What are the physiological effects of too much g-force? © Getty Images

What are the physiological effects of too much g-force?

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Don't let all those Gs go to your head...

Asked by: Adhuay Rao, by email


It depends on the direction. An upwards acceleration of about 5g is enough to overwhelm the ability of your heart to pump blood to your brain. This causes oxygen starvation and you will black out within a few seconds.

Downward, or negative, g-force is even worse. The blood pools in your head, your face swells up and your lower eyelids are forced over your eyes. This is called ‘redout’ because all you see is the light shining through your eyelids. At negative 3g, the blood can’t get back to your lungs to re-oxygenate, so you pass out.

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luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.


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