Thread: prolonged exposure to g forces

hi all! got a couple questions about how the body deals with g forces for long periods.

first - how long can a person tolerate -1G? (suspended upside down) assume normal health, untrained individual, not very fit


second - how long can that same person tolerate +3G? force is "towards toes" & "away from head"

just need a rough clue of times like 1 minute, 10 minutes, half hour, couple hours. cant find much on google aside from stuff about fighter pilots. a whole different ball game!


some background (if anyones interested) a buddy of mine works at a tiny (and I mean TINY) amusement park running the kamikaze ride - its like a massive fast looping swing
he gets in a couple hours before the park opens & he offered to take me on a really LONG spin on the ride. or should i say dared me LOL. the parks so small the owners dont mind.

this ride can hang you upside down indefinitely & at top speed spins at +3G. so i kinda want to know what my PHYSICAL limits are. how long can i safely spin non stop for & how long can i get hung upside down for? i dont care about comfort lol

thanx guys

What did you find when you Googled the question?

Originally Posted by Sealeaf

What did you find when you Googled the question?

not alot that answers my question. lots of links about pilots. not relevant - forces are much higher & time is much shorter.

another link says nasa tried to train civilians to survive +2G for 20 hours. wasn't successful!

nobody want to take a wild guess? i haven't got a clue what the limits are. any personal experiences & feelings would help!



heres my feelings. how do these numbers sound?

hanging upside down - no prob hanging upside down for 30 seconds. i guess i could do 5 minutes safe enough? 30 minutes sounds too long! what about 15 minutes? sounds within reach? i know its gonna be uncomfortable!

+3G - there are amusement rides that last a couple minutes at 3G. force cant be strong enough to force the blood out of the brain otherwise you would pass out immediately! i guess 30 minutes or more isn't gonna be a problem then?

Originally Posted by cody

first - how long can a person tolerate -1G? (suspended upside down) assume normal health, untrained individual, not very fit

Almost indefinitely although it would surely be pretty uncomfortable.

second - how long can that same person tolerate +3G? force is "towards toes" & "away from head"

Seated in a semi-reclined position? Again almost indefinitely. Standing? Not long; the limit there is your circulatory system's ability to pull blood out of your legs.

this ride can hang you upside down indefinitely & at top speed spins at +3G. so i kinda want to know what my PHYSICAL limits are. how long can i safely spin non stop for & how long can i get hung upside down for? i dont care about comfort lol

It will hang you upside down indefinitely and pull a constant +3G's? Those two don't add up. If it is occasional instances of both you can probably do it for hours without serious effects (other than things like nausea etc.) But in any case "stop the ride if I black out" would probably be good advice to give him.

Originally Posted by billvon

Almost indefinitely although it would surely be pretty uncomfortable.

wow. are you sure about that? that feeling when all the blood rushes to your head is pretty intense. seems like there would be some kinda physical limit there?if not then that's cool! i was thinking upside down would be the shortest time limit!

Seated in a semi-reclined position? Again almost indefinitely. Standing? Not long; the limit there is your circulatory system's ability to pull blood out of your legs.

i'll be seated, backs of the seats are pretty much vertical, not reclined at all. but my legs will be in the normal sitting position. would that be ok indefinitely?

It will hang you upside down indefinitely and pull a constant +3G's? Those two don't add up.

its under full manual control. the ride will either be looping at +3G, or stopped upside-down. how often it switches between the two is up to the ride operator.

i'm gonna suggest NOT switching between -1G and +3G too frequently. sounds like a bad idea with the blood pressure changes that could cause. so lets say 2 minutes between changes at minimum.

sounds like there isn't really a maximum time to worry about? like if the first half of the ride time was spent at +3G and the remaining time was spent hanging upside down, that would be no better or worse than switching between +3G and -1G every 2 minutes throughout the ride?

the ride can spin slower. +2G at the bottom and 0G at the top. that might be a way to get "relief time" if switching +3G and -1G is gonna be too physically demanding non stop. but i did agree to ride it "at full speed" so its gonna take some scientific limits to get my buddy to agree to slow it down LOL.

thanx billvon. its very helpful!