When exercise helps with exhaustion

I managed to quite thoroughly overload the muscles in my thighs. Partly from Laser Game and partly from dance class. After both activities I had a shower and massaged out the muscles. Imagine my surprise the next morning when I felt pain the moment I bent my leg... Every step was accompanied by a strong pull just above the knee, and after sitting for a while things didn't improve. Massaging it out didn't help. Hot shower didn't help. Warming gel didn't help. What did? Krav Maga training! I could still really feel it before the session... afterwards I could run like a deer. Don't ask me how... I don't understand it myself. But I'm glad.