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> With the body it is almost always use it or lose it. It is wild how intense this effect is. Last year, I broke my ankle. I couldn't use that leg at all. With

> With the body it is almost always use it or lose it. It is wild how intense this effect is. Last year, I broke my ankle. I couldn't use that leg at all. Within two months, almost all of the muscle in that calf was gone. Just eight weeks and while one leg still looked normal and the other was a stick. Even the flesh that was still there was soft and spongy. When I got an X-ray later, the surgeon said I had the bones of an 80-year-old in that leg. All the bone density, just gone. It's crazy how rapidly a human body will cannibalize itself if you don't use something. From what I've heard, this is an evolutionary adaptation unique to humans. Most other animals just have the muscles they have regardless of use. But, perhaps because we went through a narrow population window during the Ice Age, we've evolved this ability to harvest our own resources to survive. Probably great for not starving to death, but a real bummer if you're trying to be fit.

purple-leafy 2y ago
Sorry to hear about your leg! When they said “80 year old bones” is that just due to the reduced usage from the broken ankle? Or something more? I feel like my bone density must’ve decreased over the years from arthritis (diagnosed at ~ 25) - less usage of the legs, less bone density. But getting back into it now, and have found a happy middle ground where I can still be pretty active and not in the pain. Cycling is the way to go, and many shorter walks more often
- munificent 2y ago
  > When they said “80 year old bones” is that just due to the reduced usage from the broken ankle? Yes, just lowered bone density from not using it. Bone density increases in response to stress placed on the bone, especially impact stress. No stress on the bone and it basically hollows out. > Cycling is the way to go Yeah, I started biking to work a few years ago for my health. That's how I broke my ankle. :-/ Slipped in a puddle and landed really wrong. Trimalleolar fracture with dislocation and severe fracture blisters.
SuperNinKenDo 2y ago
It really is wild. I don't know how your recovery is going, but for anyone worried about this kind of thibg, I will say, that the body does seem to have some kind of memory for prior use snd development generally. For those of us who have worked out moderately to intensely only to suffer an injury or life getting in the way of maintaining consistent practice at the same level, you will find that when you return to working out, you tend to return to fairly close to your prior peak in far less time than it took to get there. Similar to how muscle memory can lead to very quick progression back to your prior level of skill in something that you haven't done in years. You won't be back to your prior peak, but you'll close 70-90% of the gap shockingly quick. EDIT: One thing to look out for in situations like GP though, in which development becomes lopsided, is your body will develop lopsided compensation for the disaprity. A lot of physiotherapy often involves learning to force your body to not engage in these compensatory measures so that the diminished or injured part of your body can rebuild its strength and stability correctly.
- Baeocystin 2y ago
  Due to a gnarly accident, my right arm was in a cast for six months. They had to change the cast several times due to shrinking soft tissue, and by the time the cast came off, from wrist to elbow was all the same width. It was awful. But, like you said, it came back to the 80% level very quickly. At first I was genuinely worried that I'd never recover, but at three months I was already two-thirds of the way to normal, and was at 95% by a year.
- katzenversteher 2y ago
  I've read somewhere that the peviously trained cells, while after injury and long rest period smaller and fewer are still built with a large number of mitochondria (that was needed for the previous performance levels). This seems to be one of the muscle memory mechanisms.
  - jaggederest 2y ago
    For muscles, at least, which are not single cells but actually syncytia with multiple nucleuses, weight-bearing exercise produces an increase in the number of nucleuses and thus a relatively permanent increase in the ability of the syncytia to synthesize protein. So retraining tends to be about double or even triple the speed of the original adaptation. This is one additional reason you should be extremely skeptical about "before and after" photos
paulddraper 2y ago
I remember in high school biology watching a video describing how bone structures will literally change if your gait changes. The body is amazingly adaptable.
irjustin 2y ago
This is why people who spend even medium amounts of time in space are so crippled when they return. For any length of stay > 4 months their return home workouts are insane like 2+ hours per day.
- inglor_cz 2y ago
  This sort-of indicates that once someone goes, say, to the Moon, and stays there for five years or so, they might not be able to come back on Earth at all, or need extremely long adaptation. The difference between 0.16G and 1G would be massive. Any deployment of people to the Moon will have to take this into account. And kids born and grown in lunar gravity may not be able to come to Earth under any circumstances.
  - tsimionescu 2y ago
    It should be noted that it's not even sure that people could survive with such low gravity for a truly long time, or at least thrive. It could be that various parts of the body get weakened to a point that is even dangerous in the low gravity conditions (for example, you might find that you get a bone fissure in your leg every time you bump into the bed corner). Also, it's not at all clear that people could procreate and (especially) have a normal pregnancy in very low g conditions. We have nowhere near the kind of understanding of the gestational process that could allow us to know for sure before trying it out.
    - TeMPOraL 2y ago
      I guess the corollary here is that if it turns out some people could survive and procreate living in low-g, and some of their children could do the same, then the problem will sort itself out in couple generations :).
      - Schiendelman 2y ago
        Kind of. The problem thete is that most of the cost of your space program becomes: - palliative care for astronauts you spent millions of dollars training and billions of dollars sending to space. - childcare for their kids before they're useful.
rglynn 2y ago
I would be sceptical about such a unique evolutionary adaptation occurring in such a short time period. _The_ ice age (the last one) was just yesterday in evolutionary terms.
- throwup238 2y ago
  Punctuated equilibrium [1] is one of the predominant theories of evolution so it’s not at all far fetched. In that theory population bottlenecks are one of the main mechanisms of cladogenesis. [1] https://en.wikipedia.org/wiki/Punctuated_equilibrium https://en.wikipedia.org/wiki/Punctuated_equilibrium
  - rglynn 2y ago
    I had not heard of this before, thank you for sharing!
- ssivark 2y ago
  Adaptation need not only mean genetic (slow), it could just as well be epigenetic. The latter is not well-understood enough to be taught in school textbooks yet, but has been of great interest in recent decades. https://en.wikipedia.org/wiki/Epigenetics https://en.wikipedia.org/wiki/Epigenetics
- orlp 2y ago
  We "evolved" dog breeds in microseconds in evolutionary terms. As long as the selective pressure is high change can come fast.
  - deleted 2y ago
    [deleted]
- bmacho 2y ago
  Both the phenotype and the genotype of a species/population can, and do change overnight. Think about nazis killing people with big noses. The average nose size for humans shrank, and the responsible genes disappeared. Evolution (as the change of the characteristics of a species) working in million years is stupid. It doesn't even need one generation.
deleted 2y ago
[deleted]
safety1st 2y ago
Not to necessarily contradict your experience, but to balance it with a bit of optimism... Weight lifters who stop training often find they do lose muscle faster than they'd like. BUT, once it's packed on, muscle seems to require a lower minimum volume of training to maintain. AND, when they start training again, it comes back much faster than it did the first time around. So, there are no excuses to not get a pump :)
- jajko 2y ago
  I've been weightlifting quite a bit, nothing extreme but all the usual full body stuff plus targeted ones. I've broken my legs several times in past few years, always something unique. Last one was nasty - bad paragliding fall right on tarmac with my heels taking brunt of the hit (better them than spine). Both legs broken, 1 month wheelchair (before wheelchair came I was literally crawling between spots at home, interesting experience for sure), 2 months crutches since one leg took most of the hit and calcaneus was to pieces (yet somehow magically they stayed together so no surgery & metals required). Needless to say, after those 3 months, leg was concrete level of stiff with 0 stability working and yes all muscles gone, quads most visibly. especially jarring when next to it was a leg which still was 1 month fully out of order, and just used in 2 months, they look like from different people next to each other. That leg was the stronger and slightly but visibly bigger one before. What I want to say - losing muscles is a trivial issue, an afterthought compared to losing all flexibility and strength in tendons and ligaments, especially if you used to do tons of sports. Our joints are always the weak spot, going away much sooner than some muscles and bones, taking much longer to build safely (you really don't want to sprain or tear one). Training that takes much longer, and rebuilding muscles can only follow what connective tissues allow. I've spent countless hours in hands of physiotherapists since they come each time with novel ways and equipment use to challenge these tissues, also part of it was in the pool, really cool idea. yet still after 3 months of therapy there are still big differences in everything, at least I can walk cca ok and did a small easy skitour last weekend. Comparatively, I can easily re-build all muscles I need with just some basic home free weight equipment, you just need few good exercises done in good form, with mild variations.
- baxtr 2y ago
  Going to the gym to weight lift 2-3 a week for 30-45 minutes has changed my life profoundly. I feel more energized. My back stopped hurting. I’m in such a good mood on those days. Makes we wonder why I re-started so late.
copypasterepeat 2y ago
Does anyone have more information regarding whether this effect is only observed in humans? I've always assumed that this is just how most animal bodies work, for the obvious energy and resource conservation reasons.
MisterTea 2y ago
> but a real bummer if you're trying to be fit. Do you mean buff instead of fit?
- munificent 2y ago
  I meant "fit" in the general sense of "having good fitness" not as in "slim".

purple-leafy 2y ago

Sorry to hear about your leg! When they said “80 year old bones” is that just due to the reduced usage from the broken ankle? Or something more? I feel like my bone density must’ve decreased over the years from arthritis (diagnosed at ~ 25) - less usage of the legs, less bone density. But getting back into it now, and have found a happy middle ground where I can still be pretty active and not in the pain. Cycling is the way to go, and many shorter walks more often

munificent 2y ago
> When they said “80 year old bones” is that just due to the reduced usage from the broken ankle? Yes, just lowered bone density from not using it. Bone density increases in response to stress placed on the bone, especially impact stress. No stress on the bone and it basically hollows out. > Cycling is the way to go Yeah, I started biking to work a few years ago for my health. That's how I broke my ankle. :-/ Slipped in a puddle and landed really wrong. Trimalleolar fracture with dislocation and severe fracture blisters.

SuperNinKenDo 2y ago

It really is wild. I don't know how your recovery is going, but for anyone worried about this kind of thibg, I will say, that the body does seem to have some kind of memory for prior use snd development generally. For those of us who have worked out moderately to intensely only to suffer an injury or life getting in the way of maintaining consistent practice at the same level, you will find that when you return to working out, you tend to return to fairly close to your prior peak in far less time than it took to get there. Similar to how muscle memory can lead to very quick progression back to your prior level of skill in something that you haven't done in years. You won't be back to your prior peak, but you'll close 70-90% of the gap shockingly quick. EDIT: One thing to look out for in situations like GP though, in which development becomes lopsided, is your body will develop lopsided compensation for the disaprity. A lot of physiotherapy often involves learning to force your body to not engage in these compensatory measures so that the diminished or injured part of your body can rebuild its strength and stability correctly.

Baeocystin 2y ago
Due to a gnarly accident, my right arm was in a cast for six months. They had to change the cast several times due to shrinking soft tissue, and by the time the cast came off, from wrist to elbow was all the same width. It was awful. But, like you said, it came back to the 80% level very quickly. At first I was genuinely worried that I'd never recover, but at three months I was already two-thirds of the way to normal, and was at 95% by a year.
katzenversteher 2y ago
I've read somewhere that the peviously trained cells, while after injury and long rest period smaller and fewer are still built with a large number of mitochondria (that was needed for the previous performance levels). This seems to be one of the muscle memory mechanisms.
- jaggederest 2y ago
  For muscles, at least, which are not single cells but actually syncytia with multiple nucleuses, weight-bearing exercise produces an increase in the number of nucleuses and thus a relatively permanent increase in the ability of the syncytia to synthesize protein. So retraining tends to be about double or even triple the speed of the original adaptation. This is one additional reason you should be extremely skeptical about "before and after" photos

paulddraper 2y ago

I remember in high school biology watching a video describing how bone structures will literally change if your gait changes. The body is amazingly adaptable.

irjustin 2y ago

This is why people who spend even medium amounts of time in space are so crippled when they return. For any length of stay > 4 months their return home workouts are insane like 2+ hours per day.

inglor_cz 2y ago
This sort-of indicates that once someone goes, say, to the Moon, and stays there for five years or so, they might not be able to come back on Earth at all, or need extremely long adaptation. The difference between 0.16G and 1G would be massive. Any deployment of people to the Moon will have to take this into account. And kids born and grown in lunar gravity may not be able to come to Earth under any circumstances.
- tsimionescu 2y ago
  It should be noted that it's not even sure that people could survive with such low gravity for a truly long time, or at least thrive. It could be that various parts of the body get weakened to a point that is even dangerous in the low gravity conditions (for example, you might find that you get a bone fissure in your leg every time you bump into the bed corner). Also, it's not at all clear that people could procreate and (especially) have a normal pregnancy in very low g conditions. We have nowhere near the kind of understanding of the gestational process that could allow us to know for sure before trying it out.
  - TeMPOraL 2y ago
    I guess the corollary here is that if it turns out some people could survive and procreate living in low-g, and some of their children could do the same, then the problem will sort itself out in couple generations :).
    - Schiendelman 2y ago
      Kind of. The problem thete is that most of the cost of your space program becomes: - palliative care for astronauts you spent millions of dollars training and billions of dollars sending to space. - childcare for their kids before they're useful.

rglynn 2y ago

I would be sceptical about such a unique evolutionary adaptation occurring in such a short time period. _The_ ice age (the last one) was just yesterday in evolutionary terms.

throwup238 2y ago
Punctuated equilibrium [1] is one of the predominant theories of evolution so it’s not at all far fetched. In that theory population bottlenecks are one of the main mechanisms of cladogenesis. [1] https://en.wikipedia.org/wiki/Punctuated_equilibrium https://en.wikipedia.org/wiki/Punctuated_equilibrium
- rglynn 2y ago
  I had not heard of this before, thank you for sharing!
ssivark 2y ago
Adaptation need not only mean genetic (slow), it could just as well be epigenetic. The latter is not well-understood enough to be taught in school textbooks yet, but has been of great interest in recent decades. https://en.wikipedia.org/wiki/Epigenetics https://en.wikipedia.org/wiki/Epigenetics
orlp 2y ago
We "evolved" dog breeds in microseconds in evolutionary terms. As long as the selective pressure is high change can come fast.
- deleted 2y ago
  [deleted]
bmacho 2y ago
Both the phenotype and the genotype of a species/population can, and do change overnight. Think about nazis killing people with big noses. The average nose size for humans shrank, and the responsible genes disappeared. Evolution (as the change of the characteristics of a species) working in million years is stupid. It doesn't even need one generation.

deleted 2y ago

[deleted]

safety1st 2y ago

Not to necessarily contradict your experience, but to balance it with a bit of optimism... Weight lifters who stop training often find they do lose muscle faster than they'd like. BUT, once it's packed on, muscle seems to require a lower minimum volume of training to maintain. AND, when they start training again, it comes back much faster than it did the first time around. So, there are no excuses to not get a pump :)

jajko 2y ago
I've been weightlifting quite a bit, nothing extreme but all the usual full body stuff plus targeted ones. I've broken my legs several times in past few years, always something unique. Last one was nasty - bad paragliding fall right on tarmac with my heels taking brunt of the hit (better them than spine). Both legs broken, 1 month wheelchair (before wheelchair came I was literally crawling between spots at home, interesting experience for sure), 2 months crutches since one leg took most of the hit and calcaneus was to pieces (yet somehow magically they stayed together so no surgery & metals required). Needless to say, after those 3 months, leg was concrete level of stiff with 0 stability working and yes all muscles gone, quads most visibly. especially jarring when next to it was a leg which still was 1 month fully out of order, and just used in 2 months, they look like from different people next to each other. That leg was the stronger and slightly but visibly bigger one before. What I want to say - losing muscles is a trivial issue, an afterthought compared to losing all flexibility and strength in tendons and ligaments, especially if you used to do tons of sports. Our joints are always the weak spot, going away much sooner than some muscles and bones, taking much longer to build safely (you really don't want to sprain or tear one). Training that takes much longer, and rebuilding muscles can only follow what connective tissues allow. I've spent countless hours in hands of physiotherapists since they come each time with novel ways and equipment use to challenge these tissues, also part of it was in the pool, really cool idea. yet still after 3 months of therapy there are still big differences in everything, at least I can walk cca ok and did a small easy skitour last weekend. Comparatively, I can easily re-build all muscles I need with just some basic home free weight equipment, you just need few good exercises done in good form, with mild variations.
baxtr 2y ago
Going to the gym to weight lift 2-3 a week for 30-45 minutes has changed my life profoundly. I feel more energized. My back stopped hurting. I’m in such a good mood on those days. Makes we wonder why I re-started so late.

copypasterepeat 2y ago

Does anyone have more information regarding whether this effect is only observed in humans? I've always assumed that this is just how most animal bodies work, for the obvious energy and resource conservation reasons.

MisterTea 2y ago

> but a real bummer if you're trying to be fit. Do you mean buff instead of fit?

munificent 2y ago
I meant "fit" in the general sense of "having good fitness" not as in "slim".