Today my coach had us do 10x1000 at 2:55 with 90 seconds rest in the morning followed by 8x800 at 2:15 with 70 seconds rest in the afternoon. It was the hardest day I've ever done. My last 4 800s weren't even sub 2:20. I don't read about training, so I'm wondering if this workout was too hard and what the benefits of two sessions in one day like this is?
I'm a 5k runner with a PR of 14:32 if that helps.