Humans in a high-g environment

[lugge]

There are a lot of topics discussing humans in a low-gravity environment.
Well, what about the opposite?

Imagine we were to land on some celestial body with a more-than-1-g gravity (Please don't discuss the existence of such a body or the reason behind such journy. Lets assume we discover a new minor planet made of Unobtanium and some billionaire sets up a base there just for fun).
I guess we have to limit the gravity force to some value a human can endure for a longer period of time, would 1.5 - 2g be OK?

1) What would it feel like for an astronaut which arives at this base?
I guess it would be a hard time for him. A 85kg guy would now have a weight of 130-170kg (yeah I know kg is mass, not force of weight ;-) ) He would be exhausted quickly.
However, he would adapt (imho), because he is training all the time.
Imagine we have a gym up there. If he does his exercises (well, even going to work is an exercise up there) do you think his body could adapt after some months/years?
Would a normal guy look like Schwarzenegger after a few years?

2) When our astronaut comes back to earth he will lose his muscles and hardiness because its not longer needed.
However, for a few days/weeks/month he would be unusual strong.
Remember, he endured a constant 1.5-2g environment for years. Do you think he can compete with professional runners and weigthlifters?
Would he be some kind of Superman? ;-)

3) This scenario is even more scifi: Lets imagine our base grows and there are babys born up there?
Is this possible?
If yes, what would it be for such a spacekid when he comes to earth for the first time?

[KSK]

Interesting questions. As a quick aside to begin with, I don't think we need unobtanium, just a habitable world that's bigger than Earth but with comparable density. But that wasn't really the point of the thread so I'll move on.

1).  It would certainly be tough, especially at the start. In general, the human body is pretty economical with its resources. If you're living in zero-g, your system adapts to the reduced loads by losing surplus (for the current environment) bone strength and muscle tone. The human body can adapt back to 1g conditions (regain muscle tone and bone strength) after extended periods in 0g but it's not easy, as any astronaut returning from the ISS will tell you.

I have no idea how well that works the other way. Weightlifters and other 'extreme strength' athletes can do some pretty crazy things, so I'm guessing that your skeletomuscular system can adapt to higher gravity given time and could probably be helped along the way with steroids and the kind of drugs that are used to treat osteoporosis. However, the rest of the squishy bag of water that you call your body ( ) might not be able to adapt as easily. Your heart might not cope well with pumping heavier blood day in, day out? Your lymphatic system (that drains excess intracellular fluid from your tissues) essentially relies on 'passive pumping' caused by normal movements to work - that might not work so well either in higher gravity. Even little things like your eyeballs distorting under higher gravity might lead to complications later on.

2.  It would probably depend on the sport. Not all muscle fibres are the same, so muscles adapted for living in high G might not be whatt you want in a sprinter for example. My best 'pulled out of thin air' guess, is that our astronaut might be competitive at weightlifting and jumping, probably less so at running.

3.  Possibly, although it would be highly dependent on how much the fetus could adapt in utero.  If it is possible, the poor newborn would probably have a really rough time of it, and all the normal bumps and falls associated with learning to walk are going to be nasty in high G. You would probably be better off delivering by c-section too - being delicate about it, giving birth naturally with muscles adapted to high-G living might not be a great plan.

Edited February 29, 2016 by KSK

[RizzoTheRat]

I'd have thought a relatively small increase in g would be adapted for relatively easily.  Our bodies can already adapt to an increase in bodyweight by probably 25-50% without major problems (ie on earth you can get that big and still move around, and this would be fit people without cholesterol blocking their arteries), but it would take time as we see with astronauts adapting to 1 g again.

However as you get heavier you're going to start having much more trouble,  If you compare human bones to those of heavier mammals the bones are considerably thicker for a given length, this is because the bone material has a similar structure strength, so it needs to be thicker to support the weight.  There's a limit to how thick that bone can become and still maintain movement in the joints, and the required muscle mass around it, strong enough tendons, etc.  Bigger animals are generally less agile, and the really big ones need to be supported by sea water.

Then there's the question of how you're carrying that weight.  Someone may be able to lift their own bodyweight in a deadlift, or carry it in a rucksack, but how far could they lean over before their back gave way?  Could they break their fall if they tripped over at 2g?  Could they get up again?

My glasses start to slide down my nose at about 2.5g so there'd be no room on a high g planet for us speccy types

Edited February 29, 2016 by RizzoTheRat

[Scotius]

Hmm. Let's see - due to higher gravity you would have a body with greater muscle mass and bone density. You would also probably grow shorter - which would be beneficial if you'd happen to fall. So, generally after couple of generations you would be a proud member of the Dwarf race

[KSK]

And on a high G world you definitely do not toss a dwarf.

[RizzoTheRat]

But mining might well be a major reason for going...

[Randazzo]

As mentioned earlier, our body may be able to adapt to a certain degree, but it would (theoretically) take many generations in that environment until you have a fully adapted human being.
 

I'm more inclined to think we'd be able to adapt with technology in the interim by the time we're able to settle other planets. We already have exo-skeleton suits capable of enabling paraplegic individuals to walk for short times. If they can maintain a body upright in 1g by themselves, they should be enough to make it easy to walk around in a 2g environment. Positive airflow breathing apparatus could help with the breathing.

This of course relies on better, smaller, and more reliable power supplies by that time, but I think that's not an unreasonable assumption considering all the other things we're assuming.

[YNM]

There's this (old) link at NASA's website :

http://science.nasa.gov/science-news/science-at-nasa/2003/07feb_stronggravity/

 

 

 

 

 

[Wjolcz]

I would totally want to go to some Super Earth planet and live there for a few years. It would be a never ending workout there, but it would probably ruin your spine after a while, but then again I'm no physiotherapist, so can't be sure.

[magnemoe]

1 hour ago, Scotius said:

Hmm. Let's see - due to higher gravity you would have a body with greater muscle mass and bone density. You would also probably grow shorter - which would be beneficial if you'd happen to fall. So, generally after couple of generations you would be a proud member of the Dwarf race

 

Why should you be shorter? You would be stronger because of extra exercise, This would double for people doing lots of lifting and carrying stuff not just walking around. 
Kids raised on the planet might be shorter, this depend on how growth work in higher gravity here we do not know however as they will spend over half the day sitting or lying down the effect might not be so large main effect will be increased strength. The effect would not be inherited. 

[fredinno]

6 minutes ago, magnemoe said:

Why should you be shorter? You would be stronger because of extra exercise, This would double for people doing lots of lifting and carrying stuff not just walking around. 
Kids raised on the planet might be shorter, this depend on how growth work in higher gravity here we do not know however as they will spend over half the day sitting or lying down the effect might not be so large main effect will be increased strength. The effect would not be inherited. 

`I think her was talking about the kids.

[Shpaget]

I'm no xenobiologist, but I see no reason why a child growing up on a high g planet wouldn't cope just fine.

If he's born there he would not need to adapt at all. Yes, perhaps he would start walking a bit later compared to little earthlings, but with proper nutrition his bones and muscles would work just fine.

After all, the difference between astronauts returning to Earth after months at ISS and this scenario is quite large.

Here we are talking about the increase in gravity by factor of 2.

Returning to 1g from 0g is the increase by factor of... well, my mom told me to always eat my veggies and never to divide by 0.

[Scotius]

For the same reason people in developed countries can't cope with obesity, caused by sudden (it appeared just couple of generations ago) abundance of food. Not enough time to adjust.

[sevenperforce]

It's not really accurate to compare the shift from 0 g to 1 g with the shift from 1 g to 2+ gees, because it's a completely different set of issues. In high gravity, your capillaries will expand and you'll have a heightened risk of embolisms. Your feet will swell and suffer permanent tissue damage. Your blood pressure will go up considerably, shortening lifespan, and you'll end up with a lot of scarring due to increased incidence of muscle microtearing. There is a limit to human adaptation.