Im hoping that although Im a total noob to Penis Enlargement youll read this because I know some stuff about whats involved (its part of my degree - I have to know what it should look like, what a diseased stuff looks like and how to make it better - and how its function changes in the above states - Okay its in animals but were nothing but mammals etc.) so Ill have a go..
and Im really sorry its so long, but "knowledge is power" etc.
Well.. the penis is made of smooth muscle among other things.. It's a little bit like skeletal muscle (biceps etc.) - because it contains the same molecules - but it is arranged much differently, is not excited by neuronal stimulation and contracts slightly differently.
Briefly: If weightlifiting the increase in muscle size is due to lifting heavier
weights which causes the following:
The number of sarcomeres increases, and the distance between M-line and Z-disk decreases. So you pack more muscle into the space you orignially have by making things more compact and shoving more in. (Think a line of beer cans - if you do weightlifting - you crush all these cans into shorter ones and add more shorter ones on the end to keep the line of cans the same length - but there would be many more cans in the line after crushing them)
Picture of structure of skeletal muscle to help explination:
http://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Sarcomere.svg/775px-Sarcomere.svg.png
Now for the penis:
Ive looked at a few articles on google about smooth muscle growth - and what a surprise.. not much is known.
But there is some interesting information about how they have grown vascular smooth muscle (whats in the cock) which was under constant mecanical stress for 48 hours. And in 48hours there was an overall 40% increase in the number of cells.
This was done on glass plates though and isnt specific to penis tissue (though it is the same)
There was probably also a selection of growth factors (hormones) specifically for the promotion of the growth of this tissue.
As for the other tissues in the penis:
If you (for some reason) really really badly wanted to do the splits it would be wise to take it slow to avoid injury.
If you were really commited 20minutes a day of stretches and eventually you would get there. (I understand that the anaolgy uses tendons instead of ligaments but the difference is not massive, apart from in the above analogy there would also be a level of skeletal muscle stretch which would make it easier)
So taking the above information - for growth of smooth muscle I think it is not -as- required to take a break for more than 24 hours in comparioson to the other cell types down there.
(Note: cell death was not measured in the study)
But for all the other tissues in the penis - I would say may need a bit more time to adjust to the stresses. A break to avoid damage. (Think skiiers or super-obese (is that what its termed?) people that over do it and damage their cruciate ligament.
So, If it hurts then stop doing it (obviously!) proliferation rates can be quite remarkable, the body is well designed to adjust to stess. If the stretches are heavy you'll need more time for the cells to proliferate and heal compared to light stretches,
I personally think you could find a level at which you stretch everything and only need the hours from sleep to recover which would give you the best gains. - No breaks and working to your maximum level. (I feel the same for bodybuilding - and am experimenting at this moment with both Penis Enlargement and bodybuilding)
I would suggest the older guys here took more breaks though because they are at more risk of ligament damage... and Its supposed to be very painful.
That took ages.
And I await people to disagree with me.
But I hope that because I went into depth (sortve) I give somone with more knowlege an Idea.
WW10