A practical guide for people who train, written for a smart, non-scientist audience.

Where this started. This deep dive began with Dr. Ashley Froese’s video Your Mitochondria Can Reset – Here’s How on her channel This Is Not Covered. Dr. Froese is a family physician who has a real gift for making cell biology clear, practical, and motivating. Her four-phase framework (stop the sabotage, take out the trash, force adaptation, provide raw materials) is the backbone this document is built on. Everything here started as a question her video prompted. Where this document adds nuance or updates a detail (see Appendix A), that’s the natural next step of a deep dive, not a criticism. Her video is the best short introduction to this topic we’ve found, and we recommend watching it first. More of her work: drafroese.com.

Read this first. This is an educational write-up, not medical advice. Talk to your own doctor before starting, stopping, or changing anything, especially medications. Peptides mentioned here are sold largely through an unregulated gray market in 2026. Sourcing deserves serious scrutiny, and using unapproved peptides is prohibited in tested sport (WADA category S0 and others).

How to read this document

The document moves from what it is → how it changes → what to do about it:

Evidence labels

Every important claim is tagged with how strong the evidence is. This matters because the mitochondria space is full of confident claims built on mouse studies.

• [Strong]: consistent results across multiple human randomized trials or meta-analyses.
• [Moderate]: some human trials, but results are mixed, small, or limited to certain groups.
• [Early]: one or two small human studies, or data only from people with a specific disease.
• [Mechanistic]: cell studies, animal studies, or biochemical reasoning. Plausible, but not shown to matter in people.

Part 1: The Machinery

1.1 Mitochondria: more than the powerhouse

Mitochondria are descendants of bacteria that moved into our ancestors’ cells roughly two billion years ago and never left. They still carry their own small, circular genome of 37 genes, 13 of which build parts of the energy-making machinery. You inherit them almost entirely from your mother.

Yes, they make most of your ATP. But calling them batteries misses most of what they do. Mitochondria are signaling hubs. They sense nutrients, oxygen, hormones, and stress, and they send signals back to the nucleus and the rest of the body. They help decide when a damaged cell should self-destruct, buffer calcium, generate heat, start the production of steroid hormones like testosterone and cortisol, and alert the immune system when something goes wrong.

They aren’t fixed objects either. In muscle they form a living network that constantly fuses, divides, and recycles worn-out parts. Hard-working tissues like heart, brain, and muscle pack in the most. Mature red blood cells have none.

For anyone who trains, the key point is that your mitochondrial network adapts. It grows with training and shrinks with inactivity. That makes it worth understanding.

Go deeper: Picard & Shirihai, Mitochondrial signal transduction, Cell Metabolism 2022. This review makes the case that mitochondria work as the cell’s information-processing system, not just its power plant.

1.2 ATP and the three energy systems

What ATP is

ATP (adenosine triphosphate) is the energy currency of every cell. It’s a molecule with three phosphate groups attached. Snapping off the last phosphate releases energy that powers muscle contraction, nerve signals, protein building, and nearly everything else. What’s left is ADP (two phosphates), which gets recharged back into ATP.

The key fact: you store very little ATP. At any moment your whole body holds on the order of 100 to 250 grams. Yet standard biochemistry estimates put daily ATP turnover at tens of kilograms, roughly your body weight. Every ATP molecule is recycled hundreds of times a day. Fitness, in energy terms, is how fast and how long you can recharge ADP back into ATP.

Three ways to recharge it

These systems don’t take turns. They all run at once, with the mix shifting by intensity and duration. Gastin’s review of the research found that the aerobic system contributes much earlier and more than older textbooks claimed. In an all-out effort, aerobic and anaerobic contributions are roughly equal somewhere between one and two minutes in. [Strong]

Example: A 7 to 10 minute CrossFit workout like Jackie (1000 m row, 50 thrusters, 30 pull-ups) feels like a lactate fest, but most of its total energy is paid for aerobically. Mitochondrial capacity matters a lot for workouts like that, even though local muscular fatigue and skill also play a role.

Source: Gastin, Energy system interaction and relative contribution during maximal exercise, Sports Medicine 2001.

Where creatine fits

Creatine is the backbone of the phosphocreatine system. Muscle stores creatine as phosphocreatine, which can recharge ADP to ATP almost instantly. It also acts as a shuttle: mitochondria hand their newly made energy to creatine, which carries it to the working muscle fibers. So creatine isn’t separate from mitochondrial energy. It’s part of the delivery system.

What the evidence shows:

• Creatine monohydrate raises muscle creatine stores and improves high-intensity performance and training adaptations. It has a long safety record, including multi-year use in healthy people. [Strong] (ISSN position stand, Kreider et al. 2017)
• In older adults, creatine combined with resistance training increases lean mass and strength more than training alone, regardless of dosing strategy. [Strong] (Forbes, Candow et al. 2021 meta-analysis)
• Typical dosing is 3 to 5 g/day. An optional loading phase saturates muscle faster but isn’t necessary.

A less obvious connection to NAD. Your body makes about 1 to 2 grams of creatine a day, and that process is the single largest consumer of methyl groups (from SAMe, the body’s universal methyl donor). Creatine synthesis may use around 40% of them. Taking creatine reduces how much your body has to make, which in theory frees up methyl groups for other jobs. One of those jobs is clearing excess nicotinamide from NAD⁺ boosters (see section 1.5). [Mechanistic] (Brosnan et al. 2011)

Questions worth asking

• Which energy system limits my performance? Am I gassing out in 30 seconds, or fading at minute 8?
• Does my training cover all three systems, or just the one I enjoy?
• Am I taking creatine? For most people who train, especially masters athletes, it’s the best-supported supplement in this whole document.
• Oral “ATP” supplements exist. Does swallowing ATP even make sense, given how much the body makes and recycles on its own? (Short answer: be skeptical.)

1.3 The electron transport chain (ETC)

What it is

The ETC is the assembly line inside mitochondria that turns food and oxygen into most of your ATP. It sits on the inner mitochondrial membrane, which is folded into ridges called cristae to fit in as many assembly lines as possible.

How it works, in four steps:

1. Food becomes electrons. Carbohydrates, fats, and proteins are broken down, and their energy is captured as high-energy electrons. Those electrons are carried by NADH (see 1.5) and FADH₂.
2. Electrons pass down the chain. They hop from Complex I (or II), to Coenzyme Q10, to Complex III, to cytochrome c, to Complex IV, losing a little energy at each step.
3. That energy pumps protons. The complexes use it to pump protons (H⁺) across the membrane, creating a charge difference like water behind a dam.
4. ATP synthase is the turbine. Protons flow back through ATP synthase (sometimes called Complex V), which spins and makes ATP.

At the end of the line, electrons are handed to oxygen, which becomes water. That’s why you breathe. VO₂ (oxygen consumption) is literally a measurement of how fast your electron transport chains are running.

The “exhaust”: reactive oxygen species (ROS)

A small fraction of electrons leak out early and react with oxygen to form reactive oxygen species. In excess, ROS damage nearby lipids, proteins, and mitochondrial DNA. But ROS are also signals. A burst of ROS during exercise is one of the ways your muscles learn they need to adapt. This idea is called mitohormesis, and it creates a real conflict with antioxidant supplements (see Part 3).

In one well-known trial, young men took high-dose vitamin C (1000 mg/day) and vitamin E (400 IU/day) during four weeks of training. The supplements blocked the improvement in insulin sensitivity that the training produced in the placebo group, along with the body’s own antioxidant defense response. [Moderate]: a small study in young men, but influential and consistent with other work. (Ristow et al. 2009)

How behavior affects the ETC

Questions worth asking

• Am I on medications that affect this system (statins, certain antibiotics, metformin)? If so, is that a conversation to have with my doctor, not a reason to stop them on my own?
• Am I taking high-dose antioxidants around training and blunting the signal I’m training for?
• If I’m on a statin, is CoQ10 worth a trial? (It’s low-risk; the evidence is mixed.)
• Ubiquinone vs. ubiquinol: is the more expensive “active” form worth it? (Covered in Part 3.)

1.4 Cardiolipin

What it is

Cardiolipin is a fat (phospholipid) found almost exclusively in the inner mitochondrial membrane. It’s also found in bacteria, another clue to where mitochondria came from. It’s unusual: where most membrane fats have two fatty-acid tails, cardiolipin has four, which gives it a cone shape. That shape lets it do jobs other fats can’t:

• It shapes the cristae. Its cone shape helps the inner membrane bend into its tightly folded ridges, maximizing space for assembly lines.
• It glues the assembly line together. It binds the ETC complexes and helps organize them into efficient “supercomplexes.”
• It anchors cytochrome c, one of the electron carriers.
• It’s a self-destruct signal. When cardiolipin is oxidized, cytochrome c is released and the cell can start programmed death (apoptosis).

Cardiolipin sits right next to where ROS are produced, and its tails are highly unsaturated, so it’s especially vulnerable to oxidative damage. Damaged cardiolipin means looser cristae, less efficient ETC, and more ROS: a downward spiral. [Mechanistic], well established in lab research. (Paradies et al. 2014)

A wrinkle in the “seed oils are bad” story. The main form of cardiolipin in human heart and skeletal muscle is built mostly from linoleic acid, the omega-6 fat that dominates seed oils. That doesn’t settle the seed-oil debate, which is about oxidation, processing, and overall dietary balance. But “omega-6 = bad for mitochondria” is too simple. The real question is oxidized vs. fresh fats, not omega-6 vs. none.

Barth syndrome shows how much cardiolipin matters. It’s a rare genetic disease in which cardiolipin can’t be properly remodeled. The result is heart failure, muscle weakness, and severe fatigue.

Cardiolipin antibodies: what a blood test can and can’t tell you

You can get an anticardiolipin antibody blood test; it’s common and inexpensive. But it is not a test for mitochondrial damage:

• These antibodies are used mainly to diagnose antiphospholipid syndrome (APS), an autoimmune disorder that causes blood clots and pregnancy complications. In APS the antibodies mostly target cardiolipin bound to a blood protein (β2-glycoprotein I), not cardiolipin leaking from damaged mitochondria. (2023 ACR/EULAR APS classification criteria, Barbhaiya et al.)
• Antibodies that react with cardiolipin also show up with certain infections. Classic syphilis screening tests (VDRL and RPR) use a cardiolipin-based antigen for this reason. They can also be raised temporarily by other infections and some medications.
• A positive result usually means “talk to a hematologist or rheumatologist,” not “your mitochondria are damaged.”

What does signal mitochondrial damage? When mitochondria break apart, they release fragments the immune system recognizes as “bacterial,” including mitochondrial DNA and formyl peptides. These act as danger signals and trigger inflammation. (Zhang et al. 2010, Nature) Researchers measure circulating cell-free mitochondrial DNA, along with stress hormones like GDF-15 and FGF-21. These are research and specialist tools, not routine labs yet. Part 4 covers what they can and can’t tell a healthy person.

SS-31 (elamipretide): a peptide that targets cardiolipin

SS-31 is a small peptide that concentrates in the inner mitochondrial membrane and binds cardiolipin directly. In lab studies it stabilizes cristae, preserves electron transport, and blocks cytochrome c’s damaging activity. (Szeto 2014)

The human evidence, honestly summarized:

Takeaway: SS-31 has the most serious clinical program of any mitochondria-targeted peptide, and its mechanism is well understood. But evidence that it improves performance in healthy, trained people doesn’t exist yet. Anecdotes like “my workout time dropped two minutes” are real experiences, but they can’t separate the peptide from training, pacing, familiarity, or expectation. Part 4 covers how to test yourself more rigorously.

Questions worth asking

• If I see “anticardiolipin antibodies” on a lab report, what does it actually mean? (Usually autoimmune or clotting risk, not mitochondrial damage.)
• What markers would actually reflect mitochondrial stress, and are any of them useful for me? (Part 4.)
• For SS-31: what population was the evidence in, what dose and route, and what outcome? Does any of it apply to a healthy athlete?
• Am I protecting cardiolipin in boring ways first: avoiding oxidized fats, training consistently, not smoking?

1.5 NAD⁺: what it is, and the NMN/NR confusion

What it is

NAD⁺ (nicotinamide adenine dinucleotide) is a molecule built from vitamin B3. It has two very different jobs, and confusing them is the root of most NAD marketing.

Job 1: Electron shuttle (it’s recycled, not used up). NAD⁺ picks up electrons from broken-down food and becomes NADH. NADH delivers those electrons to Complex I of the electron transport chain and turns back into NAD⁺. This cycle happens constantly and doesn’t “spend” NAD.

Job 2: Fuel for signaling and repair enzymes (it’s consumed). Three enzyme families break NAD⁺ apart to do their work:

• Sirtuins: regulators of metabolism and stress responses.
• PARPs: DNA repair enzymes, mostly in the nucleus. (The video’s description of PARPs repairing mitochondrial DNA is a stretch; their role inside mitochondria is still debated.)
• CD38: an immune and inflammation enzyme. CD38 levels rise with age, and in mice CD38 is a main driver of the age-related decline in NAD⁺. It also breaks down NMN. [Mechanistic], with supporting human tissue data. (Camacho-Pereira et al. 2016)

When those enzymes break NAD⁺ apart, the leftover nicotinamide is recycled back into NAD⁺ through a salvage pathway. The bottleneck enzyme in that pathway is called NAMPT.

So NAD⁺ decline with age may be as much a consumption problem (more CD38, more inflammation) as a supply problem. That reframes the supplement question.

The precursor family tree

Tryptophan ──(long route)─────────────────────────┐
Niacin (nicotinic acid) ──(3 steps)───────────────┤
Nicotinamide (NAM) ──NAMPT──┐                     ├──► NAD⁺
Nicotinamide riboside (NR) ─┴─► NMN ──(1 step)────┘

• NAD⁺ pills: largely broken down in the gut before absorption.
• NAD⁺ IV: popular in clinics, expensive, very little controlled human data. [Early]
• NMN: one step from NAD⁺. In the U.S., the FDA reversed its 2022 position in September 2025 and confirmed NMN can be sold as a dietary supplement. (Venable summary)
• NR: two steps from NAD⁺, more clinical trials than NMN.
• Niacin / nicotinamide: cheap and effective at raising NAD⁺, but niacin causes flushing, and high-dose nicotinamide has its own trade-offs (see methylation below).

Does NMN “work as well as NAD”?

The real questions are: does it raise NAD⁺ where it matters (muscle, brain), and does that change anything you care about?

The pattern: NMN and NR reliably raise NAD⁺ in blood. [Strong] Effects on muscle function, metabolism, and performance are small, inconsistent, and mostly from short, small trials. [Early]

How much NMN? Does weight or age change the dose?

• Human trials have used 250 to 1200 mg/day. A 4-week safety trial at 1250 mg/day found no safety problems in healthy adults. (Fukamizu et al. 2022)
• No human study has established a dose by body weight or age. Any formula you see online (e.g., “X mg per kg”) is extrapolated from mice or invented.
• Age plausibly matters in theory (more CD38 means more breakdown), but that hasn’t been tested as a dosing rule.
• Supplement quality varies. Third-party testing matters.

The free NAD⁺ booster: exercise

Twelve weeks of training increased muscle NAMPT, the salvage pathway’s bottleneck enzyme, by 12–28% with aerobic training and 25–30% with resistance training. The largest gains were in adults over 55. Fitness (VO₂peak) was the best predictor of NAMPT levels. [Moderate] (de Guia et al. 2019)

The methylation link (and where creatine comes in)

Excess nicotinamide is cleared by an enzyme (NNMT) that uses up methyl groups from SAMe. High-dose B3 can therefore increase methyl demand and raise homocysteine. This is well shown with high-dose nicotinamide, less clear at typical NMN or NR doses. [Mechanistic/Early] (Frontiers in Pharmacology review, 2024)

As covered in 1.2, creatine synthesis is the body’s biggest methyl-group consumer. Supplementing creatine reduces the body’s own creatine production, which may spare methyl groups. Some people also add TMG (trimethylglycine) alongside NAD⁺ precursors for the same reason. That combination makes sense in theory but is [Mechanistic]; it hasn’t been tested as a combination.

Creatine vs. NAD⁺, side by side: both are “energy” molecules, but they do different jobs. NAD⁺ helps make ATP (electron carrier). Creatine helps buffer and deliver ATP (phosphate reserve). One doesn’t replace the other.

Questions worth asking

• Is my NAD⁺ actually low, and how would I know? (Consumer NAD⁺ blood tests exist; validation is limited. More in Part 4.)
• Am I training enough to get the free NAMPT boost before paying for precursors?
• What outcome am I hoping NMN or NR will change, and how will I measure it?
• Am I considering my methylation load (homocysteine on bloodwork, creatine, TMG) if I’m taking high doses?
• Is my product third-party tested?

1.6 AMPK, PGC-1α, and MOTS-c

AMPK: the fuel gauge

AMPK (AMP-activated protein kinase) is the cell’s energy sensor. When ATP is being spent faster than it’s replaced, AMP and ADP levels rise and AMPK switches on. Once active, it:

• Increases glucose uptake into muscle, independent of insulin. This is one reason exercise helps blood sugar even in insulin-resistant people.
• Increases fat burning.
• Turns on cleanup (autophagy and mitophagy, covered in Part 2).
• Turns off building: it inhibits mTOR, the main muscle-growth switch. This is the root of the AMPK vs. mTOR conflict covered in Part 3.
• Activates PGC-1α, the master switch for making new mitochondria. AMPK directly modifies PGC-1α, and in mice much of AMPK’s effect on muscle genes depends on it. [Mechanistic], foundational. (Jäger et al. 2007)

“How do I get more AMPK?” is the wrong question. You don’t want AMPK on all the time. You want strong, temporary pulses of activation followed by recovery and refueling. What switches it on: exercise (especially hard or long), energy deficit and fasting, and cold exposure. Some drugs (metformin) and compounds (berberine, AICAR) activate it too, with trade-offs covered in Part 3.

Also, exercise reaches PGC-1α through several routes besides AMPK: calcium signaling from muscle contraction, stress-sensing pathways, and adrenaline. That’s one reason no pill fully replaces training.

MOTS-c: the mitochondria’s own exercise signal

MOTS-c is a 16-amino-acid peptide encoded inside mitochondrial DNA, not the nucleus. That makes it a way for mitochondria to send messages to the rest of the body (a “mitokine”).

How it works: MOTS-c disrupts the folate cycle in muscle. That causes a molecule called AICAR to build up, and AICAR activates AMPK. So yes, MOTS-c affects AMPK, indirectly. In mice it prevented diet-induced obesity and age-related insulin resistance. [Mechanistic] (Lee et al. 2015)

What is it for, then? The best current answer is that MOTS-c is part of how muscle responds to exercise:

• Exercise raises MOTS-c in human muscle and blood. In mice, injected MOTS-c improved physical capacity even when started late in life. [Mechanistic] in mice, [Early] for the human exercise response. (Reynolds et al. 2021)
• Blood MOTS-c is lower in older men than in younger men, while levels in muscle are higher. That may reflect changes in muscle fiber type with age. [Early]: small, cross-sectional study. (D’Souza et al. 2020)
• There are no published human trials of injected MOTS-c for performance, body composition, or longevity.
• It’s prohibited in sport. WADA lists MOTS-c by name as an AMPK activator under S4 (hormone and metabolic modulators). USADA notes it is marketed by wellness clinics despite not being approved for human use. (USADA, 2025 Prohibited List)

The honest pitch for MOTS-c is “an exercise mimetic.” The honest counterpoint is that exercise already raises your own MOTS-c, along with everything else exercise does that MOTS-c doesn’t.

Questions worth asking

• Am I getting real AMPK pulses (hard training, occasional fasting) and then recovering and refueling properly?
• Am I stacking AMPK activators (metformin, berberine, MOTS-c, long fasts) in a way that might work against my strength and muscle goals? (Part 3.)
• What would MOTS-c give me that training doesn’t, and what evidence would convince me?
• If I compete in tested sport: MOTS-c is explicitly banned.

Part 1 summary: five things to remember

1. Mitochondria are signaling hubs that adapt. Training is the strongest signal they respond to.
2. ATP can’t be stockpiled, only recycled. Fitness is recharge rate. Even 7 to 10 minute workouts run mostly on aerobic (mitochondrial) energy.
3. ROS are both damage and signal. That makes “more antioxidants” a bad default for people who train.
4. Lab tests and peptides need context. Anticardiolipin antibodies don’t mean mitochondrial damage. SS-31’s evidence is in sick people, not athletes.
5. NAD⁺ precursors raise blood levels reliably; performance benefits are unproven. Exercise boosts NAD⁺ recycling for free. Creatine is better supported than anything else here.

Part 2: Quality Control

Part 1 covered the machinery. Part 2 covers how your body builds, maintains, and scraps that machinery. This is where training actually changes your mitochondria, and where the “more vs. better” question gets answered.

2.1 The life cycle at a glance

Think of your mitochondria as a fleet that is constantly being expanded, serviced, and retired:

 SIGNAL                BUILD                 MAINTAIN                 RECYCLE
 (energy stress,  ──►  Biogenesis      ──►   Fusion & fission    ──►  Mitophagy
  calcium, ROS,        PGC-1α switches       Network shares parts,    Damaged pieces are
  heat)                on new parts          splits off damage        tagged and digested
        ▲                                                                  │
        └──────────── raw materials are reused to build new parts ◄────────┘

Two points that are easy to miss:

• You never build a mitochondrion from scratch. New mitochondria come only from growing and dividing existing ones. Biogenesis means expanding the network you already have.
• Building and recycling are coupled. A healthy system runs both at once. Building new parts without clearing old ones just adds clutter. Clearing without rebuilding means losing capacity.

2.2 Biogenesis: building more

The master switch: PGC-1α

PGC-1α is a “coactivator”: a protein that switches on whole programs of genes at once. When it’s activated, it:

1. Turns on nuclear genes for mitochondrial proteins. More than 1,000 mitochondrial proteins are encoded in the nucleus, versus only 13 in mitochondrial DNA.
2. Activates TFAM, which copies mitochondrial DNA so the new parts can be built from both genomes.
3. Coordinates the assembly of new ETC complexes, new membrane, and new cardiolipin.

As covered in 1.6, AMPK activates PGC-1α directly. But exercise reaches it through several channels at once: calcium released during muscle contraction, the ROS signal, stress-sensing pathways, and adrenaline. That’s why exercise is so much more effective than any single compound that pulls one lever.

What triggers biogenesis in humans

A note on the heat study: sauna is the obvious practical version, but the study used targeted muscle heating, not whole-body sauna. “Sauna builds mitochondria” is a reasonable hypothesis, not a demonstrated fact.

2.3 Dynamics: fusion and fission

In muscle, mitochondria aren’t separate beans floating in the cell. They form a connected network that is constantly reshaping itself.

• Fusion (driven by proteins called mitofusins and OPA1) merges mitochondria together. This lets them share contents: a mitochondrion with some damaged DNA or proteins can borrow working parts from a neighbor. It also helps distribute energy across the cell.
• Fission (driven by a protein called Drp1) splits them apart. This lets the cell separate damaged sections so they can be disposed of, and distribute mitochondria when cells divide.

Balance is the point. Too much fusion means damage can’t be isolated. Too much fission leaves a fragmented, inefficient network. In mice, knocking out either the fusion or the fission machinery in muscle sharply reduces exercise performance and mitochondrial function. [Mechanistic] (review: PMC8348122)

There’s no supplement that “tunes” fusion and fission in humans. Exercise appears to keep the cycle active, and that’s mostly supported by animal studies. [Mechanistic]

2.4 Mitophagy: taking out the trash

Why recycle instead of repair?

The video says mitochondria are “terrible at repairing their own DNA.” That’s partly right. Mitochondria do have some DNA repair (base excision repair, which fixes small chemical damage). But they lack several repair systems the nucleus has. The more important point is that each mitochondrion holds multiple copies of its DNA and the cell holds hundreds to thousands of mitochondria. So the efficient strategy is quality control by selection: find the bad units, remove them, and let healthy units grow and divide to replace them. [Mechanistic], well established.

How damaged mitochondria are flagged: PINK1 and Parkin

1. PINK1 is the sensor. In a healthy mitochondrion, PINK1 is constantly imported and destroyed. When a mitochondrion loses its voltage (membrane potential), PINK1 can’t be imported and builds up on the outside.
2. Parkin is the tagger. Accumulated PINK1 recruits and activates Parkin, which coats the damaged mitochondrion in “eat me” tags (ubiquitin).
3. The cell digests it. A membrane wraps around the tagged mitochondrion and delivers it to the lysosome (the cell’s recycling center), where it’s broken down into reusable raw materials.

Mutations in PINK1 and Parkin cause inherited forms of Parkinson’s disease, which shows how important this cleanup is for long-lived cells like neurons. (Narendra, Walker & Youle 2012) There are also other mitophagy routes that respond to low oxygen and energy stress, which exercise can trigger.

Mitophagy appears to decline with age, and exercise appears to restore it. Most of this comes from animal studies. Measuring mitophagy directly in human muscle is technically hard, so human data are thin. [Mechanistic] (review: PMC10142204)

Urolithin A

Urolithin A is made by gut bacteria from ellagitannins, polyphenols found in pomegranates, walnuts, and some berries. Whether you make it depends on your microbiome. Researchers classify people as producers of urolithin A, producers of A plus other urolithins, or non-producers, and the mix shifts with age. (Cortés-Martín et al. 2018) In the lab, urolithin A switches on mitophagy. The question is whether that does anything in people.

Takeaway: Urolithin A has better human evidence than most “mitochondrial” supplements: real randomized trials, real muscle outcomes. The effects are modest, the populations were untrained, and all three trials were run by the company that sells the leading product (Mitopure/Timeline). There are no trials in trained athletes. If you’re a non-producer, supplementing gets you what producers make from food. Whether that adds anything on top of serious training is unknown.

2.5 Is mitochondrial decline caused by aging, or by inactivity?

This question matters most for masters athletes.

The case for aging: In 146 healthy adults aged 18 to 89, muscle mitochondrial DNA, mitochondrial gene activity, and ATP production all fell with age. Lower ATP production tracked with lower aerobic capacity and worse glucose tolerance. (Short et al. 2005) But this was a cross-sectional study, and older people in most populations are also less active.

The case for inactivity: When researchers compared endurance-trained older adults (59–76) with sedentary ones, the trained group did not show the age-related decline in mitochondrial oxidative capacity, and had more mitochondrial protein and DNA. Some age effects remained, but they were small next to the effect of training. (Lanza et al. 2008)

The case for trainability: In a 12-week trial, high-intensity interval training improved mitochondrial respiration in both young and older adults and reversed many age-related differences in muscle proteins, especially mitochondrial ones. Resistance training improved insulin sensitivity and lean mass but not, in that study, mitochondrial respiration. Combined training got most of both. (Robinson et al. 2017)

Bottom line: Some decline is genuinely age-related, but a large share of what we call mitochondrial aging is detraining, and older muscle stays highly trainable. [Moderate–Strong]

2.6 More vs. better, and how to get both

What the research separates

Mitochondrial adaptation has two dimensions that don’t always move together:

• Content (more): how much mitochondrial machinery you have. It’s usually measured with an enzyme marker called citrate synthase.
• Function (better): how well each unit of mitochondria works. It’s measured as respiration per unit of mitochondria.

David Bishop’s group has argued that training volume mainly drives content and training intensity mainly drives function. (Bishop, Granata & Eynon 2014; Granata, Jamnick & Bishop 2018) Key studies:

How to reconcile them: For the same amount of work, intensity is a stronger stimulus. But total volume sets how much machinery you end up with, and the gains reverse within weeks when volume drops. The authors themselves describe the evidence as thin. [Moderate]

Can you get both? Yes.

The evidence supports a combined approach. Details on programming, timing, and conflicts are in Part 3. The structure looks like this:

Where peptides fit: In theory, SS-31 targets better (cardiolipin and cristae integrity) and MOTS-c amplifies the signal (AMPK). But neither has been tested alongside training in healthy people, so there’s no evidence they add anything to a well-designed program. If you experiment, measure carefully (Part 4) and change one variable at a time.

Questions worth asking

• Is my weekly training volume enough to build content, or am I doing only short, intense sessions?
• Am I doing any truly hard interval work, or is everything at the same medium effort?
• Am I lifting consistently? Muscle is the house mitochondria live in.
• What happens to my mitochondria during a deload, injury, or vacation? (Gains from a high-volume block can largely disappear within about 2 weeks of cutting volume. Plan deloads so they don’t become accidental detraining.)
• If I take urolithin A, am I a non-producer who might benefit more, and is the cost worth a modest effect?

Part 2 summary: five things to remember

1. Mitochondria are a fleet that is constantly being built, serviced, and scrapped. Health depends on all three steps running together.
2. Exercise is the strongest biogenesis signal because it hits PGC-1α through several channels at once. Lifting counts too.
3. Mitophagy is quality control by selection. Urolithin A has real but modest human evidence, all of it industry-funded and none of it in athletes.
4. Much of “mitochondrial aging” is detraining. Trained older adults keep most of their capacity, and older muscle responds strongly to training.
5. Volume builds more; intensity builds better. Combine aerobic volume, hard intervals, and lifting, and stay consistent, because gains fade within weeks.

Part 3: Levers and Conflicts

Parts 1 and 2 explained how the system works. Part 3 covers what you can pull on, and where those levers work against each other. That second part is where most protocols go wrong: stacking good things without asking whether they cancel out.

3.1 The priority stack

Before the details, here’s the order of importance. Each layer only matters if the ones beneath it are in place.

            ▲   EXPERIMENTAL    Peptides, research compounds          [Mechanistic/Early]
           ▲▲▲  TARGETED        Urolithin A, NAD⁺ precursors, CoQ10   [Early/Moderate]
          ▲▲▲▲▲ PROVEN SUPPS    Creatine, protein, omega-3 (older)    [Strong/Moderate]
        ▲▲▲▲▲▲▲ FOUNDATION      Training, sleep, enough food & protein, [Strong]
                                not sabotaging (alcohol, meds review)

A perfect peptide stack can’t make up for 5 hours of sleep and inconsistent training. The reverse is often true.

3.2 Training

Part 2 established the structure: aerobic volume for more mitochondria, hard intervals for better ones, and lifting for the muscle that houses them. The practical questions are about combining them.

Does cardio kill gains? (The “interference effect”)

The old worry was that endurance work blunts strength and muscle gains through AMPK suppressing mTOR (see 3.7). A 2022 meta-analysis of 43 studies found:

• Concurrent training does not compromise muscle growth or maximal strength compared with lifting alone. [Strong]
• It does slightly reduce explosive strength (jumps, power). That effect was clear when both were done in the same session, and disappeared when sessions were at least 3 hours apart. [Moderate]
• Age, training status, and cycling vs. running didn’t change the results.

(Schumann et al. 2022)

Practical rules:

• If power matters to you (CrossFit, sport), separate lifting and conditioning by 3+ hours when you can.
• If you must combine them, do the quality most important to you first.
• Most people who train for health don’t need to worry about interference at all.

A sample week (for orientation; Part 5 tailors it)

A note for CrossFit athletes: metcons tend to live in the medium-hard middle. They’re good training, but if all your training lives there, you may be missing both the easy volume and the truly maximal work that drive the two kinds of mitochondrial adaptation.

3.3 Nutrition

Eat enough, and enough protein

• Energy. Chronic under-eating undermines adaptation. Mitochondria can’t build new machinery without materials. This is a common, quiet problem in lean, hard-training masters athletes. [Strong] as a general principle.
• Protein. In a meta-analysis of 49 trials, protein supplementation added to gains in strength and muscle during resistance training. The benefit plateaued around 1.6 g/kg/day of total protein. The effect on muscle mass was smaller with increasing age, which fits the idea that older muscle needs a bigger protein signal. [Strong] (Morton et al. 2018)

Carbohydrates: “train low”?

“Train low” means doing some sessions with low carbohydrate stores to amplify the AMPK and PGC-1α signal. The evidence is genuinely split:

• A “sleep low” protocol in triathletes improved performance. (Marquet et al. 2016)
• A well-controlled study in elite athletes found no extra benefit over normal carbohydrate intake. Both groups improved about equally. (Gejl et al. 2017)

[Moderate], conflicting. If you try it, use it for easy sessions only. Quality sessions need fuel.

Fasting

Fasting activates AMPK and autophagy, but direct human evidence that it builds muscle mitochondria is limited. [Mechanistic] For lifters, especially masters athletes, the trade-off is protein timing: long fasting windows make it harder to spread enough protein across the day. Fasted easy aerobic sessions are a reasonable middle ground. Fasted heavy lifting and prolonged fasts work against muscle goals.

Fats

• Omega-3s (EPA/DHA): in healthy adults aged 60–85, about 3–4 g/day of fish-oil omega-3s for 6 months increased thigh muscle volume (~3.6%) and strength vs. a corn-oil control. [Moderate] (Smith et al. 2015) In older adults, omega-3s also reduced mitochondrial ROS production without changing respiration. [Early] (Lalia et al. 2017)
• Oxidized fats (repeatedly heated fryer oils, rancid oils): reasonable to minimize, as covered in 1.4. [Mechanistic]

Polyphenols and alcohol

• Polyphenol-rich foods (berries, pomegranate, walnuts, olive oil, tea) are a low-risk way to feed the bacteria that make urolithin A. Unlike high-dose antioxidant pills, food-level polyphenols haven’t been shown to blunt training adaptations.
• Alcohol is a direct mitochondrial stressor and disrupts sleep, which makes it a double hit. [Mechanistic] for the mitochondrial effect; strong evidence for the sleep effect.

3.4 Recovery: sleep, stress, heat, and cold

Sleep

Five nights of 4 hours of sleep reduced mitochondrial respiration, muscle protein synthesis, and glucose tolerance in young men. A group that added three HIIT sessions during the same sleep restriction avoided those declines. [Early] (Saner et al. 2021)

Two takeaways: sleep loss hits mitochondria directly, and when sleep is unavoidably short, a short hard session may protect you better than skipping training.

Stress

Chronic psychological stress was linked to lower mitochondrial function in one study (1.3). [Early] The practical point is to count life stress as part of your training load.

Heat

Repeated muscle heating increased mitochondrial capacity (2.2). Sauna is a reasonable add-on for recovery and heat adaptation, but its mitochondrial benefit is [Early] at best. Timing doesn’t appear to matter much.

Cold: timing matters a lot

In a 12-week study, men who took a 10-minute cold-water plunge after every strength session gained less muscle and strength than men who did an active cool-down. The cold also blunted muscle-building signals for up to 2 days. [Moderate]: a small study, but a striking result. (Roberts et al. 2015)

Strategy: don’t cold plunge right after lifting if muscle and strength are goals. Use cold on rest days, after conditioning, or several hours away from strength work. (The video promotes cold plunging for mitochondria without mentioning this conflict.)

3.5 Supplements

Creatine, NAD⁺ precursors, and urolithin A were covered in detail in Parts 1 and 2. This table puts everything in one place.

About ALA and acetyl-L-carnitine: the video is right that they’re used for diabetic neuropathy. That’s a disease setting. There’s no good evidence they improve performance or mitochondrial function in healthy, trained people. ALA is also an antioxidant, so the same timing caution applies.

3.6 Peptides and research compounds

Each compound gets the same profile. “Trial dose” means what was used in published human studies, not a recommendation. None of these has evidence of benefit in healthy, trained people.

SS-31 (elamipretide)

• What it is: A small peptide that binds cardiolipin in the inner mitochondrial membrane (1.4).
• Mechanism: Stabilizes cristae and the ETC; reduces harmful cytochrome c activity. Targets mitochondrial quality.
• Human evidence: FDA accelerated approval for Barth syndrome (2025). Missed primary endpoints in mitochondrial myopathy. A single IV dose produced a borderline, transient ATP increase in older adults. No trials in healthy or trained people.
• Trial dose: 40 mg/day subcutaneously (Barth label, MMPOWER-3).
• Sport status: Now an FDA-approved drug, so WADA’s S0 “non-approved substance” category may no longer apply. Check the current WADA list before assuming either way.
• Bottom line: The most credible mitochondria-targeted peptide, with a real mechanism and real clinical data, but not in healthy people. [Early] for anything performance-related.

MOTS-c

• What it is: A 16-amino-acid peptide encoded in mitochondrial DNA (1.6).
• Mechanism: Folate cycle → AICAR → AMPK activation. Amplifies the energy-stress signal.
• Human evidence: Exercise raises your own MOTS-c. No published human trials of injected MOTS-c.
• Trial dose: None established in humans.
• Sport status: Prohibited, listed by name under WADA S4 as an AMPK activator.
• Bottom line: Interesting mouse data. As an AMPK activator, it carries the same theoretical conflict with muscle growth as metformin (3.7). [Mechanistic]

SLU-PP-332

• What it is: Not a peptide. It’s a small-molecule activator of estrogen-related receptors (ERRs), which help drive the endurance program in muscle.
• Mechanism: Shifts muscle toward oxidative (endurance) fiber types and increases fat burning.
• Human evidence: None. In mice it increased oxidative muscle fibers and running endurance, and reduced obesity. (Billon et al. preprint) No registered human trials.
• Trial dose: None in humans.
• Sport status: Unapproved, so it falls under WADA S0.
• Bottom line: Marketed as “exercise in a bottle” from mouse data alone. [Mechanistic]

5-amino-1MQ

• What it is: A small-molecule inhibitor of NNMT, the enzyme that methylates nicotinamide (1.5).
• Mechanism: Blocking NNMT may keep more nicotinamide available for NAD⁺ recycling and spare methyl groups.
• Human evidence: None. In obese mice it reduced body weight and fat mass without changing food intake. (Neelakantan et al. 2018)
• Trial dose: None in humans.
• Sport status: Unapproved, so it falls under WADA S0.
• Bottom line: Clever biochemistry linking NAD⁺ and methylation, with no human data. [Mechanistic]

General rule for this section: with no human data, you don’t know the effective dose, the side effects, or whether the vial contains what the label says. That’s the real cost of experimenting at this layer.

3.7 The conflicts, and how to manage them

Conflict 1: Antioxidants vs. adaptation

The problem: Training creates a ROS signal that tells muscle to adapt. High-dose antioxidants can mute that signal.

Rating: [Moderate]. The cellular effect is consistent. The performance effect is less clear.

Strategy:

• Avoid high-dose vitamin C (≥1 g) and E supplements during training blocks, especially around sessions.
• Get antioxidants from food. Polyphenol-rich diets haven’t shown this problem.
• Reserve high-dose antioxidants for specific situations (illness, a competition week where adaptation isn’t the goal), and only after discussing it with a professional.

Conflict 2: AMPK vs. mTOR (endurance signal vs. growth signal)

The problem: AMPK (energy stress) suppresses mTOR (building). Stacking fasting, AMPK-activating compounds, and long conditioning sessions can tilt the balance away from muscle, which is the opposite of what masters athletes need.

What the evidence says: For training itself, the interference is smaller than feared. Concurrent training doesn’t hurt hypertrophy or maximal strength (3.2). The bigger risk is chronic, compounded AMPK activation: training, plus long fasts, plus AMPK drugs or peptides, plus under-eating.

Strategy:

• Pulse, don’t flood. Let AMPK spike during training, then switch to building: eat protein and carbohydrate after sessions.
• Keep fasting to easy days or easy sessions. Don’t lift fasted when muscle is the goal.
• Separate lifting and hard conditioning by 3+ hours when power matters.
• Be skeptical of adding AMPK activators (MOTS-c, berberine, metformin) on top of a training program that already provides the signal.

Conflict 3: Metformin (and other AMPK activators) vs. training

The evidence is human, randomized, and in older adults:

Rating: [Moderate–Strong]. Two independent randomized trials agree.

Strategy:

• If you take metformin for diabetes or prediabetes, don’t stop it on your own. Its benefits in that setting are real. Discuss timing or alternatives with your doctor.
• If you’re considering metformin purely for longevity and you train, the current evidence suggests it may cost you some of your training gains.
• Berberine activates AMPK through a similar route. There are no human training studies, but the same concern applies in theory. [Mechanistic]

Conflict 4: Cold plunge vs. strength gains

Covered in 3.4. Regular cold immersion right after lifting reduced muscle and strength gains. [Moderate]

Strategy: keep cold away from strength sessions (rest days, after conditioning, or several hours later).

Conflict 5: Too many stressors at once

Fasting, cold, heat, hard training, poor sleep, and life stress are all stressors. Each is useful in the right dose. Together, they can exceed your ability to recover, especially past 40, when recovery is slower. This is the least studied conflict and probably the most common one among biohackers. (No direct research here. This is practical judgment, not an evidence rating.)

Strategy: add one stressor at a time, and track recovery (resting heart rate, HRV, sleep, motivation, performance; see Part 4).

Questions worth asking

• Is my foundation solid (sleep, consistent training, enough food and protein) before I add anything from the upper layers?
• Am I taking anything that might be cancelling my training: high-dose antioxidants, metformin, cold plunges after lifting?
• Am I stacking AMPK activators (fasting, berberine, MOTS-c) when what I actually need is more building?
• For any peptide or research compound: what human evidence exists, what dose was tested, how do I know the product is what it says, and how will I measure whether it worked?
• If I compete in tested sport: what’s the current WADA status of everything I take?

Part 3 summary: five things to remember

1. Foundation first. Training, sleep, food, and protein outrank every supplement and peptide.
2. Cardio doesn’t kill muscle gains. Separate hard sessions by 3+ hours when power matters.
3. Some popular “health” moves cancel training benefits: high-dose antioxidants, metformin for longevity, and cold plunges right after lifting.
4. Creatine, protein, and omega-3s are the supplements with real support. Most “mitochondrial” supplements are early-stage, and some are only proven for disease.
5. Peptides and research compounds have little to no human data in healthy people. If you experiment, change one thing at a time and measure it (Part 4).

Part 4: Measurement

Everything in Parts 1–3 leads to one practical question: how do you know if anything is working? Nobody can look at your mitochondria directly outside a research lab. But you can measure what they do, and you can set up your own tests so the results mean something.

4.1 Why “it felt like it worked” isn’t enough

Any time you retest yourself, the result is a mix of the real effect and noise:

• Day-to-day variation. Even well-controlled performance tests vary by about 1–2% between attempts. Less controlled tests vary more.
• Learning effect. The first repeat of a test is noisier and usually better. In a large review of test reliability, variation between the first two trials was 1.3 times larger than between later trials. (Hopkins, Schabort & Hawley 2001)
• Training. If you’re training while you test a supplement or peptide, both are changing at once.
• Expectation. Knowing you took something can change how hard you push.

None of this means anecdotes are worthless. It means a single before-and-after comparison can’t tell you why you improved. Section 4.5 shows how to set up a test that can.

4.2 Field tests (cheap, repeatable, and most useful)

These are the workhorses. They don’t measure mitochondria directly, but they track the outputs mitochondria drive.

4.3 Lab tests (more precise, cost money)

Research-only tests (good to know about)

• ³¹P-MRS (phosphocreatine recovery): an MRI-based scan that measures how fast muscle rebuilds phosphocreatine after exercise. It’s the best non-invasive measure of mitochondrial capacity, highly reproducible (CV about 4.6%), and it tracks lab measurements on biopsied mitochondria. (Lanza et al. 2011) It’s mostly limited to research centers.
• NIRS (near-infrared spectroscopy): small sensors on the skin that track muscle oxygen use. In a lab study, NIRS recovery times closely matched ³¹P-MRS. (Ryan et al. 2013) Consumer NIRS devices exist, but their protocols aren’t standardized. [Early]
• Muscle biopsy with respirometry: the gold standard used in most of the studies in this document. Research only.

4.4 Blood markers: what’s useful, what’s not

Context labs worth having

These don’t measure mitochondria. They measure the inputs and conditions that affect mitochondria, and they catch fixable problems.

Specialty “mitochondrial” markers

Bottom line on blood: there is no validated blood test for mitochondrial health in healthy people. Use context labs to catch fixable problems, and use performance tests to track change.

4.5 Running your own experiment

If you’re going to try a supplement or peptide, a little structure turns an anecdote into useful information.

The protocol

1. Ask one question with one main outcome. For example: “Does X lower my heart rate at a fixed rowing pace?”
2. Get a real baseline. Do the test 2–3 times over 2–4 weeks before changing anything. This uses up the learning effect and shows how noisy your test is.
3. Hold everything else steady. Same training plan, sleep habits, diet, caffeine, and equipment. Log anything that changes.
4. Change one thing. Not a new stack, a new program, and a new peptide in the same month.
5. Give it enough time. The urolithin A trials ran 4 months. Training adaptations take weeks. Two weeks rarely tells you anything.
6. Retest under identical conditions. Same time of day, warm-up, and fed or fasted state.
7. Compare against your noise. If your baseline tests varied by 2%, a 1.5% improvement isn’t a signal. Look for changes clearly larger than your baseline variation.
8. Stop and retest (the “ABA” design). Measure baseline (A), then on (B), then off again (A). If the effect fades after you stop, that’s much stronger evidence than a one-way change.
9. Blind it if you can. Have someone else prepare capsules, including look-alike placebos. That’s hard with injections, so be honest about the limitation.

Worked example: testing SS-31 with Jackie

How to read the results:

• Jackie improves, but fixed-pace HR doesn’t change: likely pacing, skill, or familiarity, not a mitochondrial effect.
• Fixed-pace HR drops during B and comes back up during the second A: consistent with a real effect from the intervention.
• Fixed-pace HR drops and stays down after stopping: probably training adaptation, or a lasting effect. You can’t tell which.
• Everything improves steadily across all phases: your training is working, and the intervention’s added effect is unclear.

This won’t produce published-study certainty, but it’s far more informative than one before-and-after workout.

4.6 A practical testing menu

Part 5 maps these onto the four reader profiles.

Questions worth asking

• What’s my baseline? Do I have real numbers, or just a feeling?
• Is my test repeatable? Same conditions, same equipment, same time of day?
• Is the change I’m seeing bigger than my normal day-to-day variation?
• Am I measuring something that reflects mitochondrial function (fixed-effort HR, lactate, fat oxidation), or something with many moving parts (a benchmark workout)?
• Am I paying for a “mitochondrial” blood test that hasn’t been validated for healthy people?

Part 4 summary: five things to remember

1. There’s no validated blood test for mitochondrial health in healthy people. Track performance and use blood work for context.
2. The fixed-effort heart rate test is the best do-it-yourself mitochondrial test. It’s cheap, submaximal, and repeatable.
3. VO₂max is one of the strongest predictors of lifespan we have. It’s worth measuring properly once a year.
4. Benchmark workouts are great motivation but poor evidence. Pair them with a cleaner test.
5. Get a real baseline, change one thing, then stop and retest. The ABA design turns anecdotes into useful information.

Part 5: Application

This is where everything turns into a plan. Part 5 starts with a core protocol that applies to everyone, then shows how it changes for four types of people.

Before you start: if you’re sedentary, over 40, on medications, or have symptoms like chest pain, unusual shortness of breath, or dizziness with exertion, get medical clearance first. Never stop a prescribed medication (statins, metformin, blood pressure drugs) on your own. Bring this document to your doctor and have the conversation.

5.1 The core protocol (everyone)

The structure mirrors the video’s four phases, corrected and filled in with the evidence from Parts 1–4.

1. Stop the sabotage

• Sleep 7–9 hours. Five nights of short sleep measurably reduced mitochondrial function (3.4).
• Limit alcohol. It’s a mitochondrial stressor and a sleep disruptor.
• Review medications with your doctor. Statins and CoQ10, antibiotics when there’s a choice, and metformin if it’s being taken for longevity rather than diabetes (1.3, 3.7).
• Minimize oxidized fats and ultra-processed food. [Mechanistic], but low cost.
• Don’t cancel your training: no high-dose vitamin C or E around training, and no cold plunge right after lifting (3.7).

2. Train for both “more” and “better”

3. Recover and refuel

• Protein: work toward about 1.6 g/kg/day, spread across meals (3.3).
• Eat enough. Chronic under-eating undermines adaptation.
• Pulse, don’t flood: stress (training, fasting, cold, heat) followed by real recovery (3.7).

4. Raw materials (supplements, only after 1–3 are in place)

• Creatine monohydrate, 3–5 g/day: the one supplement that makes sense for almost every profile. [Strong]
• Everything else depends on the profile (below).

5. Measure

• Pick one fixed-effort heart rate test and one performance test (4.2). Test at baseline and every 4–8 weeks.
• Get context labs once a year (4.4).

5.2 How the four profiles differ

5.3 Masters athlete (40+, healthy and fit)

Who: trains consistently, probably 4+ days a week, often CrossFit, endurance, or mixed. Wants to keep performing and age well.

What the evidence says matters most for you:

• You can keep most of your mitochondrial capacity. Trained older adults don’t show most of the age-related decline (2.5).
• Muscle mass and power are what slip. Protein responsiveness falls with age (3.3). Lifting and creatine matter more, not less.
• Recovery is slower, so stacking stressors costs you more (3.7).

Tests

Training

• Polarize your week: 2–3 truly easy aerobic sessions (conversational), 1–2 truly hard interval sessions, and fewer medium-hard metcons than you probably do now (3.2).
• Lift heavy 2–3x/week, and keep some explosive work (jumps, Olympic lifts, sprints). Power is the quality most hurt by doing conditioning in the same session, so separate lifting and hard conditioning by 3+ hours when you can (3.2).
• Plan deloads, but keep some easy aerobic volume during them so they don’t turn into accidental detraining (2.6).

Nutrition

• Protein ≥1.6 g/kg/day, in 3–4 meals with a solid dose each.
• Fuel hard sessions. Use fasted training, if at all, only for easy aerobic work.
• Omega-3s (about 3–4 g/day EPA+DHA was used in the muscle studies in older adults) (3.3).

Supplements

Peptides (if you choose to use them)

• One at a time, using the ABA protocol (4.5), with a fixed-effort HR test as the main outcome.
• SS-31 has the strongest mechanism and clinical program, but no data in healthy people (3.6).
• MOTS-c adds an AMPK signal. If you already train hard, that’s the signal you have plenty of, and it’s the one that works against muscle building. It’s also banned by name in tested sport.
• Tested competition: check the current WADA list for everything you take (MOTS-c is explicitly prohibited; unapproved compounds fall under S0).

Watch out for

Cold plunges right after lifting; too many stressors at once (fasting + cold + heat + hard training + poor sleep); under-eating protein; letting every session become a medium-hard metcon.

5.4 20–40 athlete (healthy and fit)

Who: trains regularly, recovers well, wants to perform.

What the evidence says matters most for you:

• Your mitochondria are highly responsive to training. This is the best time to build a large aerobic base and a strength foundation that will carry into your 40s and beyond.
• Volume and consistency are your biggest levers. The big gains in the training studies came from high volume (2.6).
• Shortcuts have the least to offer you. Most supplement and peptide evidence comes from older, sedentary, or sick people. Healthy young athletes have the least room for improvement from them.

Tests

• Every 4–8 weeks: fixed-effort HR test and one time trial.
• Once (optional): a CPET gives you training zones and a baseline for later life.
• Labs: a baseline panel. Ferritin matters for endurance athletes, especially women.

Training

• Build volume progressively. It’s the main driver of mitochondrial content.
• 1–2 hard interval or sprint sessions per week for function.
• Lift 2–3x/week. Separate from hard conditioning when power is a priority.

Nutrition and supplements

• Protein around 1.6 g/kg/day, and enough total food for the training load.
• Creatine is the only supplement with a clear case.
• Skip high-dose antioxidants around training and “exercise mimetics.”

Peptides

Hard to justify. There’s no evidence of benefit in healthy, trained people, the risks of gray-market products are real, and tested sport prohibits them. Your training has far more to give you.

5.5 Couch to gym (40+, sedentary, borderline health)

Who: mostly inactive, heading toward diabetes, high blood pressure, or similar. Possibly on medications already.

What the evidence says matters most for you:

• You have the most to gain of anyone in this document. Low fitness carries the highest mortality risk, and every 1-MET improvement is linked to about 13% lower risk (4.3).
• Lifestyle beats medication for preventing diabetes. In the Diabetes Prevention Program, 3,234 people with prediabetes were assigned to lifestyle change (150 min/week of activity plus 7% weight loss), metformin, or placebo. Lifestyle cut new diabetes cases by 58%; metformin cut them by 31%. [Strong] (Knowler et al. 2002)
• Older muscle is very trainable. Interval training improved mitochondrial function in older adults about as much as in young ones (2.5).

Tests (keep them simple)

• Before starting: medical clearance and labs (HbA1c, fasting glucose and insulin, lipids, blood pressure, thyroid, vitamin D).
• Every 4–6 weeks: a walking HR test (same route, same pace, record average HR; it should drop as fitness improves), resting HR, grip strength, waist measurement.
• At 6–12 months: repeat labs. A CPET is a great motivator once you’re training consistently.

Training: a 12-week on-ramp

Nutrition and supplements

• Protein at each meal (aim toward about 1.6 g/kg/day, adjusted for kidney health with your doctor).
• Cut back on alcohol and ultra-processed food, and eat more vegetables, fruit, and oily fish.
• Creatine once you’re lifting regularly. It has strong evidence for older adults (1.2).
• Skip NAD⁺ precursors, urolithin A, and anything else until training is consistent. They’re expensive and the training will do far more.

Medications

• Don’t stop anything on your own. If you’re on a statin and get muscle aches, ask about CoQ10 (1.3). If you’re on metformin for blood sugar, it’s doing a job. Ask your doctor whether timing or dose matters for your training.

Peptides

No. There’s no evidence for this population (outside rare diseases), and the basics will deliver far larger benefits.

5.6 Normal people (20–40, borderline health)

Who: busy, mostly sedentary, maybe gaining weight or with creeping blood pressure or blood sugar. Not sick yet.

What the evidence says matters most for you:

• This is the cheapest time to fix things. Young muscle responds quickly, and the habits you build now compound for decades.
• The basics are the intervention: sleep, movement, less alcohol, real food.

Tests

• Baseline: a simple fitness test (e.g., a 20-min walk or easy jog at a fixed pace with average HR, or a 2k row), resting HR, waist, and a basic lab panel (HbA1c, lipids, blood pressure).
• Every 6–8 weeks: repeat the fitness test.

Training

• Start with the couch-to-gym on-ramp (5.5), but progress faster if you feel good. Many people can add intervals by weeks 4–6.
• Aim for 150+ min/week of aerobic activity plus 2 strength sessions within 2–3 months.
• Choose something you’ll actually keep doing. For this group, consistency matters more than the perfect program.

Nutrition and supplements

• Protein at each meal, fewer ultra-processed foods, less alcohol.
• Creatine is optional and helpful once you’re lifting. Nothing else is needed.

Peptides

No. Not needed, not studied in this population, and the basics will do far more.

Part 5 summary: the whole document on one page

1. Mitochondria are adaptive signaling hubs. They respond to how you live, and training is their strongest signal.
2. Volume builds more mitochondria; intensity makes them better; lifting builds the muscle they live in. Do all three, consistently.
3. Stop the sabotage first: sleep, alcohol, medication review, and not cancelling your training (antioxidants, cold after lifting, metformin for longevity).
4. Eat enough protein and take creatine. Most other “mitochondrial” supplements are early-stage. Urolithin A is the most credible of them.
5. Peptides have mechanisms, not proof in healthy people. If you use them, use one at a time and measure properly.
6. Measure what mitochondria do: fixed-effort heart rate, VO₂max, and lactate, plus context labs. No blood test tracks mitochondrial health in healthy people.
7. The person who goes from sedentary to consistently active gains more than any biohacker can add with any stack.

Appendix A: Video claim check

This appendix goes through the main claims in Dr. Froese’s video, Your Mitochondria Can Reset – Here’s How, and compares each with the research covered in this document.

The headline: the video holds up very well. Its framework is sound, its core science is accurate, and its most important message, that you can’t just take a pill; you have to force adaptation, is exactly what the evidence shows. Most of the items below are rated “Simplified” for a good reason: a short video for a general audience has to simplify. The notes add detail for readers who want to go deeper.

Ratings:

• Accurate: matches the evidence.
• Simplified: right direction; the full picture has more nuance.
• Overstated: the evidence is weaker than the wording suggests.
• Unverified: we couldn’t find a solid source for the specific figure.

The machinery

Phase 1: Stop the sabotage

Phase 2: Take out the trash

Phase 3: Force adaptation

Phase 4: Raw materials

Overall

Out of about 30 claims, none are wrong. Most are accurate or simplified in ways that are reasonable for a short video. A few overstate the evidence (urolithin A, cold plunging), and two specific figures couldn’t be verified. What this document adds is mostly context: how strong each piece of evidence is, where interventions conflict, and how to measure results.

Appendix B: Glossary

Appendix C: References

All sources cited in this document, grouped by where they first appear. Evidence ratings are in the main text.

Source video

• Froese A. Your Mitochondria Can Reset – Here’s How. This Is Not Covered (YouTube). Link

Part 1: The Machinery

• Picard M, Shirihai OS. 2022. Mitochondrial signal transduction. Cell Metabolism. Link
• Gastin PB. 2001. Energy system interaction and relative contribution during maximal exercise. Sports Medicine. Link
• Kreider RB et al. 2017. ISSN position stand: creatine supplementation. J Int Soc Sports Nutr. Link
• Forbes SC, Candow DG et al. 2021. Creatine ingestion strategies, lean mass, and strength in older adults (meta-analysis). Nutrients. Link
• Brosnan JT et al. 2011. The metabolic burden of creatine synthesis. Amino Acids. Link
• Ristow M et al. 2009. Antioxidants prevent health-promoting effects of physical exercise in humans. PNAS. Link
• Qu H et al. 2018. Effect of statins on circulating CoQ10 (meta-analysis). Eur J Med Res. Link
• Qu H et al. 2018. CoQ10 for statin-induced myopathy (meta-analysis). J Am Heart Assoc. Link
• Kalghatgi S et al. 2013. Bactericidal antibiotics induce mitochondrial dysfunction and oxidative damage in mammalian cells. Sci Transl Med. Link
• Picard M et al. 2018. A mitochondrial health index sensitive to mood and caregiving stress. Biological Psychiatry. Link
• Paradies G et al. 2014. Functional role of cardiolipin in mitochondrial bioenergetics. Biochim Biophys Acta. Link
• Barbhaiya M et al. 2023. ACR/EULAR antiphospholipid syndrome classification criteria. Link
• Zhang Q et al. 2010. Circulating mitochondrial DAMPs cause inflammatory responses to injury. Nature. Link
• Szeto HH. 2014. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. Br J Pharmacol. Link
• U.S. FDA. 2025. FDA grants accelerated approval to first treatment for Barth syndrome. Link
• Karaa A et al. 2023. Efficacy and safety of elamipretide in primary mitochondrial myopathy: MMPOWER-3. Neurology. Link
• Roshanravan B et al. 2021. In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide. PLOS ONE. Link
• Camacho-Pereira J et al. 2016. CD38 dictates age-related NAD decline and mitochondrial dysfunction. Cell Metabolism. Link
• Venable LLP. 2025. FDA declares nicotinamide mononucleotide is a dietary supplement. Link
• Yoshino M et al. 2021. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. Link
• Liao B et al. 2021. NMN supplementation enhances aerobic capacity in amateur runners. J Int Soc Sports Nutr. Link
• Igarashi M et al. 2022. Chronic NMN supplementation elevates blood NAD⁺ and alters muscle function in healthy older men. npj Aging. Link
• Elhassan YS et al. 2019. Nicotinamide riboside augments the aged human skeletal muscle NAD⁺ metabolome. Cell Reports. Link
• Dollerup OL et al. 2018. A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men. Am J Clin Nutr. Link
• Fukamizu Y et al. 2022. Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adults. Scientific Reports. Link
• de Guia RM et al. 2019. Aerobic and resistance exercise training reverses age-dependent decline in NAD⁺ salvage capacity in human skeletal muscle. Physiol Rep. Link
• NNMT and nicotinamide methylation review. 2024. Frontiers in Pharmacology. Link
• Jäger S et al. 2007. AMPK action in skeletal muscle via direct phosphorylation of PGC-1α. PNAS. Link
• Lee C et al. 2015. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism. Link
• Reynolds JC et al. 2021. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline. Nature Communications. Link
• D’Souza RF et al. 2020. Increased expression of MOTS-c in skeletal muscle of healthy aging men. Aging. Link
• USADA. 2025. What’s new on the 2025 WADA Prohibited List. Link

Part 2: Quality Control

• Porter C et al. 2015. Resistance exercise training alters mitochondrial function in human skeletal muscle. Med Sci Sports Exerc. Link
• Hafen PS et al. 2018. Repeated exposure to heat stress induces mitochondrial adaptation in human skeletal muscle. J Appl Physiol. Link
• Review: mitochondrial dynamics and mitophagy in skeletal muscle health and sarcopenia. Link
• Narendra DP, Walker JE, Youle RJ. 2012. Mitochondrial quality control mediated by PINK1 and Parkin. Cold Spring Harb Perspect Biol. Link
• Review: exercise, the mitochondrial unfolded protein response, and mitophagy in aging muscle. 2023. Link
• Cortés-Martín A et al. 2018. The gut microbiota urolithin metabotypes revisited. Food & Function. Link
• Andreux PA et al. 2019. The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humans. Nature Metabolism. Link
• Liu S et al. 2022. Effect of urolithin A supplementation on muscle endurance and mitochondrial health in older adults. JAMA Network Open. Link
• Singh A et al. 2022. Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in middle-aged adults. Cell Reports Medicine. Link
• Short KR et al. 2005. Decline in skeletal muscle mitochondrial function with aging in humans. PNAS. Link
• Lanza IR et al. 2008. Endurance exercise as a countermeasure for aging. Diabetes. Link
• Robinson MM et al. 2017. Enhanced protein translation underlies improved metabolic and physical adaptations to different exercise training modes in young and old humans. Cell Metabolism. Link
• Bishop DJ, Granata C, Eynon N. 2014. Can we optimise the exercise training prescription to maximise improvements in mitochondria function and content? Biochim Biophys Acta. Link
• Granata C, Jamnick NA, Bishop DJ. 2018. Training-induced changes in mitochondrial content and respiratory function in human skeletal muscle. Sports Medicine. Link
• Granata C et al. 2016. Training intensity modulates changes in PGC-1α and p53 protein content and mitochondrial respiration. FASEB J. Link
• Granata C et al. 2016. Mitochondrial adaptations to high-volume exercise training are rapidly reversed after a reduction in training volume. FASEB J. Link
• MacInnis MJ et al. 2017. Superior mitochondrial adaptations in human skeletal muscle after interval compared to continuous single-leg cycling matched for total work. J Physiol. Link

Part 3: Levers and Conflicts

• Schumann M et al. 2022. Compatibility of concurrent aerobic and strength training for skeletal muscle size and function. Sports Medicine. Link
• Morton RW et al. 2018. Protein supplementation and resistance training-induced gains in muscle mass and strength (meta-analysis). Br J Sports Med. Link
• Marquet LA et al. 2016. Enhanced endurance performance by periodization of carbohydrate intake: “sleep low” strategy. Med Sci Sports Exerc. Link
• Gejl KD et al. 2017. No superior adaptations to carbohydrate periodization in elite endurance athletes. Med Sci Sports Exerc. Link
• Smith GI et al. 2015. Fish oil-derived n-3 PUFA therapy increases muscle mass and function in healthy older adults. Am J Clin Nutr. Link
• Lalia AZ et al. 2017. Influence of omega-3 fatty acids on skeletal muscle protein metabolism and mitochondrial bioenergetics in older adults. Aging. Link
• Saner NJ et al. 2021. Exercise mitigates sleep-loss-induced changes in glucose tolerance, mitochondrial function, and protein synthesis. Molecular Metabolism. Link
• Roberts LA et al. 2015. Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. J Physiol. Link
• Mijnhout GS et al. 2012. Alpha lipoic acid for symptomatic peripheral neuropathy in patients with diabetes (meta-analysis). Int J Endocrinol. Link
• Veronese N et al. 2017. Effect of acetyl-L-carnitine in the treatment of diabetic peripheral neuropathy (meta-analysis). Eur Geriatr Med. Link
• Billon C et al. 2022. SLU-PP-332 ERR agonist in mice (preprint). bioRxiv. Link
• Neelakantan H et al. 2018. Selective NNMT inhibitors reverse high-fat diet-induced obesity in mice. Biochem Pharmacol. Link
• Gomez-Cabrera MC et al. 2008. Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations. Am J Clin Nutr. Link
• Paulsen G et al. 2014. Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans. J Physiol. Link
• Konopka AR et al. 2019. Metformin inhibits mitochondrial adaptations to aerobic exercise training in older adults. Aging Cell. Link
• Walton RG et al. 2019. Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults (MASTERS). Aging Cell. Link

Part 4: Measurement

• Hopkins WG, Schabort EJ, Hawley JA. 2001. Reliability of power in physical performance tests. Sports Medicine. Link
• Granero-Gallegos A et al. 2020. HRV-based training for improving VO₂max in endurance athletes (meta-analysis). Int J Environ Res Public Health. Link
• Leong DP et al. 2015. Prognostic value of grip strength: findings from the PURE study. Lancet 386:266–273.
• Molina-Garcia P et al. 2022. Validity of estimating VO₂max by consumer wearables (meta-analysis). Sports Medicine. Link
• Mandsager K et al. 2018. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Network Open. Link
• Kodama S et al. 2009. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events (meta-analysis). JAMA. Link
• San-Millán I, Brooks GA. 2018. Assessment of metabolic flexibility by means of measuring blood lactate, fat, and carbohydrate oxidation responses to exercise. Sports Medicine. Link
• Lanza IR et al. 2011. In vivo ³¹P-MRS vs. in vitro measures of mitochondrial capacity. J Magn Reson Imaging. Link
• Ryan TE et al. 2013. NIRS vs. ³¹P-MRS measures of muscle oxidative capacity. J Appl Physiol. Link
• Lehtonen JM et al. 2016. FGF21 is a biomarker for mitochondrial translation and mtDNA maintenance disorders. Neurology. Link
• Trumpff C et al. 2019. Acute psychological stress increases serum circulating cell-free mitochondrial DNA. Psychoneuroendocrinology. Link
• Picard M. 2021. Blood mitochondrial DNA copy number: what are we counting? Mitochondrion. Link

Part 5: Application

• Bull FC et al. 2020. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. Link
• Knowler WC et al. 2002. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. Link

Last updated: October 2026. Evidence summaries reflect sources available at that time. Supplement regulations, WADA lists, and drug approvals change, so check current status before acting.