For years, I've always played around doing fartlek training and never pushed myself to run fast (7-min/miles is fast for me) for more than one mile.
Today, I decided to run 7-min/miles for as long as possible. At mile 1.8, I felt good but my quads completely shut down. I had to start walking. To my absolute shock, after about 1-minute I was able start running again (but a much slower 10-min/mile pace which I can run at for several miles with no problems).
Can you really clear enough lactic acid in just 1-minutes out of quadriceps to go from just being able to walk to being able to run again? That does surprise me. Or, maybe something else is happening to make my quads tap-out. The issue is simply my quads are not strong enough to support my body weight which builds up the lactic acid, right? My quads don't "hurt", somehow I just know/sense they cannot absorb any more impact.