I’m having trouble finding non-paywalled sources on the deterioration of mitochondria as we age, and it all seems to be mice research on life-span, which wouldn’t show that it relates to the vague concept of “having less energy”. There also seems to be multiple lines of newer research that call into question it being much of a factor even for life-span.
I’d be happy to learn something new if someone has good sources though.
Technical, but interesting:
Almost everyone here is comparing younger adults to older adults. Here’s the lone exception:
Indeed, children can literally run circles around adults, or even teens. If we could know why, that might answer this whole thread. Is there any research to back up naita’s explanation?
I think it’s mostly just physics, but that’s a layman’s evaluation. If you look at animals though, there is a general trend towards higher bodylengths/time “speeds” for smaller animals.
Here’s a quote from one of the papers cited. That’s just one paper from the critical side, but it seems pretty clear to me here that our knowledge of what happens to our mitochondria and what effect it has macroscopically, is being oversold in this thread.
Despite decades of research and recent advances in generating mouse models with increased mutational loads, the study of mitochondrial DNA mutations in aging still has not reached a stage at which clear, definitive conclusions can be drawn regarding causal relationships. Although multiple elegant and plausible hypotheses have been formulated, the functional relevance of mtDNA mutation accumulation in human and mouse aging, or even in mutator mouse premature aging, remains unclear
This is definitely in the realm of hypotheses that require further research, and – like many things in medicine – I think the consensus will tend to swing pendulum-style until a basic consensus is reached, but … it surely seems to make a lot of sense, and to comport with current knowledge, that much of what we perceive as energy is highly dependent on our mitochondria:
http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/mitochondria.html
http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/enercyc.html
There’s a bit of a ‘quantum physics’ aspect to all of this. I’m not sure how near we are to the ‘very foundation of our humanity’ from a biochemical/molecular biology perspective, but mitochondria may be akin to the batteries that power many of our most basic functions.
If and as those batteries begin to age …
So you looked at a review paper that examined (and cited) many studies on mitochondria in humans and came to the conclusion that a decrease in mitochondrial function is correlated with ageing…and chose to find something from among the cites that seems to sound equivocal and jumped on that?
Anyway, the conclusion of that specific paper seems entirely consistent with what I said. I said that the exact reason(s) why mitochondrial function declines is disputed. It is – so we can’t say for sure yet that it is mtDNA mutation accumulation. Additionally I said that whether it’s a primary cause or merely one of the results of ageing is also unclear.
What is clear is the correlation, and the effect it has on, for example, skeletal muscle endurance.
And while it’s possible to maintain much of mitochondrial function with regular interval training, for a while, as with all aspects of ageing there are diminishing returns.
My perception is that it sure takes A LOT more effort to be very fit at 60, than it did at 40 or 50. I admit I am considerably less active than I used to be (tons of martial arts/lifting/marathons), but I still bike hard 25-35 miles 2-3x/week, and I swam 2-3x/week pre-COVID.
Watching my grandkids kicks my ass more than raising my kids did 30+ years ago. And boy, do I love my naps. Every time I go to a doctor, the comment on what good shape I’m in, but I feel like a creaky/soft old man compared to what I used to feel/see in the mirror.
Yeah, I’m in my 50’s. I wasn’t an athlete so much, but I was a linesman for AT&T and did more physical work in a week than most did in a month. I was very fit and strong.
Now granted, I got hurt at work and “broke” my back in my late 30’s, limiting the physical work I can do today. But I’ve met very few at my age that don’t long for their energy levels of their 20s.
And maybe it just isn’t energy levels, hell I don’t have the motivation I did when I was younger.
And to let you all know, I’m not a couch potato, I work a lot. Last month averaging 75 hours a week. What can I say I like to work.
No, I skimmed through the review noticed it was quite equivocal in all its positive statements and included a lot of references to research showing mitochondria deteriorating without an increase in aging effects that the writers considered important to include, and used one of them as an example of that. If I was going to argue against your specific post overselling mitochondria over psychological factors I would have quoted this line from the review itself instead:
Interestingly, endurance exercise also conferred phenotypic protection and prevented the premature mortality observed in the mitochondrial mutator mice mentioned above.
And I’ll repeat myself again: the main problem with this topic is that “less energy” is not a clear an unambiguous statement. When the OP now distinguishes it from motivation and mentions “energy levels” that doesn’t really help either. Humans don’t have easily measurable “energy levels” that influence their activity.
Quite the opposite. Having kids forced me to be far more physically active than I had been. Kids run around and you have to keep up. Kids need to be lifted, for comfort, for diaper changes, for games, and to move them from place to place.
I completely believe that regular physical activity increases your subjective energy level. But that’s an independent effect from how aging decreases your subjective energy level. Good for you if you’ve never noticed it, but most people do. I’m surprised this claim is even a little controversial.
The conclusion and abstract are pretty unequivocal however, so the simple fact is that this review does indeed support the conclusion of a decrease in mitochondrial function with age, and this being associated with decreased endurance / performance.
There’s certainly potential for ambiguity or misunderstandings here, I’d agree with that. But I don’t see it as such a big issue; I think it’s only necessary to clarify first “If you mean you get tired by physical exertion more quickly, then …”. That’s the most obvious interpretation.
There was a thread recently about “What surprised you about getting older?” or something like that, and one of the main responses was about energy levels. e.g. Older dopers complained that they had to basically plan one major activity for the day, as a long shopping trip or whatever might leave them pooped out.
I knew I should have been more specific. Having children can of course involve more physical activity, depending on one’s baseline level, but it’s not necessarily the kind of physical activity one wants to gain or maintain high “energy”.
It’s right there in the term “subjective energy level”. People interpret it differently.
But that also correlates with being out of shape. How many of those older dopers had a history of keeping up the medically recommended level of cardio? There’s also the question of what one considers “old”. The OP is 55 and compares his “energy” to when he was 20-30.
There’s also research showing our idea of what it means to get older influences our experience of it. Expecting to slow down as one ages is a self-reinforcing attitude, and expecting to stay at the same “energy level” helps counteracting a lot of the factors involved in feeling ones “energy levels” are lower.
I’m sure we wouldn’t be all that far apart in opinion if we took the time to map out the various factors influencing “subjective energy levels” and changes in physical fitness as one ages. I certainly don’t disagree that our bodies get less capable, more achy, etc. as we age.
Everything about us ages, it would be very strange if the amount of work we could do somehow remained constant.
To be clear on my position, let’s go to something like bone density where there’s far less possibility of misunderstanding. A good diet and exercise are important in maintaining bone density for a long time. From your 40s onwards though, the decline becomes harder to completely ameliorate, and by your 60s the most perfect diet we know of can only reduce the speed of decline, not halt it entirely.
A lot of factors of ageing are like this, and it’s no surprise that mitochondrial output follows a similar pattern.
If someone were to say their latest bone density test showed a decrease between the ages of 30 and 55, sure, we can offer advice on trying to improve that stat. But we should not imply that they themselves have necessarily caused the issue with their lifestyle choices as all else being equal this is the pattern we expect to see on average.
Are you me?
That describes exactly my situation, down to the 50 km a week (though imperial units allow me some slack time, as I my target is 30mi while your 50km is 31mi.)
As much as I fight the inevitable, the effects of middle age manifest themselves in me not being to run as quickly as when I was younger nor as far. And there are more odd aches and pains.
I also agree with Mijin. We just slow down as we age, some faster than others, and lifestyle makes a difference to how fit you are when you are older, or indeed, if you even become old.
Speaking from experience, I have noticed a decline in energy about every decade. It starts young; even the most hyperactive teenager can’t keep up with a five year old for sheer energy, but then five year olds don’t have much endurance. And one aspect of getting older is that you have to pace yourself more, not least because you don’t bounce back so quickly from injuries or over-exertion or over-anything, for that matter.
I know of people who seem full of energy even when older, but I wonder how long that can last, and whether they need to a rest when I am not looking.
But, looked at from another perspective, we are expecting too much. Nature designed us to reproduce and to live long enough to bring up the kiddies, since homo sapiens takes a very long tome to be physically mature when compared with other animals. (Yes, we are animals. Some more so than others. But I digress) And if you compare animals, take a look at dogs. Bounding around, full of energy, always ready for a game. But they do not live all that long in human terms, and an old dog is a different matter. They too get tired and weary.
Essentially, humans were not designed to live beyond about 35 or 40, by which time we see signs of aging even today. We can cheat Nature up to a point, but not indefinitely. The aging process can be slowed, but not stopped or reversed at our current state of medical knowledge. Whether that will ever change is a moot point. Exercise is beneficial. but that is all.
Cool, I finally meet my doppelganger / organ backup 
50km was just a WAG average, you may run more than me.
And yeah, my experience is the same as yours; times and distances are going down. 10km at a time is still fun, but half marathons or more have become gruelling
Good point; animals would have been a better counterpoint to the arguments above about energy levels being a matter of “attitude”.
Right. And I know it’s tough for many people to accept.
Looking back, I think when I was young, I did subconsciously see ageing as largely self-inflicted: from smoking, eating junk, not getting enough exercise, not moisturizing.
That’s partly because of how the cosmetics industry and pop-medical media presents things. And partly because we all know at least one guy with substance abuse issues who looks like shit at 30.
So I felt like since I was doing the right things I would essentially be peter pan (also, crazy futuristic dates like “2021” seemed unimaginably far away).
So for me, as absurd as it sounds, there was a point, as a grown adult, of needing to come to terms with the fact that I will get old. I can maintain more of my health and function for longer with the right behaviour. But I am swimming against an increasingly powerful tide.
“…the arguments above about energy levels being a matter of “attitude””
Attitude and determination go only so far; there comes a point when the body says “no more.” In the past when mountaineering, I could push myself more and draw on a reserve of erengy, as it were. The, on a trip when I was 35, I found that the reserve was no longer there. I had to manage with what I had. Funny, but these “steps” in energy decline or bodily aging seemed to come at or close to mid-decade, 25, 35, 45, 55, 65.
I live a very healthy lifestyle, but so did my brother. Until he died from cancer. And that is the bugbear of all anti-aging programs or bodily renewal schemes. Revitalizing the body cells makes us very vulnerable to cancer, due to faults in cell duplication. The faults accumulate as we get older.
“But I am swimming against an increasingly powerful tide.”
It’s like the Norse sagas, where Loki wrestles with a little old man who finally wears him down. As Loki found, nobody can beat old age.
An interesting take on this is The Hobbit, where the ring confers strange powers to the wearer. When Bilbo Baggins has the ring, he does not become any older. But he also lives a very quiet, withdrawn life. It brings to mind those sponges in the Antarctic ocean that are supposed to be thousands of years old. What is time to a sponge? What sort of existence is it anyway? And would the ring have conferred, if not immortality, a lifespan exceeding that of Methuselah?
Another issue with an extended lifespan is preserving the brain. Not in formalin in a bottle, but maintaining its functions during life. Dementia is becoming an increasing problem in a population that increasingly reaches three digits. The brain seems to have problems of its own with maintaining its energy.