I hit the track this morning for a 5x1000m workout. I was shooting for 5K race pace, which should have been about 4:43 for each 1000m, but I ended up hitting much lower than that. My first 1000m was 3:56 and let me say I am far from a sub 20 min 5K. Needless to say the rest of the repeats were much slower in 4:15, 4:16, 4:26 and 4:30. It was pretty hard, but you don't get faster by running slow.