Effects on the human body of living in lower than Earth gravity

For muscles, this is easy. Mostly Iso metric exercises, jogging in place, or tread mills, and any other resistant type training to keep the muscles toned but not bulked up. I can see them also wearing special clothing that helps muscles exercise during normal activity.

Muscles though are really the easy part to remedy...

You also have to worry about bone density in space, long term exposure to even low doses of radiation and how it affects the reproductive systems and internal organs, even the brain...

As to someone from earth visiting, there will be trade offs. Lots of astronauts get space sickness, which is like sea sickness. I would also think there would be a quarantine period to make sure they are not carrying something into an environment that is contained. I don't see why they would appear stronger unless there is some type of physical activity they perform that others would struggle with...

http://science.nasa.gov/science-news/science-at-nasa/2001/ast02aug_1/ (which was one of the top sites on the search recommended by Medievalist) is an easy to read non technical basic info from NASA that is good if you don't want to get technical. The short answer is those raised at 0.9 would probably adjust to it and only have problems when they shifted to 0.2 or to 1.0. The thing is we evolved at 1.0 so we really don't know how well we'd adapt to a permanent new baseline. It might be asy. It might be technically impossible. It might be minor weaknesses now might be relative strengths then. We really don't know and won't know until there is a permanent off world colony.

Healthy people would probably endure the stress but people with borderline problems might manifest with all sorts of things. Going to a lower gravity even for a few days will cause fluid shifts resulting in relative congested sinuses, congestive heart failure worsening peripheral vascular disease, (there's even been priapism), demineralization of the bones causing increased serum and urine calcium (among other things) which can trigger tremors, kidney stones. Theoretically those going from 0.9 to 1.0.

Going to a lower gravity would relatively and temporarily seem like the 1.0 is stonger than the 0.9 and even moreso compared to the 1.2, but the muscles atrophy pretty quickly.

Would moving to a higher gravity reverse all that stuff? Sort of, maybe. The metabolic stuff, perhaps; the bone strength and muscle mass, likely no or it would take a drastically long time.

Detail for you: Low G or zero G gives you wasp waist: your organs are no longer being pulled down within your body cavity and retract a bit into your ribcage.

P

Becky Black said:

I know I've seen astronauts returning to Earth after long missions having to be carried out of their vehicles because their muscles were wasted from being in microgravity for so long.

Click to expand...

Actually, I don't believe that's true. I remember some time ago a discussion about this where it turned out there's another good reason why astronauts are pampered after landing from long flights; they do exercise in orbit to maintain muscles, I have a feeling the other reason was somehow related to blood flow changes in microgravity? And in some cases I believe they're not supposed to stand after landing because the doctors want to study the effects that microgravity has had on them.

However, I would suggest that if your characters are far enough in the future to be living full time in space, then they're far enough in the future to be genetically modified so that low gravity isn't a problem anymore.

Even then the psychological effects might be significant. I remember a Russian astronaut saying that when he returned from Mir after months in orbit he took some time to get used to being unable to float around the room. Shifting between 0.2 and 0.9 could be problematic until the characters are used to the substantial differences between those gravity levels.

Becky Black said:

By the same token does it make people "taller" the way they say you're taller in the morning after lying down for several hours, giving your spine time to stretch back out after being compressed when you're upright?

Click to expand...

Yes.