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One of the most often cited drawbacks to settlement of other planets and satellites is the negative health effects of reduced gravity. Among the most severe of these is loss of bone density, reduced muscle mass, and weakened immune system. It seems that at least the first two of these effects could be directly solved by simply increasing a person's effective weight.

In other words, would wearing heavy clothing or other equipment be enough to mitigate the negative effects of reduced gravity?

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  • $\begingroup$ Note: Mars has a reduced gravity compared to ours, Europa has an increased gravity compared to ours. So the highest drawback would be different gravities, not just reduced gravity. Imagine how much harder it would be to even land or walk on a planet with three times the gravity! $\endgroup$ – RhysW Jul 17 '13 at 12:51
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    $\begingroup$ @RhysW Europa has a surface gravity of 1.314 m/s², Earth has 9.81 m/s². Did you perhaps confuse 1.314 m/s² with 1.314g? $\endgroup$ – gerrit Jul 17 '13 at 16:49
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    $\begingroup$ @Gwenn, there are also muscles within the body that will atrophy; weights only work for the locomotion muscles. $\endgroup$ – user39 Jul 17 '13 at 19:09
  • $\begingroup$ Related: space.stackexchange.com/questions/6420/… $\endgroup$ – Russell Borogove Apr 27 '18 at 5:26
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To fully counteract the reduced gravity, the extra weight would need to be distributed evenly across every cell in your entire body.

Why?

The idea of weighted clothing would certainly help with muscles like those in your legs, which serve to support you. Other areas of your body, however, wouldn't be helped.

Take, for example, your vital organs. Your organs are optimized to function at 9.81-ish m/s². What if a problem with the heart is discovered when immensely long amounts of time are spent in a different gravitational field? You would need to apply the extra weight to at least every cell in the heart.

Another area to note is digestion. Since your digestive system is optimized to function at 1 g, there may be problems when in 0.7 g, etc. You would then probably need to apply the extra weight to every cell of food that enters the astronaut.

Nonetheless, the idea of wearing a weighted vest would solve, or at least reduce, some of the problems with reduced gravity, such as reduced bone mass in your legs, etc.


But really, who wants to wear a weighted vest when you could jump nine feet high?

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    $\begingroup$ +1 for a good answer. Do you have any citations for the digestive problems? I haven't read anything about it from the ISS experiments, so I've always thought that 0.7g, etc would be close enough. $\endgroup$ – Gwen Jul 21 '13 at 21:55
  • $\begingroup$ No, no citations, purely theoretical. Still, there has to be something that would go wrong. I'll look for citations sometime soon :) $\endgroup$ – Undo Jul 21 '13 at 21:56
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Known problems from reduced gravity:

  • Osteoporosis
  • Motor muscle atrophy
  • Heart muscle atrophy

The natural process of bone replacement is compromised in 0-G. It's also been shown by experiments to be compromised by lack of long-axis stress on the long bones - stresses like walking induce microfractures which proceed to get "healed" with stronger bone. How much gravity is needed to maintain bone health is not yet known, but the lack of long-bone stress can be compensated by vigorous exercise with elastic bands holding one down. (This has been demonstrated on US space stations.)

Motor muscle atrophy can be partially compensated by vigorous exercise with elastic resistance. This is not sufficient to maintain full pre-flight strength for those in microgravity.

Peripheral cardiovascular effects are apparently temporary (cite). The heart muscle, like all muscle, will not maintain condition and muscle density when loading is reduced. Lower gravity will require less pressure to push blood up into the brain; this reduced effort will result in lowered heart muscle condition, and eventually, atrophy. (cite)

The use of a weighted vest will increase both required muscle effort for walking, and impact stress from walking. The decreased velocity, however, will still not result in the same effect as normal gravity, at least not without excessive mass. (Remember, E=MV^2.)

The use of a weighted vest will not, however, result in increased direct load on the cardiovascular system, so heart atrophy is likely.

TLDR: No, a weighted suit will not eliminate the health effects of reduced gravity. It will ameliorate some of them.

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  • $\begingroup$ This is a good answer, @aramis, but please note that I was asking specifically about low gravity on other planets, not 0g/microgravity. I think that most of what you say still applies, but could you rephrase your answer to reflect that? Thanks! $\endgroup$ – Gwen Jul 21 '13 at 21:57
  • $\begingroup$ Much better and more substantiated answer than the accepted one. $\endgroup$ – AtmosphericPrisonEscape Mar 6 '16 at 0:29
  • $\begingroup$ E=1/2 MV^2 actually, do not confuse kinetic energy with the mass-energy equivalence (E=MC^2). $\endgroup$ – Marandil Apr 27 '18 at 7:02
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Yes, lifting weights, wearing a weighted vest and doing cardio workouts would significantly reduce the effects of lower gravity. On the ISS this has been proven to be true but on the ISS weights have little effect because there is pretty much no gravity at all. On Mars if you had enough weight equal to a human body weight (e.g 90kg on earth, 3 times this in Mars) to carry around your bones and muscle would have to maintain an ability to carry a human Earth body. So almost all problems would be reduced. There may even be no problem at all they just don’t know yet. It’s never been tested so it's definitely going much better than the ISS and probably going to be less of a problem than we think. In fact it may be that a vest and some gym daily is enough to ward off all the issues.

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  • $\begingroup$ Weights may reduce some but not all effects of lower gravity. $\endgroup$ – Uwe Apr 27 '18 at 8:43

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