Being an experienced masturbater ;) I can tell you this:

> With all this blood and constant irritation of the nerves in my penis, will this eventually cause my penis to grow more sensitive or less sensitive?

* I venture to say that what happens depends upon how you go about stimulating your penis during one of your sessions; for example, if you stimulate your penis just enough to maintain an erection and thus the pleasant sensations of it being erect then this is not enough to harm the nerves.

If you stimulate your penis with the intent of enjoying multiple orgasms during a session, then eventually your penis will become less reactive and require more effort to bring about each succeeding climaxes. Eventually, your body will refuse to respond for several hours and no amount of stroking, rubbing, or playing will bring about another orgasm in the string. Depending upon your age and how you are "wired", you may be able to enjoy three, four, or if really young--even more orgasms before your body says "ENOUGH ALREADY".

In order to fully recharge you system, you will probably have to wait about 72 hours. This does not mean that you cannot enjoy an orgasm sooner, only that these will be weaker than normal. The problem now becomes one of management. Do you want to wait a couple of days in order to have a strong climax--or, do you need to relieve pent up stress sooner than later?

* Extended and vigorous stroking often will result in one or more friction burns on the shaft. These are small spots in which the skin has been rubbed raw. Each is somewhat painful, yet the discomfort is stimulating in and of itself when rubbed. The problem is that you want to continue to endure the discomfort in order to derive the pleasure. The result is that if you do, you will most likely keep rubbing the scab off.

* Use a lubricant along with a light grazing of the skin along the shaft. You will receive stronger sensations without the tight grasp normally used.

> Almost every time i touch myself i do it for an extended period of time (hours) where I maintain an erection for that time through stimulating myself.

I think every guy at one time or another has enjoyed extended sessions. What worries me about you is that you state that you do this "almost every time". Don't you have a "life"? I recommend learning to manage the "need" with the "desire", particularly so that you can take care of the need when the need arises and not be able to because your pleasures have temporarily exhausted your body's ability to respond.

Question: Why do you spend hours at this? Is it simply to enjoy the feelings derived from having an erect penis and also stroking it? Is it to enjoy multiple orgasms? Personally, when I spent lots of time doing this, it was to enjoy multiple orgasms and not just to keep my penis hard and erect. (BTW, I hope you are not keeping it erect for more than four hours as warned in the Viagra ads.)

No, nothing bad will happen permanently to the sensitive nerve endings along the shaft or around the glans. As noted, above, if you stroke your penis to excess, either vigorously or duration, you may end up with one or more tiny friction burns that will take several days to heal. Secondly, if you strive to enjoy multiple orgasms during one session, each successive one will be harder to trigger than the previous ones--and at some point your body will simply refuse to respond for several hours.

I hope this is of help. Got questions?