Impact of physical activity on physical function, mitochondrial energetics, ROS production, and Ca2+ handling across the adult lifespan in men

[qBx123Yk]

Link here

https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(25)00041-2

Thorough analysis by GetHealthspan

Exercise Preserved Mitochondrial Energy Production Into the 90s. It Didn’t...

Much of what we call “mitochondrial aging” in muscle may be inactivity, not age. Older people move less, and muscle mitochondria respond to how much you move on a timescale of days, not decades. Nearly every study comparing young and old muscle has unknowingly compared active people to sedentary ones. This study broke that confound by profiling 139 men aged 20 to 93 and sorting them by physical activity, not just age, so it could ask what genuinely changes with age once movement is accounted for.

Mitochondrial energy production does not decline with age. In men who stayed active, maximal respiration held steady across the entire adult lifespan; a man in his nineties had mitochondria that respired like a man in his twenties. Where a decline appeared in inactive men, it tracked how little they moved, not how old they were. Exercise does not build better mitochondria, it builds more of them: when respiration was measured per unit of mitochondria, the differences between young and old, and between active and inactive, disappeared.

Oxidative “damage” does not rise with age either. Mitochondrial free-radical production was flat across seven decades, and, counterintuitively, active men produced more of it, not less, because free radicals are partly a signal the muscle uses to adapt to exercise. Critically, the men who produced the most showed no loss of muscle mass, strength, or function. The free-radical theory predicts the opposite, and it did not hold.

This undercuts the rationale for mitochondria-targeted antioxidant supplements. If aging muscle does not overproduce mitochondrial free radicals, there is nothing for these supplements to correct. Consistent with that, mitochondria-targeted antioxidants have repeatedly failed to prevent muscle loss in animal studies, and mice engineered for lifelong high oxidative stress do not develop accelerated muscle aging. The finding is specific to muscle and does not speak to antioxidants for heart, brain, or eye conditions.

The one genuine, age-driven defect is in calcium handling. Mitochondria buffer the calcium that drives muscle contraction, but only up to a threshold, beyond which a channel called the permeability transition pore snaps open and the mitochondrion shuts down. That threshold, the calcium retention capacity, declined with age, and unlike energy and free radicals, it was the mitochondrial function that actually tracked how strong and mobile these men were.

Exercise did not protect the calcium threshold at all. This is the pivot of the study. Physical activity protected function, body composition, insulin sensitivity, and mitochondrial number, but the calcium-handling defect declined with age regardless of how active a man was, and it was reduced even in lifelong master athletes. Exercise remains the most powerful intervention available for aging muscle; it simply does not reach this particular defect.

The decline is not gradual, it is a change of state after 60. Calcium retention capacity held nearly flat from the twenties through the fifties, then dropped sharply after 60. This matters because it means the risk builds in a specific decade rather than eroding evenly, and a study using only a young and an old group would have missed the shape entirely, drawing a straight line through a cliff.

When the pore opens, it links muscle aging to inflammation. A pore that opens too easily spills mitochondrial DNA into the cell, where the immune system treats it as a bacterial invader and triggers the same cGAS-STING and inflammasome alarms behind chronic age-related inflammation. This is a plausible mechanistic bridge between failing muscle and the broader “inflammaging” that accompanies aging, though the downstream steps were established in other work, not measured in these men.

This is one careful study, and its limits are real. It included only men, was cross-sectional so it cannot prove the calcium defect causes muscle loss rather than accompanying it, and drew from an unusually healthy, high-socioeconomic-status cohort. A serious alternative explanation, that age-related nerve loss drives both the muscle decline and the calcium changes, remains open, and the analyses that would help resolve it are not yet published.

The practical lesson is to measure your trajectory before decline announces itself. The defect this study identifies is invisible while it develops, accelerates in a specific decade, and leaves traces in physical function, body composition, and blood markers. Like blood pressure or cholesterol, the window to act is before symptoms appear, on the evidence of a measured number rather than a feeling. No single marker tells the story, but a panel tracked over time can show where you stand and where you are heading.

[CronosTempi]

@qBx123Yk

The one genuine, age-driven defect is in calcium handling. Mitochondria buffer the calcium that drives muscle contraction, but only up to a threshold, beyond which a channel called the permeability transition pore snaps open and the mitochondrion shuts down.

Yep, it’s calcium handling. For years now, I’ve been paying attention to calcium handling just because it keeps turning up as the critical pathway in aging and cell degeneration, especially in the context of NDDs.

Incidentally, wrt. muscle, this is where statins are a negative. Much as I love statins, the evidence is quite clear. Statins are not friendly to muscle tissue, and again, they affect calcium handling - not all statins equally, but all do to some extent. I think the trade off is still worth it, but the effect is there. YMMV.

[qBx123Yk]

@CronosTempi

For years now, I’ve been paying attention to calcium handling just because it keeps turning up as the critical pathway in aging and cell degeneration, es

How do you track calcium handling?

When you have time, feel free to share any posts or papers you have on that, this is not something I’ve been paying attention to.

[CronosTempi]

Well, there are tons of papers on PubMed, I’ve posted many a couple of years ago in the big Parkinson’s thread here and some other threads.

Calcium handling is specific to a given cell and tissue, so you can’t really measure it yourself, this is all molecular level investigations.

[RobTuck]

@qBx123Yk

Much of what we call “mitochondrial aging” in muscle may be inactivity, not age. Older people move less, and muscle mitochondria respond to how much you move on a timescale of days, not decades.

This is a useful study and a cautionary note even though I disagree with this generalization it attempts to make.

I have been exercising in a dedicated, serious way since I was a teenager. I have always lifted weights and for several decades I ran competitively. In my 60s and 70s, my non exercising days were filled with felling trees, cutting rounds, and splitting and stacking logs in the summer months and shoveling snow in the winter months. To this day, I generally hike steep hills once every week or two. Throughout these decades I have eaten well and taken supplements, many of which quench free radicals, even based on now decade’s old nutritional data. In fact, the only substantive dietary changes I have made in the past two decades are eliminating alcohol from my diet, significantly reducing my sugar intake, and rounding my diet to contemporary Mediterranean standards.

Nonetheless, now in my ninth decade of life, I am observing substantial and accelerating decline in mitochondrial energy production, especially in my lower body. I’m sure the decline has been playing out for decades before that but the observational knee of the curve occurred in my late 60s and the rate of change continues to accelerate despite my best efforts. This is not a complaint or even a lament. I’m grateful that I can still do almost everything physical that I was able to do as a young man. It is, however, a challenge to any claim that most of the decline I note in myself or my friends and family is associated to inactivity. When I get time, I’ll unpack this study to examine its flaws, which are surely there. Perhaps they lie only in the way of excessive claims.

[RobTuck]

Mystery solved. I don’t disagree with the claims made in the original research article. In fact, they offer findings that directly support the claims I made above when they say, “. . . mitochondrial calcium retention capacity decreases with aging regardless of physical activity and correlates with muscle mass, performance, and the stress-responsive metabokine/mitokine growth differentiation factor 15 (GDF15).” The errors appear to be limited to the Healthspan article that attempted to summarize the research.

[CronosTempi]

@RobTuck

It is, however, a challenge to any claim that most of the decline I note in myself or my friends and family is associated to inactivity

I sympathize with your frustration. However, I come at the same frustration from the other side. The endless nattering about the importance of exercise as if it’s a cureall obscures the cold hard fact that decline, aging and death are not nearly as malleable as the exercise propagandists would have you believe. The consequence of this propaganda (ahem, Peter Attia) is that we are not focusing on the real problem, which is the aging decline itself on a systemic level. “Go exercise” is the equivalent of “take two aspirin and be on your way” while cancer is ravaging your body.

You describe a life full of exercise. Fantastic - because you enjoy it - I genuinely am happy for you… find happiness wherever you can, it’s all good! I am the opposite. I resent it - your description of lifelong exercise reads like a horror story to me. I exercise only because I must - there’s a gun to my head. I would much prefer not to have that gun aimed at me. I would much rather spend that time in a concert hall, museum, national park, or having a quiet joyful conversation with friends. To me time spent in a dank gym is time spent in a torture chamber. No thanks.

The truth is: if healthspan and lifespan are your only goal, you can get away with much, much less exercise than is commonly pushed (ahem, Peter Attia) by those for whom exercise is a passion. If you want to achieve feats of lifting, running and record setting, or just really love exercise - by all means, exercise to your heart’s content (careful with that heart though with extreme endurance!). For the rest of us: do just enough, and don’t worry about perfection - it will buy you nothing you either want or actually need. Make sure you’re active enough so that your ADL are fully under your own power - it doesn’t take much at all; don’t feel guilty and don’t feel like you have to keep up with that fellow who spends all his free time in the basement displacing weights.

All that exercising and down we go right on schedule. As I lay dying, I strongly doubt that what I’ll regret most is that I didn’t spend more time at the office or at the gym. If I would have a regret it would be that I didn’t spend more time exploring the cultural fruits of human civilization, that greatest expression of Life in our cold universe. YMMV.

[qBx123Yk]

Looking at the graphs:

• there is zero correlation between mCRC and physical activity
• there is positive correlation with muscle mass: Higher mCRC correlates directly with greater skeletal muscle mass and superior physical performance

Seems contradictory, but you could just say that exercise just builds a bigger buffer of mCRC capacity, without fixing the age-related drop in mitochondrial calcium retention capacity.

[RobTuck]

I support my friends to choose to live on any part of the physical and weight bearing activity returns curve that suits them. Those for whom the thought of a gym conjures the noun ‘dank’ (what kind of gym did you visit – my gym is bright, state of the art HVAC, and full of life from toddlers to nonagenarian) can make a rational choice to enjoy life on the early part of that curve. One claim they cannot make – and this is where Attia is unarguably correct – is that they will be able to engage in the same physical activities in their last decade of life that they were able to do in previous decades: hoist a grandchild with one arm and swing them in the air, play catch or tag football, take hikes with the kids and grandkids, or especially important to me, push their airplane back in the hanger by hand when most of the 60-year-old “kids” have already purchased electric tugs.

I have good friends who choose to enjoy life on the minimalist side of the curve. To a person, they say they can do everything they could when they were younger but it is sadly painful to the rest of us that they are deceiving themselves. We slow for them in ways we hope they will not notice and become self-conscious, we let them “push” or “lift” with us, pretending that they are helping. In truth, every one of my minimalist friends in his or her 80’s is feeble by objective standards, this in spite of their claims to the contrary, which seem grow in proportion to their loss of function. What they can manage is a daily walk, albeit not too fast. The net metabolic logic is inescapable: those who do not live on the mid to upper part of the physical performance curves will lose capacity sooner than those who do and, at some point, the margin will become obvious.

Finally, I see the exercise v. anything comparisons as false logic. There is no doubt that my time spent exercising returns 1-2x in productive time – a net gain in non-exercise mental energy.

[qBx123Yk]

@qBx123Yk

This undercuts the rationale for mitochondria-targeted antioxidant supplements. If aging muscle does not overproduce mitochondrial free radicals, there is nothing for these supplements to correct. Consistent with that, mitochondria-targeted antioxidants have repeatedly failed to prevent muscle loss in animal studies, and mice engineered for lifelong high oxidative stress do not develop accelerated muscle aging. The finding is specific to muscle and does not speak to antioxidants for heart, brain, or eye conditions.

This means that makes the case that there is no need to take the following popular antioxidant:

• MitoQ
• CoQ10 / Ubiquinol
• Alpha-Lipoic Acid
• PQQ

@qBx123Yk

Mitochondrial energy production does not decline with age. In men who stayed active, maximal respiration held steady across the entire adult lifespan; a man in his nineties had mitochondria that respired like a man in his twenties. Where a decline appeared in inactive men, it tracked how little they moved, not how old they were. Exercise does not build better mitochondria, it builds more of them: when respiration was measured per unit of mitochondria, the differences between young and old, and between active and inactive, disappeared.

Very surprising to me. So now I’m wondering if those mitochondrial transplant therapies are just a waste of time for age-related muscle loss

[CronosTempi]

@RobTuck

The net metabolic logic is inescapable: those who do not live on the mid to upper part of the physical performance curves will lose capacity sooner than those who do and at some point, the margin will become obvious.

Maybe. What I find intriguing is the individual variability. Anecdote time. Back in my early 20’s I did zero exercise of any kind - I didn’t start exercising regularly until I reached mid to late 20’s. However, I of course had plenty of friends who were exercise buffs lifting and running and all that good stuff. Yet, in unscheduled challenges of the very kind you describe (equivalent to pushing the airplane etc.), it was almost a rule, that I could perform such feats at a superior level to my friends - although not things like endurance. Just explosive power, grip strength and the like. At the time this was simply put down to a quirk in the universe of some kind that went against conventional wisdom.

Today, I think science has given us a gread deal more context. Muscle size is not strictly correlated with strength. And even performance is not driven by strength in turn. It transpires that what is just if not more important is the nerve activation starting with the CNS and down the line to the muscle tissue. Some people naturally retain performance despite minimal training - whilst others must buy their performance through extensive training. I think it’s luck of the draw.

There was an interesting discussion back in the day about grip strength. I always had an iron grip, even back when I did no exercise whatsoever. I could do a hang for longer than many of my friends who specifically trained for it. The correlation between grip strength and health/longevity naturally led to the question of “trained vs untrained” being a marker - and it fell on it being a legitimate marker if you had an untrained grip strength. Merely training your grip is of some help (insofar as it allows you to lift weights better), but it doesn’t affect the underlying capacity - it’s like measuring someone’s height marking it off on a chart and then when transfering you add 10 inches - you changed the marker, but not the actual height.

Speed of reflexes, balance, proprioperception - these are not something you can readily train for, while being critical in ADL long term in the very old. You can of course train for specific situations, like balancing on a beam, but it won’t necessarily translate to better sense of balance overall, just better specific application adaptation to balancing on a beam.

People are different. Just as there are hard gainers in a gym (I happen to be a remarkably easy gainer), people have different natural reserves in muscle performance just as with all other aspects of aging, whether trained or not. And that’s how you get the non-exercising 100 year old merrily ambling about while the master athlete croaking at 86.

Some people need exercise more than others. And we should always attempt individualized medicine. You may need more exercise. Or less. There’s a very interesting study - posted somewhere on this site - where those who had naturally very high VO2Max capacity genetically also had more health problems unless they exercised a lot. Interesting variable - reflected in those rat experiments where rats that were bred to naturally have high performance and exercise levels lived shorter lives than their more sedentary cousins (Dr. Greger did a yt video about that when discussing exercise, I posted it on this site).

So, to sum up - I wouldn’t make blanket statements about the necessity of exercise one way or another. It’s fine as far as it goes, but pay attention to the individual vs the population, because ultimately all of us are individuals. We place our chips and spin the wheel. YMMV.

[RobTuck]

On your points of individual differences, I agree and even if I did not, the evidence is plentiful. There is however a debate to be had on the borderline between outliers and individual differences. For a few years in my 30s, my training schedule as a runner was identical to Frank Shorter’s. I had won a state contest and was therefore permitted to run in the regionals in Denver where Frank Shorter was the celebrity runner. I was delighted. He and I spoke a bit as we were both at the head of a group of ~1,200 runners. When the gun fired, it was perhaps 45 seconds before Frank was so far ahead of me that I could no longer make out his number. He was an outlier. I was a well trained average Joe. Genes matter and they are largely responsible for the variance that we view as exceptional and outliers, ceteris paribus. Science can be informed by these outliers but generalizations cannot reliably flow from them.

So, yes, you as a low exerciser may be stronger for your age than someone who is a high exerciser but having lived my life in gyms and on the tracks, I can tell you that it will be a significant exception. In a crowd of 30 or 300 mid-level exercisers, you will show up as the low exerciser you are.

A final point on this and with complete respect as I note your age as I see it on your profile. I generally tell people in their 60s or early 70s that they – like Attia does frequently – lack the understanding necessary to appreciate some of these issues. At age 70, I was still feeling robust and invincible. By 75, I had become aware of some of the issues I am sharing. Looking back, my appraisal of the situation – for me and for my similarly aged friends – could not have been much more wrong. This is why I generally chuckle (or grimace) when a 40-year-old podcaster offers to tell me how to exercise. My 97 year old father-in-law was telling me that after his physical, he asked his physicians if he should be doing anything differently. One of them laughed and told him it would be the height of arrogance for him – a 50 year old doc) to make any suggestions about how to eat, sleep, or exercise.

So will we gym and track rats live longer? I have no idea. I can conjecture that we might if the salient threat rests on strength and agility. I can also conjecture that a severe exercise injury could sideline us and lead to a death spiral.

[CronosTempi]

I take you at your word. It’s entirely possible that I will suddenly in my more advanced years (75+) feel weak and perform poorly with my ADL.

Of course, it’s hard to reconcile with plentiful examples of non-exercisers in very good shape in their 90’s and beyond. Just as you look at people around you, so do I. I know of several people in the Mel Brooks phenotype bucket - terrible diet, zero exercise, terrible sleeping habits, but spry and sharp as all get out in their 90’s (now 100+). OK, we don’t need to look at the total outliers rare as hen’s teeth - that’s not a sensible expectation. I’m talking about “ordinary” folks - really it’s not that rare, the average diet, active but not formal exerciser - 80’s and 90’s.

But here’s the tradeoff from my perspective. I see time as the most precious commodity at my age. I would rather prioritize my current time and proportionally discount time in my 80’s and 90’s or more (assuming I even reach that). If a concert I want to go to or exhibition comes up and so happens it requires my skipping exercise, I do so happily. I want to experience life with my mind less affected by age now - it will always be a decline. From a QOL point of view, a year NOW will always be better than a year in my 90’s. So I will gladly trade time now (including taking time away from exercise) for a slightly greater decline later. Not to mention the uncertainty that I’ll even be around later to enjoy life - accidents happen. I’m not saving for my 150’th birthday, I’m spending it now - to use a cliche, a ride in a sports covertible at 69 is more fun than at 89, especially if you happen to croak at 85. It’s all a gamble and we all calculate the odds differently. To each their own. Good discussion!

[RobTuck]

@qBx123Yk

This means that makes the case that there is no need to take the following popular antioxidant:

• MitoQ
• CoQ10 / Ubiquinol
• Alpha-Lipoic Acid
• PQQ

I can see the logic in this but, by whatever mechanism, CoQ10 increases the energy I bring to strenuous exercise. Since I have made no systematic observations, it is possible that my judgment is misattributed. I’m going to observe more closely.

[qBx123Yk]

There could be an argument for taking coq10 if on a statin, although clinical outcomes for physical performance in general are neutral. I’m tempted to look at my levels next time I test, although results would only tell me about circulating levels in the blood, not intracellular levels.

[John_Hemming]

I thought I would ask Claude for the relationship between calcium and the membrane potential:

Mitochondrial calcium handling and membrane potential (ΔΨm) are locked in a tight, bidirectional relationship — each drives the other, and together they form a control loop that’s central to both energy production and cell death.

The starting point is that mitochondria are a major calcium sink for the cell. The mitochondrial calcium uniporter (MCU complex) sits on the inner membrane and lets Ca²⁺ flow into the matrix. This isn’t active transport — it’s driven purely by the electrochemical gradient the electron transport chain builds up. The matrix sits around -150 to -180 mV relative to the cytosol, so the positively charged Ca²⁺ ion is pulled in electrophoretically. That means uniporter-mediated uptake is entirely dependent on ΔΨm being maintained: a healthy, polarized membrane gives mitochondria strong calcium-buffering capacity, while a depolarized one loses it (and can even reverse, releasing calcium back into the cytosol via the Na⁺/Ca²⁺ exchanger, NCLX).

The relationship runs the other way too. Every Ca²⁺ ion that enters the matrix carries positive charge in, which consumes a bit of the membrane potential — a transient, small depolarization. The electron transport chain compensates by pumping protons harder, which is exactly why calcium entry also stimulates respiration: matrix Ca²⁺ directly activates three key dehydrogenases (pyruvate dehydrogenase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase), accelerating the TCA cycle, boosting NADH supply to the ETC, and increasing proton pumping. So under normal physiological conditions, calcium acts as a feed-forward signal that matches ATP output to demand — a rise in cytosolic Ca²⁺ (say, during muscle contraction or neuronal firing) tells mitochondria to work harder, and ΔΨm is largely maintained or even slightly reinforced.

The dangerous part of the relationship shows up under calcium overload. If matrix Ca²⁺ rises too high — especially alongside oxidative stress, depleted adenine nucleotides, or elevated phosphate — it triggers opening of the mitochondrial permeability transition pore (mPTP), a large nonselective channel in the inner membrane. Once that opens, the membrane becomes freely permeable, ΔΨm collapses essentially instantly, ATP synthesis stops (the F1F0-ATPase can even run in reverse, burning ATP trying to restore the gradient), the matrix swells, and pro-apoptotic factors like cytochrome c leak out. This is the core mechanism behind excitotoxic neuronal death and ischemia-reperfusion injury, and it creates a vicious cycle: depolarization impairs the cell’s ATP-dependent calcium pumps (like plasma membrane and SERCA Ca²⁺-ATPases), which lets cytosolic calcium climb further, which drives more mitochondrial calcium loading and more mPTP opening.

Given the aging angle you’ve been working on with GFH, this loop is often cited as a hallmark of mitochondrial decline generally: aged mitochondria tend to run a lower resting ΔΨm and have a lower threshold for mPTP opening, so they buffer calcium less effectively and are more prone to tipping from the “healthy signaling” regime into the “overload and collapse” regime — which in turn increases ROS output (calcium-stimulated dehydrogenase activity and ETC dysfunction both contribute) and accelerates further mitochondrial and mtDNA damage.

[qBx123Yk]

Improved Calcium Homeostasis and Force by Selenium Treatment and Training in Aged Mouse Skeletal Muscle:
https://www.nature.com/articles/s41598-020-58500-x

AI summary

This study investigates how selenium supplementation and lifelong training mitigate age-related muscle decline (sarcopenia) by targeting excitation-contraction (EC) coupling and calcium release from the sarcoplasmic reticulum (SR) in mice.

Core Findings

Effects of Aging on Muscle

• Aging (22-month-old mice) leads to reduced voluntary running activity, decreased twitch and tetanic muscle force, increased fatigability, and elevated reactive oxygen species (ROS) production following contractions.

• At the protein level, aging causes a significant drop in functional ryanodine receptor type 1 (RyR1) and Selenoprotein N (Sepn) levels, accompanied by an accumulation of degraded RyR1.

Selenium Supplementation vs. Lifelong Training

• Selenium Feeding (8 weeks): Improved normalized grip force, restored in vitro twitch and tetanic force in fast-twitch (EDL) muscle, enhanced fatigue resistance, doubled SR Ca^2+ release flux, and significantly elevated Selenoprotein N levels in aged mice.

• Lifelong Running: Preserved functional, intact RyR1 content near youthful levels, reduced RyR1 degradation, tripled SR Ca^2+ release flux, and improved muscle force and fatigue resistance.

• Key Difference: While training preserved RyR1 channel protein integrity, selenium’s protective effect operated primarily by boosting Selenoprotein N to enhance SR Ca^+ efflux rates and counteract contraction-induced oxidative stress.

Muscle Mass Does Not Equal Performance

• Hyper-muscular myostatin-deficient mice (Compact strain) maintained high muscle mass into old age but exhibited lower normalized grip force, impaired SR Ca^2+ release, and increased fatigability compared to control aged mice.

• The authors conclude that acquiring excess muscle mass at a young age does not prevent age-dependent loss of physical performance or muscle quality.

Conclusion

Selenium supplementation acts as an effective nutritional strategy to rescue SR calcium kinetics and muscle contractility in aging, achieving functional improvements in muscle performance comparable to lifelong exercise.

AI synthesis of both papers, which seems to make a good case for selenium supplmentation. Selenium attacks the issue from another starting point.

Both papers address how calcium handling and oxidative stress drive age-related muscle decline, but they target two distinct cellular compartments using two different mechanisms:

Functional Feature	Sarcoplasmic Reticulum (SR) (Selenium Study)	Mitochondria (First Paper)
Primary Organelle	Sarcoplasmic Reticulum (SR) / Cytosol	Mitochondrial Matrix & Inner Membrane
Key Calcium Machinery	RyR1 (Ryanodine Receptor) & SERCA	mPTP & MCU
Pathology Mode	Reduced SR Ca^2+ release flux & elevated resting cytosolic Ca^2+	Reduced calcium retention capacity (mCRC) causing pore overload
Role of ROS	Contraction-induced ROS degrades RyR1 and impairs release kinetics	ROS sensitizes mPTP, lowering the opening threshold
Primary Biomarker	Selenoprotein N (Sepn) depletion	Elevated serum GDF15 (mtISR activation)

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1. The Interplay Between SR Release and Mitochondrial Calcium Overload

• SR Dysfunction Drives Mitochondrial Stress: The selenium paper demonstrates that aged muscle suffers from elevated resting cytosolic Ca^2+ and sluggish SR release flux due to RyR1 degradation. When the SR fails to properly sequester and regulate calcium, the surrounding mitochondria are exposed to chronic calcium leakage.

• Overload Threshold: In the first paper, aged mitochondria already suffer from a reduced calcium retention capacity (mCRC). The chronic cytosolic Ca^2+ elevation documented in the selenium study further pushes these sensitive mitochondria past their lowered mCRC threshold, triggering mPTP opening, energy failure, and GDF15 release.

2. Antioxidant Efficacy: SR Protection vs. Mitochondrial Resistance

• Why Selenium Works for the SR: The first paper notes that general mitochondria-targeted antioxidants often fail to stop sarcopenia because aging muscle does not overproduce the mitochondrial free radicals required to trigger mPTP opening. However, the selenium paper shows that ROS is actively generated during tetanic muscle contractions and degrades RyR1 in the SR.

• Targeted Recovery: Selenium succeeds where mitochondrial antioxidants fail because it upregulates Selenoprotein N, specifically protecting the SR calcium release channel (RyR1) from contractile oxidative stress rather than attempting to fix intrinsic mitochondrial retention mechanics.

3. The Myostatin Paradox (Mass vs. Quality)

• Both papers confirm that increasing muscle mass without fixing calcium handling is ineffective:

• The selenium paper shows that myostatin-deficient (Compact) mice maintain large muscle mass into old age but suffer from severe SR $\text{Ca}^{2+}$ release defects, high resting cytosolic Ca^2+, and rapid fatigability.

• The first paper explains the downstream consequence: expanding mass without restoring mCRC or protecting calcium channels leaves the enlarged tissue reliant on organelles vulnerable to mPTP opening and metabolic failure under stress.

Summary of the Connection
Selenium rescues muscle performance by fixing cytosolic calcium kinetics at the level of the SR (upregulating Selenoprotein N to protect RyR1). This improvement in SR function indirectly shields mitochondria by preventing the cytosolic calcium spikes and baseline accumulation that would otherwise trigger mPTP opening, mtISR activation, and elevated GDF15.

[qBx123Yk]

Another good opttion for Ca^2+ homeostatis is Urolitihin A, which works by triggering mitophagy. This in turn helps make better mitochondria that have a higher calcium buffer.

Urolithin A (UA)—formulated commercially under names like Mitopure—has been evaluated in several randomized clinical trials (RCTs) specifically targeting older adults, sarcopenia, and age-related decline in muscle function.

Instead of increasing muscle mass (hypertrophy), Urolithin A acts on muscle quality and endurance by activating mitophagy—clearing out dysfunctional, calcium-leaking mitochondria to restore overall mitochondrial network efficiency.

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Key Clinical Trials in Older & Middle-Aged Adults

1. The JAMA Network Open Trial (Older Adults, Average Age 72)

• Design: A randomized, double-blind, placebo-controlled trial evaluating 1,000 mg/day of Urolithin A vs. placebo for 4 months in adults aged 65–90.
• Key Findings:
• Muscle Endurance: Participants taking UA showed a statistically significant increase in first-to-last repetition muscle endurance (measured via handgrip and leg muscle contractions until fatigue) compared to placebo.
• Mitochondrial Health & Inflammation: Muscle biopsies revealed up-regulated plasma acylcarnitines and lowered circulating C-reactive protein (CRP) and proinflammatory cytokines, indicating improved cellular energetics and less chronic inflammation.
• Functional Benchmark: The 6-minute walk distance (6MWT) did not show a statistically significant increase over placebo, demonstrating that UA’s primary effect is delaying local muscle fatigue rather than boosting global aerobic distance in non-frail cohorts.

2. The ATLAS Trial / Cell Reports Medicine Study (Middle-Aged to Older Adults, Ages 45–70)

• Design: Randomized trial testing 500 mg and 1,000 mg/day doses for 4 months in overweight/sedentary adults.
• Key Findings:
• Muscle Strength: Showed a ~12% increase in muscle strength (measured via hamstring maximum voluntary contraction and knee flexion) in the absence of any prescribed exercise intervention.
• Aerobic & Peak Performance: The 1,000 mg cohort showed significant trends toward increased $\text{VO}_2$ peak, increased power output, and a mean increase of +33 meters on the 6-minute walk test.
• Biomarker Modulation: Muscle biopsies confirmed up-regulated expression of mitochondrial oxidative phosphorylation (OXPHOS) genes.

3. Ongoing/Recent Trials on Sarcopenia & Frailty (65–85 Years)

• Frailty & Sarcopenic Atrophy: Active trials are evaluating Mitopure in frail, elderly cohorts (65–85 years) to measure changes in mitochondrial ATP production rate and recovery from extended physical exhaustion.
• Synergy with Exercise: Studies investigating UA in combination with resistance training in sarcopenic patients show that UA enhances exercise adaptation by improving Ca^2+ buffering in skeletal muscle cells and lowering exercise-induced damage markers (such as creatine kinase).

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How Urolithin A Targets Sarcopenic Ca^2+ Dysfunction

In sarcopenia, damaged mitochondria leak reactive oxygen species , which oxidizes adjacent $SERCA$ pumps and $RyR1$ channels, causing a chronic cytosolic Ca^2+ spill.

1. Restoring Ca^2+ Buffering through Mitophagy: UA selectively clears these “leaky” mitochondria before they trigger widespread Ca^2+ dysregulation and apoptosis.
2. Mitigating Muscle Strain: By stabilizing the remaining mitochondrial network, UA lowers intracellular oxidative stress, preserving SERCA pump re-uptake speed during contraction.

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Dosing & Safety Highlights in Clinical Literature

• Effective Dose: 500 mg to 1,000 mg daily.
• Safety Profile: Trials up to 2,500 mg/day demonstrate high tolerability with no serious adverse events reported, leading to FDA GRAS (Generally Recognized as Safe) status.

[MJB]

Years of research on APOE4 genes say that genotype responds better to exercise than any other measure. I think people are different in many, many ways and there is not one answer for anyone. We have to get to know our bodies and our challenges and look at our family history and lab work to increase the accuracy of our guessing game and do our very best and the rest is for God to decide.

[MJB]

I have used all of these and PQQ made a noticeable difference in my energy. Nothing with the others. I took ALA for years hoping my hearing would be spared but it’s heading south…