At times when my bladder is so full that it hurts (i.e. when I wake up in the morning, after a night of being too lazy to get up to pee), my pee comes out so slowly that I literally have to bear down and push it out. Sometimes it won’t all come out until I get off the toilet, walk around a bit, and then return to the toilet ten minutes later. It’s been happening my whole life.
Does anybody else experience this and/or known what causes it?
I’ve noticed the same problem sometimes. I’m not an anatomy expert, but from what I understand there are two sets of muscles involved in bladder and bowel control. One set in consciously controlled; it’s what you consciously relax to go to the bathroom (or conversely, tighten to “hold it in”). The other set is controlled unconsciously by reflex, and is what keeps you from wetting your bed or otherwise letting go accidentally*.
So; my speculation is that for whatever reason the unconscious set of muscles in such incidents has “decided” it’s not time to urinate and is still trying to hold it in. Perhaps they are somewhat stuck in the “clench shut” mode after a long period of holding it in.
*I heard this (possibly here) in context of “why do you suddenly need to ‘go’ much worse when you are almost but not quite in the bathroom.” The answer given was that the unconscious muscle set lets go, leaving your conscious set to do all the work. The opposite side of the coin from your problem.
The bladder is a muscle. When it’s dilated and stretched out for lengthy periods, its tone is not very good; it can’t contract strongly. That’s why folks pass some urine slowly and stop, dribbling as they go. Then if they rest for a few minutes, they can pass a lot more, more strongly, as the bladder regains tone.
The problem is exacerbated in older men by benign prostatic hypertrophy, which puts a cork in the neck of the bottle as it were.
This is all a gross simplification, and the real picture is more involved.
True, but it doesn’t just happen in older men. I’m 46 and have been dealing with BPH for the last 5-6 years.
Depends on your definition of “older”. 
I’m 43, and for about 5 years I thought I was dealing with BPH. First urologist only did an ultrasound and determined that, while I didn’t have an enlarged prostate, I had a “tight” one. He said sometimes it acts like a clamp, which made sense. I took uroxatral daily and this gave me some relief.
Just this past summer I went to a 2nd urologist for another opinion. He asked me undergo a cystoscopy. I agreed since he made it sound pretty routine. He performed it under general anesthesia and took a couple if bladder biopsies. It ended up being torture for about a month, with me urinating big blood clots for about a month.
But in retrospect, I’m glad I did it. He said that my prostate is open and my symptoms are due to some inflamation (cystosis) in the bladder. He asked to me to take Bactrim for 60 days. It didn’t really help. I still take the uroxatral daily since it still helps with the symptoms. But I know that I don’t have BPH.
Sorry for the hijack but I just wanted to inform other younger men who have been diagnosed with BPH to seek another opinion. The 2nd doc flat out said that there no way I had BPH as soon as he met me. The subsequent cytoscopy confirmed this.