On gravity and human endurance

[Broomstick]

I think the legs can take a load of about 2.5 times their owner's weight, so 2.5 should be the absolute upper limit, as any higher and they won't be able to walk. Even then, standing might be hard, and you wouldn't be able to walk very long or run at all. (Not that most people can anyway nowadays.)

I'm curious where you got that number - I seem to recall hearing that the g-force on a runner's legs is higher than that. I may be misremembering, of course, just would like to know how solid that number is.

[Simon_Jester]

I don't think it can be all that solid.

For taking a sustained load on the legs, well... what it really comes down to is "how much weight can you lift in a leg squat?" If you can stand on one leg, in terms of physically being able to support your own weight, you can handle 2 g right there. Most people could probably stand on one leg while supporting an extra load without their leg buckling on them; they could handle more. 2.5 g, in terms of the burden your legs are trying to support, would be equivalent to standing on one leg while carrying 25% of your body weight in burden (say, a loaded backpack). I'm sure there are people who couldn't do that because their leg would give way. But I imagine there are plenty of people who could handle more.

So I suspect the maximum gravity at which people could walk (slowly and very, very carefully) will be more than 2.5 g for those in very good physical condition, but it's still there and it's not going to be more than, say, 5 g.

[avianmosquito]

I think the legs can take a load of about 2.5 times their owner's weight, so 2.5 should be the absolute upper limit, as any higher and they won't be able to walk. Even then, standing might be hard, and you wouldn't be able to walk very long or run at all. (Not that most people can anyway nowadays.)

I'm curious where you got that number - I seem to recall hearing that the g-force on a runner's legs is higher than that. I may be misremembering, of course, just would like to know how solid that number is.

That number is OR, I tested three adult males, myself included. The first one was in typical (poor) condition, the second obese, the third was me. Their force output for one leg was 1067, 1617, and 1860n. Average: 1515n (no adrenalin) Their mass was 98, 156, and 84kg. Average: 112kg.

1515/112=13.5n/kg (1.38g)

13.5*2=27n/kg (2.76g)

[Simon_Jester]

So... what's the standard deviation? Have you considered using more men to get more reliable results? Have you considered the fact that the obese subject is skewing your data, and that obese people would be idiotic to go to a high-g world in the first place, and are therefore unlikely to exist on that world?

[avianmosquito]

So... what's the standard deviation? Have you considered using more men to get more reliable results? Have you considered the fact that the obese subject is skewing your data, and that obese people would be idiotic to go to a high-g world in the first place, and are therefore unlikely to exist on that world?

1. I did what I could with what resources I had. You con't ask more than that.
2. It was [art of a comparison of physical condition based on lifestyle, (one man who ate well but didn't exercise, one exercised but didn't eat well, and one ate well and exercised) I just used its data.
3. Yeah but they make up, what is it now, 40% of the american population and counting?

[Broomstick]

Well, it's a good starting benchmark, but hardly definitive. After all, our hypothetical 2g colonists won't be standing 24/7, they'll be walking, which will impose even greater loads on them, even if they landed on the world obese they likely wouldn't stay that way (they'd either get in shape or die), and a momentary or short term load is not at all like a long term load. The human body has some capacity to add bone and muscle when repeatedly under load, how much is the question.

2.5 might be the upper limit for an acclimatized human to endure, but if you took a long time to get to the colony planet (which, presently, would seem to be the case) you might be able to gradually increase the g forces people are living under to give them maximum time to adjust and thus arrive at a higher ultimate tolerance.

[Ghost Rider]

So... what's the standard deviation? Have you considered using more men to get more reliable results? Have you considered the fact that the obese subject is skewing your data, and that obese people would be idiotic to go to a high-g world in the first place, and are therefore unlikely to exist on that world?

1. I did what I could with what resources I had. You con't ask more than that.
2. It was [art of a comparison of physical condition based on lifestyle, (one man who ate well but didn't exercise, one exercised but didn't eat well, and one ate well and exercised) I just used its data.
3. Yeah but they make up, what is it now, 40% of the american population and counting?

Actually yes, he could ask more. Your standard deviation is nothing more then looking at your friends and concluding it must be so...because your data pool is that damned limited. And fuck, your last point is complete leap of your inept logic. Thus you are concluding that since your limited data is agreeing with you it must be so and then giving a completely random percentage to skew your conclusion to be favorable instead of finding out data and coming to a conclusion based on it.

So yes, he can damn well ask more if you want to prove your point is the one that the facts favor.

[Simon_Jester]

1. I did what I could with what resources I had. You con't ask more than that.

No kidding I can ask for more. You're making a claim about the entire human species. Not just you and your two buddies, but everyone, including the people doctors would pass to go colonize a high-g alien planet.

I think I have a right to more evidence than "me and my two buddies." For example, would the obese guy realistically end up on this planet in the first place? Would any sane doctor say he could go? If not, why do you include him in the data set?

Likewise, I think I have a right to ask for standard deviations. They're really quite easy to calculate, especially for a set as small as three points. I'm sure you can do it; the real question is whether you know why you need to.

2. It was [art of a comparison of physical condition based on lifestyle, (one man who ate well but didn't exercise, one exercised but didn't eat well, and one ate well and exercised) I just used its data.

Do you understand the limitations of the data? Why they may not be as relevant as you think? In other words, are you educated enough to grasp the implications of your own methods?

3. Yeah but they make up, what is it now, 40% of the american population and counting?

What percentage of colonists sent to a random alien planet will they make up? Do you really think they won't have a physical exam for the colonists?

Actually yes, he could ask more. Your standard deviation is nothing more then looking at your friends and concluding it must be so...

Strictly speaking, his standard deviation is a number. But looking at his data, giving it would greatly weaken his conclusion...

[avianmosquito]

1. I did what I could with what resources I had. You con't ask more than that.

No kidding I can ask for more. You're making a claim about the entire human species. Not just you and your two buddies, but everyone, including the people doctors would pass to go colonize a high-g alien planet.

Ask for a rough figure, I don't have any other data on the matter other than the one figure on the internet, its results are close, and I don't trust that any furter. (It states 90kg, 1125n/leg, 2.54g total)

I think I have a right to more evidence than "me and my two buddies." For example, would the obese guy realistically end up on this planet in the first place? Would any sane doctor say he could go? If not, why do you include him in the data set?

Search google then. They'll give you a thousand different figures, all horribly skewed, ranging from 2-3g. The one the internet gave me was 2.54g, which seems to be about the average result overall. As far as the obese guy, he wasn't my friend, and he is applicable, because when the obese are such a large part of the population, they can effectively limit the number of possible colonists for whatever world if its gravity is too high for them.

Likewise, I think I have a right to ask for standard deviations. They're really quite easy to calculate, especially for a set as small as three points. I'm sure you can do it; the real question is whether you know why you need to.

2. It was [art of a comparison of physical condition based on lifestyle, (one man who ate well but didn't exercise, one exercised but didn't eat well, and one ate well and exercised) I just used its data.

Do you understand the limitations of the data? Why they may not be as relevant as you think? In other words, are you educated enough to grasp the implications of your own methods?[/quote]

I understad it was shitty. I also understand it was a biology project I did for highschool in 2003. It's the only figure I have. It's a crappy one, but it's better than nothing.

3. Yeah but they make up, what is it now, 40% of the american population and counting?

What percentage of colonists sent to a random alien planet will they make up? Do you really think they won't have a physical exam for the colonists?

Actually yes, he could ask more. Your standard deviation is nothing more then looking at your friends and concluding it must be so...

Strictly speaking, his standard deviation is a number. But looking at his data, giving it would greatly weaken his conclusion...[/quote]

Got it. Shitty number. 2003 biology project. Not very relevent.

Nonetheless, it's still the only number I have that didn't come off the internet. I could check my wife's laptop for a much more comprehensive study she did in 1999, but that would require waking her up. If you guys can wait until morning, I can provide you data based off of a standard of 20(still not much, I know) individuals for each age group and level of physical conditioning, (from 1-5. 1 being "dead man walking" 5 being "olympian athlete") 10 for each sex. 5 age groups, (0-3, 4-6, 7-10, 11-14, 15-20) 5 levels of conditioning, 500 people in total. It'll be here in the morning.

[CaptainChewbacca]

Also, at a certain surface gravity hydrogen and lighter gasses can no longer escape from the planet, and the world will turn into a gas giant during its' formation. I have a chart somewhere but I think its not a whole lot higher than 3.5g.