The role of smooth muscle tissue

Hi all,
I haven’t found much on the forums regarding the smooth muscle tissue surrounding the base of the tunica (have I got this right?). I’ve been interested in the role this plays in our PE efforts, and particularly in it’s response to trauma.

A few months ago I became fed up with fluid retention and ED caused by jelqing and around the waist all day stretching. However, I didn’t experience the effects to the same degree when performing regular horse 440’s. I’m guessing that the smooth muscle tissue plays a significant part in this.

Can anyone offer any thoughts?