise.
Whyc-Myc is the Yamanaka transcription factor most strongly induced by exercise in human skeletal muscle, and resistance exercise drives it far higher than endurance exercise. Yamanaka factors activate thousands of downstream genes simultaneously and are capable of shifting the epigenetic landscape toward a more youthful, plastic cellular state.
CaveatsThe ideal dose (sets × reps) for maximizing c-Myc induction has not been formally studied. Any level of resistance exercise likely produces the pulse; the priority is consistency and progressive loading, not optimizing for c-Myc specifically.
Murach's time-course biopsy study (with his Swedish collaborator Ferdinand) compared the same subjects doing resistance exercise (three sets of 10, squats and leg extensions) versus 45-minute cycling. Biopsies at 30 min, 3 hours, 8 hours, and 24 hours showed c-Myc rose 'way higher' with resistance versus endurance. This tracks with MetaX data aggregated across dozens of published exercise studies, where resistance exercise consistently showed stronger c-Myc induction. The implication: if someone can only do one modality, resistance wins for this specific epigenetic pathway.
Mechanism
c-Myc (MYC) is a transcription factor and one of the four classical Yamanaka factors (OCT4, SOX2, KLF4, c-Myc). It acts as a master regulator capable of turning on thousands of genes simultaneously and rewriting the epigenetic code (not the DNA sequence). In the context of exercise, the transient c-Myc pulse is hypothesized to shift aging muscle cells toward a more plastic state, enabling better adaptation to training stimuli — a partial 'epigenetic rejuvenation' of the adaptive machinery.
it goes up a lot specifically with resistance exercise it does go up with endurance exercise as well but it does increase in response to resistance exercise quite largely to a pretty large extent
Allow full c-Myc recovery between training sessions — the 24-hour pulse cycle is the epigenetic signal
WhatStructure training so that each resistance session is followed by adequate recovery before the next activation, respecting the ~24-hour return-to-baseline kinetics of c-Myc in muscle tissue. Avoid training the same muscle group again before the c-Myc pulse has fully resolved.
WhenWhen programming split training or any program targeting the same major muscle groups on consecutive days.
Dosec-Myc peaks at approximately 3 hours post-exercise and returns to baseline by approximately 24 hours. Minimum recovery of 24 hours per muscle group is consistent with the c-Myc kinetics.
For whomAnyone programming high-frequency resistance training, coaches working with advanced athletes, anyone concerned about the cancer-biology implications of high-volume training.
WhyThe biological benefit of c-Myc induction comes from its pulsatile nature — a sharp rise followed by complete return to baseline. Constitutive elevation of c-Myc is oncogenic. Training the same muscle daily without recovery could sustain c-Myc at elevated levels longer than physiologically intended, which in theory shifts toward the pathological constitutive activation pattern rather than the beneficial pulse.
CaveatsSkeletal muscle fibers are relatively resistant to cancer formation. The constitutive c-Myc concern is more theoretical in muscle than in epithelial tissues. Standard resistance training programs have not shown cancer risk; this is a mechanistic framing for optimal epigenetic benefit, not a clinical safety warning.
Murach uses mTOR as a parallel to illustrate the same principle: mTOR, the 'master regulator of muscle growth,' causes atrophy and pathology when switched on chronically — yet it is the same pathway that drives hypertrophy when transiently activated by exercise. The principle applies broadly to most growth-signaling molecules: it is the pulsatile on-off rhythm that is healthy, not the level of the peak or the duration of baseline. The exercise session creates the pulse; the recovery period creates the return to baseline.
Mechanism
Pulsatile c-Myc activates downstream gene networks that promote cellular plasticity and adaptation, then returns to baseline, allowing those gene programs to resolve. Chronic c-Myc maintains a constitutively active transcriptional program that bypasses normal growth checkpoints, driving abnormal cell proliferation.
it needs to be controlled in this way that's kind of pulsatile and more transient because if you just turned it on all the way and left it on that would be really bad
Use resistance exercise as epigenetic medicine for aging muscle — not just hypertrophy
WhatFrame resistance training in older adults not only as a tool for muscle hypertrophy but as an epigenetic intervention that activates cellular reprogramming machinery to make aging muscle more plastic and adaptive. Prioritize resistance training even in individuals who are primarily cardiovascular-focused.
WhenAny time working with aging adults (roughly 40+) who show declining muscle quality, anabolic resistance, or reduced training adaptation despite consistent effort.
DoseStandard resistance training volumes (multiple sets per session, 2–4 sessions per week) are sufficient to create repeated c-Myc pulses. The cumulative epigenetic effect accumulates over months of consistent training.
For whomAging adults with anabolic resistance; clinicians and coaches working in longevity medicine or sports medicine with older populations.
WhyMurach's research focus is specifically on whether c-Myc induction can be leveraged to make aging muscle 'at least adapt more like a younger muscle' — because c-Myc as a Yamanaka factor has the capacity to partially reset the epigenetic state of a cell toward a younger, more plastic configuration.
CaveatsThis is emerging research. The claim that exercise-induced c-Myc 'rejuvenates' aging muscle should be phrased carefully: it appears to make aging muscle more adaptive, but this is not the same as the full epigenetic reprogramming Yamanaka factor induction in a dish, which fully reverts cells to pluripotency.
Murach has been studying muscle stem cells for six years and is deliberate about the distinction between regeneration (a stem cell process) and epigenetic adaptation (a mature fiber process). The c-Myc exercise story is the latter: aging mature muscle fibers become less responsive to training over time, and the Yamanaka factor pulse from resistance exercise may help reset their responsiveness. This is distinct from attempting to regenerate muscle through satellite cell activation, which is a separate downstream process.
Mechanism
With aging, both the magnitude and duration of exercise-induced gene expression responses decline. If the c-Myc pulse is blunted in older muscle, the downstream gene networks that enable adaptive remodeling are less activated. Restoring the c-Myc pulse via resistance training may partially restore the epigenetic responsiveness of aging muscle to the level of younger tissue.
can it be leveraged to make older muscle at least adapt more like a younger muscle because it has this role as the yanaka factor that can kind of make older cells appear younger again
Use MetaX to look up whether any gene of interest responds to resistance vs endurance exercise
WhatNavigate to the MetaX database (created by Julian Zierath / Niklas Pold at Karolinska Institute) and search for any gene of interest to see its expression response across all published human exercise biopsy studies.
WhenWhen evaluating the exercise-responsiveness of any molecular target relevant to your training, health, or research goals — before assuming a supplement or intervention that targets a given pathway is necessary.
DoseA single search query takes seconds. The database aggregates dozens of exercise biopsy studies; results show the direction and magnitude of expression change across modalities.
For whomPractitioners, coaches, researchers, and motivated patients interested in the molecular biology of exercise. Useful for evaluating claims in longevity supplement marketing against the actual exercise-science evidence base.
WhyMetaX provides evidence-based confirmation of whether exercise alone activates a given biological target, removing the need for expensive or speculative supplementation to hit a pathway that free exercise already activates.
Murach used MetaX to systematically screen all published exercise-responsive transcription factors and identify c-Myc as the most potent Yamanaka factor response to exercise. The database is publicly accessible, created by a group at Karolinska (Julian Zierath / Niklas Pold). It aggregates RNA sequencing and microarray data from all published biopsy studies comparing before-and-after exercise gene expression, and allows any user to query a specific gene to see its response across resistance exercise, endurance exercise, and different cohorts.
there's a little website you can go to and plug in your favorite Gene and see if it gets turned on with exercise and muscle it's really cool it's called metax
Interpret 'anabolic resistance' in aging muscle as potential mTOR dysregulation — not just mTOR depletion
WhatWhen assessing why an older adult is not responding to training or protein feeding, consider the possibility that mTOR is basally elevated (dysregulated upward) rather than simply depleted — meaning the pathway cannot generate a proper acute pulse on top of a chronically elevated baseline.
WhenClinical or coaching assessment of older adults who report plateau in muscle gain, loss of training adaptation, or poor response to increased protein intake despite adequate total protein.
For whomClinicians, coaches, and practitioners working with older adults showing blunted hypertrophy responses despite adequate training and nutrition.
WhyThe conventional model predicts declining mTOR with aging as the cause of anabolic resistance. Murach flags that mTOR paradoxically rises with aging — suggesting the problem is aberrant tonic activation, not reduced baseline activity. This implies the therapeutic target may be normalizing mTOR tone (e.g., through consistent exercise pulsing, caloric cycling, or mTOR modulators) rather than simply stimulating it further.
CaveatsThis is a mechanistic research observation, not yet a standard clinical diagnostic target. mTOR levels in muscle are not routinely measured in clinical settings. This framing is useful for conceptualizing anabolic resistance, not for driving immediate clinical decisions without further evidence.
mTOR is called the master regulator of muscle protein synthesis and is activated by both mechanical loading (resistance exercise) and amino acids (particularly leucine). The conventional aging narrative is that mTOR signaling capacity declines, causing anabolic resistance. The emerging observation Murach raises — that basal mTOR actually rises with aging — suggests a more complex picture: aging muscle may be stuck in a constitutively active but low-amplitude mTOR state that blunts the fold-change response to feeding or exercise, rather than simply having an underactive pathway.
Mechanism
mTOR complex 1 (mTORC1) phosphorylates S6K1 and 4E-BP1 to promote protein synthesis. Constitutive activation may deplete downstream effectors, desensitize feedback loops, or chronically suppress autophagy — all of which would reduce the net anabolic response to an acute stimulus even when the pathway is nominally active.
turning on like mtor for instance you know they call that the master regulator of muscle growth mtor when you turn that on constitutively for like long periods of time it actually results in pathology and muscle atrophy like it needs to be controlled and interestingly as you get older mtor actually gets goes higher
What's new
Personal practice updates, fresh positions, predictions
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c-Myc is the dominant Yamanaka factor activated by resistance exercise in skeletal muscle
Of the four classical Yamanaka factors (OCT4, SOX2, KLF4, c-Myc), c-Myc (MYC) is the one most robustly induced by exercise in skeletal muscle — and resistance exercise drives it significantly higher than endurance exercise. Murach's lab confirmed this in a time-course biopsy study co-authored with a collaborator in Sweden.
Why this matters: Provides the first mechanistic link between the most common exercise modality (resistance training) and epigenetic reprogramming machinery that normally governs cellular fate and embryonic development.
Background
Yamanaka factors were discovered by Shin Yamanaka around 2006 (Nobel Prize in Physiology or Medicine). Their classical use: overexpressing all four in a differentiated cell in a dish converts it back to a pluripotent stem cell. The question Murach's lab is investigating is whether exercise transiently activates the same factors in vivo to make aging muscle more adaptive.
Murach describes using the MetaX database — a compendium of all published exercise biopsy gene-expression studies assembled by Julian Zierath's group at Karolinska — to screen systematically for exercise-responsive transcription factors. When he searched for the Yamanaka factors in MetaX, c-Myc stood out as the most strongly exercise-induced. He then confirmed it in his own time-course study: biopsies taken at 30 min, 3 hours, 8 hours, and 24 hours after a standard resistance-exercise bout (three sets of 10, squats and leg extensions) versus a 45-minute cycling bout showed c-Myc went 'way higher' with the resistance session.
the one that gets turned on the most with exercise is this one called Mick which is um or C mic um myyc and so we found that first of all it goes up in muscle a lot with exercise second of all it goes up a lot specifically with resistance exercise
Also said
“we published a study where we did a Time course of biopsies after resistance and endurance exercise... and yeah we found that Mick went way higher with the resistance versus the endurance”— Murach's own published data directly comparing modalities — resistance exercise clearly superior for c-Myc induction.
c-Myc kinetics after exercise: peaks at ~3 hours, back to baseline by 24 hours — pulsatile by design
After a resistance exercise bout, c-Myc rises in muscle tissue, peaks around 3 hours post-exercise, then returns to baseline by approximately 24 hours. This transient, pulsatile pattern is not a bug — it is the appropriate biological response, because sustained c-Myc expression is oncogenic.
Why this matters: The 24-hour return-to-baseline window has direct programming implications: the epigenetic reprogramming pulse needs adequate recovery time to complete before the next session activates it again. It also reframes rest days as biologically necessary for the epigenetic signal, not just muscular repair.
Murach draws an explicit analogy to mTOR: both c-Myc and mTOR are powerful activators of muscle growth/adaptation, and both become pathological when switched on constitutively. In cancer, c-Myc is one of the earliest implicated oncogenes. In skeletal muscle specifically, which is relatively cancer-resistant, the clinical risk of transient exercise-induced c-Myc is low — but the principle of pulsatility versus constitutive activation is fundamental to the safety of what might otherwise be a concerning oncogenic pathway.
it's not a big sustained increase it's not like you do an individual bout of exercise and it stays elevated for 96 hours you know like it goes up maybe it Peaks at three hours and starts coming back down it's back to Baseline by like 24 hours or so so it's kind of like this pulse and then that goes back down to Baseline
Also said
“Mick goes up after exercise and it comes back down and if you were to leave it up that would be bad because it's an oncogene as well and so Mick was one of the first genes implicated in the progression of cancer”— Explains why the pulsatile recovery to baseline is biologically critical — persistent c-Myc is a cancer driver.
Constitutive Yamanaka factor or mTOR activation causes pathology — exercise leverages pulses, not permanent upregulation
Both c-Myc and mTOR are powerful growth regulators that produce muscle adaptation when transiently activated but cause atrophy and pathology when chronically constitutively active. With aging, mTOR paradoxically rises rather than falls — suggesting aging muscle is dysregulated rather than depleted.
Why this matters: Upends the naive model that 'more mTOR = more muscle' and 'less mTOR with aging is why we lose muscle.' The reverse may be partly true for the baseline tone of mTOR.
Background
mTOR (mechanistic target of rapamycin) is classically labeled the 'master regulator of muscle growth.' The conventional aging narrative is that anabolic signaling declines with age. Murach flags the counterintuitive finding that basal mTOR goes up with aging.
This observation creates a more nuanced picture of anabolic resistance in aging muscle: it's not that the growth-signaling machinery is simply underactive — it may be that it is basally overactive (stuck in a chronically elevated state) and therefore less responsive to the acute pulse from exercise or protein feeding. The therapeutic implication is that both undershooting and overshooting of these pathways is harmful; exercise creates the right pulsatile pattern that aging may blunt.
turning on like mtor for instance you know they call that the master regulator of muscle growth mtor when you turn that on constitutively for like long periods of time it actually results in pathology and muscle atrophy like it needs to be controlled
Also said
“and interestingly as you get older mtor actually gets goes higher”— The counterintuitive finding: aging muscle has ELEVATED basal mTOR, not depleted — suggesting dysregulation rather than depletion.
Yamanaka factors reprogram epigenetics — not genetics — to shift cells toward a more plastic, adaptable state
What Yamanaka factors actually do in vivo (in muscle, with exercise) is not literal rejuvenation or regeneration — they rewrite the epigenetic code (DNA methylation patterns, histone marks) to make a cell 'more plastic,' i.e., better able to respond and adapt. This is mechanistically distinct from regeneration, which involves muscle stem cells.
Why this matters: Corrects the common misuse of the word 'rejuvenation' in longevity circles. The Yamanaka factor story in exercise is an epigenetic adaptability story, not a stem-cell regeneration story.
Background
Murach spent six years studying muscle stem cells prior to his current focus on exercise epigenetics. He has considered the regeneration question carefully and deliberately distinguishes it from the plasticity/adaptation question.
The distinction matters for translational expectations: exercise-induced c-Myc pulsing will make aging muscle more responsive to training stimuli (shift it toward a younger adaptive profile) but it will not regenerate damaged tissue or reverse the number of satellite cells. The epigenetic reprogramming story is about the quality of the response machinery, not the structural repair machinery. Murach likens the state induced by Yamanaka factors to greater cellular plasticity — 'a greater ability to adapt potentially' — which is the right framing for an exercise-science audience.
when we induce these yamanaka factors we're kind of Shifting them towards a state where they are I guess more plastic so have a greater ability to adapt potentially
Also said
“the reason how we become a fully formed human being is through these changes in epigenetics we start with stem cells which could almost become just about any type of cell and then these epigenetic changes happen as the cell progresses through its fate transition to become whatever it is”— Establishes the developmental biology foundation: Yamanaka factors are the same machinery that governs cellular fate transitions in embryogenesis.
MetaX: a publicly searchable database of exercise-induced gene expression across all published biopsy studies
Julian Zierath's group at Karolinska assembled MetaX — a compendium of gene-expression data from all published exercise biopsy studies, queryable by gene name — that allows any researcher to see whether their gene of interest is upregulated or downregulated by exercise in human muscle. Murach used it to systematically identify c-Myc as the most exercise-responsive Yamanaka factor.
Why this matters: Makes the entire field of exercise molecular biology navigable in minutes for anyone with a gene of interest — a genuinely useful public research tool for practitioners following the mechanistic literature.
The tool was created by Julian Zierath (Karolinska) and Niklas Pold. Murach describes it as 'a little website you can go to and plug in your favorite gene and see if it gets turned on with exercise and muscle.' For clinicians or coaches interested in whether a specific signaling molecule (e.g., AMPK, PGC-1α, myostatin, FOXO3) responds to resistance vs endurance exercise, MetaX aggregates the evidence base into one searchable interface rather than requiring a manual literature review.
there's a little website you can go to and plug in your favorite Gene and see if it gets turned on with exercise and muscle it's really cool it's called metax
Recommendations
Products, supplements, and tools mentioned in the episode
A publicly accessible database aggregating gene expression data from all published human exercise biopsy studies. Users can query any gene and see how it responds to resistance versus endurance exercise. Created by Julian Zierath and Niklas Pold at Karolinska.
Murach describes MetaX as the tool he used to systematically identify c-Myc as the dominant Yamanaka factor in exercise-responsive muscle tissue. The database aggregates microarray and RNA-seq data from dozens of studies that took muscle biopsies before and after different exercise modalities. It is 'really cool' in Murach's words because it lets any researcher — or curious clinician or coach — search for their gene of interest without needing to do a full literature review. This is the kind of resource that closes the gap between bench science and practitioners, making translational exercise science more accessible.
there's a little website you can go to and plug in your favorite Gene and see if it gets turned on with exercise and muscle it's really cool it's called metax
Regular resistance training as epigenetic reprogramming practice for aging muscle
Practice
Framing consistent resistance exercise not only as a hypertrophy tool but as a way to repeatedly activate the c-Myc Yamanaka factor pulse, making aging muscle more plastic and adaptive over time.
Murach's research program is specifically aimed at understanding whether the c-Myc induction from resistance exercise can be harnessed to make aging muscle adapt more like younger muscle. The practical translation is that any consistent resistance training program — even standard three-sets-of-ten protocols — is already engaging this epigenetic machinery. There is no special protocol required; the key variables are choosing resistance over endurance when the goal is epigenetic reprogramming, and maintaining training consistency so that the c-Myc pulse fires repeatedly over months and years.
vs alternatives
Endurance exercise (cycling, running) also induces c-Myc but to a significantly lower magnitude than resistance exercise. For the specific goal of maximizing the epigenetic reprogramming signal in skeletal muscle, resistance training is the evidence-based modality of choice.
can it be leveraged to make older muscle at least adapt more like a younger muscle because it has this role as the yanaka factor that can kind of make older cells appear younger again
Muscle biopsy time-course design as the gold standard for exercise-induced gene expression kinetics
Tool
Murach describes the study design that revealed c-Myc kinetics: biopsies at 30 min, 3 hours, 8 hours, and 24 hours post-exercise, comparing resistance versus endurance bouts — the reference method for mechanistic exercise science.
Lyon raises how to measure Yamanaka factor induction in humans, and Murach confirms muscle biopsy is the required technique — there is no non-invasive proxy. The time-course design is critical because a single post-exercise biopsy at 30 minutes would miss the c-Myc peak at 3 hours and might incorrectly conclude no effect. Understanding kinetics requires multiple time points. This is why many published exercise biopsy studies using a single post-exercise time point may underestimate transcription factor response magnitude.
he took a biopsy before and then took biopsy 30 minute 3 hours eight hours and 24 hours after a resistance exercise bout and an endurance exercise bout
Lines worth pulling out — contrarian, specific, or perfectly phrased
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the one that gets turned on the most with exercise is this one called Mick which is um or C mic um myyc and so we found that first of all it goes up in muscle a lot with exercise second of all it goes up a lot specifically with resistance exercise
Murach's core finding: of all Yamanaka factors, c-Myc is the exercise-responsive one, and resistance exercise is the superior modality — the central mechanistic claim of the episode.
it Peaks at three hours and starts coming back down it's back to Baseline by like 24 hours or so so it's kind of like this pulse and then that goes back down to Baseline
Quantifies the c-Myc kinetics with precision — peak at 3h, baseline by 24h — giving the listener a concrete time window for programming recovery.
Mick goes up after exercise and it comes back down and if you were to leave it up that would be bad because it's an oncogene as well and so Mick was one of the first genes implicated in the progression of cancer
The key safety caveat: the same factor that benefits aging muscle is an oncogene — making the pulsatile nature of exercise-induced activation the biological safeguard.
when we induce these yamanaka factors we're kind of Shifting them towards a state where they are I guess more plastic so have a greater ability to adapt potentially
Murach's careful, scientifically precise reframing of 'rejuvenation': the correct word is 'plasticity' — enhanced adaptability, not literal age reversal.
turning on like mtor for instance you know they call that the master regulator of muscle growth mtor when you turn that on constitutively for like long periods of time it actually results in pathology and muscle atrophy like it needs to be controlled and interestingly as you get older mtor actually gets goes higher
The counterintuitive aging finding: mTOR rises with age rather than falling, suggesting anabolic resistance is a story of dysregulation, not depletion.
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Educational summary of the cited expert source — not medical advice. Open the source recording linked above and consult a qualified physician before acting on any protocol.
