a) that you fell
b) that I missed this because two blocks out of my house my quad when twang and I decided that running up and down hills fast might not be a great idea. These days are always so fun, though.
Ouch! But clearly you were trying hard, if you can catch yourself you're not going fast enough for speed work, right?
I was jogging down the hill. Had had a good 4 minutes of recovery at that point... just not paying any attention, and paid for that.