[ukulele]

> Staying in a seated position for too long allows gravity to pull more blood down into the pelvis

I could concede that more blood might end up in the pelvis, but surely this is not the reason?

[coldtea]

Why "surely"?

[ukulele]

Because the torso is upright either way, and gravity doesn't care if you're sitting or standing

[coldtea]

Gravity does the pulling, and sure the blocking is caused by the lack of movement and the sitting position that obstructs the free flow of blood.

I guess we could say it's not the gravity itself, and it would be correct, but also like saying it's not the bullet that kills you, it's the hole.

[javagram]

Gravity pulls blood down, your circulatory system works to more evenly distribute the blood but is impaired when sitting.

The same phenomenon is observed when sitting on an airplane for a long time resulting in slightly enlarged feet due to blood distribution.

[ukulele]

So then wouldn't the mechanism be that less blood is able to flow upward due to pressure on the skin?

[VygmraMGVl]

Blood flows in veins due to contractions of surrounding muscle. When you're sitting, your lower body is largely relaxed, which causes blood to pool in your lower body. It's a serious (acute) issue in people who are bedridden for long periods of time. I suppose the article is suggesting there's a downside to chronic, low grade exposure as well.