When I was in physical therapy before, when I was done with the exercises the therapist would have you lie on your back and she would look for "sore spots" as she called them and she would take her tiny hand (she was a little thing) and she would press on certain spots and send you through the roof. When you would groan from the pain, she would ask if you could stand it for 10 more seconds. And you know, within 10 seconds of her pressing on that spot, the pain was gone. I'm guessing that she was pushing on or manipulating some kind of nerve.