Why is the pee-pee dance so effective?

Asked by AstroChuck (37609) December 9th, 2009 from iPhone

Much of the day here it has been in the upper 30’s, which is pretty damn cold for Sacramento. As many of you know I carry the US mail, and due to the cold I’ve had to hit the restroom a little more frequently than usual on my route today. Most of my route is walking and at one point, not long before a bathroom break, I came up to this apartment cluster box, where I just stand and drop the mail inside. As soon as I stopped to open the box I realized just how badly I needed to evacuate my bladder. Now I don’t want to dance around and look silly so I just kind of rocked back and forth from my left foot to my right and vice versa in order to squelch some of the urgency while standing there. Anyway, afterwards I went on my merry way and was okay for the next few minutes as I was back to walking. Shortly afterwards I came to the business on my route where I can do my business. And that is just what I did. During this heavenly emission I began wondering why moving around seems to relieve some of the discomfort of a full bladder, whether doing the full blown pee-pee dance or just walking.
So, now that I’m empty for the time being, I ask you why this is.