Can pull up exercise (at a younger age, say, before 15 years old) increase height? My guess is yes, since weight lifting could decrease height (Or that is another myth?) If yes, by how much?
Why do you think this? By what means? Doing a quick google search all that comes up are crackpot looking websites.
I don't know why either. You may have to provide a legitimate reference to where you got that idea.Now, I don't know why I'm comparing gravity with bone stretch.
That's cool! So why don't we lie down on the floor and stretch all our 4 limbs into 4 or 2 directions ?Hanging from either your arms or your feet does reverse the pressure on the inter-vertebral disks (the compression pressure has now become an expansion pressure), and so it makes sense that it will increase your height. However, this increase is likely to be very marginal at best, my guess is on the order of a millimeter or so in the time frame that pull-ups are usually done for (a few minutes at most).
The end result is that you will have an expansion pressure on your inter-vertebral disks for a few minutes, no pressure on the disks for the 8 hours a day you are lying down, and regular compression pressure for the other 16 hours.
So no, doing pull-ups won't make you taller, and frankly doing weights won't make you shorter either using similar logic. Any height change from any exercise is likely to be from spinal injury or curving, and not from anything else. Certainly there is no way that the length of anyone's bones will change, in the absence of a bad break.