What causes girth gains?

[Loggerhead]

So what exactly is taking place that causes the girth gains? Is it the extreme blood pressurization or is it the friction, squeezing and rolling effect of exercises such as is caused during a jelq session? Or is it both?

[ebon00]

Basically it's expanding the layers of the tunica beyond their normal range enough times for the to adapt to that new stress. The tunica is just fibrous tissue kind of like ligaments (and almost exactly like the fascia covering your skeletal muscles) and it can be stretched with proper stimulus.