Yesterday I went to the track and did a series of short intervals. Here is the workout:

5 x 100 meters, 200, 400, 600, 400, 200, 100, 100, 200, 300, 400, 300, 200, 100. 3800 meters total.

My pace was 21 seconds per 100 meters to 18 seconds per 100 meters.

My times for the last descending set were 400 - 1:19, 300 - 1:00, 200 - 0:37, 100 - 0:18.