Ran quarters at the track. Times were 1:48, 1:37, 1:32, 1:31, 1:37 and 1:44. Then did two laps in 3:58.

I noticed on the quarters my knees felt really good. Thought at first it was the more forgiving track surface. But then on the half mile while running slower I felt it very slightly in my knees. In retrospect with the faster running I was using the muscles in the front of my legs to keep the balls up and let my heel strike first but then have a controlled roll onto the balls. With the slower running I quit doing this and had a far less controlled, less smooth kind of landing that felt like breaking, landed more flat footed instead of rolling from my heels to the balls.

Basically when running faster I simply had to use a better form. Which did take a bit of energy. With the slower running it's like I relax too much perhaps and get a bit floppy. Maybe. In the past my fastest running was even worse on my knees but back then perhaps I just didn't even have the muscles to manage a smooth run. Anyway, hope to run more and more quarters in the future.