Toughness of the tunica

[Big Al]

1. Would be correct in my opinion because of the need of more force and time to achieve tunica expansion optimal enough for size increase. Once somebody was getting that expansion, the gains should come rolling in. I always took it if you're tunica was able to greatly expand, the cc's size would then follow. So the only limitation to one's size is the tunica, and genetics or both

Things that really work the tunica, heavy long girth sessions, pumping, clamping. Just my thoughts. I'm not saying this as fact, but just what I strongly believe.
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Ensuring that you are able to deliver more blood to your penis via stamina work should help balance this out

[Big Al]

The sentiment I'm getting (and please correct me if I'm wrong) is that there has to be some kind of trade off. All other things being equal- if your training is balanced and you're focusing on maximizing blood flow as well as concentrating on exercises that induce maximal tension, your tunicae should be expanding and getting stronger. Stronger is not always synonymous with more inflexible- that part should be noted as its something not ordinarily seen in inorganic materials (which the tunicae is often compared to)!

The same intense stretches that cause expansion should (when combined with the rest of your training) also be contributing to its strengthening.

Surely there are cases where some trainees' tunicae need targeted work, but a full assessment of the situation should be done to make sure that any other weak points in your development are addressed as well.

Now, in cases where you're trying to induce maximal expansion without focusing too much on increasing tensile strength, you'll likely want to engage in very light but sustained stretches (as in extender work). For those who have cross trained you'll note the very different effect that an extender has on your penis as compared to a brief, intense manual stretching or heavy hanging workout- where you encounter "high tension" generating mechanisms.