Well I banged up both my knees, by hitting the ground while pulling Yoshi out of an altercation that he caused. My knees are pretty bruised, but I don't thing that anything horrible has happened to them. Though my climbing pants have a hole in the knee now (grrrr.)
So given that I rode a recumbent exercise bike for an hour instead of running. Did a hill course mostly at level 7 and dropped down to level 6 at the end. Pulse rate was around 115-120 but at times I could push is up to 130-135.